title: Design of allele-specific protein methyltransferase inhibitors.
abstract: Protein arginine methyltransferases, which catalyze the transfer of methyl groups from S-adenosylmethionine (SAM) to arginine side chains in target proteins, regulate transcription, RNA processing, and receptor-mediated signaling. To specifically address the functional role of the individual members of this family, we took a "bump-and-hole" approach and designed a series of N(6)-substituted S-adenosylhomocysteine (SAH) analogues that are targeted toward a yeast protein methyltransferase RMT1. A point mutation was identified (E117G) in Rmt1 that renders the enzyme susceptible to selective inhibition by the SAH analogues. A mass spectrometry based enzymatic assay revealed that two compounds, N(6)-benzyl- and N(6)-naphthylmethyl-SAH, can inhibit the mutant enzyme over the wild-type with the selectivity greater than 20. When the E117G mutation was introduced into the Saccharomyces cerevisiae chromosome, the methylation of Npl3p, a known in vivo Rmt1 substrate, could be moderately reduced by N(6)-naphthylmethyl-SAH in the resulting allele. In addition, an N(6)-benzyl-SAM analogue was found to serve as an orthogonal SAM cofactor. This analogue is preferentially utilized by the mutant methyltransferase relative to the wild-type enzyme with a selectivity greater than 67. This specific enzyme/inhibitor and enzyme/substrate design should be applicable to other members of this protein family and facilitate the characterization of protein methyltransferase function in vivo when combined with RNA expression analysis.
authors.affiliation: Department of Chemistry and Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
authors.forename: Q
authors.initials: Q
authors.lastname: Lin
authors.forename: F
authors.initials: F
authors.lastname: Jiang
authors.forename: P G
authors.initials: PG
authors.lastname: Schultz
authors.forename: N S
authors.initials: NS
authors.lastname: Gray
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D001665:Binding Sites; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D011484:Protein-Arginine N-Methyltransferases / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012436:S-Adenosylmethionine / Q000031:analogs & derivatives / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D004791:Enzyme Inhibitors; D012436:S-Adenosylmethionine; D011484:Protein-Arginine N-Methyltransferases