Molecular and Genetic Analysis of the Snf7 Gene in Saccharomyces Cerevisiae

Mutations in the SNF7 gene of Saccharomyces cerevisiae prevent full derepression of the SUC2 (invertase) gene in response to glucose limitation. We report the molecular cloning of the SNF7 gene by complementation. Sequence analysis predicts that the gene product is a 27-kDa acidic protein. Disruption of the chromosomal locus causes a fewfold decrease in invertase derepression, a growth defect on raffinose, temperature-sensitive growth on glucose, and a sporulation defect in homozygous diploids. Genetic analysis of the interactions of the snf7 null mutation with ssn6 and spt6/ssn20 suppressor mutations distinguished SNF7 from the SNF2, SNF5 and SNF6 genes. The snf7 mutation also behaved differently from mutations in SNF1 and SNF4 in that snf7 ssn6 double mutants displayed a synthetic phenotype of severe temperature sensitivity for growth. We also mapped SNF7 to the right arm of chromosome XII near the centromere.