NZ219435A - Production of glucoamylase by recombinant techniques - Google Patents

Description

© >'Fl, BI9Q7 * A 0 F IV f_ 3 Pricrity Da;e(s): "t^&.. ia-.>2.&3 Complete Specification Filed: ^). .1 Class: ,C>3«a^.,.Q^D6l0D C01HCU.j.O+ ?1943S Publication Date: P.O. Journal. Nr: f 8 JAN 1988 » I • I r< I • r f « < >•50 D Under tin provisions o* Rogu^ l&cion 23 (I) the . . » Q fitofl/fc Specification has been ante-dated: 3.1 ,..?f?.*1 to XMiL initials —I ~Jj NEW ZEALAND Divided from: No-. 207000 Date: 31 January 1984 PATENTS ACT. 1953 COMPLETE SPECIFICATION "PROCESS FOR PRODUCING GLUCOAMYLASE" XI/We, CETUS CORPORATION, a corporation organized and existing under the laws of the State of Delaware, United States of America, of 1400 Fifty-third Street, Emeryville, California 94608, United States of America, hereby declare the invention for which we pray that a patent may be granted to ooe(/us, and the method by which it is to be performed, to be particularly described in and by the following statement:- (followed by page -la-) 'v. 2 194 3 PROCESS FOR PRODUCING GLUCOAMYLASE REFERENCES: The following publications are referred to by corresponding number in this application: 1. Lineback, et al., Cereal Chemistry, 49:283 (1972). la. Svensson, et al., Carlsberg Res. Commun., 47:55 (1982). 5 lb. Svensson, et al., Abstract IV-27, Xlth International Carbohydrate Symposium, Vancouver, British Columbia, Aug., 1982. lc. Botstein, et al., in The Molecular Biology of the Yeast Saccharo-nryces-Metabolism and Gene Expression, ed. by Stratherfi, et al. O (New York: Cold Spring Harbor Laboratory, 1982), p.607ff.

Id. Struhl, Nature, 305:391 (1983). * le. European Pat. Application 81303155.6 (Publication 45573 dated February 10, 1982) to Stanford University. 2. Chirgwln, et al., Biochem., 18:5294 (1979). 3. Sehgal, Methods in En^ymology, 79:111 (1981), at p. 117. 15 -^'4. Pelham, et al., Eur. J. Biochem., 67:247 (1976).

. Maniatis, et al., Molecular Cloning: A Laboratory Manual, publ., Cold Spring Harbor, N.Y. (1982), pp. 344-349. 6. Ivarie, et al., Anal. Biochem., 97:24 (1979). 7. Chang, et al., Nature, 275:617 (1978). 8. Doel, et al., Nucleic Acids Res., 4:3701 (1977). 9. Southern, J. Hoi. Biol., 98:503 (1975). ^ 10. Sanger, et al., Proc. Nat. Acad. Sci. USA, 74:5463 (1977). —- 11. Messing, et al., Nucleic Acid Res., 9:309 (1981). 12. Maxam, et al., Proc. Nat. Acad. Sci. USA, 74:560 (1977). 25 13. Mount, Nucl. Acids Res., 10:459 (1982). 14. Langford, et al., Proc. Natl. Acad. Sci. USA, 80:1496 (1983).

. Langford, et al., Cell, 33:519 (1983). ^ 16. Holland, et al., J. Biol. Chem., 256:1385 (1981). 16a. Sutcliffe , Cold Spring Harbor Symposium on Quantitative Bio-30 logy, 43: 77 (1978). ♦available on request - ' wmjuwH 2 J9 16b. Broach, et al., Gene, 8: 121 (1979). 16c. Beach, et al., Nature, 290: 140 (1981). 17a. Erllch, et al.. J. Biol. Chem., 254:12,240 (1979). 17b. Erllch, et al.. Inf. and Imm., 41:683 (1983). 18. Dewald, et al., 1n Methods in Enzyroology, Vol. XXXII, Blomem-branes, Part B, ed. by Fleischer et al. (New York: Academic Press, 1974), p.87-88.

BACKGROUND OF THE INVENTION The present Invention relates to a process for producing glucoamyl ase.

The techniques of genetic engineering have been successfully applied to the pharmaceutical industry, resulting in a number of novel products. Increasingly, 1t has become apparent that the same technologies can be applied on a larger scale to the production of enzymes of value to other industries. The benefits of achieving commercially jjseful processes through genetic engineering are expected to include: (1) cost savings in enzyme production, (2) production of enzymes in organisms generally recognized as safe which are more suitable for food products, and (3) specific genetic modifications at the DNA level to improve enzyme properties such as thermal stability and other performance characteristics.

One important industrial application of genetic engineering involves improving the ability of industrial yeast strains to degrade complex carbohydrate substrates such as starch. Yeasts such as Saccharomyces cerevisiae which are suitable for alcoholic fermentation do not produce an enzyme capable of hydrolyzing starch to utlUzable substrates. Currently, starch used as a food source 1n alcoholic fermentation uust be saccharified, either chemically or enzymatically, in a separate process to produce utilizable substrates for the fermenting yeast. 2 1 Q /T .■>" It would thus be desirable to construct, by genetic recombination methods, a fermentation yeast such as S. cerevisiae which itself has the capacity to synthesize one or more enzymes capable of breaking down starch to utilizable substrates. European Pat. Appln. 0,034,470 discloses preparing recombinant DNA containing an amylase encoding gene by cleaving a bacterial donor microorganism to obtain DNA and inserting those fragments 1n a vector. The amylase enzymes produced from the DNA which are used to hydrolyze starch are preferably alpha-amylase, beta-amylase or a pullulanase.

The reader's attention 1s directed to NZ. Patent Specification No. 207000 which is concerned with constructing a fermentation yeast which contains, 1n recombinant form, a gene coding for a glucoamylase which is active in hydrolyzlng starch at both alpha 1-4 and alpha 1-5 linkages to generate glucose.

The invention of NZ Patent Specification No. 207000 generally concerns the construction of a glucoamylase gene which can be introduced in recombinant form into a foreign host including but not limited to yeast or bacteria. Such host may also Include virus, plant or animal cells.

According to one aspect of the invention of NZ Patent Specification No. 207000, there is provided a modified DNA seauence coding for funqall glucoamylase protein or its single or multiple base substitutions, deletions, insertions or inversions, wherein said DNA sequence is derived from natural, i synthetic or semi-synthetic sources and is capable, when correctly combined with a cleaved expression vector, of expressing a non-native protein having glucoanylase enzyme activity upon transformation by the vector of a microorganism host. Most preferably the expression vector is the plasmid pACl described further hereinbelow which has been cleaved at Its HindiII site so that the sequence can be inserted at that site.

According to another aspect of the invention of NZ Patent i Specification 207000, it has been discovered that A^. awamori cells, when grown under conditions which induce glucoamylase, cpntain a relatively high concentration of ap- 219435 proximately 2.2 kilobase poly A RNA which is not detected in cells grown under noninducing conditions. The induced poly A RNA (mRNA) is capable of directing the synthesis. In a cell-free protein synthesizing system, of an unglycosylated polypeptide which has a molecular 5 weight of between about 70,000 and 74,000 daltons. The polypeptide produced is imnunologically reactive with antibodies prepared against A. awamori glucoamylase.

A radioactively labeled cDNA copy of the induced poly A RNA is produced which is used in hybridization studies to Identify A_. awamori genomic DNA fragments containing portions of the glucoamylase gene. The hybridization studies suggest that A. awamori contains a single glucoarrylase gene.

Similarly, the cDNA is used to identify phage or plasmid vectors containing such genomic DNA fragments in recombinant form.

The Identified cloning vectors may be used in determining gene polynucleotide sequences and sequence homology with the cDNA.

When a HindiII fragment containing the A. awamori gluco-anylase gene is inserted into yeast, neither transcription nor ^translation fn these heterologous hosts 1s detected.

The invention of NZ Patent Specification 207000 also provides for recombinant DNA expression vectors containing the DNA sequence. Preferably, the host to be transformed* by the"vectors is a selected foreign microorganism host, which permits expression of the gene, although the vectors may also be usec* transform homologous hosts or foreign yeast hosts. The exogenous gene which is' expressed may be genomic DNA, synthetic DNA or a cDNA obtained from a mRNA by use of reverse transcriptase.

* NZ Patent Specification 207000 also discloses a novel method for producing a glucomaylase gene containing the appropriate DINA sequence which generally includes producing genomic digest fragments, providing a glucoamylase probe, using the probe to Identify genomic digest fragments containing glucoamylase gene regions, aolecularly cloning the identified genomic digest fragments, nolecularly cloning partial cDNA, sequencing the genomic and cDNA clones, comparing the sequenced glucoantylase gene regions with all or a portion of the amino acid sequence of the mature glucoamylase enzyme to determine the existence and location of all the introns and exons 21943a 1n the genomic clones, and constructing a gene whose codon sequence fs substantially Identical to that of the genomic glucoamylase gene when the sequences comprising the introns are deleted.

In a preferred embodiment of the method, the glucoamylase probe is provided by selecting a fungal source capable of producing a level of glucoantylase, when grown on starch, which is at least about ten times that produced by the fungal species when grown on xylose or glycerol 1n the absence of starch, culturing cells of the selected fungus under conditions which induce secretion of glucoamylase into the culture medium, obtaining mRNA from the cultured cells, fractionating the mRNA obtained according to size, selecting an mRNA which is detectable as having a relatively high concentration with respect to the equivalent-sized mRNA produced by cells of the selected fungal species cultured under conditions which do not induce secretion of glucoamylase into the culture medium, and copying the selected mRNA to produce the glucoamylase probe.

In yet another embodiment of the Invention of NZ Patent Specification 207000 is provided a host organism transformed with a DNA expression vector comprising a promoter fragment that functions in that host and a DNA segment having a modified DNA sequence coding for fungal glucoamylase protein, the ffNA segment being in an orientation with the promoter fragment such that in the host it 1s expressed to produce a non-native glucoamylase protein.

The gene herein, when expressed 1n a host organism transformed by an expression vector comprising the gene, produces an enzyme having glucoamylase activity. Preferably the glucoamylase enzyme is produced as a preprotein with a signal sequence at its N^-terminus which Is processed by the host organism during secretion.

The reader's attention is also directed to New Zealand Patent Specification No. 219946 which relates to a process for producing glucose by saccharification of starch using a recombinant glucoamylase gene.

The invention of NZ Patent Specification ito. 219946 al so relates to a process "for producing ethanol by simultaneous saccharification and fermentation which comprises growing, on a nonfermentable carbon source ■■■■■ 2 19 4 "K c — <o ' .•»? ,^ r which Is a substrate for glucoamylase enzyme, a host organism transformed by the DNA expression vector described above. The carbon source is preferably starch, soluble starch, maltose or Isomaltose.

It is an object of this Invention to provide a process for producing a glucoamylase which at least provides the public with a useful choice.

Accordingly, in one embodiment, the invention may broadly be said to consist in a process for secreting a glucoamylase extracellularly which comprises growing a host organism in a culture medium, which host is transformed by a DNA expression vector comprising a promoter fragment which functions in the host organism, a signal sequence having substantially the following amino acid sequencer MET SER PHE AUG SER LEU LEU ALA LEU SER GLY LEU VAL CYS THR GLY LEU ALA ASN VAL ILE SER LYS ARG and a DNA segment which codes for the glucoamylase.

The vector may or may not contain a DMA segment which functions as an origin of replication, a selectable marker or a transcription terminator seg-rment.

In a further embodiment, the invention consists in a process for producing glucoamylase characterized by growing a host organism in a culture medium, which host is transformed by a DNA expression vector containing a promoter fragment which functions in said host organism and a DNA segment having a modified DNA sequence, said modified DNA sequence characterized in that it codes for fungal glucoamylase protein or its single or multiple base substitutions, deletions, insertions, or inversions, it is derived from natural, synthetic or semi-synthetic sources, and each is capable when correctly combined with a cleaved expression vector, of expressing a non-native protein having glucoamylase enzyme (l,4-°e-D-glucan glucohydrolase (EC 3.2.1.3)) activity, the DNA segment being in an orientation with the promoter fragment such that in the host it is expressed to produce a non-native glucoamylase enzyme. 2 t94 3 5 In the Invention herein, the glucoamylase enzyme obtained when the heterologous gene is expressed in yeast is found to be glycosylated. In addition, a significant portion (e.g., greater than 90S) of the glucoamylase Is secreted in the media. Also, when the N-terrainus of the non-native glucoamylase protein secreted in the media (having a purity of greater than 855) was sequenced, the first 29 amino acids were found to be identical to the mature glucoamylase protein secreted by Aspergillus. TJie apparent molecular weight as determined by SOS polyacrylamide gel electrophoresis of the glucoamylase protein obtained herein 1s similar to that observed for the mature processed and glycosylated form of the native glucoamylase secreted by Aspergillus. Further, the carboxy terminal amino acid is Identical to that of the large molecular weight form of glucoamylase produced by Aspergillus. • s. 2 1943s BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 represents gel electrophoretic patterns showing In vitro translation of k. awamori mRNA from cells grown in medium containing xylose or starch as carbon source. Translation products were Inmunoprecipitated using rabbit anti-glucoamylase antibody (lane 1, xylose-grown cells; lane 3, starch-grown cells) or normal rabbit antibody (lane 2, xylose-grown cells; lane 4, starch-grown cells).

