Identification of a second trans-acting gene controlling maltose fermentation in Saccharomyces carlsbergensis.

Maltose fermentation in Saccharomyces spp. requires the presence of a dominant MAL locus. The MAL6 locus has been cloned and shown to encode the structural genes for maltose permease (MAL61), maltase (MAL62), and a positively acting regulatory gene (MAL63). Induction of the MAL61 and MAL62 gene products requires the presence of maltose and the MAL63 gene. Mutations within the MAL63 gene produce nonfermenting strains unable to induce the two structural gene products. Reversion of these mal63 nonfermenters to maltose fermenters nearly always leads to the constitutive expression of maltase and maltose permease, and constitutivity is always linked to MAL6. We demonstrated that for one such revertant, strain C2, constitutivity did not require the MAL63 gene, since deletion disruption of this gene did not affect the constitutive expression of the structural genes. In addition, constitutivity was trans acting. Deletion disruption of the MAL6-linked structural genes for maltase and maltose permease in this strain did not affect the constitutive expression of a second, unlinked maltase structural gene. We isolated new maltose-fermenting revertants of a nonfermenting strain which carried a deletion disruption of the MAL63 gene. All 16 revertants isolated expressed maltase constitutively. In one revertant studied in detail, strain R10, constitutive expression was demonstrated to be linked to MAL6, semidominant, trans acting, and residing outside the MAL63-MAL61-MAL62 genes. From these studies we propose the existence of a second trans-acting regulatory gene at the MAL6 locus. We call this new gene MAL64. We mapped the MAL64 gene 2.3 centimorgans to the left of MAL63. The role of the MAL64 gene product in maltose fermentation is discussed.

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Repeated Family of Genes Controlling Maltose Fermentation in Saccharomyces carlsbergensis

Molecular and Cellular Biology ◽

10.1128/mcb.3.5.796-802.1983 ◽

1983 ◽

Vol 3 (5) ◽

pp. 796-802

Author(s):

Richard B. Needleman ◽

Corinne Michels

Keyword(s):

Genetic Analysis ◽

Structural Gene ◽

Regulatory Gene ◽

Regulatory Protein ◽

Physical Analysis ◽

Saccharomyces Carlsbergensis ◽

Maltose Permease ◽

Maltose Fermentation ◽

Complex Locus ◽

Dna Fragment

Maltose fermentation in Saccharomyces spp. requires the presence of any one of five unlinked genes: MAL1, MAL2, MAL3, MAL4 , or MAL6. Although the genes are functionally equivalent, their natures and relationships to each other are not known. At least three proteins are necessary for maltose fermentation: maltase, maltose permease, and a regulatory protein. The MAL genes may code for one or more of these proteins. Recently a DNA fragment containing a maltase structural gene has been cloned from a MAL6 strain, CB11, to produce plasmid pMAL9-26. We have conducted genetic and physical analyses of strain CB11. The genetic analysis has demonstrated the presence of two cryptic MAL genes in CB11, MAL1g and MAL3g (linked to MAL1 and to MAL3 , respectively), in addition to the MAL6 locus. The physical analysis, which used a subclone of plasmid pMAL9-26 as a probe, detected three Hin dIII genomic fragments with homology to the probe. Each fragment was shown to be linked to one of the MAL loci genetically demonstrated to be present in CB11. Our results indicate that the cloned maltase structural gene in plasmid pMAL9-26 is linked to MAL6. Since the MAL6 locus has previously been shown to contain a regulatory gene, the MAL6 locus must be a complex locus containing at least two of the factors needed for maltose fermentation: the structural gene for maltase and the maltase regulatory protein. The absence of other fragments which hybridize to the MAL6 -derived probe shows that either MAL2 and MAL4 are not related to MAL6 , or the DNA corresponding to these genes is absent from the MAL6 strain CB11.

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Repeated Family of Genes Controlling Maltose Fermentation inSaccharomyces carlsbergensis

Molecular and Cellular Biology ◽

10.1128/mcb.3.5.796 ◽

1983 ◽

Vol 3 (5) ◽

pp. 796-802 ◽

Cited By ~ 19

Author(s):

Richard B. Needleman ◽

Corinne Michels

Keyword(s):

