Increased A:T-->C:G mutations in the mutT strain upon 8-hydroxy-dGTP treatment: direct evidence for MutT involvement in the prevention of mutations by oxidized dGTP.
The Escherichia coli MutT protein hydrolyzes 8-hydroxy-dGTP (8-OH-dGTP) in vitro, and mutT gene deficiencies cause increased spontaneous A:T-->C:G mutations. However, no direct evidence exists for enhanced mutagenicity of 8-OH-dGTP in mutT cells. In this study, 8-OH-dGTP was introduced into wild type and mutT E. coli cells, and mutations of a chromosomal gene were monitored. 8-OH-dGTP induced mutations of the rpoB gene, the degree of the mutation induction in the mutT strain being approximately 6-fold higher than that in the wild type strain. On the other hand, 2-hydroxy-dATP, which is not a substrate of the MutT protein, increased the mutation to similar degrees in the two strains. These results constitute the first evidence that the MutT protein suppresses mutation by 8-OH-dGTP in vivo.
Kamiya
Hiroyuki
H
Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo 060-0812, Japan. hirokam@pharm.hokudai.ac.jp
Ishiguro
Chieko
C
Harashima
Hideyoshi
H
D000255:Adenosine Triphosphate / Q000737:chemistry; D004252:DNA Mutational Analysis; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D003854:Deoxyribonucleotides / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics*; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D009154:Mutation; D010100:Oxygen / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics*; D011755:Pyrophosphatases
D003854:Deoxyribonucleotides; D029968:Escherichia coli Proteins; C057674:8-hydroxyguanosine triphosphate; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D012321:DNA-Directed RNA Polymerases; C105078:RNA polymerase beta subunit; D010744:Phosphoric Monoester Hydrolases; D011755:Pyrophosphatases; C052211:mutT protein, E coli; D010100:Oxygen