FIGURES 2A and 2B represent gel electrophoretic patterns Identifying glucoamylase wRNA. In FIG. 2A, poly A-containing mRNA from cells grown in medium containing starch (lane 1) or xylose (lane 2) was analyzed by MeHgOH-agarose gel electrophoresis. Human and E_. coll ribosomal RNAs provide molecular weight markers. The /I. awamori ribosomal RNAs are indicated as '28S' and "18S'. The major 'Induced' mRNA (arrow) was isolated from the gel and used to direct in vltro translation. In FIG. 2B, total translation products of reactions containing no exogenous mRNA (lane 1) or the isolated major 'induced' wRNA (lane 2) are shown. Immunoprecipitation of protein 'products In lane 2, using rabbit anti-glucoamylase antibody, is shown in lane 3.

FIGURE 3 shows a restriction endonuclease map of _A. awamori genome surrounding the glucoamylase gene. The entire structural gene Is contained within the 3.4 kilobase EcoRI fragment isolated from the Charon 4A library. The protein-encoding regions of the glucoamylase gene are indicated as solid boxes and the arrow indicates the direction and extent of transcription.

FIGURE 4 shows gel electrophoretic patterns where pGARl is used to hybridize to, and select, glucoamylase mRNA. Total A. awamori nRNA (lane 1) and nftNA Isolated by virtue of hybridization to pGARl DMA (lane 2) was translated in vitro and the protein products are displayed. Protein products of lane 2 are inmunoprecipitated using rabbit anti-glucoamylase antibody (lane 3) or normal rabbit antibody (lane 4). -<•7 2 1943 FIGURE 5 illustrates primer extension to determine 5' termini of glucoamylase mRNA and the sequence which was determined. The products of primer extension at 42'C (lane 1) and 50SC (lane 2) are displayed on a sequencing gel In parallel with ml3/dideoxynucleo-5 tide sequencing reactions of this region, utilizing the identical 15-»er primer. The sequence presented represents the glucoamylase mRNA sequence and is complementary to that read from the sequencing reactions shown.

FIGURE 6 illustrates a restriction nap of the EcoRI fragment 10 containing the genomic glucoamylase gene, where the shaded boxes under the sequence represent the exors or coding regions of the glucoamylase gene and the arrow represents the direction of iirtNA transcription.

FIGURE 7 Illustrates a plasmid map for pGC21.

FIGURE 8 illustrates a plasmid map for pGAC9.

FIGURE 9 Illustrates plate assays for degradation of Baker's starch by various transformed yeast strains. The strains given below were streaked on minimal media containing histidine at 40 mg/1 and 2% ^.w/v Baker's starch. After 12 days incubation at 30°C the plates were stained with iodine vapors. The starch was stained purple, and the 20 clear zones represent regions in which the starch has been hydrolyzed.

Area Plate of Plate Yeast Plasmid 1 a C468 pACI t> C458 pGAC9 c C468 pGC21 d C468 pGC21 2 a C468 pACI b C468 pGAC9 c C468 pGAC9 d C468 pGAC9 3 a H18 pACI b H18 pGAC9 c C303 d H18 pGAC9 *C303 strain fs S. diastaticus.

- *C~-> 219435 FIGURE 10 shows DEAE-Sepharose chromatography of glucoamylase produced by the recombinant yeast In a 10-liter fermentor.

FIGURE II shows gel electrophoretic patterns of: BioRad High Molecular Height Protein Standards (lane 1), 25 yg _A. awamori 5 glucoamylase-I (lane 2 and 5), 25 ng A. awamori glucoamylase-II (lane 3 and 6), and 25 ^g recombinant glucoamylase (lane 4 and 7). Lanes 1- 4 were stained with Coomassie Blue stain and lanes 5-7 with Periodic Acid Schlff's stain.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following terms used in the description are defined below: 0* "DNA sequence" refers to a linear array of nucleotides connected one to the other by phosphodlester bonds between the 3" and 5' carbons of adjacent pentoses.

"Modified DNA sequence" refers to a DNA sequence which is 15 altered from the native glucoamylase DNA sequence such as by removing _,the introns from or modifying the Introns of the native sequence. The examples illustrate sequences which are free of introns. Sequences substantially free of introns means greater than 80% free.

"Glucoamylase enzyme activity* refers to the amount in units/liter 20 by which the enzyme in contact with an aqueous slurry of starch or starch hydrolysate degrades starch to glucose molecules.

"Single or multiple base substitutions and deletions, inser-(jjp tions and inversions" of the basic modified DNA sequence refer to degeneracy in the DNA sequence where the codons may be mutated or the 25 deoxyribonucleotides may be derivatized to contain different bases or other elements, but the DNA sequence thus altered is still capable, on transformation in a host, of expressing protein with glucoamylase enzyme activity.

"Fungal glucoamylase protein" refers to protein which is not derived from a bacterial source, but rather from a fungal source such 30 as a strain from the genus Aspergillus. Thus, a modified DNA sequence 2 19435 -u -*to- codlng for fungal glucoamylase protein signifies that the DNA 1s not derived from a bacterial donor microorganism.

'Non-native glucoamylase protein" refers to glucoamylase protein not produced naturally or natively by the microorganism used as the host.

"Nonfermentable carbon source which Is a substrate for glucoamylase* refers to substrates for the glucoamylase enzyme which the host cannot ferment, such as starch, maltose, isomaltose and other starch derived oligosaccharides. Cellulose 1s not a substrate for glucoamylase and thus Is not contemplated in this definition.

In one aspect, the present invention relates to the use of a modified DNA sequence and an expression vector into which the gene has been introduced by recombinant DNA techniques, which, when transformed in a host organism, expresses glucoamylase. The modified DMA sequence may be derived from ■ a natural, synthetic or semi-synthetic source. Preferably it Is derived from a selected native fungal source which produces an induced level of glucoamylase which is at least about ten times Its uninduced level. The Induced level is that which is produced by the fungal "'species when grown on starch as a sole or primary carbon source, and the uninduced level, that observed when the fungal species is grown on glycerol or xylose.

The selected fungus for producing glucoamylase 1s suitably cultured under glucoamylase-induction conditions and a poly A RNA fraction from the cultured cells is isolated and size fractionated to reveal a glucoamylase mRNA present in a detectably higher concentration than in artNA from uninduced cells. A glucoamylase cDNA is produced by copying the mRNA, using a reverse transcriptase.

A preferred DNA sequence contemplated 1s the sequence coding for the fungal glucoamylase (amylo-glucosldase) from filamentous fungi, preferably a species of the class Ascomycetes, preferably the filamentous Ascomycetes, more preferably from an Aspergillus species, and most preferably Aspergillus awamori. The native enzyme obtained from these sources 1s active In breaking down high molecular weight starch, and 1s able to hydrolyze C -t 2- 2 194 3 5 alpha 1-6 branch linkages as well as alpha 1-4 chain linkages. Relatively high levels of the enzyme are produced and secreted in A. awamori cultures grown on starch and a variety of 6-carbon sugars, such as glucose.

Although the Invention will be described with particular reference to K_. awamori as a source of tlie DNA sequence, it 1s recognized that the invention applies to other fungal species which have an Inducible glucoamylase, preferably species of the Aspergillus gents. In particular, k. awamori glucoamylase appears to be similar, if rot 10 Identical, to Aspergillus niger glucoamylase, as will be seen below.

The fungal species A. awamori was selected for detailed study. This fungal species, when grown on starch as a sole or primary carbon source, produces an amount of glucoamylase in the culture medium, based on measurable enzyme activity per cell dry weight, which 15 1s about 200 times that of cells grown on xylose or glycerol.

A. awamori, when grown on starch, produces and secretes at least two physically distinguishable glucoamylase enzymes. One of ^,these enzymes, referred to as glucoamylase-I, has a molecular weight of about 74,900 daltons, as reported in Reference 1, and 1s glycosyl-20 4.ted at some or all of the peptide serine and threonine residues. A second enzyme, glucoamylase-11, has a molecular weight of about 54,300 daltons, as reported in Reference 1, and 1s also glycosylated. It is noted that the sizes of the glycosylated glucoamylase protein given herein are only approximate, because glycoproteins are difficult to 25 characterize precisely.

Several lines of evidence suggest that the two_A. awamori glucoamylase enzymes are derived from a cciimon polypeptide. Antibodies prepared against each enzyme form react imnunospecifically with the other form, as will be seen below. The two enzymes have Identical 30 amino acid sequences In N-terminal fragments containing about 30 amino acids each. Further, these N-terminal sequences are fdentical to those 1n glucoamylase I and II forms from Aspergillus niger, and the two A. niger glucoamylase forms appear to be derived from a common polypeptide, as reported 1n Reference la. Experiments performed in 2 19 4 3 -»r5* ~*2- support of the present application, discussed below, indicate that a single A. awamori glucoamylase gene codes for a single glucoamylase polypeptide precursor, which Is very similar, if not Identical, to that produced by _A. niger.

According to one aspect of the invention, 1t has been discovered that cells of a selected fungal species, when grown under conditions which induce the secretion of glucoamylase into the culture medium, contain poly A RNA which is essentially undetectable in cells grown under noninducing conditions. The poly A RNA is capable of directing the synthesis, in a cell-free protein synthesizing system, of a polypeptide which is immunologically reactive with antibodies prepared against the glucoamylase from that fungal species.

Because the gene Is not expressed 1n yeast hosts with its Intact regulatory elements, it is necessary to delete or modify the Introns and to exchange promoters so that the yeast will transcribe the gene, translate the mRNA, and produce an active glucoamylase.

The introns may be removed from the glucoamylase gene either J* methods known In the literature for removing introns or by the simpler method described in section B of Example 2 below using Specific restriction enzymes in various steps to create fragments which are then 1igated together and using site-directed mutagenesis.

In the mutagenesis technique the 5'-most intron of the glucoamylase gene is removed using a primer which is homologous to sequences on both sides of the intron and annealing this primer to a single-stranded DNA template of the glucoamylase genomic clone. The primer 1s then used to prime DNA synthesis of the complementary strand by extension of the primer on an H13 single-stranded phage DNA template. The resulting molecules were double-stranded circular molecules with single-stranded loops containing the intron sequence. When the molecules are transformed Into cells, these loops may be excised, thereby removing the Intron, but even without excision DNA replication will generate the correct progeny. If the introns are present in the gene, little or no glucoamylase enzyme is produced In a yeast In which the gene Is expressed. — 2 1913s After the Introns have been removed therefrom, the glucoamylase gene may be Inserted by genetic recombination into a DNA expression vector, preferably a plasmid, which may then be used to transform a microorganism host. Suitable microorganisms for this purpose include bacteria such as JE. coli, viruses and yeasts. The microorganism host useful 1n this present Invention must contain the appropriate genetic background for transformation thereof, I.e., the expression vector Is compatible with the genetic background of the host strain. For example, the host recipient yeast strains C468 and H18, which are haploldj^. cerevisiae laboratory strains employed 1n the following examples Illustrating yeast hosts, are deficient in p-Isopropylmalate dehydrogenase activity and therefore are complemented to leucine prototrophy by Inserting Into the expression vector the selectable marker p-tsopropylmalate dehydrogenase (LEU 2). While the expression vector Bay by itself be capable of phenotypic selection by containing a selectable marker, it need not be so capable because the host can be screened or selected for the glucoamylase gene.

The preferred bacterial host herein 1s_E_. coli. The preferred yeast host strain herein 1s from a species of the genus Saccharomyces, preferably cerevisiae, S_. uvarum, S_. carlsbergensis, Or mixtures or mutants thereof, more preferably a S_. cerevfslae strain, and most preferably yeast strain C468 described further here-inbelow.

DNA expression or DNA transfer vectors suitable for transfer and replication have been described, e.g., in References lc and Id.

Many of the yeast vectors 1n present use are derived from E.coli vectors such as pBR322. These references, lc and Id in particular, describe Integrative transformation where the microorganism host is transformed with vectors with no origin of replication that integrate into the hsot chroaosome and are maintained and replicated as part of that chromosome. In another embodiment of this invention the host may be transformed by autonomous replication where the vectors contain DNA j; segments which serve as origins of DNA replication in the host cell. I f Vectors containing autonomously replicating segments are also described in Reference le. Preferably the DNA segment capable of * 9 -IS~ -M- 2 1943 functioning as an origin of replication Is from yeast. Two types of such origins of replication from yeast are: one derived from a naturally occurring yeast plasmid, commonly referred to as the 2 micron circle, which confers the ability to replicate independently of 5 yeast chromosomal DNA, and one derived from the yeast chromosomal replication origin containing a replication origin sequence termed ars (autonomous replication sequence), which also provides autonomous replication capability. r in x' The expression vector/of this invention necessarily contains a promoter fragment which functions in aicroorganfsms, i.e., the host being employed, as well as the modified DNA sequence coding for the fungal glucoamylase protein. The protein-encoding segment must be so O oriented with the promoter fragment that In a microorganism host 1t is expressed to produce non-native glucoamylase. For bacteria such as _E. 15 coli a trp promoter 1s preferred. For yeast, a yeast promoter fragment 1s preferred. Among possible yeast promoter fragments for purposes herein are included, e.g., alcohol dehydrogenase (ADH-I), 3-phosphoglycerokinase (PGK), pyruvate kinase (PKK), triose phosphate ^•isomerase (TPI), beta-Isopropylmalate dehydrogenase (LEU2), glycer-20 aldehyde 3-phosphate dehydrogenase (TDH), enolase I (EN01), and the Like. A preferred promoter fragment for purposes herein is from the enolase I gene.

