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Yeast Lrg1p acts as a specialized RhoGAP regulating 1,3‐β‐glucan synthesis
Author(s) -
Watanabe Daisuke,
Abe Mitsuhiro,
Ohya Yoshikazu
Publication year - 2001
Publication title -
yeast
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.923
H-Index - 102
eISSN - 1097-0061
pISSN - 0749-503X
DOI - 10.1002/yea.742
Subject(s) - biology , gtpase , mutant , gene , phosphorylation , genetics , protein subunit , yeast , effector , mutation , microbiology and biotechnology
Selection of an extragenic suppressor of fks1‐1154 Δfks2 , mutations in the catalytic subunits of yeast 1,3‐β‐glucan synthase (GS) conferring temperature‐sensitivity, led to the LRG1 gene, which was originally identified as a L IM‐ R ho G AP homologous gene. Mutations in the LRG1 gene restore impaired 1,3‐β‐glucan synthesis in the fks1‐1154 Δfks2 mutant as well as that in rho1‐2 , a temperature‐sensitive mutant of Rho‐type GTPase that functions as a regulatory subunit of GS. Two‐hybrid analyses of Lrg1p, which contains a sequence conserved among Rho GTPase‐activating proteins (GAPs), revealed its specific interactions with the active form of Rho1p. Among eight potential yeast RhoGAPs, Lrg1p is the only member that negatively regulates GS activity: mutations in the rest of GAPs, including bem2 , Δbem3 , Δsac7 , Δbag7 , Δrga1 , Δrga2 and Δrgd1 , do not suppress impairment of 1,3‐β‐glucan synthesis. Analyses of Mpk1p phosphorylation revealed the inability of Lrg1p to regulate the Pkc1p–MAP kinase cascade, a distinct Rho1p‐regulating signalling pathway known to be affected by the GAPs, Bem2p and Sac7p. Thus, different groups of Rho1p GAPs control the activity of different Rho1p‐effector proteins. Copyright © 2001 John Wiley & Sons, Ltd.