scholarly journals The Identification and Characterization of ADR6, a Gene Required for Sporulation and for Expression of the Alcohol Dehydrogenase II Isozyme From Saccharomyces cerevisiae

Genetics ◽  
1987 ◽  
Vol 116 (4) ◽  
pp. 523-530
Author(s):  
Aileen K W Taguchi ◽  
Elton T Young

ABSTRACT The alcohol dehydrogenase II isozyme (enzyme, ADHII; structural gene, ADH2) of the yeast, Saccharomyces cerevisiae, is under stringent carbon catabolite control. This cytoplasmic isozyme exhibits negligible activity during growth in media containing fermentable carbon sources such as glucose and is maximal during growth on nonfermentable carbon sources. A recessive mutation, adr6-1, and possibly two other alleles at this locus, were selected for their ability to decrease Ty-activated ADH2-6 c expression. The adr6-1 mutation led to decreased ADHII activity in both ADH2-6c and ADH2+ strains, and to decreased levels of ADH2 mRNA. Ty transcription and the expression of two other carbon catabolite regulated enzymes, isocitrate lyase and malate dehydrogenase, were unaffected by the adr6-1 mutation. adr6-1/adr6-1strains were defective for sporulation, indicating that adr6 mutations may have pleiotropic effects. The sporulation defect was not a consequence of decreased ADH activity. Since the ADH2-6c mutation is due to insertion of a 5.6-kb Ty element at the TATAA box, it appears that the ADR6+-dependent ADHII activity required ADH2 sequences 3′ to or including the TATAA box. The ADH2 upstream activating sequence (UAS) was probably not required. The ADR6 locus was unlinked to the ADR1 gene which encodes another trans-acting element required for ADH2 expression.

Genetics ◽  
1987 ◽  
Vol 116 (4) ◽  
pp. 531-540
Author(s):  
Aileen K W Taguchi ◽  
Elton T Young

ABSTRACT The alcohol dehydrogenase II (ADH2) gene of the yeast, Saccharomyces cerevisiae, is not transcribed during growth on fermentable carbon sources such as glucose. Growth of yeast cells in a medium containing only nonfermentable carbon sources leads to a marked increase or derepression of ADH2 expression. The recessive mutation, adr6-1, leads to an inability to fully derepress ADH2 expression and to an inability to sporulate. The ADR6 gene product appears to act directly or indirectly on ADH2 sequences 3' to or including the presumptive TATAA box. The upstream activating sequence (UAS) located 5' to the TATAA box is not required for the Adr6- phenotype. Here, we describe the isolation of a recombinant plasmid containing the wild-type ADR6 gene. ADR6 codes for a 4.4-kb RNA which is present during growth both on glucose and on nonfermentable carbon sources. Disruption of the ADR6 transcription unit led to viable cells with decreased ADHII activity and an inability to sporulate. This indicates that both phenotypes result from mutations within a single gene and that the adr6-1 allele was representative of mutations at this locus. The ADR6 gene mapped to the left arm of chromosome XVI at a site 18 centimorgans from the centromere.


Genetics ◽  
1992 ◽  
Vol 132 (2) ◽  
pp. 351-359 ◽  
Author(s):  
L Karnitz ◽  
M Morrison ◽  
E T Young

Abstract Using a new selection protocol we have identified and preliminarily characterized three new loci (ADR7, ADR8 and ADR9) which affect ADH2 (alcohol dehydrogenase isozyme II) expression. Mutants were selected which activate ADH2 expression in the presence of an over-expressed, normally inactive ADR1 allele. The mutants had very similar phenotypes with the exception that one was temperature sensitive for growth. In the absence of any ADR1 allele, the mutants allowed ADH2 to partially escape glucose repression. However, unlike wildtype strains deleted for ADR1, the mutants were able to efficiently derepress ADH2. The mutations allowed a small escape from glucose repression for secreted invertase, but had no effect on the glucose repression of isocitrate lyase or malate dehydrogenase. The mutations were shown to be nonallelic to a wide variety of previously characterized mutations, including mutations that affect other glucose-repressed enzymes.


Genetics ◽  
1990 ◽  
Vol 124 (3) ◽  
pp. 515-522
Author(s):  
L P Wakem ◽  
F Sherman

Abstract Approximately 290 omnipotent suppressors, which enhance translational misreading, were isolated in strains of the yeast Saccharomyces cerevisiae containing the psi+ extrachromosomal determinant. The suppressors could be assigned to 8 classes by their pattern of suppression of five nutritional markers. The suppressors were further distinguished by differences in growth on paromomycin medium, hypertonic medium, low temperatures (10 degrees), nonfermentable carbon sources, alpha-aminoadipic acid medium, and by their dominance and recessiveness. Genetic analysis of 12 representative suppressors resulted in the assignment of these suppressors to 6 different loci, including the three previously described loci SUP35 (chromosome IV), SUP45 (chromosome II) and SUP46 (chromosome II), as well as three new loci SUP42 (chromosome IV), SUP43 (chromosome XV) and SUP44 (chromosome VII). Suppressors belonging to the same locus had a wide range of different phenotypes. Differences between alleles of the same locus and similarities between alleles of different loci suggest that the omnipotent suppressors encode proteins that effect different functions and that altered forms of each of the proteins can effect the same function.


1998 ◽  
Vol 329 (2) ◽  
pp. 383-388 ◽  
Author(s):  
Isabel ORDIZ ◽  
Pilar HERRERO ◽  
Rosaura RODICIO ◽  
M. Juana GANCEDO ◽  
Fernando MORENO

Isocitrate lyase, encoded by ICL1, is one of the key enzymes of the glyoxylate pathway, which operates as an anaplerotic route for replenishing the tricarboxylic acid cycle; it is required for growth of Saccharomyces cerevisiae on carbon sources such as ethanol, but is dispensable when fermentable carbon sources are available. The positive regulation of the ICL1 gene by an upstream activating sequence (UAS) element located between -397 and -388 has been previously reported. In this paper we show that the ICL1 promoter sequence 5ʹ-AGTCCGGACTAGCATCCCAG-3ʹ located between -261 and -242 contains an upstream repressing sequence (URS) element. We have identified and partially purified a 27 kDa protein that binds specifically to both the UAS and URS sequences of the ICL1 promoter. For both UAS and URS, binding requires the protein Snf1 (Cat1), a protein kinase essential for the derepression of genes repressed by glucose. Binding does not take place with extracts from glucose-grown strains, unless they lack Mig1, a negative regulatory protein involved in glucose repression.


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