The expression vector herein also preferably contains a microorganism transcription terminator segment following the segment 25 coding for the protein, 1n a direction of transcription of the coding segment. Examples of possible transcription segments include the 3' """ segments of the above-listed genes. A preferred transcription termi nator segment 1s from the enolase I gene. , A preferred host system consists of the ^S. cerevisiae yeast 30 host strain C468 transformed by the plasmid pGAC9. This preferred transformed yeast strain was deposited with the American Type Culture Collection (ATCC), 12301 Parklawn Drive, Rockville, MD 20852 on November 17, 1983 and assigned ATCC Deposit Number 20,690. Another preferred host system consists of the Z. coli host strain MH70 trans- 11 11. m i leiwwyNi^'f imr"/'1 r > i» '»"■> ;, ... i 2 19435 formed by trie plasmid pGC24, which transformant was deposited with the ATCC on December 16, 1983, and assigned ATCC Deposit Number 39,537.

The A. awamori glucoamylase signal sequence described below is shown to function in yeast for the efficient processing and secre-5 tion of glucoamylase from yeast. This sequence could also be used for the secretion of other proteins from yeast and preferably for the secretion of proteins that are normally secreted by their native ^ host. Examples of such proteins Include amylases, cellulases, prote ases, interferons, lymphoidnes, Insulin, and hormones.

The following examples serve to exemplify the practice of the invention. They are presented for Illustrative purposes only, and should not be construed as limiting the Invention in any way. Percentages are by weight unless specified otherwise. All experiments were performed following the NIH (U.S.A.) guidelines for containment.

EXAMPLES All of the strains employed in the examples which have been ^deposited in depositories were deposited either with the U.S. Department of Agriculture Agricultural Research Service, National Regional Besearch Laboratories (NRRL) of Peoria, IL 61604 or with the American Type Culture Collection (ATCC) of RocJcville, MD 20852. Each strain 20 deposited with ATCC has the individual ATCC designations indicated in the examples pursuant to a contract between the ATCC and the assignee of this patent application, Cetus Corporation. The contract with ATCC provides for permanent availability of the progeny of these strains to the public on the Issuance of the U.S. patent describing and identi-25 fying the deposits or the publications or upon the laying open to the public of any U.S. or foreign patent application, whichever comes first, and for availability of the progeny of these strains to one determined by the U.S. Commissioner of Patents and Trademarks to be entitled thereto according to 35 U.S.C. 122 and the Commissioner's 30 rules pursuant thereto (including 37 CFR 1.14 with particular reference to 886 OG 638). The assignee of the present application has agreed that If any of these strains on deposit should die or be lost -*£ 2 19 ■*. 3 5 o or destroyed when cultivated under suitable conditions, it will be promptly replaced on notification with a viable culture of the same strain. The NRRL deposits mentioned in the examples and not designated patent deposits have been freely available to the public prior to the filing date of this application. In the examples all parts and percentages are given by weight and all temperatures in degrees Celsius unless otherwise rioted.

EXAMPLE 1 Determination of Nucleotide Sequence of Glucoamylase Gene Experimentally, A. awamori cells were grown on either starch or xylose, as a primary source of carbon. The A. awamori cells were obtained from NRRL, Deposit Number 3112, and have been recently re- deposited and assigned NRRL Deposit Number 15271. Aspergillus awamori _ cells, available from NRRL, are described in the book by Thorn and Raper, i entitled A Manual of the Aspergilli (Baltimore, The Williams and Wilkins 1 Co., 1945). Fungal growth was initiated from a suspension of spores in I crater. The fungal cells were grown in an agitated culture at 30°C for 2-5 days in a standard growth medium (1% w/v yeast extract, 0.01 M ammonium sulfate, 0.025 M potassium phosphate buffer, pH 7.0) together with 5% w/v of either starch or xylose. As noted above, cells grown on starch produced an amount of glucoamylase in the culture medium, based on measurable enzyme activity per cell dry weight, that was about 200 times that of cells grown on xylose.

Total cellular RNA was isolated from the fungal cultures by a guanidium thiocyanate/CsCl procedure essentially as described in — Reference 2. Briefly, mycelia were wrung dry in cheese-cloth, frozen in liquid nitrogen, and ground to a powder in a mortar and pestle in liquid nitrogen. The cell powder was homogenized in a guanidium thio-cyanate solution containing 20 mM adenosine: V0SC4 complex. Following centrifugation to pellet cellular debris, CsCl was added to the homog- — enate and the RNA was pelleted through a pad of CsCl by a high speed centrifugation.

Poly A containing RNA (poly A RNA) was isolated from total RNA by two passages over oligo-dT cellulose, conventionally, and the poly A RNA was size-fractionated by agarose gel electrophoresis, according to standard procedures.

The Induced pol,y A RNA was extracted from the agarose gel essentially as described in Reference 3. Briefly, the gel was melted and then frozen to release the RNA Into solution. The solidified agarose was removed by centrifugation. The extracted poly A RNA was extracted with phenol and precipitated with ethanol.

To examine the translation products of the induced poly A RNA in a cell-free protein synthesizing system, antibodies against A. awamori glucoamylase were prepared. Glucoamylase-I and II f rom A_. awamori were obtained from the filtrate of a culture of_A. awamori cells grown under glucoamylase induction conditions. The filtrate was fractionated by ion exchange chromatography using a diethyl aminoethyl-cellulose column. Elution with a pH gradient ranging from pH 8.0 to pH 3.0 yielded two protein peaks that showed glucoamylase activity. The enzyme that eluted at the lower pH included the larger glucoamylase-I, and the other peak, glucoamylase-!I. Gel electrophoresis Indicated that glucoamylase-II was pure, but that gluccamylase-I was ' not. Glucoamylase-I was purified further by molecular sieve chromatography on a cross-linked dextran, Sepharcryl S-200 column. Two 'peaks were observed, one of them containing glucoamylase-I, which was shown to be pure. For both enzyme forms, enzyme purity was established by polyacrylamide gel electrophoresis under non-detergent conditions, and by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE).

The two purified glucoamylase forms were used separately to raise anti-glucoamylase antibodies 1n rabbits. Each of the two 1ninunoglobul1n G(IgG) antibody fractions produced were able to neutralize the glucoamylase activity of both glucoamylase forms. Further, Ouchterlony analysis of the two antibody fractions with the two enzyme forms indicated that each antibody reacts immunospecifically with both enzyme forms.

Poly A RNA from induced and noninduced A^. awamori was used to direct the synthesis of radioactive-methionine-labeled polypeptides ft ^ 9 *" 2 194 55 In a rabbit reticulocyte lysate kit obtained from New England NucTear Co., Boston, Mass., and sold as Reticulocyte Lysate/Methionine L-[^S]-Translat1on System. References 4 and 5 describe typical reticulocyte lysate systems. After a defined reaction period, aliquots of 5 the lysate were removed and analyzed, either before or after reaction with anti-glucoamylase antibody or normal rabbit iimnunoglobulin G <IgG), by SDS-PAGE. The immunoresctive products were precipitated essentially according to the method described in Reference 6.

O determine the molecular basis for the accumulation of glucoamylase protein In starch-grown, but not xylose-grown, cultures of £. awamori, glucoamylase mRNA levels were examined. Total cellular mRNA was Isolated and used to direct the synthesis of A. awamori protein 1n a rabbit reticulocyte lysate system. The translation products were inmunoprecipitated using rabbit anti-glucoamylase antibody 15 (lane 1, xylose-grown cells; lane 3, starch-grown cells) or normal rabbit antibody (lane 2, xylose-grown cells; lane 4, starch-grown cells). The results are shown 1n FIG.1 and demonstrate the presence Cf translatable glucoamylase mRNA in RNA from starch-grown cells. In -tontrast, no glucoamylase mRNA was detected in xylose-grown cells.

This correlates with the 200-fold difference in glucoamylase protein observed in culture supernatants of these cells. Thus, the accumulation of glucoamylase protein in starch-grown cultures appears to result from a comparable increase 1n translatable glucoamylase mRMA.

MeHgOH-agarose gel electrophoresis of mRNA from starch-grown 25 cells revealed a major approximately 2.2 kilobase mRNA (indicated by an arrow), which was absent in mRNA from xylose-grown cells (FIG. 2A). It appeared likely that this predominant 'induced' mRNA represented the mRMA of the highly expressed, 'induced' glucoamylase. To identify the 'induced' mRNA, the approximately 2.2-30 kilobase sttNA band was eluted from a gel and translated 1n the rabbit reticulocyte lysate system. Immunop red pi tatlon of the protein product with rabbit anti-glucoamylase antibody demonstrated the presence of mRNA encoding glucoamylase within the approximately 2.2-kilobase 'induced' mRNA band (FIG. 2B). 2 1943 -1_C ' ~vr- According to one aspect of the invention, Isolated glucoamylase mRNA from the selected fungal species was used to produce a glucoamylase cDNA by reverse transcription of the mRNA. Experimentally, induced poly A RNA from^. awamori was pretreated with 10 nW HeHgOH to denature the RNA, and then introduced into a reaction containing oligo-dT as a primer and 2 nW adenosine: VOSO4 as an RNAse Inhibitor. The reader 1s referred to Reference 7 for a discussion of this general technique. Following cDNA synthesis, the poly A RNA was destroyed by treatment with NaOH. The synthesized cDNA was size fractionated by gel electrophoresis to separate the full-length cDNA from incompletely formed fragments. A typical gel electrophoretic pattern of the cONA fraction showed a single detectable band in the approximately 2.2 kilobase size region.

The Induced glucoamylase mRNA and the cONA produced therefrom were radiolabeled to provide probes for identifying genomic DNA fragments containing all or portions of the homologous glucoamylase gene. The cDNA »ay be labeled readily by performing its synthesis in the presence of radiolabeled nucleotides.

The basic method used for radiolabeling mRNA is discussed in Reference 8. In one example, Induced poly A RNA from A. awamori was — 1 M ■ —1 partially degraded, using sodium hydroxide to generate fragments containing 5'-OH groups. These fragments were subsequently phosphorylated with radioactive-phosphate (^P)-ATP using a poly- 32 nucleotide kinase. The P-labeled RNA fragments span the entire length of the Isolated RNA, and are thus advantageous for use as probes for genomic DNA fragments containing end portions of the glucoamylase gene.

Total genomic DNA isolated from A. awamori was digested to completion with each of a number of restriction endonucleases. The fragments were size-fractionated by gel electrophoresis and hybridized to one of the above RNA or cDNA probes by the Southern blot method (Reference 9). Details of this method are found generally by Reference 5, at page 387. Briefly, a prehybridization step was performed at 42°C for 24 hours, using a five-times concentrate of standard * _-2« - -£' 2 *9«3 saline citrate (0.15M sodium chloride, 0.0I5M trlsodium citrate).

This was followed by a hybridization step carried out at 42°C for 24 hours, using a two-times concentrate of the standard saline citrate. In the studies involving A. awamori genomic DNA, several of 5 the endonucleases used—Including Hindlll, Xhol, Bell, and Pvul— generated only one fragment which hybridized to the above_A. awamori labeled RNA or cONA probes. Some of the single gene fragments are in the same size range as the RNA transcript, strongly Indicating that JL awamori contains only one gene which codes for the glucoamylase poly-10 peptide. EcoRI generated a 3.4 kilobase fragment which hybridized to the labeled cDNA.

The A. awamori genomic DNA fragments produced by digestion with EcoRI were spliced, by conventional techniques, Into a lambda Charon 4A phage vector. The library of EcoRI fragments were screened 15 for recombinants which hybridized to the A_. awamori glucoamylase cDNA. Hybridizing plaques were purified, and all contained a common 3.4 kilobase EcoRI fragment which hybridized to the glucoamylase cDNA probe. This 3.4 kilobase EcoRI fragment was then subcloned into the ^ EcoRI site of a pACYC184 plasmid {ATCC Deposit No. 37,033), producing 20 a recombinant plasmid which is designated herein as pGARl. A sample of E. coli K12 strain MM294 transformed with pGARl was deposited in the American Type Culture Collection, 12301 Parklawn Drive, Rockville, MD 20852, USA on December 2, 1983, and has been assigned ATCC Number 39,527. Subsequent libraries were screened using pGARl as probe. 25 Approximately 20 kllobases of A. awamori genomic DNA surrounding the glucoamylase gene was Isolated from EcoRI, Hind!11 and BglII libraries. A composite restriction map of this 20 kilobase region is shown 1n FIG. 3; the EcoRI fragment insert is expanded. The locations of the cleavage sites of the designated restriction endonucleases were 30 determined by digesting the plasniids with selected combinations of the endonucleases, and size-fractionating the fragments obtained, according to known methods. The five solid rectangles represent sequenced protein-encoding regions of the glucoamylase gene. The direction of transcription of the nrtNA Is Indicated by the 5' to 3' line. 0 ■ >-- 2 * o 1 ^5 The plasmid pGARl was confirmed to contain glucoamylase gene sequences by virtue of Its ability to hybridize to and select^. awamori glucoamylase mRNA sequences. pGARl DNA was immobilized onto nitrocellulose and hybridized to total A. awamori mRNA. The selected 5 mRNA was translated in vitro, and the products were identified by Immunoprecipitatlon with rabbit anti-glucoamylase antibody. The results, shown in FIGURE 4, confirm the Identification of pGARl, and thus of the approximately 2.2 kilobase "induced" mRNA, as encoding ^ glucoamylase. In FIGURE 4 total A. awamori mRNA (lane 1) and mRNA Isolated by virtue of hybridization to pGARl DNA (lane 2) was translated _1n.^itro^ and the protein products are displayed. Protein products of lane 2 were inmunoprecipitated using rabbit ant1glucoamylase antibody (lane 3) or normal rabbit antibody (lane 4).

Subclone pGARl containing the K. awamori glucoamylase gere 15 was digested substantially to completion with various restriction enzymes whose sequences are included within the EcoRI fragment (i.e., those 1n FIGURE 6), and several of the fragments were subcloned into M13 vectors M13mp8 and M13mp9. These bacteriophage vectors are avail-able from Bethesda Research Laboratories, P.O. Box 6009, Gaithersburg, 20 MD 20877.