Genetic Analysis ◽

Structural Gene ◽

Regulatory Gene ◽

Regulatory Protein ◽

Physical Analysis ◽

Maltose Permease ◽

Maltose Fermentation ◽

Complex Locus ◽

Dna Fragment

Maltose fermentation inSaccharomycesspp. requires the presence of any one of five unlinked genes:MAL1, MAL2, MAL3, MAL4, orMAL6.Although the genes are functionally equivalent, their natures and relationships to each other are not known. At least three proteins are necessary for maltose fermentation: maltase, maltose permease, and a regulatory protein. TheMALgenes may code for one or more of these proteins. Recently a DNA fragment containing a maltase structural gene has been cloned from aMAL6strain, CB11, to produce plasmid pMAL9-26. We have conducted genetic and physical analyses of strain CB11. The genetic analysis has demonstrated the presence of two crypticMALgenes in CB11,MAL1gandMAL3g(linked toMAL1and toMAL3, respectively), in addition to theMAL6locus. The physical analysis, which used a subclone of plasmid pMAL9-26 as a probe, detected threeHindIII genomic fragments with homology to the probe. Each fragment was shown to be linked to one of theMALloci genetically demonstrated to be present in CB11. Our results indicate that the cloned maltase structural gene in plasmid pMAL9-26 is linked toMAL6.Since theMAL6locus has previously been shown to contain a regulatory gene, theMAL6locus must be a complex locus containing at least two of the factors needed for maltose fermentation: the structural gene for maltase and the maltase regulatory protein. The absence of other fragments which hybridize to theMAL6-derived probe shows that eitherMAL2andMAL4are not related toMAL6, or the DNA corresponding to these genes is absent from theMAL6strain CB11.

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Alpha-factor structural gene mutations in Saccharomyces cerevisiae: effects on alpha-factor production and mating.

Molecular and Cellular Biology ◽

10.1128/mcb.5.4.787 ◽

1985 ◽

Vol 5 (4) ◽

pp. 787-796 ◽

Cited By ~ 50

Author(s):

J Kurjan

Keyword(s):

Saccharomyces Cerevisiae ◽

Structural Gene ◽

Gene Mutations ◽

Alpha Cells ◽

Structural Genes ◽

Coding Region ◽

Considerable Decrease ◽

Factor Production ◽

Alpha Factor

The role of alpha-factor structural genes MF alpha 1 and MF alpha 2 in alpha-factor production and mating has been investigated by the construction of mf alpha 1 and mf alpha 2 mutations that totally eliminate gene function. An mf alpha 1 mutant in which the entire coding region is deleted shows a considerable decrease in alpha-factor production and a 75% decrease in mating. Mutations in mf alpha 2 have little or no effect on alpha-factor production or mating. The mf alpha 1 mf alpha 2 double mutants are completely defective in mating and alpha-factor production. These results indicate that at least one alpha-factor structural gene product is required for mating in MAT alpha cells, that MF alpha 1 is responsible for the majority of alpha-factor production, and that MF alpha 1 and MF alpha 2 are the only active alpha-factor genes.

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Alpha-factor structural gene mutations in Saccharomyces cerevisiae: effects on alpha-factor production and mating

Molecular and Cellular Biology ◽

10.1128/mcb.5.4.787-796.1985 ◽

1985 ◽

Vol 5 (4) ◽

pp. 787-796

Author(s):

J Kurjan

Keyword(s):

Saccharomyces Cerevisiae ◽

Structural Gene ◽

Gene Mutations ◽

Alpha Cells ◽

Structural Genes ◽

Coding Region ◽

Considerable Decrease ◽

Factor Production ◽

Alpha Factor

The role of alpha-factor structural genes MF alpha 1 and MF alpha 2 in alpha-factor production and mating has been investigated by the construction of mf alpha 1 and mf alpha 2 mutations that totally eliminate gene function. An mf alpha 1 mutant in which the entire coding region is deleted shows a considerable decrease in alpha-factor production and a 75% decrease in mating. Mutations in mf alpha 2 have little or no effect on alpha-factor production or mating. The mf alpha 1 mf alpha 2 double mutants are completely defective in mating and alpha-factor production. These results indicate that at least one alpha-factor structural gene product is required for mating in MAT alpha cells, that MF alpha 1 is responsible for the majority of alpha-factor production, and that MF alpha 1 and MF alpha 2 are the only active alpha-factor genes.

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The Constitutive, Glucose-Repression-Insensitive Mutation of the Yeast MAL4 Locus Is an Alteration of the MAL43 Gene

Genetics ◽

10.1093/genetics/116.1.23 ◽

1987 ◽

Vol 116 (1) ◽

pp. 23-31

Author(s):

Maureen J Charron ◽

Corinne A Michels

Keyword(s):

Glucose Repression ◽

Regulatory Gene ◽

Constitutive Expression ◽

Structural Genes ◽

Wild Type ◽

Gene Encoding ◽

Maltose Permease ◽

Genes Expression ◽

Constitutive Production ◽

Saccharomyces Yeasts

ABSTRACT Mutations resulting in constitutive production of maltase have been identified at each of the five MAL loci of Saccharomyces yeasts. Here we examine a dominant constitutive, glucose-repression-insensitive allele of the MAL4 locus (MAL4-C). Our results demonstrate that MAL4-C is an alteration in the MAL43 gene, which encodes the positive regulator of the MAL structural genes, and that its product is trans-acting. The MAL43 gene from the MAL4-C strain was cloned and integrated into a series of nonfermenting strains lacking a functional regulatory gene but carrying copies of the maltose permease and maltase structural genes. Expression of the maltase structural gene was both constitutive and insensitive to glucose repression in these transformants. The MAL4-C allele also results in constitutive expression of the unlinked MAL12 gene (encoding maltase) in this strain. In addition, the cloned MAL43 gene was shown to be dominant to the wild-type MAL63 gene. We also show that most of the glucose repression insensitivity of strains carrying the MAL4-C allele results from alteration of MAL43.

