title: Species-specific differences in the regulation of the aminoacylation activity of mammalian tryptophanyl-tRNA synthetases.
abstract: Tryptophanyl-tRNA synthetases (TrpRSs) catalyze the aminoacylation of tRNA(Trp). Previously, I demonstrated that Zn(2+)-depleted human TrpRS is enzymatically inactive and that binding of Zn(2+) or heme to human TrpRS stimulates its aminoacylation activity. In the present study, bovine and mouse TrpRSs were found to be constitutively active regardless of the presence of Zn(2+) or ferriprotoporphyrin IX chloride. Mutagenesis experiments demonstrated that the human H130R mutant is constitutively active and that the bovine R135H, E438A double mutant binds with Zn(2+) or heme to enhance its aminoacylation activity as does human wild-type TrpRS. These results provide the first evidence of species-specific regulation of TrpRS activity.
authors: Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan. wakasugi@bio.c.u-tokyo.ac.jp
authors: Keisuke
authors: K
authors: Wakasugi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D006427:Hemin / Q000378:metabolism*; D006801:Humans; D051379:Mice; D009154:Mutation; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism*; D013045:Species Specificity; D046249:Transfer RNA Aminoacylation; D014369:Tryptophan-tRNA Ligase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism*
chemical_list: D012346:RNA, Transfer, Amino Acyl; D006427:Hemin; D014369:Tryptophan-tRNA Ligase; D015032:Zinc