The fragments of the glucoamylase genomic region subcloned Into the vectors M13mp8 and N13mp9 were sequenced by the dideoxy-nucleotide chain termination method described in References 10 and 11. Portions of the sequence" were confirmed by the Haxam-Gilbert 25 sequencing technique (Reference 12). The entire sequence of the 3.4 kilobase EcoRI fragment is shown 1n Table I below.

TABLE I GAATTCAAGC TAGATGCTAA GCGATATTGC ATGGCAATAT GTGTTGATGC 50 ATGTGCTTCT TCCTTCAGCT TCCCCTCGTG CAGATGAAGG TTTGGCTATA 100 AATTSAAGTG GTTGGTCGGG GTTCCGTGAG GGGCTGAAGT GCTTCCTCCC 150 TTTTAGACGC AACTGAGAGC CTGAGCTTCA TCCCCAGCAT CATTACACCT 200 CAGCA ATG TCG TTC CGA TCT CTA CTC GCC CTG AGC GGC CTC 6TC 244 •- ■*-W. .„.. (. ,My^f 2 * *r* ? 2T ' ■ ■■> MET SER PHE ARG SER LEU LEU ALA LEU SER GLY LEU VAL -12 TGC CYS ACA THR GGG TTG GLY LEU GCA ALA AAT ASN GTG VAL AH TCC ILE SER AAG LYS CGC GCG ARG Ala ACC Thr TTG GAT Leu Asp 289 4 TCA Ser TGG Trp TTG AGC Leu Ser AAC Asn GAA Glu GCG Ala ACC GTG Thr Val GCT Ala CGT ACT Arg Thr GCC Ala ATC CTG He Leu 334 19 AAT Asn AAC Asn ATC GGG He Gly GCG Ala GAC Asp GGT Gly GCT TGG Ala Trp GTG Val TCG GGC Ser Gly GCG Ala GAC TCT Asp Ser 379 34 GGC Gly ATT He GTC GTT Val Val GCT Ala AGT Ser CCC Pro AGC ACG Ser Thr GAT Asp AAC CCG Asn Pro GAC Asp T 419 47 gtatgtttcg agctcagatt tagtatgagt gtgtcattga ttgattgatg 469 ctgactggcg tgtcgtttgt tgtag AC TTC Tyr Phe TAC Tyr ACC TGG Thr Trp ACT Thr CGC GAC . Arg Asp 517 55 TCT Ser GGT Gly CTC GTC Leu Val CTC Leu AAG Lys ACC Thr CTC GTC Leu Val GAT Asp CTC TTC Leu Phe CGA Arg AAT GGA Asn Gly 562 70 GAT Asp ACC Thr AGT CTC Ser Leu CTC Leu TCC Ser ACC Thr ATT GAG He Glu AAC Asn TAC ATC Tyr He TCC Ser GCC CAG Ala Gin 607 85 GCA Ala ATT lie GTC CAG Val Gin GGT Gly ATC He AGT Ser AAC CCC Asn Pro TCT Ser GGT GAT Gly Asp CTG Leu TCC AGC Ser Ser 652 100 GGC GCT Gly Ala GGT Gly CTC GGT Leu Gly GAA Glu CCC Pro AAG Lys TTC AAT Phe Asn GTC Val GAT GAG Asp G1u ACT Thr GCC TAC Ala Tyr 700 116 - ACT Thr GGT Gly TCT TGG Ser Trp GGA Gly CGG Arg CCG Pro CAG CGA Gin Arg GAT Asp GGT CCG Gly Pro GCT Ala CTG AGA Leu Arg 745 131 GCA Ala ACT Thr GCT ATG Ala Met ATC lie GGC Gly TTC Phe GGG CAA Gly Gin TGG Trp CTG err Leu Leu gtatgttctc 791-142 • cacccccttg cgtctgatct gtgacatatg tagctgactg gtcag GAC AAT 842 Asp Asn „ 145 GGC TAC ACC AGC ACC GCA ACG GAC ATT GTT TGG CCC CTC GTT AGG 837 Gly Tyr Thr Ser Thr Ala Thr Asp lie Val Trp Pro Leu Val Arg 160 AAC GAC CTG TCG TAT GTG GCT CAA TAC TGG AAC CAG ACA GGA TAT 932 Asn Asp Leu Ser Tyr Val Ala Gin Tyr Trp Asn Gin Thr Gly Tyr 175 G gtgtgtttgt tttattttaa atttccaaag atgcgccagc agagctaacc 933 cgcgatcgca g AT CTC TGG GAA GAA GTC AAT GGC TCG TCT TTC 1026 Asp Leu Trp Glu Glu Val Asn Gly Ser Ser Phe 186 - i W ^ ■"■/ ' ■ ..v. ,; y - Z," j~zf- 2 19 4 3 5 TTT Phe ACG Thr ATT 6CT He Ala GTG CAA CAC CGC Val Gin His Arg GCC Ala cn Leu GTC GAA GGT AGT Val Glu Gly Ser GCC Ala 1071 201 TTC Phe GCG Ala ACG GCC Thr Ala GTC GGC TCG TCC Val Gly Ser Ser TGC cys TCC Ser TGG TGT GAT TCT Trp Cys Asp Ser CAG Gin 1116 216 GCA Ala CCC Pro GAA ATT Glu lie CTC TGC TAC CTG Leu Cys Tyr Leu CAG Gin TCC Ser TTC TGG ACC GGC Phe Trp Thr Gly AGC Ser 1161 231 TTC Phe An lie CTG GCC Leu Ala AAC TTC GAT AGC Asn Phe Asp Ser AGC Ser CGT Arg TCC GGC AAG GAC Ser Glv' Lys Asp GCA Ala 1206 246 AAC Asn ACC THr CTC CTG Leu Leu GGA AGC ATC CAC Gly Ser He His ACC Thr ITT Phe GAT CCT GAG GCC Asp Pro Glu Ala GCA Ala 1251 261 TGC Cys GAC Asp GAC TCC Asp Ser ACC TTC CAG CCC Thr Phe Gin Pro TGC Cys TCC Ser CCG CGC GCG CTC Pro Arg Ala Leu GCC Ala 1296 276 AAC Asn CAC His AAG GAG Lys Glu GTT GTA GAC TCT Val Val Asp Ser TTC Phe CGC Arg TCA ATC TAT ACC Ser lie Tyr Thr CTC Leu 1341 291 AAC Asn GAT Asp GGT CTC Gly Leu AGT GAC AGC GAG Ser Asp Ser Glu GCT Ala GTT Val GCG GTG GGT CGG Ala Val Gly Arg TAC Tyr 1386 306 CCT Pro GAG Glu GAC ACG Asp Thr TAC TAC AAC GGC Tyr Tyr Asn Gly AAC Asn CCG Pro TGG TTC CTG TGC Trp Phe Leu Cys ACC Thr 1431 321 TTG Leu GCT Al a GCC GCA Ala Ala GAG CAG TTG TAC G1u 61n Leu Tyr GAT Asp GCT Ala CTA TAC CAG TGG Leu Tyr Gin Trp GAC Asp 1476 336 - AAG lys CAG Gin GGG TCG Gly Ser TTG GAG GTC ACA Leu Glu Val Thr GAT Asp GTG Val TCG CTG GAC TTC Ser Leu Asp Phe TTC Phe 1521 351 AAG Lys GCA Ala CTG TAC Leu Tyr AGC GAT GCT GCT Ser Asp Ala Ala ACT Thr GGC Gly ACC TAC TCT TCG Thr Tyr Ser Ser TCC Ser 1566 366 AGT Ser TCG Ser ACT TAT Thr Tyr AGT AGC ATT GTA Ser Ser He Val SAT Asp GCC Al a GTG AAG ACT TTC Val Lys Thr Phe GCC Al a 1611 381 GAT Asp GGC Gly TTC GTC Phe Val TCT ATT GTG gtaagtctac gctagacaag cgctcatatt Ser He Val 1662 388 gacagagggt gcgtactaac agaagtag GAA ACT CAC GCC GCA AGC AAC Glu Thr His Ala Ala Ser Asn 1711 395 GGC Gly TCC ATG TCC Ser Met Ser GAG CAA TAC GAC Glu Gin Tyr Asp AAG Lys TCT GAT GGC GAG CAG Ser Asp Gly Glu Gin CTT Leu 1756 410 TCC Ser GCT CGC GAC Ala Arg Asp CTG ACC TGG TCT Leu Thr Trp Ser TAT Tyr GCT GCT CTG CTG ACC Ala Ala Leu Leu Thr GCC Ala 1801 425 AAC AAC CGT CGT AAC GTC GTG CCT TCC GCT TCT TGG GGC GAG ACC Asn Asn Arg Arg Asn Ser Val Val Pro Ala Ser Trp Gly Glu Thr 1846 ' 440 / •+ 3 11.k»P» :^"'*V -if* ' -Jt>- 2 ?943J TCT GCC AGC AGC GTG CCC GGC ACC TGT GCG GCC ACA TCT GCC ATT 1891 Ser Ala 5er Ser Val f>r() Gly ^ Cys Ala Ala ^ ^ Ala Ile 455 i GGT ACC TAC AGC AGT GTG ACT GTC ACC TCG TGG CCG AGT ATC GTG 1936 \ ; Gly Thr Tyr Ser Ser Va1 Thr Val Thr Ser Trp Pro Ser He Val 470 _! [ GCT ACT GGC GGC ACC ACT ACG ACG GCT ACC CCC ACT GGA TCC GGC 1981 Ala Thr Gly Gly Thr thr Thr Thr Ala Thr Pro Thr Gly Ser Gly 485 ) O 1°° ST? JfC ICG i£C *GC ACC SC6 ACT GCT AGC MG ACC 2026 } j Ser Val Tnr Ser Thr Ser Lys Thr Thr Ala Thr Ala Ser Lys Thr 500 AGC ACC AGT ACG TCA Yc* ACC TCC TGT ACC ACT CCC ACC GCC GTG 2071 '"r *r '"r Ser Thr Ser Cys Thr Thr Pro Thr Ala Val 515 S?T ST? J£T HC 6AT CTG ACA 601 ACC ACC MZ TAC GGC GAG AAC 2116 Ala ¥al Thr Phe AsP leu Thr Ala Thr Thr Thr Tyr Gly Glu Asn 530 ATC TAC CTG GTC GGA TCG ATC TCT CAG CTG GGT GAC TGG GAA ACC 2161 . lie Tyr Leu Val Gly $«r Ile ^ Gln Leu Gly tep Trp Glu Thr 545 AGC GAC GGC ATA GCT (£TG AGT GCT GAC AAG TAC ACT TCC AGC GAC 2206 *5 Ser Asp Gly lie Ala Ser Ala Asp Lys Tyr Thr Ser Ser Asp -560 CCG CTC TGG TAT GTC *CT GTG ACT CTG CCG GCT GGT GAG TCG TTT 2251 ~ Pro Leu Trp Tyr Val ^rhr Val Thr Leu Pro Ala Gly Glu Ser Phe 575 g ^ GAG TAC AAG TTT ATC £<£ ATT GAG AGC GAT GAC TCC GTG GAG TGG 2296 * Glu Tyr Lys Phe He *rg lie Glu Ser Asp Asp Ser Val Glu Trp 590 ! - GAG AGT GAT CCC AAC GAA TAC ACC GTT CCT CAG GCG TGC GGA 2341 Glu Ser Asp Pro Asn *rg S1l) Tyr p,,. Yal Pr0 Gln Ala Cys Gly 605 ACG TCG ACC GCG ACG (fcTG ACT GAC ACC TGG CGG TAGACAATCA . 2384 Thr Ser Thr Ala Thr fhr /^p -pjj. -jyp Arg 616 ATCCATTTCG CTATAGTTA* AGGATGGGGA TGAGGGCAAT TGGTTATATG 2434 ATCATGTATG TAGTGGGTG ^ 6C AT AAT AGT AGTGAAATGG AAGCCAAGTC 2484 ATGTGATTGT AATCGACCS* CGuAATTGAG GATATCCGGA AATACAGACA 2534 ' CCGTGAAAGC CATGGTCTT^ CCTTCGTGTA 6AAGACCAGA CAGACAGTCC 2584 .

