In:
Eukaryotic Cell, American Society for Microbiology, Vol. 12, No. 2 ( 2013-02), p. 368-377
Abstract:
In the budding yeast Saccharomyces cerevisiae , Rho4 GTPase partially plays a redundant role with Rho3 in the control of polarized growth, as deletion of RHO4 and RHO3 together, but not RHO4 alone, caused lethality and a loss of cell polarity at 30°C. Here, we show that overexpression of the constitutively active rho4 Q131L mutant in an rdi1 Δ strain caused a severe growth defect and generated large, round, unbudded cells, suggesting that an excess of Rho4 activity could block bud emergence. We also generated four temperature-sensitive rho4-Ts alleles in a rho3 Δ rho4 Δ strain. These mutants showed growth and morphological defects at 37°C. Interestingly, two rho4-Ts alleles contain mutations that cause amino acid substitutions in the N-terminal region of Rho4. Rho4 possesses a long N-terminal extension that is unique among the six Rho GTPases in the budding yeast but is common in Rho4 homologs in other yeasts and filamentous fungi. We show that the N-terminal extension plays an important role in Rho4 function since rho3 Δ rho4 Δ 61 cells expressing truncated Rho4 lacking amino acids (aa) 1 to 61 exhibited morphological defects at 24°C and a growth defect at 37°C. Furthermore, we show that Rho4 interacts with Bem2, a Rho GTPase-activating protein (RhoGAP) for Cdc42 and Rho1, by yeast two-hybrid, bimolecular fluorescence complementation (BiFC), and glutathione S -transferase (GST) pulldown assays. Bem2 specifically interacts with the GTP-bound form of Rho4, and the interaction is mediated by its RhoGAP domain. Overexpression of BEM2 aggravates the defects of rho3 Δ rho4 mutants. These results suggest that Bem2 might be a novel GAP for Rho4.
Type of Medium:
Online Resource
ISSN:
1535-9778
,
1535-9786
Language:
English
Publisher:
American Society for Microbiology
Publication Date:
2013
detail.hit.zdb_id:
2071564-X
SSG:
12
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