Identification and biochemical characterization of a unique Mn2+-dependent UMP kinase from Helicobacter pylori.
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.
Lee
Mon-Juan
MJ
Institute of Biotechnology, National Tsing Hua University, Hsinchu 30013, Taiwan.
Chien-Liang
Liu
L
Tsai
Ju-Ying
JY
Sue
Wae-Ting
WT
Hsia
Wan-Shun
WS
Huang
Haimei
H
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
D001426:Bacterial Proteins; D008345:Manganese; D006160:Guanosine Triphosphate; C023276:uridine monophosphate kinase; D009703:Nucleoside-Phosphate Kinase; D008274:Magnesium