CTGATTTACC CTSCACAAAt*: CACTAGAAAA TTAGCATTCC ATCCTTCTCT 2634 ~ GCTTGCTCTG CTGATATCAC; T5TCATTCAA TGCATAGCCA TGAGCTCATC 2684 TTAGATCCAA GCACGTAAT'- -CCATAGCCGA GGTCCACAGT GGAGCAGCAA 2734 CATTCCCCAT CATTGCTTTU; CCCAGGGGCC TCCCAACGAC TAAATCAAGA 2784 -z>- j»3«» GTATATCTC7 ACCGTCCAAT AGATCGTCTT TTCCAAGAGG GTCCCCATCC ATCAAACCCA CATGGTGGAG TCAATTAGGC AGTATTGCTG GGTGGTCATT GGCCGCCTGT GATGCCATCT ATCCACCGCC CACGAGGGCG TCTTTGCTTT ACTCTCTCTG CAGCTCCAGT CCAACGCTGA TCTGATCGGC TCCATCAGAG CTATGGCGTT AATCGCTATC TTGATCGCAA CCTT6AACTC CTTGGTGACG GAGTGTCGGT GAGTGACAAC TGATACGGAA TTGTCGCTCC CATCATGAT6 CCTATTCGTG GGATCGATGC CCTCCTGTGC 6AGGAGCCAT CGGTCTCTGC ACGCAAACCC GGATGATCAG GATCTCCGGA TGAATTC 2 19435 CGCTTCAAAA TCTTTGACAA 2834 GTTCAATAAT AGCCSAGATG 2884 GAATGTCGGG GCCAGTTCCG 2934 GCCACTAAAT CCGATCATTG 2984 TTGCGCGGCG TCCAGGTTCA 3034 CTGACTAGTT TACCTACTGG 3084 ATCCCGTGCC GTTGCTGCGC 3134 ACTCTTGTTT TAATAGTGAT 3184 CAACATCGTG CAAGGGAGAT 3234 TTCTTGCCGG CTTTGTTGGC 3284 AGCAGCAGGT ACTGCTGGAT 3334 AACTTCCTCT TCATTCTCAC 3384 3411 The nucleotide sequence obtained was compared, in a com- r'~ puter-programmed matching operation, with the regions of known amino acid sequence of k. niger (References la and lb) and A_. awamori. The hatching operation examined the nucleotide sequence in each of the six possible reading frames for codon correspondence with the given amino add sequence. Tlie matching operation produced nearly complete correspondence between coding regions of the glucoamylase gene and the regions of known amino acid sequence of glucoamylase from h. awamori. The amino acid sequence of one of the internal peptides of A* n^9er (Pig- 7 of Reference la) was found not to be contiguously encoded by the nucleic acid sequence (nucleotides 753-895 of Table I). An intervening sequence of 55 nucleotides was presumed to interrupt this protein coding region. The introns in the glucoamylase gene are in lower case. The amino acid sequence of the glucoamylase gene Is Indicated below the appropriate nucleotides and is numbered below the nucleotide sequence numbers at the right. Amino acids -24 to -1 (all capital letters) represent the signal sequence of the pre-glucoamylase protein.

• ,V|.. -y~*Pr 7^'':'"** "* '/ 219:3. «-26- ~ To confirm the identification of this Interrupting sequence as the intervening sequence, and to identify other intervening sequences within the glucoamylase gene, the cDNA sequences derived from glucoamylase mRNA were molecularly cloned. Double-stranded cDNA was prepared from mRNA of starch-grown A. awamori and a cDNA library was prepared in pBR322, also available from Bethesda Research Laboratories, as described above. Sixteen glucoamylase cDNA-containing plasniids were Identified using pGARl probe; the largest plasmid, p24A2, which was deposited with the national Regional Research Laboratory in Peoria, Illinois, USA on December 7, 1983 and assigned NRRL No. B-14217, contained 1.8 kilobases of sequence derived from the 3'-end of the approximately 2.2 kilobase glucoamylase nRNA. The nucleotide sequence of the glucoamylase cDNA in p24A2 was determined and found to span the genomic sequence, shown 1n Table I, from nucleotide 501 through the polyadenylation site at position 2489-2491. (The precise polyadenylation site cannot be determined unambiguously due to the presence of two A residues at nucleotides 2490-2491.3 Comparison of the nucleotide sequence of the molecularly cloned glucoamylase gene .with that of the glucoamylase mRNA, as determined from molecularly cloned glucoamylase cDNA, and with glucoamylase amino acid sequence, has revealed the presence of four intervening sequences (Introns) within the _A. awamori glucoamylase gene. (The junctions of the first intervening sequence were deduced from incomplete amino acid sequence data at residues 43-49 of A. awamori glucoamylase-I.) The intervening sequences were short (ranging from 55 to 75 base pairs) and were all located within protein-encoding sequences. These sequences adjoining the intervening sequence junctions of the glucoamylase gene were compared to consensus splice junction sequences from eucar^ctes in general (Reference 13) and from S. cerevisiae in particular (Reference 1*). Splice junctions within the glucoamylase gene conform closely to the consensus sequences at the 5' and 3* intervening sequence termini. Sequences related to the consensus sequence TACTAACA postulated by Langford, et al. in Reference 15 to be required for splicing in_S. cerevisiae are found near the 3' terminus of all glucoamylase intervening sequences. **. . -w+- C ; ' -,sr- 2 '1, ■? —27- ~ ' J The 5' end of the glucoamylase aRNA wis determined using a synthetic oligonucleotide to prime reverse transcriptase synthesis from the mRNA template. Four major primer extension products were synthesized using the pentadecamer 5'GCGAGTAGAGATCGG3' which is complementary to sequences within the signal peptide-encodlng region near the 5' end of the glucoamylase mRNA, as Indicated In FIGURE 5.

The shorter band of the doublets is Interpreted to represent the Incompletely extended form of the longer band. To examine possible effects of RNA secondary structures on this pattern, primer extension was preferred at 42 and 50*C. The products of primer extension at 42*C (lane 1) and 50*C (lane 2) are displayed on a sequencing gel described in Reference 16 in parallel with ml3/di-deo^ynucleotide sequencing reactions of this region, using the Identical pentadecamer primer. The sequence presented 1n FIGURE 5 represents the glucoamylase mRNA sequence and is complementary to that read from the sequencing reactions shown. The pattern of primer extension was unchanged, supporting the conclusion that four distinct 5* termini exist within the population of glucoamylase mRNA. Primer ^extension reactions performed 1n the presence of dideoxynucleotides confirmed the colinearity of genomic and nrtNA sequences in this -region. The primer extension products nap to T residues, at positions -71, -66, -59, and -52 from the site of translation initiation, and are indicated in Table I. To the extent that reverse transcriptase is able to copy the extreme terminal nuclectide(s) of the mRNA, the 5' termini of the glucoamylase mRMAs are localized to these four regions. DNA sequences 5' of the region of transcription initiation were found to contain sequences homologous to consensus sequences previously shown to be involved in transcription Initiation by RNA polymerase II.

Table 11A Illustrates the nucleotide sequence encoding the mature glucoamylase polypeptide.

A * 2f$ TABLE IIA GCG ACC TTG SAT TCA TGG TTG AGC AAC GAA GCG ACC GTG GCT CGT ACT CCC ATC CTG AAT AAC ATC GGG GCG GAC GGT GCT TGG GTG TCG GGC GCG GAC TCT GGC AH GTC GTT GCT AGT CCC AGC ACG GAT AAC CCG GAC TAC T7C TAC ACC TGG ACT CGC GAC TCT GGT CTC GTC CTC AAG ACC CTC GTC GAT CTC TTC CGA AAT GGA GAT ACC AGT CTC CTC TCC ACC AH GAG AAC TAC ATC TCC GCC CAG GCA ATT GTC CAG GGT ATC AGT AAC CCC TCT GGT GAT CTG TCC AGC GGC GCT GGT CTC GGT CCC AAG TTC AAT GTC GAT GAG ACT GCC TAC ACT GGT TCT TGG GGA CGG CCG CAG CGA GAT GGT CCG GCT CTA AGA GCA ACT GCT ATG ATC GGC FTC GGG CAA TGG CTG CTT GAC AAT GGC TAC ACC AGC ACC GCA ACG GAC ATT GT7 TGG CCC CTC GTT AGG AAC GAC CTG TCG TAT GTG GCT CAA TAC TGG AAC CAG ACA GGA TAT GAT CTC TGG GAA GAA GTC AAT GGC TCG TCT TTC TTT ACG AH GCT GTG CAA CAC CGC GCC CTT GTC GAA GGT AGT GCC TTC GCG ACG GCC GTC GGC TCG TCC TGC TCC TGG TGT GAT TCT CAG GCA CCC GAA ATT CTC TGC TAC CTG CAG TCC TTC TGC ACC GGC AGC TTC ATT CTG GCC AAC TTC GAT AGC AGC CGT TCC GGC AAG GAC GCA AAC ACC CTC CTG GGA AGC ATC CAC ACC TTT GAT CCT GAG GCC GCA TGC GAC GAC TCC ACC TTC CAG CCC TGC TCC CCG CGC GCG CTC GCC AAC CAC AAG GAG GTT GTA GAC TCT TTC CGC TCA ATC TAT ACC CTC AAC GAT GGT CTC AGT GAC AGC GAG GCT GTT GCG GTG GGT CGG TAC CCT GAG GAC ACG TAC TAC AAC GGC AAC CCG TGG TTC CTG TGC ACC TTG GCT GCC GCA GAG CAG TTG TAC GAT GCT CTA TAC CAG TGG GAC AAG CAG GGG TCG TTG GAG GTC ACA GAT GTG TCG CTG GAC TTC TTC AAG GCA CTG TAC AGC GAT GCT GCT ACT GGC ACC TAC TCT TCG TCC AGT TCG ACT TAT AGT AGC ATT GTA GAT GCC GTG AAG ACT TTC GCC GAT GGC TTC GTC TCT ATT GTG GAA ACT CAC / •V ' • urn JnniKWiiii. awiliww^Mp'WW**^ - ^=29- 2l?:Ss SCO GCA AGC AAC GGC TCC ATG TCC GAG CAA TAC GAC AAG TCT GAT GGC GAG CAG CTT TCC GCT CGC GAC CTG ACC TGG TCT TAT GCT GCT CTG CTG ACC GCC AAC AAC CGT CGT AAC GTC GTG CCT TCC GCT TCT TGG GGC GAG ACC TCT GCC AGC AGC GTG CCC GGC ACC TGT GCG GCC 5 ACA TCT GCC ATT GGT ACC TAC AGC AGT GTG ACT GTC ACC TCG TGG CCG AGT ATC GTG GCT ACT GGC GGC ACC ACT ACG ACG GCT ACC CCC ACT GGA TCC GGC AGC GTG ACC TCG ACC AGC AAG ACC ACC GCG ACT GCT AGC AAG ACC AGC ACC AGT ACG TCA TCA ACC TCC TGT ACC ACT 10 CCC ACC GCC GTG GCT GTG ACT TTC GAT CTG ACA GCT ACC ACC ACC TAC CGC GAG AAC ATC TAC CTG GTC GGA TCG ATC TCT CAG CTG GGT GAC TGG GAA ACC AGC GAC GGC ATA GCT CTG AGT GCT GAC AAG TAC ACT TCC AGC G/C CCG CTC TGG TAT GTC ACT GTG ACT CTG CCG GCT 15 GGT GAG TCG TTT GAG TAC AAG TTT ATC CGC ATT GAG AGC GAT GAC TCC GTG GAG TGG GAG AGT GAT CCC AAC CGA GAA TAC ACC GTT CCT CAG GCG TGC GGA ACG TCG ACC GCG ACG GTG ACT GAC ACC TGG CGG Nucleotides 206 to 277 encode the signal sequence for the k. awamori glucoamylase. As used in the specification and claims, the term "signal sequence" refers generally to a sequence of amino acids which are responsible for Initiating export of a protein chain. A signal sequence, once having initiated export of a growing protein 25 chain, is cleaved from the mature protein at a specific site. The term also includes leader sequences or leader peptides. The preferred signal sequence herein is the deduced signal sequence from the A_. awamori glucoanylase gene given in Table IIB.

V ^ 2 7 9 ■-*;■ j TABLE IIB MET SER PHE ARG SER LEU LEU ALA LEU SER GLY LEU VAL CYS THR GLY LEU ALA ASN VAL ILE SER LYS ARG EXAMPLE 2 Expression of Glucoamylase Gene In Yeast A. Construction of Hlndlll Cassette of Genomic Glucoamylase Gene A method for expressing genes at high levels in yeast involves constructing vectors which contain the yeast enolase I promoter and terminator regions (Reference 16). The enolase segments were previously engineered so that the promoter and terminator were separated by a unique Hindlll site.

Plasmid pACI (10.67 kilobase) is an E. coli/yeast shuttle ^.vector, capable of autonomous replication in both E. coli and yeast strains. The plasmid confers resistance 1n_E. coli and related species to the p-lactam antibiotic ampicillin and related compounds as a result of synthesis of the TEM type I p-lactamase. Further, the plasmid carries the yeast LEU2 gene which Is expressed in both col i and $_. cerevisiae strains. Thus, the presence of the plasmid in either JE. coli or cerevisiae strains reverses a leucine growth requirement resulting from loss of p-isopropylmalate dehydrogenase activity.

Plasmid pACI is comprised of the following DNA segments. Numbering starts at the EcoRI site of the enolase I promoter fragment and proceeds In a clockwise direction. Coordinates 0 to 725 comprise a 725 base pair EcoRI to HindiII DNA fragment derived from a similar fragment in the plasmid p eno 46 (Reference 16), containing DNA from the 5' untranslated region of the S. cerevisiae Enol gene. This fragment has been modified in the region just prior to the initiation codon (ATG) of the enolase gene in order to create a Hindi 11 site. - *30- J ~3i - 9 f o ^ ^ ' ' xJ Specifically, the sequence was changed from CACTAAATCAAAATG to CACGGTCGAGCAAGCTT(ATG). Coordinates 726 to 2281 comprise the 1.55 kilobase HindiII to Bglll DNA fragment from the 3' untranslated region of the S. cerevisiae Enol gene and was originally obtained from the plasmid peno 46 (Reference 16). Coordinates 2282 to 2557 comprise a 275 basepair DNA fragment from the plasmid pBR322 (Reference 16a) between the Banfll and Sail recognition sites (pBR322 coordinates 375 to 650). Coordinates 2558 to 4773 comprise the 2.22 kilobase Xhol to Sail DNA fragment from cerevisiae that encodes the LEU2 gene product, (Msopropylmalate dehydrogenase. The plasmid YEpl3 (Reference 16b) provided a convenient source for the desired 2215 basepair DNA fragment. Coordinates 4474 to 8528 comprise a 3.75 kilobase DNA fragment which permits autonomous replication of the plasmid AC1 1n yeast strains. This region encodes a portion of the yeast 2*i plasmid and was derived from the plasmid pDB248 (Reference 16c). Digestion of plasmid pDB248 with the enzymes EcoRI and Sail liberated the desired 3.75 kilobase DNA fragment incorporated in plasmid AC1. Coordinates 8529 to 10672 comprise DNA sequences which permit autonomous replication in E. coli host strains and confer ampicillin resistance. The desired 2143 basepair DNA fragment was obtained from E_. coli plasmid pBR322 as a Tthllll to EcoRI DNA "fragment (pBR322 coordinates 2213 and 4360, respectively). A sample of E_. coli K12 strain MM294 transformed with pACI was deposited in the American Type Culture Collection on December 2, 1983 and has been assigned ATCC No. 39,532.

