| Title: | GTPase-activating proteins for Cdc42 |
| Author(s): | Smith GR; Givan SA; Cullen P; Sprague GF; |
| Address: | "Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403-1229, USA" |
| DOI: | 10.1128/EC.1.3.469-480.2002 |
| ISSN/ISBN: | 1535-9778 (Print) 1535-9786 (Electronic) 1535-9786 (Linking) |
| Abstract: | "The Rho-type GTPase, Cdc42, has been implicated in a variety of functions in the yeast life cycle, including septin organization for cytokinesis, pheromone response, and haploid invasive growth. A group of proteins called GTPase-activating proteins (GAPs) catalyze the hydrolysis of GTP to GDP, thereby inactivating Cdc42. At the time this study began, there was one known GAP, Bem3, and one putative GAP, Rga1, for Cdc42. We identified another putative GAP for Cdc42 and named it Rga2 (Rho GTPase-activating protein 2). We confirmed by genetic and biochemical criteria that Rga1, Rga2, and Bem3 act as GAPs for Cdc42. A detailed characterization of Rga1, Rga2, and Bem3 suggested that they regulate different subsets of Cdc42 function. In particular, deletion of the individual GAPs conferred different phenotypes. For example, deletion of RGA1, but not RGA2 or BEM3, caused hyperinvasive growth. Furthermore, overproduction or loss of Rga1 and Rga2, but not Bem3, affected the two-hybrid interaction of Cdc42 with Ste20, a p21-activated kinase (PAK) kinase required for haploid invasive growth. These results suggest Rga1, and possibly Rga2, facilitate the interaction of Cdc42 with Ste20 to mediate signaling in the haploid invasive growth pathway. Deletion of BEM3 resulted in cells with severe morphological defects not observed in rga1delta or rga2delta strains. These data suggest that Bem3 and, to a lesser extent, Rga1 and Rga2 facilitate the role of Cdc42 in septin organization. Thus, it appears that the GAPs play a role in modulating specific aspects of Cdc42 function. Alternatively, the different phenotypes could reflect quantitative rather than qualitative differences in GAP activity in the mutant strains" |
| Keywords: | "Amino Acid Sequence GTPase-Activating Proteins/genetics/*metabolism Gene Deletion Genes, Fungal Genes, Reporter Haploidy Lac Operon Molecular Sequence Data Mutation Phenotype Saccharomyces cerevisiae/genetics/growth & development/*metabolism Saccharomyces;" |
| Notes: | "MedlineSmith, Gregory R Givan, Scott A Cullen, Paul Sprague, George F Jr eng GM-30027/GM/NIGMS NIH HHS/ T32 GM007413/GM/NIGMS NIH HHS/ GM-07413/GM/NIGMS NIH HHS/ GM-19888/GM/NIGMS NIH HHS/ T32 HD007348/HD/NICHD NIH HHS/ HD-07348/HD/NICHD NIH HHS/ R01 GM030027/GM/NIGMS NIH HHS/ F32 GM019888/GM/NIGMS NIH HHS/ Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S. 2002/11/29 Eukaryot Cell. 2002 Jun; 1(3):469-80. doi: 10.1128/EC.1.3.469-480.2002" |
