Genes Required for Transcription of STA1 encoding an Extracellular Glucoamylase in the Yeast Saccharomyces

Abstract

Mutants of Saccharomyces diastaticus with defects in starch fermentation were isolated. In addition to the mutations in the STA1 structural gene for glucoamylase (sta1) and in the transcription factor (gam1), we recovered two new complementation groups, designated gam2 and gam3. These starch-nonfermenting mutants secreted little or no glucoamylase. The gam1 and gam2 mutants were pleiotropically defective in use of nonfermentable carbon sources, and consequently did not undergo meiosis and sporulation. No pleiotrophy was detected in the gam3 mutant. RNA blot analysis revealed that GAM2 and GAM3 are also required for transcription of STA1