title: Three nth homologs are all required for efficient repair of spontaneous DNA damage in Deinococcus radiodurans.
abstract: Deinococcus radiodurans is a bacterium that can survive extreme DNA damage. To understand the role of endonuclease III (Nth) in oxidative repair and mutagenesis, we constructed nth single, double and triple mutants. The nth mutants showed no significant difference with wild type in both IR resistance and H(2)O(2) resistance. We characterized these strains with regard to mutation rates and mutation spectrum using the rpoB/Rif(r) system. The Rif(r) frequency of mutant MK1 (△dr0289) was twofold higher than that of wild type. The triple mutant of nth (ME3)generated a mutation frequency 34.4-fold, and a mutation rate 13.8-fold higher than the wild type. All strains demonstrated specific mutational hotspots. Each single mutant had higher spontaneous mutation frequency than wild type at base substitution (G:C → A:T). The mutational response was further increased in the double and triple mutants. The higher mutation rate and mutational response in ME3 suggested that the three nth homologs had non-overlapped and overlapped substrate spectrum in endogenous oxidative DNA repair.
authors.affiliation: Key Laboratory of Chinese Ministry of Agriculture for Nuclear-Agricultural Sciences, Institute of Nuclear-Agricultural Sciences, Zhejiang University, Hangzhou, 310029, China. xthua111@gmail.com
authors.forename: Xiaoting
authors.initials: X
authors.lastname: Hua
authors.forename: Xin
authors.initials: X
authors.lastname: Xu
authors.forename: Mingfeng
authors.initials: M
authors.lastname: Li
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.forename: Bing
authors.initials: B
authors.lastname: Tian
authors.forename: Yuejin
authors.initials: Y
authors.lastname: Hua
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004260:DNA Repair / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism*; D034301:Deinococcus / Q000201:enzymology* / Q000235:genetics; D043224:Deoxyribonuclease (Pyrimidine Dimer) / Q000235:genetics / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D009154:Mutation; D016877:Oxidants / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D016877:Oxidants; D006861:Hydrogen Peroxide; D043224:Deoxyribonuclease (Pyrimidine Dimer)