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Constitutive expression of the maltose fermentative enzymes in Saccharomyces carlsbergensis is dependent upon the mutational activation of a nonessential homolog of MAL63

Molecular and Cellular Biology ◽

10.1128/mcb.8.3.1027-1035.1988 ◽

1988 ◽

Vol 8 (3) ◽

pp. 1027-1035

Author(s):

R A Dubin ◽

M J Charron ◽

S R Haut ◽

R B Needleman ◽

C A Michels

Keyword(s):

Constitutive Expression ◽

Positive Function ◽

Gene Products ◽

Wild Type ◽

Transcript Accumulation ◽

Saccharomyces Carlsbergensis ◽

Maltose Permease ◽

Maltose Fermentation ◽

Mutational Activation ◽

Type Strains

Maltose fermentation in Saccharomyces carlsbergensis is dependent upon the MAL6 locus. This complex locus is composed of the MAL61 and MAL62 genes, which encode maltose permease and maltase, respectively, and a third gene, MAL63, which codes for a trans-acting positive regulatory product. In wild-type strains, expression of the MAL61 and MAL62 mRNAs and proteins is induced by maltose and induction is dependent upon the MAL63 gene. Mutants constitutively expressing the MAL61 and MAL62 gene products have been isolated in mal63 backgrounds, and the mutations which have been analyzed map to a fourth MAL6-linked gene, MAL64. Cloning and characterization of this new gene are described in this report. The results revealed that the MAL64-C alleles present in constitutive strains encode a trans-acting positive function required for constitutive expression of the MAL61 and MAL62 gene products. In inducible strains, the MAL64 gene is dispensable, as deletion of the gene had no effect on maltose fermentation or maltose-regulated induction. MAL64 encoded transcripts of 2.0 and 1.4 kilobase pairs. While both MAL64 mRNAs were constitutively expressed in constitutive strains, they were maltose inducible in wild-type strains and induction was dependent upon the MAL63 gene. The MAL63 and MAL64 genes are at least partially structurally homologous, suggesting that they control MAL61 and MAL62 transcript accumulation by similar mechanisms.

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Constitutive expression of the maltose fermentative enzymes in Saccharomyces carlsbergensis is dependent upon the mutational activation of a nonessential homolog of MAL63.

Molecular and Cellular Biology ◽

10.1128/mcb.8.3.1027 ◽

1988 ◽

Vol 8 (3) ◽

pp. 1027-1035 ◽

Cited By ~ 15

Author(s):

R A Dubin ◽

M J Charron ◽

S R Haut ◽

R B Needleman ◽

C A Michels

Keyword(s):

Constitutive Expression ◽

Positive Function ◽

Gene Products ◽

Wild Type ◽

Transcript Accumulation ◽

Saccharomyces Carlsbergensis ◽

Maltose Permease ◽

Maltose Fermentation ◽

Mutational Activation ◽

Type Strains

Maltose fermentation in Saccharomyces carlsbergensis is dependent upon the MAL6 locus. This complex locus is composed of the MAL61 and MAL62 genes, which encode maltose permease and maltase, respectively, and a third gene, MAL63, which codes for a trans-acting positive regulatory product. In wild-type strains, expression of the MAL61 and MAL62 mRNAs and proteins is induced by maltose and induction is dependent upon the MAL63 gene. Mutants constitutively expressing the MAL61 and MAL62 gene products have been isolated in mal63 backgrounds, and the mutations which have been analyzed map to a fourth MAL6-linked gene, MAL64. Cloning and characterization of this new gene are described in this report. The results revealed that the MAL64-C alleles present in constitutive strains encode a trans-acting positive function required for constitutive expression of the MAL61 and MAL62 gene products. In inducible strains, the MAL64 gene is dispensable, as deletion of the gene had no effect on maltose fermentation or maltose-regulated induction. MAL64 encoded transcripts of 2.0 and 1.4 kilobase pairs. While both MAL64 mRNAs were constitutively expressed in constitutive strains, they were maltose inducible in wild-type strains and induction was dependent upon the MAL63 gene. The MAL63 and MAL64 genes are at least partially structurally homologous, suggesting that they control MAL61 and MAL62 transcript accumulation by similar mechanisms.

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