title: Identification and biochemical characterization of a unique Mn2+-dependent UMP kinase from Helicobacter pylori.
abstract: Uridine monophosphate (UMP) kinase converts UMP to the corresponding UDP in the presence of metal ions and ATP and is allosterically regulated by nucleotides such as UTP and GTP. Although the UMP kinase reported to date is Mg(2+)-dependent, we found in this study that the UMP kinase of Helicobacter pylori had a preference for Mn(2+) over Mg(2+), which may be related to a conformational difference between the Mn(2+)-bound and Mg(2+)-bound UMP kinase. Similar to previous findings, the UMP kinase activity of H. pylori UMP kinase was inhibited by UTP and activated by GTP. However, a relatively low GTP concentration (0.125 mM) was required to activate H. pylori UMP kinase to a level similar to other bacterial UMP kinases using a higher GTP concentration (0.5 mM). In addition, depending on the presence of either Mg(2+) or Mn(2+), a significant difference in the level of GTP activation was observed. It is therefore hypothesized that the Mg(2+)-bound and Mn(2+)-bound H. pylori UMP kinase may be activated by GTP through different mechanisms.
authors.affiliation: Institute of Biotechnology, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Mon-Juan
authors.initials: MJ
authors.lastname: Lee
authors.forename: Liu
authors.initials: L
authors.lastname: Chien-Liang
authors.forename: Ju-Ying
authors.initials: JY
authors.lastname: Tsai
authors.forename: Wae-Ting
authors.initials: WT
authors.lastname: Sue
authors.forename: Wan-Shun
authors.initials: WS
authors.lastname: Hsia
authors.forename: Haimei
authors.initials: H
authors.lastname: Huang
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D016480:Helicobacter pylori / Q000201:enzymology* / Q000235:genetics; D008274:Magnesium / Q000378:metabolism; D008345:Manganese / Q000378:metabolism*; D008969:Molecular Sequence Data; D009703:Nucleoside-Phosphate Kinase / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D008345:Manganese; D006160:Guanosine Triphosphate; C023276:uridine monophosphate kinase; D009703:Nucleoside-Phosphate Kinase; D008274:Magnesium