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Nature

Title:		Srb10/Cdk8 regulates yeast filamentous growth by phosphorylating the transcription factor Ste12
Author(s):		Nelson C; Goto S; Lund K; Hung W; Sadowski I;
Address:		"Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada"
Journal Title:		Nature
Year:		2003
Volume:		421
Issue:		6919
Page Number:		187 - 190
DOI:		10.1038/nature01243
ISSN/ISBN:		0028-0836 (Print) 0028-0836 (Linking)
Abstract:		"The budding yeast Saccharomyces cerevisiae differentiates into filamentous invasively growing forms under conditions of nutrient limitation. This response is dependent on the transcription factor Ste12 and on the mating pheromone-response mitogen-activated protein (MAP) kinase cascade, but a mechanism for regulation of Ste12 by nutrient limitation has not been defined. Here we show that Ste12 function in filamentous growth is regulated by the cyclin-dependent kinase Srb10 (also known as Cdk8), which is associated with the RNA polymerase II holoenzyme. Srb10 inhibits filamentous growth in cells growing in rich medium by phosphorylating Ste12 and decreasing its stability. Under conditions of limiting nitrogen, loss of Srb10 protein and kinase activity occurs, with a corresponding loss of Ste12 phosphorylation. Mutation of the Srb10-dependent phosphorylation sites increases pseudohyphal development but has no effect on the pheromone response of haploid yeast. Srb10 kinase activity is also regulated independently of the mating pheromone-response pathway. This indicates that Srb10 controls Ste12 activity for filamentous growth in response to nitrogen limitation and is consistent with the hypothesis that Srb10 regulates gene-specific activators in response to physiological signals to coordinate gene expression with growth potential"
Keywords:		"Cell Division Cyclin-Dependent Kinase 8 Cyclin-Dependent Kinases/antagonists & inhibitors/*metabolism Fungal Proteins/genetics/*metabolism Gene Expression Regulation, Fungal Mutation Nitrogen/metabolism/pharmacology Phosphorylation/drug effects Phosphoser;"
Notes:		"MedlineNelson, Chris Goto, Susan Lund, Karen Hung, Wesley Sadowski, Ivan eng Research Support, Non-U.S. Gov't England 2003/01/10 Nature. 2003 Jan 9; 421(6919):187-90. doi: 10.1038/nature01243"