The glucoamylase gene, while not having a convenient restriction site closely preceding its initiation codon (ATG) useful for cloning into vectors, can have a single base pair change 32 base pairs upstream from the ATG so as to create a unique HindiII site, allowing use of the enolase promoter for initiation of transcription. Site-specific mutagenesis was used to obtain the desired mutation. A hexa-decamer oligonucleotide which 1s complementary to the region surrounding the desired Hindlll site and which contains the appropriate mismatch was used to prime DNA synthesis on a single-stranded M13 template of the glucoamylase gene. The sequence of the primer MWHP&BS -*f 2 19 /} - The hexadecamer used for priming was kinased with labeled ^P-ATP to a specific activity of 3 x 10^ cpm/^g. Nitrocellulose filters were used to bind phage DNA from the plaques by direct lifting, and these filters were denatured, neutralized and washed. After baking for 2 hours at 80'C, the filters were prehybridized for 3 hours at 45°C in 25 nl of a solution of 9 M NaCl and 0.9 M sodium citrate, sodium dodecylsulfate, 50 ml of a solution of 0.5 g bovine serum albumin, 0.5 g Ficol 1 400 (a carbohydrate polymer) and 0.5 g poly vinyl pyrrolidine, and 50 pg/ml yeast RNA.

After prehybridization, 1.5 x 10® cpm/ml of kinased primer was added, and hybridization continued overnight at 45°C. The next day, filters ) employed was : 6AGCCGAAGCTTCATC. with the mismatches underlined. A second mismatch was incorporated into the primer to aid in the screening for correct clones by hybridizing candidate plaques with the same oligonucleotide used for the primer extension, after the latter had been radioactively labeled.

One picomole of a single stranded DNA phage, M13mp9 containing a 2.3 kilobase glucoamylase gene fragment (from EcoRI to Sail), was annealed to 10 picomoles of the primer in a 15 jil reaction mix which also contained 20 bM Tris pH 7.9, 20 dM MgCl2, 100 nM NaCl, and 20 nM p-mercaptoethanol. The mixture was heated to 67°c, incubated at 37"C for 30 minutes, then placed on ice.

To the above annealing mixture 1 ^1 of each deoxynucleotide triphosphate at 10 nW was added, to a final concentration of 500 ^xM. Five units of_E. coli Klenow fragment of DNA polymerase I (0.5 ^1) was then added and the extension reaction was left on ice for 30 minutes. Starting on ice minimizes 3*-5' exonuclease digestion of the primer and subsequent mismatch correction. After 30 minutes on ice, ^»the reaction was continued at 37°C for 2 hours, then inactivated by heating at 67°C for 10 minutes.

Note that the primer was not kinased and no ligase was used in contrast to other published methods. JM103 competent cells were transformed with 1 ^1 of the reaction and either 5 ^1 or 50 ^1 were plated. 2 19435 were washed 2 times, 5 minutes each in a solution of 9 M KaCT and 0.9 M sodium citrate at roughly 5*C (to remove non-speciflcally bound counts), then once at 45°C for 5 minutes (to remove probe hybridized to non-mutant phage DNA). Filters were air dried, put on Kodak XAR (high speed) film with an intensifying screen and exposed overnight at -70°C.

One nutant clone among several thousand plaques was discovered in the first round of screening. Subsequent restriction enzyme digests of this clone confirmed the Introduction of the Hindlll site In front of the glucoamylase gene.

In the next step a Hindlll site was created at the 3' end of the glucoamylase gene. A clone with the engineered Hindlll site near the 5' end of the gene was cut with Ncol, Its sticky ends were converted to blunt ends by enzymatic repair using Klenow fragment of _E_. coli DNA polymerase-1, and 1t was cut with EcoRI. FIGURE 7 illustrates a restriction map of this region. This nethod produced a fragment containing the glucoamylase gene and having an EcoRI sticky end before the 5' end of the gene and a blunt end after the 3' end of ^the gene. This fragment was cloned into a polylinker region of plasmid pUC8, available from Bethesda Research Laboratories, to place a Hindlll site within 20 nucleotides of the 3' end of the fragment so as to produce a Hindl11 cassette.

B. Construction of Full-Length cDNA Clone of Glucoamylase Gene Lacking Introns The longest cDNA clone produced and isolated which had regions homologous to the genomic clone of the glucoamylase gene, p24A2, corresponds in sequence to the genomic clone from nucleotides 501 to 2490, minus the nucleotides corresponding to introns indicated in lower case in Table I. This clone 1s still several hundred nucleotides shorter than necessary for a full-length cONA clone. The construction of a full-length cONA copy of the gene was accontplished In several steps. The genomic clone with the Hindlll site near the 5' end of the gene was cut with EcoRI and Avail and this fragment was 2 19 "35 -34"^ purified. The longest cONA clone described above was digested with Avail and PstI, and the small Avail to PstI fragment was purified. The phage vector M13mpll, available from P-L Biochemlcals, 1037 w. McKlnley Ave., Milwaukee, WI 53205, was digested with EcoRI and PstI. and the large vector fragment was purified from the small polylinker fragment. These three fragments were ligated together to generate a M13mpll vector containing the EcoRI and PstI region of the genomic clone, but now missing the second Intron.

The longest cDNA clone was then cut with PstI using con-10 ditions supplied by the manufacturer of the restriction enzyme and the large PstI fragment was Isolated. The M13sipll vector described above was cut with PstI, and the large PstI fragment from the cDNA clone was ligated Into this site. The clones generated from this ligation were screened to identify the clone with the PstI fragment inserted in the 15 correct orientation. The clone Isolated from this step had the genomic sequence from EcoRI to Avail (containing the first intron and the new 5' Hindi 11 site) and the cDNA sequence from Avail to the PstI site beyond the poly-A tail region. The remaining intron at the 5' ''end of the gene was removed by site-directed outagenesis using a 20 nonacosamer oligonucleotide to span the intron region. The nona-tosamer, which had homology to 15 base pairs on the 5' side of the intron and 14 base pairs on the 3' side, had the sequence: ' CGGATAACCCGGACTACTTCTACACCTGG 3' » In the procedure for conducting site-directed mutagenesis, one picomole of a single-stranded DNA phage derivative designated as M13mp9 (which is commercially available), containing a 2.3 kilobase glucoamylase gene fragment (from EcoRI to Sail), was annealed to 10 picomoles of primer In 15 p.1 containing 6 mm of tris(hydroxy-methyl)aminomethane (hereinafter Tris) at pH 7.9, 6 on MgCl2 and 30 100 nrt NaCl. The mixture was heated to 67°C, Incubated at 37°C for 30 minutes, and then placed on ice. At this ten^erature, either half of the nonacosomer can anneal to Its complement on the template without the other, allowing the proper loop to be formed.

-Jo---35- 219415 To the above annealing mixture 1 p.1 of each deoxynucleotide triphosphate at 10 nrt was added, to a final concentration of 500 ^M. Five units of J_. coli Klenow fragment of DNA polymerase I (0.5 ^1) was then added and the extension reaction was left on ice for 30 minutes to minimize 3*-5' exonuclease digestion of tlie primer. After 30 minutes on ice, the reaction was continued at 37°C for 2 hours, and then Inactivated by heating at 67°C for 10 minutes.

In the procedure employed herein the primer was not kinased and no Ugase was employed in contrast to other published methods. JM 103 competent cells were transformed with 1 pi of the reaction and either 5 ^1 or 50 ^1 were plated. (JM103 1s an E. coll strain distributed by Bethesda Research Laboratories, Inc., Saithersburg, MD 20877.) The nonacosamer used for priming was kinased with labeled ^P-ATP to a specific activity of 3 x 10^ cpm/^g. Nitrocellulose filters were employed to bind phage DNA from the plaques by direct lifting, and these filters were denatured, neutralized and washed. After baking for 2 hours at 80°C, the filters "'were prehybridized for 3 hours at 55°C 1n 25 nl of a solution of 9 M NaCl, 0.9 M sodium citrate, 0.1? sodium dodecyl sulfate, 50 ml of a solution containing 0.5 g bovine serum albumin, 0.5 g Ficol 1 400 (which 1s a carbohydrate polymer obtainable from Pharmacia Fine Chemicals) and 0.5 g polyvinylpyrrolidone, and finally 50 jig/ml yeast RNA. After prehybrldization, 1.5 x 10^ cpm/ml of kinased primer was added, and hybridization was continued overnight at 55°C.

The next day, the filters were washed two times for five minutes each in a solution of 9 M NaCl and 0.9 M sodium citrate at roughly 5°C (to remove non-specifically bound counts), and then once at 55°C for five minutes (to remove probe hybridized to non-mutant phage DNA). Filters were air-dried and placed on Kodak XAR (high speed) film with an Intensifying screen and exposed overnight at -70°C.

The frequency of positives recovered was about 4%. Positive candidate plaques were further examined by preparing mini-preps and atW> •it- digesting them to see if a size reduction occurred due to reuoval of the 75 base pair intron. Sequencing of one of the positives revealed that the intron had been precisely removed.

In the final step this plasmid vector was digested with 5 EcoRI and BamHI, and the fragment was purified and used to replace the EcoRI to BamHI fragment in the genomic Hindlll cassette vector described under section A above. The result is a cONA Hindlll cassette -~j. which will have the nonnal polyadenylation signal at the 3' end of the clone but lacks all four introns. c. Yeast Strains Transformed with Yeast Expression Vector The Intron-containing Hindlll cassette of the genomic glucoamylase gene as described in section A above was excised and inserted into a yeast expression vector plasmid pACI to produce a plasmid 15 designated as pGC21, the map of which is presented in FIG. 7. A sample of _E_. coli K12 strain KM2S4 transformed with pGC21 was deposited in the NRRL on December 7, 1983 and has been assigned NRRL No. B-14215. A sample of E. coli K12 strain MM294 transformed with pACI was deposited in the American Type Culture Collection on December 2, 1983 and has been assigned ATCC No. 39,532. The E. coli K12 MM294 strain transformed with the plasmids pGARl, pGC21 and pACI is from the family enterobacteriaceae. It differs from other E. coli strains, which are described by Bergey's Manual of Determinative "Bacteriology, 8th ed., pp 340-352, Williams and Wilkins, Baltimore, 1974, by the following: end Al, thi-1, hsd R17, supE44, Lambda". It is described by Meselson and Yuan (1968) Nature 217:1110. The cassette of full-length cDNA clone lacking introns as described in section B above was similarly excised and inserted into the vector pACI to produce a plasmid designated as pGAC9, the map of which is presented in FIG. 8. f* -37 A- 1 Plasmid DNAs pGC21 and p6AC9 were amplified In E. col I. purified on a cesium chloride gradient and used to transform two strains of yeast: yeast strain C468, which Is a haplold Saccharcmyces cerevisiae! with auxotrophic markers for leucine and hlstldlne, and yeast strain H18, which Is a haplold S. cerev15lae with auxotrophic markers for leucine and hlstldlne, which lacks the ^repressor for the glucoamylase gene of Saccharomvces dlastatlcus. Leu+ transformants were screened for expression of the Aspergillus awamori glucoamylase gene. HI8 was deposited In the National Regional Research Laboratory In Peoria, Illinois, USA on December 7, 1983 and has been assigned NRRL Number Y-12842.

* The characteristics of S cerevisiae are generally as described In J. Lodder, ed The yeasts; A Taxonomlc Study, North-Hoi land Publishing Co., Amsterdam and Oxford 1970 PP 595-604 (available on request). w' rv 27 mm 2 19 * ■» - Yeast strains which were transformed with the yeast expression vectors pGC21 and pGAC9 were compared with the same strains transformed with the parent plasmid pACI as a control for growth on various starches in liquid and on solid media. Three types of starch were used: "washed" starch (a soluble starch washed three times with 70% ethanol to remove sugars and short chain carbohydrates), cassava starch, and soluble potato (Baker's) starch. Yeasts transformed with any of the three plasmids grew on the three starches; however, the cONA clones (pGAC9) always showed better growth than the other clones, both In liquid and on solid media. When Baker's starch, which is the most highly polymerized of the three starches, was used in solid media at a concentration of 21 (w/v), the plates were turbid. These plates were spread with yeast from both strains carrying the parent plasmid, the genomic clone or the cDNA clone, and with yeast strain Saccharo-myces dlastatlcust having NRRL Deposit No. Y-2044, which expresses a yeast glucoamylase. The plates are shown in FIG. 9. The strains carrying the cDNA clone (pGAC9) were able to clear the starch around the growth zone, indicating that they could degrade the starch completely. In contrast, the S_. diastaticus strain and the yeast strains ^-transformed with either the parent plasmid pACI or the genomic clone pGC21 were unable to clear the starch from around the growth area. The clearing of the highly polymerized starch exhibited by pGAC9-containing strains indicates the functional expression of the A_. awamori glucoamylase gene that has both alpha 1-4 and alpha 1-6 amylase activity.

In another test for glucoamylase expression, yeast cells carrying the control plasmid, pACI, or the cDNA clone, pGAC9, were grown in a washed starch liquid medium. The cells were harvested and lysed by ten cycles of freeze, thaw, and vortexing with glass beads.

