title: Enzymatic characterization of a class II lysyl-tRNA synthetase, LysS, from Myxococcus xanthus.
abstract: Lysyl-tRNA synthetases efficiently produce diadenosine tetraphosphate (Ap4A) from lysyl-AMP with ATP in the absence of tRNA. We characterized recombinant class II lysyl-tRNA synthetase (LysS) from Myxococcus xanthus and found that it is monomeric and requires Mn(2+) for the synthesis of Ap4A. Surprisingly, Zn(2+) inhibited enzyme activity in the presence of Mn(2+). When incubated with ATP, Mn(2+), lysine, and inorganic pyrophosphatase, LysS first produced Ap4A and ADP, then converted Ap4A to diadenosine triphosphate (Ap3A), and finally converted Ap3A to ADP, the end product of the reaction. Recombinant LysS retained Ap4A synthase activity without lysine addition. Additionally, when incubated with Ap4A (minus pyrophosphatase), LysS converted Ap4A mainly ATP and AMP, or ADP in the presence or absence of lysine, respectively. These results demonstrate that M. xanthus LysS has different enzymatic properties from class II lysyl-tRNA synthetases previously reported.
authors.affiliation: Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki-cho, Kagawa, Japan.
authors.forename: Manami
authors.initials: M
authors.lastname: Oka
authors.affiliation: Department of Bioscience and Biotechnology, Kyusyu University, Hakozaki, Higashi-ku, Fukuoka, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Takegawa
authors.affiliation: Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki-cho, Kagawa, Japan. Electronic address: kimura@ag.kagawa-u.ac.jp.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Kimura
mesh_terms: D000604:Amino Acyl-tRNA Synthetases / Q000737:chemistry*; D003198:Computer Simulation; D015226:Dinucleoside Phosphates / Q000138:chemical synthesis*; D004789:Enzyme Activation; D004795:Enzyme Stability; D007700:Kinetics; D008250:Lysine-tRNA Ligase / Q000737:chemistry*; D008345:Manganese / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D016941:Myxococcus xanthus / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D015226:Dinucleoside Phosphates; D008345:Manganese; C020733:diadenosine tetraphosphate; D000604:Amino Acyl-tRNA Synthetases; D008250:Lysine-tRNA Ligase
keywords: Diadenosine tetraphosphate; Diadenosine triphosphate; Lysyl-tRNA synthetase; Myxococcus xanthus