Cell wall integrity modulates RHO1 activity via the exchange factor ROM2

Bickle, M. and Delley, P. A. and Schmidt, A. and Hall, M. N.. (1998) Cell wall integrity modulates RHO1 activity via the exchange factor ROM2. The EMBO Journal, 17 (8). pp. 2235-2245.

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Official URL: http://edoc.unibas.ch/dok/A5258180

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The essential phosphatidylinositol kinase homologue TOR2 of Saccharomyces cerevisiae controls the actin cytoskeleton by activating a GTPase switch consisting of RHO1 (GTPase), ROM2 (GEF) and SAC7 (GAP). We have identified two mutations, rot1-1 and rot2-1, that suppress the loss of TOR2 and are synthetic-lethal. The wild-type ROT1 and ROT2 genes and a multicopy suppressor, BIG1, were isolated by their ability to rescue the rot1-1 rot2-1 double mutant. ROT2 encodes glucosidase II, and ROT1 and BIG1 encode novel proteins. We present evidence that cell wall defects activate RHO1. First, rot1, rot2, big1, cwh41, gas1 and fks1 mutations all confer cell wall defects and suppress tor2(ts). Second, destabilizing the cell wall by supplementing the growth medium with 0.005% SDS also suppresses a tor2(ts) mutation. Third, disturbing the cell wall with SDS or a rot1, rot2, big1, cwh41, gas1 or fks1 mutation increases GDP/GTP exchange activity toward RHO1. These results suggest that cell wall defects suppress a tor2 mutation by activating RHO1 independently of TOR2, thereby inducing TOR2-independent polarization of the actin cytoskeleton and cell wall synthesis. Activation of RHO1, a subunit of the cell wall synthesis enzyme glucan synthase, by a cell wall alteration would ensure that cell wall synthesis occurs only when and where needed. The mechanism of RHO1 activation by a cell wall alteration is via the exchange factor ROM2 and could be analogous to signalling by integrin receptors in mammalian cells.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Growth & Development > Biochemistry (Hall)
UniBasel Contributors:Hall, Michael N.
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Nature Publishing Group
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:09 Nov 2017 08:25
Deposited On:22 Mar 2012 13:19

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