Carbon source dependence of transposable element-associated gene activation in Saccharomyces cerevisiae.
Seven cis-dominant mutations leading to the overproduction of the glucose-repressible alcohol dehydrogenase isozyme ADHII (structural gene, ADH2) in Saccharomyces cerevisiae have previously been shown to be due to insertion of a transposable element, Ty, in the 5' regulatory region of the ADH2 gene. We showed that although mating-competent cells (a, alpha, a/a, or alpha/alpha cells) overproduced both ADHII enzyme and ADH2 mRNA, mating-incompetent cells (a/alpha or ste-cells) produced much less ADHII enzyme and ADH2 mRNA. This mating type effect on ADH2 expression was greatest in the presence of a normally derepressing carbon source, glycerol, and much less apparent in the presence of a repressing carbon source, glucose. In addition, Ty insertion led to an aberrant carbon source response in mating-incompetent cells--the normally glucose-repressible ADHII becomes glycerol repressible. The mating type effect and aberrant carbon source response in mating-incompetent cells was specific for Ty-associated mutations in the 5' flanking region of the ADH2 gene in that a non-Ty mutation in the same region did not show these effects. Finally, Ty1 RNA levels also showed a/alpha, suppression, which was apparent only during growth on a nonfermentable carbon source such as glycerol. This suggests that Ty-mediated gene expression is subject to regulation by both mating competence and carbon catabolites.
D000426:Alcohol Dehydrogenase; D000429:Alcohol Oxidoreductases / Q000235:genetics; D004251:DNA Transposable Elements; D005800:Genes, Fungal; D049770:Genes, Mating Type, Fungal; D005947:Glucose / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics; D012331:RNA, Fungal / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism
D004251:DNA Transposable Elements; D007527:Isoenzymes; D012331:RNA, Fungal; D012333:RNA, Messenger; D000429:Alcohol Oxidoreductases; D000426:Alcohol Dehydrogenase; D005947:Glucose; D005990:Glycerol