Open AccessConstitutive and Hyperresponsive Signaling by Mutant Forms of Saccharomyces cerevisiae Amino Acid Sensor Ssy1
Author(s) -
Richard F. Gaber,
Kim Ekelund Ottow,
H.A. Andersen,
Morten C. KiellandBrandt
Publication year - 2003
Publication title -
eukaryotic cell
Language(s) - English
Resource type - Journals
eISSN - 1535-9778
pISSN - 1535-9786
DOI - 10.1128/ec.2.5.922-929.2003
Subject(s) - permease , amino acid , saccharomyces cerevisiae , biology , mutant , biochemistry , extracellular , yeast , signal transduction , inducer , membrane transport protein , gene , microbiology and biotechnology , transporter
Sensing of extracellular amino acids results in transcriptional induction of amino acid permease genes in yeast. Ssy1, a membrane protein resembling amino acid permeases, is required for signaling but is apparently unable to transport amino acids and is thus believed to be a sensor. By using a novel genetic screen in which potassium uptake was made dependent on amino acid signaling, we obtained gain-of-function mutations in SSY1. Some alleles confer inducer-independent signaling; others increase the apparent affinity for inducers. The results reveal that amino acid transport is not required for signaling and support the notion that sensing by Ssy1 occurs via its direct interaction with extracellular amino acids.