This Article Full Text (PDF) References 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 Web of Science Similar articles in PubMed Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Manandhar, S. P. Articles by Schmidt, W. K. Search for Related Content PubMed PubMed Citation Articles by Manandhar, S. P. Articles by Schmidt, W. K. Social Bookmarking                         What's this?

Small-Molecule Inhibitors of the Rce1p CaaX Protease

Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia

Emily R. Hildebrandt

Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia

Walter K. Schmidt

Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, wschmidt{at}bmb.uga.edu

The Rce1p protease is required for the maturation of the Ras GTPase and certain other isoprenylated proteins and is considered a chemotherapeutic target. To identify new small-molecule inhibitors of Rce1p, the authors screened the National Cancer Institute Diversity Set compound library using in vitro assays to monitor the proteolytic processing of peptides derived from Ras and the yeast a-factor mating pheromone. Of 46 inhibitors initially identified with a Ras-based assay, only 9 were effective in the pheromone-based assay. The IC₅₀ values of these 9 compounds were in the low micromolar range for both yeast (6-35 µM) and human Rce1p (0.4-46 µM). Four compounds were somewhat Rce1p selective in that they partially inhibited the Ste24p protease and did not inhibit Ste14p isoprenylcysteine carboxyl methyltransferase, 2 enzymes also involved in the maturation of isoprenylated proteins. The remaining 5 compounds inhibited all 3 enzymes. The 2 most Rce1p-selective agents were ineffective trypsin inhibitors, further supporting the specificity of these agents for Rce1p. The 5 least specific compounds formed colloidal aggregates, a proposed common feature of promiscuous inhibitors. Interestingly, the most specific Rce1p inhibitor also formed a colloidal aggregate. In vivo studies revealed that treatment of wild-type yeast with 1 compound induced a Ras2p delocalization phenotype that mimics observed effects in rce1 ste24 null yeast. The 9 compounds identified in this study represent new tools for understanding the enzymology of postisoprenylation-modifying enzymes and provide new insight for the future development of Rce1p inhibitors. (Journal of Biomolecular Screening 2007:983-993)

Key Words: Ras • protease • CaaX protein • posttranslational modification • isoprenylation

Journal of Biomolecular Screening, Vol. 12, No. 7, 983-993 (2007)
DOI: 10.1177/1087057107307226


CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?