Each cell lysate, containing intracellular proteins, was electro-phoresed on a 75 acrylamide gel containing 0.1% sodium dodecyl sulfate (SDS) and 7.6 M urea and transferred to cellulose paper activated with cyanogen bromide. After the proteins were transferred, the paper was first probed with antiserum from a rabbit iimiunized against A. awamori glucoamylase and then with radloactively labeled Staph A protein that The characteristics of _S_. diastaticus. NRRL Y-2044,! are generally as described in 0. Lodder, ed The Yeasts: A Taxonnmir study. North-Holland Publishing Co., Amsterdam and Oxford 1970 PP 619-621, (available on request). 2 19 * --38=^ binds to antibody molecules. After unbound radioactivity was washed off, the paper was dried and exposed to X-ray film. This technique, which Is called a "Western" and is described 1n Reference 17, can be performed with antiserum or purified antibody. Protein that reacts with glucoamylase antlsera was detected 1n the lysates from the pGAC9 cDNA clones but not In the pACI controls.

The expression of the _A. awamori glucoamylase gene was also tested directly by the ability of a yeast containing such a gene to grew on an otherwise non-utilizable carbon source. For yeast strains C468 and H18, this growth test was accomplished using maltose as the carbon source, because both of these strains carry a mutation (mal) blocking the utilization of maltose as a carbon source. The ability of strains C468 and H18 containing the control plasmid pACI or the cDMA plasmid pGAC9 to grow on maltose and glucose as a carbon source 1s Indicated in Table III. The glucose plates contained histidine while the maltose plates contained both histidine and leucine supplementation. From this table 1t can be seen that the presence of the glucoamylase gene on the plasmid allows C468 to grow slowly on maltose -^and H18 to grow slightly better than the control.

These tests indicate that the presence of the glucoamylase gene complements the mal mutation in C468 and facilitates direct selection experiments where the growth of the yeast is solely dependent on proper and adequate functioning of the A_. awamori gluco-amylase gene.

All of these experiments demonstrate that yeast strain C468 containing the plasmid pGAC9 is most superior in expressing the glucoamylase gene. A sample of yeast strain C468 transformed with pGAC9 was deposited with the American Type Culture Collection on November 17, 1983 and has been assigned the ATCC Deposit No. 20,690. _ uo ' ^a^- Table III 2 194-3 5 Glucose Growth Response of Strain Carbon Source *+ Maltose Yeast Strain Plasmid day2 day4 day6 day2 day4 day6 day 10 day 13 C468 pACI* t + ♦ 0 0 0 0 0 C468 pGAC9 ± ♦ ♦ 0 0 m ± + H18 pACI* ± ♦ + 0 0 0 0 0 H18 pGAC9 ± ♦ ♦ 0 0 0 0 m ^Control 0 > no visible colonies m - nlnute colonies < 0.3 on ± - small colonies < 1 nn + ■ normal colonies 2-3 nn 21^4-Z 0. 1. Characterization of Glucoamylase Activity in Yeast Cultures Standing cultures of yeast strain C468 containing pACI or containing pGAC9 prepared as described above were grown in minimal media with glucose or washed Difgo soluble starch as the carbon sources. The cultures were harvested, after 5 days for the glucose cultures and after 7 days for the starch cultures, and cell-free supernatants were prepared by centrifugation. These supernatants were concentrated 10-20 fold using an Ajnicon concentrator with a PM10 membrane. Glucoamylase assays were negative for the supernatants from the glucose- and starch-grown cultures of yeast strain C468 containing pACI plasmid. In contrast, cells containing the control plasmid pGAC9 secreted approximately six units of glucoamylase activity per liter. (For a definition of a unit of gltcoanylase activity, see the legend to Table IV).

Glucoamylase production In aerobic shake-flask cultures of yeast strain C468 containing pGAC9 plasmid was then assayed. After two days of incubation at 30°C and agitation at 250 rpm, the culture of C468 yeast strain containing pGAC9 had consumed all of the glucose ''and was in stationary phase. The culture had achieved a cell density of approximately 2 g/liter dry weight. A glucoamylase assay on the unconcentrated supernatant indicated that approximately 47 units of activity per liter of supernatant was produced. 2. Location of Glucoamylase Activity In Cultures of Transformed Yeast Cells The experiment given below was used to resolve whether the majority of the glucoamylase activity 1s found Jn the culture medium or inside the cell.

Strains C468-pGAC9 and C468-pACl were grown 1n 500 ml of medium containing 1.45 g of Difco Yeast nitrogen base (Difco Laboratories, Detroit, MI 48232), 5.2 g of ammonium sulfate and 2» glucose per liter to a cell density of 2-3 x 10^ cells per ml. The cultures were centrifuged at 4#C and the supernatants and cell pellets were .. V-, • • .• «-r V •"•* > .f « $ 1 —- 2 1 ° • 3 processed separately. The supernatant samples were filtered through a 0.45 \i filter and then concentrated 15 to 20X using an Amicon stirred cell with a PM-10 membrane. The cell pellet was washed once in 1 M Sorbitol 0.1 M phosphate buffer pH 7.5 and then the packed cell volume 5 was determined by centrifuging at approximately lOOOxg for 5 minutes 1n a conical graduated centrifuge tube. Each ml of packed cells was resuspended to 1.5 ml in 1.0 H Sorbitol-0.1 M phosphate buffer at pH 7.5 and and equal volume of Zymelyase 5000 (Miles Laboratory, Elkhart IN 46515) was added. The cells were gently mixed at room temperature 10 for 1 hr and then centrifuged at 500xg to recover the protoplasts.

The supernatant, representing the protein that was present between the cell wall and the inner membrane, was put on ice for later processing. The space between the cell membrane and wall in yeast is referred to as the Interstitial space and this protoplast supernatant 15 sample will be referred to as the interstitial sample in the following text. The protoplasts were resuspended in 1 M Sorbitol-0.1 M KP04 buffer-10 nM NaNj and washed lx by centrifuging at 500xg. The pellet was resuspended In 5 ml 1 M Sorbitol-0.1 M KPO^ at pH 7.5-10 art NaNj and 1 ml was used to assay the glucoamylase activity present in the 20 Intact, azlde-treated protoplasts. To the remaining 4 ml of protoplast 4 ml of 50 nW Tris at pH 7.4-10 nW EDTA was added along with 6 g of sterile glass beads (0.45-0.5 nn B. Braun) and the mixture was vortexed vigorously for 20 seconds, cooled on 1ce and this procedure was repeated until microscopic observation revealed membrane 25 ghosts or particles but few or no Intact protoplasts. Sterile 2 M sucrose was added slowly with a pasteur pipette Inserted to the bottom of the tube and the lysate was floated out of the glass beads. The lysate was removed to a new tube and centrifuged along with the interstitial sample at approximately 20,000xg for 30 min at 4°C. The 30 supernatant from the broken protoplasts was designated the Intracellular sample and the pellets from the interstitial sample and the broken protoplast sample were combined to make the membrane sample. Thus the yeast culture has been fractionated Into five samples: the extracellular or supernatant sample, the Interstitial, 35 membrane associated and Intracellular samples, as well as a sample containing intact azlde-treated protoplasts.

'Ur3 ^&- 219435 The culture samples were analyzed for glucoamylase activity utilizing the peroxidase-glucose oxidase (PGO)/o-dianisfdine (OOAO) assay (Sigma Kit #510) which detects glucose released from soluble starch by the glucoamylase. The assay can be affected by other 5 enzymes present which utilize glucose or by glucose present in the samples. Each PGO-ODAD Assay mix was tested with known quantities of glucose (generally a dilution series from 0 to 550 nanomoles) and a standard curve was constructed. One glucoamylase unit is defined as the amount of glucoamylase which releases one |*mole of glucose per 10 minute from washed soluble starch at 37°C.

Samples were reacted with washed soluble starch on the day they were prepared, then boiled and frozen at -20°C for later glucose assay. A portion of each fresh sample was precipitated by addition of 3 volumes of cold 95* ethanol, then allowed to stand overnight and the 15 precipitate was collected by centrifugation at 2000xg for 5 min at 4*C. The supernatant sample required a second centrifugation to recover small floes which remained suspended in the ethanol supernatant. The pellets were dried and then resuspended in 50 nM Tris at ^pH 7.4-10 nM EDTA to one half their original volume, except the super-20 natant sample which was resuspended to one twentieth its original volume. These ethanol-precipitated samples were reacted with washed "soluble starch and then boiled and frozen -208C for assay with the fresh samples.

Intact azide-treated protoplasts were assayed in a reaction 25 oilx containing 1 M Sorbitol-0.55 washed starch and 200 ^1 of protoplasts. These mixes were Incubated at 37°C for 30 min, then centrifuged at 500xg and the supernatant was filtered, then boiled and assayed or stored at -20°C. These assays revealed that the reaction mix contained some residual glucose and that the protoplasts reduced 30 the amount of glucose In the mix during incubation. When lysed protoplasts were incubated 1n the same mix, more glucose was utilized than when the protoplasts were Intact. Values for the glucoamylase plasmid carrying strain were similar to those for the strain carrying the same plasmid without the glucoamylase DNA Insert, Implying that little, if 35 any, glucoamylase activity Is associated with the membrane. > t - «*£ 2 19435 The fresh fractionated samples were assayed and the Intracellular samples were found to have residual glucose levels that were too high for the assay. Membrane-associated and Interstitial samples from pGAC9- and pACl-transformed cells both failed to produce detect-5 able levels of glucose from soluble starch. The supernatant sample from pGAC9-trans formed yeast demonstrated glucoanylase activity of about 22 units/liter, while the sample from pACl-transformed yeast showed no glucoamylase activity. Ethanol-preclpitated samples from the pACl-transformed yeast showed negligible (less than or equal to 10 0.08 unlts/Hter) or no glucoamylase activity. Ethanol-precipitated samples from yeast transformed with pGAC9 all demonstrated glucoamylase activity of 0.15 units per liter or higher. The supernatant sample contained over 90% of the total glucoamylase activity and the intracellular, membrane associated and interstitial samples contained 15 from 1 to 4% of the total activity depending on the sample. Therefore, most of the glucoamylase enzyme is secreted into the extracellular medium.

E. Production of Recombinant Glucoamylase from Yeast 1n a 10 Liter Fermentor" To produce sufficient glucoamylase for characterization, a 10-liter fermentation of C468 yeast strain containing pGAC9 in minimal media with glucose as the sole carbon source was set up. A 100-ml seed culture was grown in minimal media to an optical density at 25 680 ran (ODggg) of 6 and added to the fermentor. The fermentor was run as an aerobic batch fermentation until it reached an ODggg of 10, and then a glucose feed was begun. The glucose feed was continued to an ODggQ of approximately 30 and then stopped, allowing the residual glucose to be consumed. Total fermentation time was approximately 32 30 hours. The final cell density was approximately 10 g/liter dry weight. Diluted samples of the unconcentrated fermentor supernatant were assayed for glucoamylase activity, with the assay data given in Table IV. The supernatant was concentrated 15-fold using an Amicon Hollow Fiber Concentration unit with a 10,000 molecular weight size 35 exclusion.

C f) 0 0 Table IV Recombinant Glucoanylase Purification Sample Glucoamylase Activity (units) Volume (ml) Protein (ng) Percent Recovery Specific Activity (un1ts/mg) Fermentor Supernatant 3146 .000 __ 100 Concentrated Supernatant 1605 660 219 51 7.3 DEAE-Sepharose Column 2300 160 173 73 13.3 One unit of glucoamylase activity Is the release of 1 iimole glucose/Minute from washed Difco soluble starch 1n 0.1 H citrate buffer, pH 5.0, at 37*C.' ** The protein concentration of the concentrated supernatant was determined using a BloRad protein assay kit. The protein concentration from the OEAE-Sepharose column was estimated by Integration of area under the OO2QQ peak (1 ODjgo units a 1 mg/ml protein). ''if-""'':- ■, ■ 2 194-3 ' U6 - J ff * / / The concentrated fermentor supernatant was adjusted to 50 mM phosphate, pH 7.5, by adding concentrated buffer thereto and was loaded on a OEAE Sepharose (CL-6B) column. The column was eluted with a pH gradient (starting pH 75, final pH 3.0). The elution profile is 5 shown In FIG. 10. Various samples from the column were analyzed by SDS-urea polyacrylamide gel electrophoresis. A photograph of the gel stained with BioRad silver stain showed that the concentrated fermentor supernatant contained only a few proteins, demonstrating that the glucoamylase was secreted into the nedia and not released by cell 10 lysis. A comparison of a sample from this concentrated fermentor supernatant with an equal volume of the peak fraction of glucoamylase activity indicated a considerable increase In the purity of the protein. Estimates Indicated that 20-301 of the supernatant protein was glucoamylase and the peak fraction was approximately 801 gluco-15 arnylase. The recombinant glucoamylase migrated with a mobility slightly slower than the _A. awamori glucoamylase, Indicating that the glucoamylase produced in the transformed yeast was also glycosylated.

An assay on the peak column fraction of glucoamylase activity Indicated that the recombinant glucoamylase has a specific activity 20 comparable to native _A. awamori glucoamylase, namely 25-50 units/mg.

Experiments prove that the recombinant glucoamylase produced by yeast C468/pGAC9 is glycosylated. Duplicate samples of K. awamori glucoamylase-I and glucoamylase-II and the recombinant glucoamylase gene were electrophoresed In a 101 polyacrylamide-SDS gel using stand-25 ard procedures. After electrophoresis, the gel was split and lanes 1-4 were stained for protein with a Coomassie Blue stain and lanes 5-8 j were stained for carbohydrate with Periodic Acid Schiff's stain.

