title: RAM2: an essential gene in the prenylation pathway of Candida albicans.
abstract: Prenylation is a post-translational protein modification process that results in correct protein localization to membranes in the cell. It is mediated by at least three prenyltransferases (PTFs) in eukaryotic cells. The RAM2 gene encodes the common alpha-subunit of two PTFs, farnesyltransferase (FTase) and geranylgeranyltransferase I (GGTase I). In this study, the RAM2 gene of the prenylation pathway in the opportunistic pathogen Candida albicans was analysed. The heterozygote trisomy test was used to demonstrate that RAM2 is essential to the viability of C. albicans. RAM2 mRNA in the yeast and hyphae growth states was not detected by Northern blot analysis, but was detected by RT-PCR. Drugs that inhibit mammalian PTFs do not alter Candida cell growth, but they do inhibit FTase and GGTase I activities in cell-free enzyme assays. The data from genetic studies and cell-free enzyme assays suggest that the drugs may not have access to the Candida cytoplasm. The regulation of PTF subunits was also examined in a strain in which RAM2 was under the control of a regulable promoter. Overall, this study demonstrated that RAM2 is essential to C. albicans, indicating that protein prenylation is an indispensable cellular process in this yeast.
authors.affiliation: Department of Pathobiology, School of Public Health and Community Medicine, University of Washington, 4 Nickerson St, Suite 200, Seattle, WA 98109-1651, USA.
authors.forename: Jia L
authors.initials: JL
authors.lastname: Song
authors.forename: Theodore C
authors.initials: TC
authors.lastname: White
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000935:Antifungal Agents / Q000494:pharmacology; D002176:Candida albicans / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015966:Gene Expression Regulation, Fungal; D020043:Genes, Essential; D006720:Homozygote; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D017368:Protein Prenylation; D011499:Protein Processing, Post-Translational; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014166:Transferases / Q000235:genetics / Q000378:metabolism*; D014314:Trisomy
chemical_list: D000935:Antifungal Agents; D004791:Enzyme Inhibitors; C077378:RAM2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014166:Transferases; D019883:Alkyl and Aryl Transferases; C083291:geranylgeranyltransferase type-I; C064911:p21(ras) farnesyl-protein transferase