A role for the noncatalytic N terminus in the function of Cdc25, a Saccharomyces cerevisiae Ras-guanine nucleotide exchange factor

Chen, R. A., Michaeli, T., Van Aelst, L., Ballester, R. (April 2000) A role for the noncatalytic N terminus in the function of Cdc25, a Saccharomyces cerevisiae Ras-guanine nucleotide exchange factor. Genetics, 154 (4). pp. 1473-1484. ISSN 0016-6731

URL: http://www.ncbi.nlm.nih.gov/pubmed/10747046

Abstract

The Saccharomyces cerevisiae CDC25 gene encodes a guanine nucleotide exchange factor (GEF) for Ras proteins. Its catalytic domain is highly homologous to Ras-GEFs from all eukaryotes. Even though Cdc25 is the first Ras-GEF identified in any organism, we still know very little about how its function is regulated in yeast. In this work we provide evidence for the involvement of the N terminus of Cdc25 in the regulation of its activity. A truncated CDC25 lacking the noncatalytic C-terminal coding sequence was identified in a screen of high-copy suppressors of the heat-shock-sensitive phenotype of strains in which the Ras pathway is hyper-activated. The truncated gene acts as a dominant-negative mutant because it only suppresses the heat-shock sensitivity of strains that require the function of CDC25. Our two-hybrid assays and immunoprecipitation analyses show interactions between the N terminus of Cdc25 and itself the C terminus, and the full-length protein. These results suggest that the dominant-negative effect may be a result of oligomerization with endogenous Cdc25. Further evidence of the role of the N terminus of Cdc25 in the regulation of its activity is provided by the mapping of the activating mutation of CDC25HS20 to the serine residue at position 365 in the noncatalytic N-terminal domain. This mutation induces a phenotype similar to activating mutants of other genes in the Ras pathway in yeast. Hence, the N terminus may exert a negative control on the catalytic activity of the protein. Taken together these results suggest that the N terminus plays a crucial role in regulating Cdc25 and consequently Ras activity, which in S. cerevisiae is essential for cell cycle progression.

Item Type: Paper
Uncontrolled Keywords: GTPASE-ACTIVATING PROTEIN SIGNAL-TRANSDUCTION YEAST GENE CYCLASE DOMAINS SOS MODULATION PATHWAY CLONING
Subjects: bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > GTPase
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > G protein
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > G protein > Ras
organs, tissues, organelles, cell types and functions > tissues types and functions > signal transduction
organism description > yeast
CSHL Authors:
Communities: CSHL labs > Van Aelst lab
Depositing User: Matt Covey
Date: April 2000
Date Deposited: 18 Dec 2013 21:43
Last Modified: 18 Dec 2013 21:43
PMCID: PMC1461032
Related URLs:
URI: http://repository.cshl.edu/id/eprint/29104

Actions (login required)

Administrator's edit/view item Administrator's edit/view item
CSHL HomeAbout CSHLResearchEducationNews & FeaturesCampus & Public EventsCareersGiving