UvrA and UvrB enhance mutations induced by oxidized deoxyribonucleotides.
Oxidatively damaged DNA precursors (deoxyribonucleotides) are formed by reactive oxygen species. After the damaged DNA precursors are incorporated into DNA, they might be removed by DNA repair enzymes. In this study, to examine whether a nucleotide excision repair enzyme, Escherichia coli UvrABC, could suppress the mutations induced by oxidized deoxyribonucleotides in vivo, oxidized DNA precursors, 8-hydroxy-2'-deoxyguanosine 5'-triphosphate and 2-hydroxy-2'-deoxyadenosine 5'-triphosphate, were introduced into uvrA, uvrB, and uvrC E. coli strains, and mutations in the chromosomal rpoB gene were analyzed. Unexpectedly, these oxidized DNA precursors induced mutations only slightly in the uvrA and uvrB strains. In contrast, effect of the uvrC-deficiency was not observed. Next, mutT, mutT/uvrA, and mutT/uvrB E. coli strains were treated with H2O2, and the rpoB mutant frequencies were calculated. The frequency of the H2O2-induced mutations was increased in all of the strains tested; however, the increase was three- to four-fold lower in the mutT/uvrA and mutT/uvrB strains than in the mutT strain. Thus, UvrA and UvrB are involved in the enhancement, but not in the suppression, of the mutations induced by these oxidized deoxyribonucleotides. These results suggest a novel role for UvrA and UvrB in the processing of oxidative damage.
Hori
Mika
M
Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo 060-0812, Japan.
Ishiguro
Chieko
C
Suzuki
Tetsuya
T
Nakagawa
Noriko
N
Nunoshiba
Tatsuo
T
Kuramitsu
Seiki
S
Yamamoto
Kazuo
K
Kasai
Hiroshi
H
Harashima
Hideyoshi
H
Kamiya
Hiroyuki
H
D000251:Adenosine Triphosphatases / Q000502:physiology*; D001483:Base Sequence; D004265:DNA Helicases / Q000502:physiology*; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins / Q000502:physiology*; D003854:Deoxyribonucleotides / Q000737:chemistry / Q000494:pharmacology*; D029968:Escherichia coli Proteins / Q000502:physiology*; D009154:Mutation; D010084:Oxidation-Reduction; D018384:Oxidative Stress
D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D003854:Deoxyribonucleotides; D029968:Escherichia coli Proteins; C058093:UvrB protein, E coli; C068631:UvrA protein, E coli; D000251:Adenosine Triphosphatases; D004265:DNA Helicases