14-3-3 Proteins are essential for regulation of RTG3-dependent transcription in Saccharomyces cerevisiae.

14-3-3 proteins comprise a family of highly conserved proteins that bind more than 60 different, mostly phosphorylated, proteins. The yeast Saccharomyces cerevisiae has two genes, BMH1 and BMH2, encoding 14-3-3 proteins. Disruption of both genes together is lethal. In this study we constructed a mutant with a single, temperature-sensitive bmh allele. Recessive mutations in SIN4 and RTG3 can suppress the temperature-sensitive phenotype of this mutant. These genes encode a global transcriptional regulator and a basic helix-loop-helix transcription factor, respectively. The yeast 14-3-3 proteins were shown to bind to the Rtg3 protein. Overexpression of RTG3 is lethal even in wild-type cells. These genetic and biochemical data are consistent with a model in which the 14-3-3 proteins are required to keep the Rtg3 protein in an inactive state, which is (one of) the essential function(s) of the 14-3-3 proteins. Copyright 2001 John Wiley & Sons, Ltd.