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Mol Microbiol

Title:		Rst1 and Rst2 are required for the a/alpha diploid cell type in yeast
Author(s):		Gelli A;
Address:		"Department of Internal Medicine, Division of Infectious and Immunologic Diseases, University of California, Davis, 1 Shields Avenue, School of Medicine, Tupper Hall, Room 3326, Davis, CA 95616, USA. acgelli@ucdavis.edu"
Journal Title:		Mol Microbiol
Year:		2002
Volume:		46
Issue:		3
Page Number:		845 - 854
DOI:		10.1046/j.1365-2958.2002.03213.x
ISSN/ISBN:		0950-382X (Print) 0950-382X (Linking)
Abstract:		"In the budding yeast Saccharomyces cerevisiae, the preservation of the mating competent haploid (a or alpha) and the mating incompetent diploid (a/alpha) is necessary to prevent aneuploidy. Once haploid cells respond to pheromone, the mating-specific signal transduction pathway is activated, and the MAP kinase Fus3 phosphorylates two specific repressor proteins Rst1 and Rst2 (also known as Dig1 and Dig2) to promote Ste12-dependent transcription of mating-specific genes. In contrast, diploid cells cannot mate because genes that encode components of the mating pathway are repressed through the combined action of the Mata1-Matalpha2 and Matalpha2-Mcm1 repressors. Surprisingly, repression of Ste12 by Rst1 and Rst2 is essential for diploid sterility. Homozygous deletion of both RST1 and RST2 (rst-) causes a/alpha diploid cells constitutively to express a-specific genes and mate preferentially as a-cells. This phenotype is sensitive to Ste12 dosage, as removal of one copy of STE12 completely reduces the ectopic activation of a-specific genes. The Matalpha2-Mcm1 complex, which normally represses a-specific genes, is defective in rst- diploids because Matalpha2 is destabilized in rst- diploids, possibly as a consequence of its relocalization from the nucleus to the cytoplasm. This study finds that Rst1 and Rst2 are necessary for the a/alpha diploid cell type. Rst1 and Rst2 are required in order to prevent the amplification of a robust Ste12 transcriptional programme that appears to over-ride Matalpha2-dependent repression of haploid and a-specific genes"
Keywords:		"*Diploidy Fungal Proteins/*metabolism *Gene Expression Regulation, Fungal Homeodomain Proteins/genetics/metabolism Phenotype Pheromones/pharmacology Repressor Proteins/genetics/metabolism Saccharomyces cerevisiae/*genetics/growth & development/physiology;"
Notes:		"MedlineGelli, Angie eng Research Support, Non-U.S. Gov't England 2002/11/02 Mol Microbiol. 2002 Nov; 46(3):845-54. doi: 10.1046/j.1365-2958.2002.03213.x"