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Mol Biol Cell

Title:		Analysis of the thresholds for transcriptional activation by the yeast MAP kinases Fus3 and Kss1
Author(s):		Winters MJ; Pryciak PM;
Address:		"Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605. Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605 peter.pryciak@umassmed.edu"
Journal Title:		Mol Biol Cell
Year:		2018
Volume:		20180110
Issue:		5
Page Number:		669 - 682
DOI:		10.1091/mbc.E17-10-0578
ISSN/ISBN:		1939-4586 (Electronic) 1059-1524 (Print) 1059-1524 (Linking)
Abstract:		"Signaling in the pheromone response pathway of budding yeast activates two distinct MAP kinases (MAPKs), Fus3 and Kss1. Either MAPK alone can mediate pheromone-induced transcription, but it has been unclear to what degree each one contributes to transcriptional output in wild-type cells. Here, we report that transcription reflects the ratio of active to inactive MAPK, and not simply the level of active MAPK. For Kss1 the majority of MAPK molecules must be converted to the active form, whereas for Fus3 only a small minority must be activated. These different activation thresholds reflect two opposing effects of each MAPK, in which the inactive forms inhibit transcription, whereas the active forms promote transcription. Moreover, negative feedback from Fus3 limits activation of Kss1 so that it does not meet its required threshold in wild-type cells but does so only when hyperactivated in cells lacking Fus3. The results suggest that the normal transcriptional response involves asymmetric contributions from the two MAPKs, in which pheromone signaling reduces the negative effect of Kss1 while increasing the positive effect of Fus3. These findings reveal new functional distinctions between these MAPKs, and help illuminate how inhibitory functions shape positive pathway outputs in both pheromone and filamentation pathways"
Keywords:		"Gene Expression Regulation, Fungal *MAP Kinase Signaling System Mating Factor/*metabolism Mitogen-Activated Protein Kinases/genetics/*metabolism Phosphorylation Saccharomyces cerevisiae/metabolism Saccharomyces cerevisiae Proteins/genetics/*metabolism *Tr;"
Notes:		"MedlineWinters, Matthew J Pryciak, Peter M eng R01 GM057769/GM/NIGMS NIH HHS/ Research Support, N.I.H., Extramural 2018/01/13 Mol Biol Cell. 2018 Mar 1; 29(5):669-682. doi: 10.1091/mbc.E17-10-0578. Epub 2018 Jan 10"