QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

Vol. 17, Issue 4, 1620-1631, April 2006

This Article Full Text Full Text (PDF) All Versions of this Article: E05-10-0933v1 17/4/1620    most recent Alert me when this article is cited Alert me if a correction is posted Services 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 Google Scholar Google Scholar Articles by García, P. Articles by Sánchez, Y. Search for Related Content PubMed PubMed Citation Articles by García, P. Articles by Sánchez, Y.

Rgf1p Is a Specific Rho1-GEF That Coordinates Cell Polarization with Cell Wall Biogenesis in Fission Yeast

Instituto de Microbiología Bioquímica, CSIC/Universidad de Salamanca and Departamento de Microbiología y Genética, Universidad de Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain

Submitted October 7, 2005; Revised December 16, 2005; Accepted January 10, 2006
Monitoring Editor: Anne Ridley

Rho1p regulates cell integrity by controlling the actin cytoskeleton and cell wall synthesis. We have identified a new GEF, designated Rgf1p, which specifically regulates Rho1p during polarized growth. The phenotype of rgf1 null cells was very similar to that seen after depletion of Rho1p, 30% of cells being lysed. In addition, rgf1⁺ deletion caused hypersensitivity to the antifungal drug Caspofungin and defects in the establishment of bipolar growth. rho1⁺, but none of the other GTPases of the Rho-family, suppressed the rgf1 phenotypes. Moreover, deletion of rgf1⁺ suppressed the severe growth defect in rga1⁺ null mutants (a Rho1-GAP, negative regulator). Rgf1p and Rho1p coimmunoprecipitated and overexpression of rgf1⁺ specifically increased the GTP-bound Rho1p; it caused changes in cell morphology, and a large increase in (1,3)-glucan synthase activity. These effects were similar to those elicited when the hyperactive rho1-G15V allele was expressed. A genetic relationship was observed between Rgf1p, Bgs4p ([1,3]-glucan synthase), and Pck1p (protein kinase C [PKC] homologue); Bgs4p and Pck1p suppressed the hypersensitivity to Caspofungin in rgf1 mutants. Rgf1p localized to the growing ends and the septum, where Rho1, Pck1p, and Bgs4p are known to function. Our results suggest that Rgf1p probably activates the Rho functions necessary for coordinating actin deposition with cell wall biosynthesis during bipolar growth, allowing the cells to remodel their wall without risk of rupture.

Address correspondence to: Yolanda Sánchez (ysm{at}usal.es).

This article has been cited by other articles:

				S. E. Siegrist and C. Q. Doe Microtubule-induced cortical cell polarity Genes & Dev., March 1, 2007; 21(5): 483 - 496. [Abstract] [Full Text] [PDF]

				X. Varelas, D. Stuart, M. J. Ellison, and C. Ptak The Cdc34/SCF Ubiquitination Complex Mediates Saccharomyces cerevisiae Cell Wall Integrity Genetics, December 1, 2006; 174(4): 1825 - 1839. [Abstract] [Full Text] [PDF]