The C-terminal domain of Snf3p mediates glucose-responsive signal transduction in Saccharomyces cerevisiae

The SNF3 protein is composed of distinct cytoplasmic and integral-membrane domains and functions as a low glucose sensor required for the expression of hexose transporters (the HXT genes) in Saccharomyces. We report herein that the C-terminal domain, when expressed independently of the integral membrane domain, leads to glucose-independent expression of HXT2 on gluconeogenic carbon sources. The C-terminal-domain-induced expression of Hxt2p is reduced in a SNF3 wild-type strain, suggesting that Snf3p competes with this C-terminal peptide for interacting downstream elements. The probable active site for the signal transducing interaction was mapped to either of the redundant 17 of 23 amino acid sequences found in this C-terminal domain. (C) 1998 Federation of European Microbiological Societies. Published by Elsevier Science B.V.