Suppression of spontaneous and hydrogen peroxide-induced mutations by a MutT-type nucleotide pool sanitization enzyme, the Escherichia coli Orf135 protein.
BACKGROUND
We recently found that the Escherichia coli Orf135 protein, a MutT-type enzyme, hydrolysed 2-hydroxy-dATP (2-OH-dATP), and less efficiently, 8-hydroxy-dGTP.


RESULTS
In this study, we examined the effects of the absence of the orf135 gene. Frequencies of spontaneous and H2O2-induced mutations were two- to three-fold higher in the orf135- strain than in the wild-type strain. These mutations include various mutations involving a G:C-->T:A transversion, the same type of mutation elicited by 2-OH-dATP. Over-expression of the Orf135 protein suppressed mutations even in the wild-type strain, as well as in the orf135- strain.


CONCLUSIONS
The mutator phenotype of bacteria lacking the Orf135 protein suggests that this protein is involved in the suppression of mutations induced by oxidized deoxynucleotides in vivo and that various MutT-type enzymes contribute to nucleotide pool sanitization.
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
Iida
Emiko
E
Murata-Kamiya
Naoko
N
Yamamoto
Yoshihiro
Y
Miki
Takeyoshi
T
Harashima
Hideyoshi
H
D001483:Base Sequence; D004252:DNA Mutational Analysis; D003854:Deoxyribonucleotides / Q000378:metabolism; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000145:classification / Q000235:genetics / Q000502:physiology*; D015870:Gene Expression; D006861:Hydrogen Peroxide / Q000633:toxicity*; D008969:Molecular Sequence Data; D009154:Mutation; D010084:Oxidation-Reduction; D010641:Phenotype; D010744:Phosphoric Monoester Hydrolases / Q000145:classification; D011755:Pyrophosphatases / Q000145:classification / Q000235:genetics / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000096964:Nudix Hydrolases
D003854:Deoxyribonucleotides; D029968:Escherichia coli Proteins; D006861:Hydrogen Peroxide; D010744:Phosphoric Monoester Hydrolases; D011755:Pyrophosphatases; D011994:Recombinant Proteins; C052211:mutT protein, E coli; C422942:nudix hydrolase Orf135; D000096964:Nudix Hydrolases