MUTATIONS IN GCR1, A TRANSCRIPTIONAL ACTIVATOR OF SACCHAROMYCES-CEREVISIAE GLYCOLYTIC GENES, FUNCTION AS SUPPRESSORS OF GCR2 MUTATIONS

The Saccharomyces cerevisiae GCR1 and GCR2 genes affect expression of most of the glycolytic genes. Evidence for Gcr1p / Gcr2p interaction h as been presented earlier and is now supported by the isolation of mut ations in Gcr1p suppressing gcr2, as assessed by growth and enzyme ass ay. Four specific mutation sites were identified. Together with use of the two-hybrid system of FIELDS and SONG, they show that Gcr1p in its N-terminal half has a potential transcriptional activating function a s well as elements for interaction with Gcr2p, which perhaps acts norm ally to expose an otherwise cryptic activation domain on Gcr1p. Comple mentation of various gcr1 mutant alleles and results with the two-hybr id system also indicate that Gcr1p itself normally functions as an oli gomer.