title: A mechanism for posttranslational modifications of proteins by yeast protein farnesyltransferase.
abstract: Protein farnesyltransferase catalyzes the alkylation of cysteine in C-terminal CaaX sequences of a variety of proteins, including Ras, nuclear lamins, large G proteins, and phosphodiesterases, by farnesyl diphosphate (FPP). These modifications enhance the ability of the proteins to associate with membranes and are essential for their respective functions. The enzyme-catalyzed reaction was studied by using a series of substrate analogs for FPP to distinguish between electrophilic and nucleophilic mechanisms for prenyl transfer. FPP analogs containing hydrogen, fluoromethyl, and trifluoromethyl substituents in place of the methyl at carbon 3 were evaluated as alternative substrates for alkylation of the sulfhydryl moiety in the peptide dansyl-GCVIA. The analogs were alternative substrates for the prenylation reaction and were competitive inhibitors against FPP. A comparison of kcat for FPP and the analogs with ksolv, the rate constants for solvolysis of related p-methoxybenzenesulfonate derivatives, indicated that protein prenylation occurred by an electrophilic mechanism.
authors.affiliation: Department of Chemistry, University of Utah, Salt Lake City 84112, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Dolence
authors.forename: C D
authors.initials: CD
authors.lastname: Poulter
mesh_terms: D019883:Alkyl and Aryl Transferases; D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003619:Dansyl Compounds; D007700:Kinetics; D008969:Molecular Sequence Data; D011106:Polyisoprenyl Phosphates / Q000378:metabolism*; D011485:Protein Binding; D017368:Protein Prenylation; D011499:Protein Processing, Post-Translational; D011506:Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D012717:Sesquiterpenes; D013379:Substrate Specificity; D014166:Transferases / Q000378:metabolism*
chemical_list: D003619:Dansyl Compounds; D011106:Polyisoprenyl Phosphates; D011506:Proteins; D011994:Recombinant Proteins; D012717:Sesquiterpenes; C004808:farnesyl pyrophosphate; D014166:Transferases; D019883:Alkyl and Aryl Transferases; C064911:p21(ras) farnesyl-protein transferase