A MEMBER OF A NOVEL FAMILY OF YEAST ZN-FINGER PROTEINS MEDIATES THE TRANSITION FROM STATIONARY-PHASE TO CELL-PROLIFERATION

The cloning and molecular characterization of the GCS1 gene from the b udding yeast Saccharomyces cerevisiae show that stationary phase is in fact a unique developmental state, with requirements to resume cell p roliferation that can be distinct from those for maintenance of prolif eration. Deletion of the GCS1 gene produces a novel phenotype: station ary-phase mutant cells do not resume proliferation at a restrictive te mperature of 15 degrees C, but mutant cells lacking GCS1 that are prol iferating at the permissive temperature of 29 degrees C continue to pr oliferate after transfer to 15 degrees C as long as nutrients are avai lable. The GCS1 gene sequence predicts a 39 kDa polypeptide with a nov el 'Zn-finger' motif. A point mutation within the finger motif produce s a phenotype that mimics that of deletion of the GCS1 gene, showing t hat the finger motif is essential for full Gcs1p activity. Gcs1p and t he products of two newly identified genes, SPS18 and GL03, constitute a family of novel Zn-finger proteins.