HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Supplementary data Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Fernandes, H. Articles by Crouzet, M. Search for Related Content PubMed PubMed Citation Articles by Fernandes, H. Articles by Crouzet, M. Agricola Articles by Fernandes, H. Articles by Crouzet, M.

The Rho3 and Rho4 small GTPases interact functionally with Wsc1p, a cell surface sensor of the protein kinase C cell-integrity pathway in Saccharomyces cerevisiae

Helder Fernandes

Olivier Roumanie

Sandra Claret

Laboratoire de Biologie Moléculaire et de Séquençage, Institut de Biochimie et Génétique Cellulaires, UMR Université Victor Segalen Bordeaux 2-CNRS 5095, box 64, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France

Correspondence
François Doignon
doignon{at}u-bordeaux2.fr

Rgd1, a GTPase-activating protein, is the only known negative regulator of the Rho3 and Rho4 small GTPases in the yeast Saccharomyces cerevisiae. Rho3p and Rho4p are involved in regulating cell polarity by controlling polarized exocytosis. Co-inactivation of RGD1 and WSC1, which is a cell wall sensor-encoding gene, is lethal. Another plasma membrane sensor, Mid2p, is known to rescue the rgd1wsc1 synthetic lethality. It has been proposed that Wsc1p and Mid2p act upstream of the protein kinase C (PKC) pathway to function as mechanosensors of cell wall stress. Analysis of the synthetic lethal phenomenon revealed that production of activated Rho3p and Rho4p leads to lethality in wsc1 cells. Inactivation of RHO3 or RHO4 was able to rescue the rgd1wsc1 synthetic lethality, supporting the idea that the accumulation of GTP-bound Rho proteins, following loss of Rgd1p, is detrimental if the Wsc1 sensor is absent. In contrast, the genetic interaction between RGD1 and MID2 was not due to an accumulation of GTP-bound Rho proteins. It was proposed that simultaneous inactivation of RGD1 and WSC1 constitutively activates the PKC–mitogen-activated protein kinase (MAP kinase) pathway. Moreover, it was shown that the activity of this pathway was not involved in the synthetic lethal interaction, which suggests the existence of another mechanism. Consistent with this idea, it was found that perturbations in Rho3-mediated polarized exocytosis specifically impair the abundance and processing of Wsc1 and Mid2 proteins. Hence, it is proposed that Wsc1p participates in the regulation of a Rho3/4-dependent cellular mechanism, and that this is distinct from the role of Wsc1p in the PKC–MAP kinase pathway.

Supplementary Fig. S1, available with the online version of this paper, shows the detection of phosphorylated and total Slt2p in isogenic WT and rho3-V51 strains grown in synthetic medium, the detection of phosphorylated and total Slt2p in a WT strain co-producing WT, GDP-blocked or GTP-blocked forms of Rho3 and Rho4 proteins from pCM185 and pCM189 plasmids, and the detection of phosphorylated and total Slt2p in a WT strain producing the GTP-blocked form of Rho3p or Rho4p from the pCM185 plasmid.

These authors contributed equally to this work.

Present address: Laboratoire de Génétique du Développement et Evolution, Institut Jacques Monod, 75251 Paris Cedex 05, France.

This article has been cited by other articles:

				D. J. Wright, E. Munro, M. Corbett, A. J. Bentley, N. J. Fullwood, S. Murray, and C. Price The Saccharomyces cerevisiae Actin Cytoskeletal Component Bsp1p Has an Auxiliary Role in Actomyosin Ring Function and in the Maintenance of Bud-Neck Structure Genetics, April 1, 2008; 178(4): 1903 - 1914. [Abstract] [Full Text] [PDF]

				H.-O. Park and E. Bi Central Roles of Small GTPases in the Development of Cell Polarity in Yeast and Beyond Microbiol. Mol. Biol. Rev., March 1, 2007; 71(1): 48 - 96. [Abstract] [Full Text] [PDF]