Details of these procedures are found in Reference 18. A comparison of glucoamylase-I (lanes 2 and 5}, glucoamylase-I I (lanes 3 and 6) and 30 the recombinant glucoamylase (lanes 4 and 7) is shown in FIGURE 11. Since the bands corresponding to these proteins also stain with the t ; carbohydrate stain, this demonstrates that the recombinant gluco amylase is glycosylated by the yeast. 2 1-943 5 EXAMPLE 3 Production of Alcohol from Transformed Yeast Yeast strain C468 containing pGAC9, and the control C468 yeast strain containing pACI were Inoculated Into 50 ml of the following medium: succinic acid 11.81 g h3po4 0.58 9 h2so4 0.31 9 KC1 0.37 9 NaCl 58.4 mg MgCl2*SH20 0.2 9 MnS04-H20 1.7 mg CuS04•5H20 0.25 mg ZnS04*7H20 1.44 mg CoCl2'6H20 1.19 mg Na2Mo04'2H20 1.21 mg h3bo3 3.09 mg CaCl2*2H20 14.7 mg FeS04*7H20 11.1 mg hlstldlne 40 mg washed soluble starch 100 9 add water in quantities sufficient to 1 liter Fermentation was carried out In 250 ml flasks which were equipped with air restrictors to restrict the flow of oxygen Into the flask. The flasks were incubated at 32°C and shaken at 200 rpm for 7 days.

The starch was washed three times in 70% ethanol to remove low molecular weight carbohydrates. The precipitate was then dried, but some ethanol and water nay have remained. ■' / * - £i/*» ~~ -47^ 7 19435 The ethanol content of each flask was evaluated using gas chromatography. The C468/pGAC9 culture contained 23.4 g/1 ethanol while tlie control C468/pACl culture contained 4.5 g/1 ethanol. The results show that the production, of glucoamylase by the C468/pGAC9 culture enabled the strain to convert the soluble starch into glucose and then to ferment the glucose to ethanol.

EXAMPLE 4 Expression of the Glucoamylase Gene in E. coli In order to express the glucoamylase gene in E_. coli, a Modification was made to the 5' untranslated region in order to make the DNA sequence more compatible with transcription and translation in E. coli. Specifically, 27 base pairs between the Hindlll site which 10 was constructed 32 base pairs upstream from the ATG initiation codon (see Example 2) and the ATG codon were deleted by oligonucleotide wjtagenesls using the procedure described in Example 2B for removal of s an intron. The oligonucleotide, which had homology to 12 base pairs on the 5' side of the region to be deleted and 11 base pairs on the 3' 15 -side, had the sequence: ' GAGC C G AAGC TTT ATGTCGTTCCG 3' Except for this deletion, the final Hindlll cassette was identical to that constructed for the yeast expression vector In Example 2.

E. coli expression vector ptrp3 was constructed by replacing the EcoRI to Clal region of pBR322 (coordinates -3 to 28, see Reference 16a) with an EcoRI to Clal fragment containing the E_. coli tryptophan promoter and ribosome binding site. The nucleotide sequence of this region is shown In Table V; the EcoRI, Clal and 25 Hindlll sites have been Identified 1n Table V. ""■■'•*' . ■■ ■<■<*&$■ • 2 19 ' 3 5 Table V GAA TTC CGA CAT CAT AAC GGT TCT GGC AAA TAT TCT GAA ATG EcoRI AGC TGT TGA CAA TTA ATC ATC GAA CTA GTT AAC TAG TAC GCA AGT TCA CGT AAA AAG GGT 5 ATC GAT AAG CTT Clal Hindlll The Hindlll cassette of the glucoamylase gene, described above In this example, was cloned Into the Hindlll site of ptrp3. Transformants were screened by DNA restriction fragment mapping in 10 order to Identify clones where the glucoamylase gene was in the same orientation as the promoter; one such clone was selected for further study as pGC24.

In order to examine expression of the glucoanylase gene using the trp promoter, plasmid pGC24 was transformed into E_. coli 15 host MH70 which had been obtained from the coli Genetic Stock Center, Yale University (their collection number is CGSC 6153). MH70 1s a mal" _E_. coll strain whose genotype is ara0139, A(argF-lac) 205, flbB5301, ptsF25, relAl?, rpsL150, aalQ63, bglR15, deoCl? The malQ nutation 1s 1n the amylomaltase gene; a mutation 1n this gene makes E_. 20 coli unable to hydrolyze maltose to glucose.

A sample of the MH70 transformed with pCG24 was deposited with the American Type Culture Collection on December 16, 1983, and has been assigned the ATCC Deposit No. 39,537.

The MH70/pGC24 transformant and strain MH70 were grown at 25 37°C and 200 rpm in 5 ml of the following medium containing tryptophan at 50 mg/1. 2 194 3 40 *1 50 mg 2 9 10 ag 2 g to 1000 nl 25X Bonner-Yogel Salts (Methods In Enzymology. XV3IA:5): 670 nl 5 9 50 g 250 g 87.5 g 1000 ■! After overnight incubation, the cells were harvested by centrifugation at 3000g for 5 minutes and resuspended in 5 ml of the same medium but without tryptophan. The cells were then subcultured In 20 wis of the medium without tryptophan to an AggQ of 0.05-0.07.

This culture was grown at 37®C and 250 rpm to an Aggg of 0.05. The 'cells were harvested from 10 mis of culture by centrifugation as above and resuspended in 1 ml of sonication buffer (15% sucrose, 50 nW Tris pH 7, 40 nW EDTA). The samples were sonicated for 3 minutes (on pulse) In a cup sonicator (Sonifier Cell Disrupter #350, Branson Sonic 10 Power Co.). The cell lysates were centrifuged for 5 minutes in an Eppendorf Microfuge and the clear supernatants were removed for further analysis. The clear lysates were electrophoresed on an polyacrylamide sodium dodecyl sulfate (SOS] gel and analyzed by Western analysis as described in Example 2C. A protein band of 15 approximately 69,000 molecular weight, the size expected for an unglycosylated form of glucoanylase, was detected 1n the MH70/pGC24 clear lysate but not In the MH70 lysate.

To further demonstrate that an active glucoamylase enzyme was produced in E. coll, MH7Q/pGC24 and MH70 were streaked on -SO -49- 25X Bonner-Vogel Salts Ampicillin Glucose Vitamin B1 Casanlno Acid Water Glass Distilled Water MgS04-7H20 Citric Acid*H20 k2hpo4 NaNH4HP04-4H20 Glass Distilled Water to 2 19435 MacConkey Agar (Difco Co., Detroit, MI 48232) plates containing IS maltose and Incubated overnight at 37*C. The fermentation of maltose results In a pH change In the media that 1s Indicated by a shift from a colorless to red color In the colonies; nonfermenting colonies 5 remain colorless. Since MH70 1s malQ", its colonies were colorless. The expression of the A. awamori glucoamylase In MH70/pGC24 permitted the hydrolysis of maltose to glucose and the fermentation of the glucose resulted In red colonies. Therefore, an active glucoamylase Is produced In col 1.

While preferred embodiments of the present Invention have been described herein, 1t will be understood that various changes and modifications nay be made without departing from the spirit of the Invention. For example, while the examples all demonstrate autonomous replication In the host, using Integrative transformation of the host 15 as described 1n References lc and Id where the gene and promoter are Integrated Into the chromosome is also possible. i -SO-

Claims (10)

WHAT WE CLAIM IS: - Sx- 219435

1. A process for secreting a glucoamylase extracellularly characterized by growing a fungal or yeast host orqanism, which host is transformed by a DNA expression vector comprisino a promoter fragment" which functions in that organism, a signal sequence encodinq substantially the followinq amino acid sequence:

2. A process for producing glucoamylase characterized by growing a host organism in a culture medium, which host is transformed by a DNA expression vector containing a promoter fragment which functions in said host organism and a DNA segment having a modified DNA sequence, said modified DNA sequence characterized in that it codes for fungal glucoamylase protein or its single or multiple base substitutions, deletions, insertions, or inversions, it is derived from natural, synthetic or semi-synthetic sources, and each is capable, when correctly combined with a cleaved expression vector, of expressing a non-native protein having glucoamylase enzyme (1,4-af-D-glucan glucohydrolase (EC 3.2.1.3)) activity, the DNA segment being in an orientation with the promoter fragment such that in the host it is expressed to produce a non-native glucoamylase enzyme.

3. A process of claim 2 wherein the DNA is cDNA and wherein the fungal glucoamylase protein for which the sequence codes is from the species A. awamori or A. niger.

4. A process of claim 3 wherein the species is A. awamori NRRL 15,271 and the DNA sequence is substantially the following, in a 5' to 3' direction: MET SER PHE ARG SER LEU LEU ALA LEU SER GLY LEU VAL CYS THR GLY LEU ALA ASN YAL ILE SER LYS ARG, and a DMA segment which codes for the glucoamylase. GCG ACC TTG GAT TCA TGG TTG AGC AAC GAA GCG ACC GTG GCT CGT ACT GCC ATC CTG AAT AAC ATC GGG GCG GAC GGT GCT TGG GTG TCG GGC GCG GAC TCT GGC ATT GTC GTT GCT AGT CCC AGC ACG GAT AAC 2 19 3 CCS GAC TAC TTC TAC ACC TGG ACT CGC GAC TCT GGT CTC GTC CTC AAG ACC CTC GTC GAT CTC TTC CGA AAT GGA GAT ACC AGT CTC CTC TCC ACC ATT GAG AAC TAC ATC TCC GCC CAG GCA ATT GTC CAG GGT ATC AGT AAC CCC TCT GGT GAT CTG TCC AGC GGC GCT GGT CTC GGT GAA CCC AAG TTC AAT GTC GAT GAG ACT GCC TAC ACT GGT TCT TGG GGA CGG CCG CAG CGA GAT GGT CCG GCT CTG AGA GCA ACT GCT ATG ATC GGC nc GGG CAA TGG CTG CTT GAC AAT GGC TAC ACC AGC ACC GCA ACG GAC ATT GTT TGG CCC CTC GTT AGG AAC GAC CTG TCG TAT GTG GCT CAA TAC TGG AAC CAG ACA GGA TAT GAT CTC TGG GAA GAA GTC AAT GGC TCG TCT nc TTT ACG ATT GCT GTG CAA CAC CGC GCC CTT GTC GAA GGT AGT GCC TTC GCG ACG GCC GTC GGC TCG TCC TGC TCC TGG TGT GAT TCT CAG GCA CCC GAA An CTC TGC TAC CTG CAG TCC nc TGG ACC GGC AGC TTC An CTG GCC AAC nc GAT AGC AGC CGT TCC GGC AAG GAC GCA AAC ACC CTC CTG GGA AGC ATC CAC ACC TTT 6AT CCT GAG GCC GCA TGC GAC GAC TCC ACC nc CAG CCC TGC TCC CCG CGC GCG CTC GCC AAC CAC AAG GAG GTT GTA GAC TCT nc CGC TCA ATC TAT ACC CTC AAC GAT GGT CTC AGT GAC AGC GAG GCT GTT GCG GTG GGT CGG TAC CCT GAG GAC ACG TAC TAC AAC GGC AAC CCG TGG TTC CTG TGC ACC TTG GCT GCC GCA GAG CAG TTG TAC GAT GCT CTA TAC CAG TGG GAC AAG CAG GGG TCG TTG GAG GTC ACA GAT GTG TCG CTG GAC TTC TTC AAG GCA CTG TAC AGC GAT GCT GCT ACT GGC ACC TAC TCT TCG TCC AGT TCG ACT TAT AGT AGC An GTA GAT GCC GTG AAG ACT TTC GCC GAT GGC nc GTC TCT An GTG GAA ACT CAC GCC GCA AGC AAC GGC TCC ATG TCC GAG CAA TAC GAC AAG TCT GAT GGC GAG CAG CTT TCC GCT CGC GAC CTG ACC TGG TCT TAT GCT GCT -213435 ctg ctg acc gcc aac aac cgt cgt aac gtc gtg cct tcc gct tct tgg ggc gag acc tct gcc agc agc g i g ccc gc-c acc tgt gcg gcc aca tct gcc att gg i acc tac agc agt gtg act gtc acc tcg tgg ccg agt atc gtg gct act ggc ggc acc act acg acg gct acc rrr www act gga tcc ggc agc GTG acc tcg av# te agc AAG acc acc gcg act gct agc aag acc a u'- ac w AGT acg tca tca ACC tcc tgt acc ac i ccc acc gcc GTG gct GTG act ttc gat ctg ACA gct acc a^„ ACC tac ggc gag aac a i tac ctg gtc GGA tcg ATC tct cag ctg ggt gac tgg GAA ac: agc gac GGC ATA gct ctg act gc i gac AAG TAC act tcc agc gac CCS CTC tgg tat c-tc al ) GTG act ctg ccg gct ggt gag tcg TTT gag tac AAG ttt t r. i cgc A. i GAG AGC gat gac tcc gtg gag tgg gag agt GAT CCC aac cga GAA tac ACC GTT CCT cag gcg tgc c-GA acs tcs • acc Gv*G acg gtg act gac ACC TGG cog

5. A process of claim 1 or claim 2 wherein the DNA expression vector is the plas.-nid pGAC9.

6. A process of any one of claims 2-5 wherein the host organism is a bacteria, a virus, or a yeast.

7. A process of claim 6 v/herein the host orga.nism is Ji. coli.

8. A process of any or.e of claims 1-6 wherein the host organism is a yeast.

S. A process of clairc.S wherein the yeast is a species of the genus Sacc'naromyces.

10. A process for producing glucoamylase substantially as herein described v/ith reference to the accompanying drawings.