HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Mazur, P. Articles by Kelly, R. Search for Related Content PubMed PubMed Citation Articles by Mazur, P. Articles by Kelly, R. Agricola Articles by Mazur, P. Articles by Kelly, R.

Purification of geranylgeranyltransferase I from Candida albicans and cloning of the CaRAM2 and CaCDC43 genes encoding its subunits

Department of Biochemistry, Merck Research Laboratories, RY80Y-200, PO Box 2000, Rahway, NJ 07065, USA

ABSTRACT

All previously characterized protein geranylgeranyltransferases I (GGTase I) are heterodimeric zinc metalloenzymes which catalyse geranylgeranylation of a cysteine residue in proteins containing a C-terminal CaaL motif (C, Cys; a, aliphatic amino acid; L, Leu). The and β subunits of GGTase I of Saccharomyces cerevisiae are encoded by RAM2 and CDC43, respectively, and are essential for yeast viability. The authors are therefore investigating the role of geranylgeranylation in the related pathogenic yeast, Candida albicans, which is the most prevalent human fungal pathogen. GGTase I was purified to near homogeneity and also found to be a heterodimeric magnesium-dependent, zinc metalloenzyme displaying selectivity for CaaL-containing protein substrates. GGTase I peptide sequences were obtained from the purified protein and used to clone the genes encoding both subunits. CaRAM2 and CaCDC43 encode proteins that are 42 and 34% identical to their corresponding S. cerevisiae homologues, respectively, and 30% identical to their human homologues. Despite the limited overall homology, key zinc- and substrate-binding residues of the β subunit (Cdc43p) are conserved. A unique feature of CaCdc43p is a tract of polyasparagine whose length varies from 6 to 17 residues among C. albicans strains and between alleles. Coexpression of both CaCDC43 and CaRAM2 under their native promoters complemented the ts defect of a S. cerevisiae cdc43 mutant but expression of the β-subunit alone did not correct the growth defect, suggesting that hybrid GGTase I heterodimers are nonfunctional.

Author for correspondence: Rosemarie Kelly. Tel: +1 732 594 6385. Fax: +1 732 594 5468. e-mail: rosemarie_kelly@merck.com

This article has been cited by other articles:

				M. A. Hast and L. S. Beese Structure of Protein Geranylgeranyltransferase-I from the Human Pathogen Candida albicans Complexed with a Lipid Substrate J. Biol. Chem., November 14, 2008; 283(46): 31933 - 31940. [Abstract] [Full Text] [PDF]

				J. L. Song and T. C. White RAM2: an essential gene in the prenylation pathway of Candida albicans Microbiology, January 1, 2003; 149(1): 249 - 259. [Abstract] [Full Text] [PDF]

				R. Kelly, D. Card, E. Register, P. Mazur, T. Kelly, K.-I. Tanaka, J. Onishi, J. M. Williamson, H. Fan, T. Satoh, et al. Geranylgeranyltransferase I of Candida albicans: Null Mutants or Enzyme Inhibitors Produce Unexpected Phenotypes J. Bacteriol., February 1, 2000; 182(3): 704 - 713. [Abstract] [Full Text]