title: Base excision repair system suppresses mutagenesis caused by 8-hydroxy-dGTP in Escherichia coli.
abstract: To examine whether base excision repair suppresses mutations induced by oxidized deoxyribonucleotide 5'-triphosphates in the nucleotide pool, 8-hydroxy-dGTP (8-OH-dGTP) was introduced into Escherichia coli strains deficient in endonucleases III (Nth) and VIII (Nei), and MutY, and mutations in the chromosomal rpoB gene were analyzed. The spontaneous rpoB mutant frequency was also examined in mutT/nth and mutT/nei strains, to assess the influence on the mutations induced by the endogenous 8-OH-dGTP accumulated in the mutT mutant. Exogenous 8-OH-dGTP increased the rpoB mutant frequency more efficiently in the nth strain than that in the wild-type strain. The spontaneous mutant frequency in the mutT/nth strain was 1.8-fold higher than that in the mutT strain. These results suggest that E. coli endonuclease III also acts as a defense against the mutations caused by 8-OH-dGTP in the nucleotide pool.
authors.affiliation: Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo 060-0812, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Suzuki
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Hideyoshi
authors.initials: H
authors.lastname: Harashima
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kamiya
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D045647:DNA Glycosylases / Q000235:genetics / Q000502:physiology; D004260:DNA Repair; D045643:DNA Repair Enzymes / Q000502:physiology*; D003848:Deoxyguanine Nucleotides / Q000378:metabolism*; D043224:Deoxyribonuclease (Pyrimidine Dimer) / Q000235:genetics / Q000502:physiology; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000502:physiology; D005798:Genes, Bacterial; D016296:Mutagenesis
chemical_list: C521293:8-hydroxy-2'-deoxyguanosine 5'-triphosphate; D003848:Deoxyguanine Nucleotides; D029968:Escherichia coli Proteins; D000080242:8-Hydroxy-2'-Deoxyguanosine; D043224:Deoxyribonuclease (Pyrimidine Dimer); C106403:NTH protein, E coli; C468346:Nei protein, E coli; D045647:DNA Glycosylases; C061738:mutY adenine glycosylase; D045643:DNA Repair Enzymes