title: Molecular actions of Escherichia coli MutT for control of spontaneous mutagenesis.
abstract: MutT protein of Escherichia coli hydrolyzes oxidized guanine nucleotides, 8-oxo-dGTP and 8-oxoGTP, to the corresponding monophosphates, thereby preventing misincorporation of 8-oxoguanine into DNA and RNA, respectively. Although the biological significance of the MutT has been established, how MutT protein actually works in vivo remains to be elucidated. The current study shows the molecular behavior of the MutT protein in vivo and in vitro with special reference to control of spontaneous mutagenesis. A single E. coli cell carries about 70-75 molecules of the MutT protein and that this number does not change even when the cells were cultured in anaerobic and hyper-oxidative conditions. Conditional gene silencing analyses revealed that about a half number of MutT molecules are needed for keeping the spontaneous mutation frequency at the normal level. The MutT functions are not needed under anaerobic condition, yet the level of the MutT protein in cell is kept constant, probably for preparing for sudden changes of oxygen pressure. There is a possibility that MutT functions in close association with other proteins, and evidence is presented that MutT protein can interact with some proteins in vivo.
authors.affiliation: Advanced Science Research Center, Fukuoka Dental College, Sawara-ku, Fukuoka 814-0193, Japan. dseto@redoxnavi.med.kyushu-u.ac.jp
authors.forename: Daiki
authors.initials: D
authors.lastname: Setoyama
authors.forename: Riyoko
authors.initials: R
authors.lastname: Ito
authors.forename: Yasumitsu
authors.initials: Y
authors.lastname: Takagi
authors.forename: Mutsuo
authors.initials: M
authors.lastname: Sekiguchi
mesh_terms: D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D006150:Guanine Nucleotides / Q000378:metabolism; D016296:Mutagenesis / Q000187:drug effects; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism; D011755:Pyrophosphatases / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology
chemical_list: D029968:Escherichia coli Proteins; D006150:Guanine Nucleotides; D011755:Pyrophosphatases; C052211:mutT protein, E coli; D010100:Oxygen