title: Repair of hydantoins, one electron oxidation product of 8-oxoguanine, by DNA glycosylases of Escherichia coli.
abstract: 8-oxoguanine (8-oxoG), induced by reactive oxygen species and arguably one of the most important mutagenic DNA lesions, is prone to further oxidation. Its one-electron oxidation products include potentially mutagenic guanidinohydantoin (Gh) and spiroiminodihydantoin (Sp) because of their mispairing with A or G. All three oxidized base-specific DNA glycosylases of Escherichia coli, namely endonuclease III (Nth), 8-oxoG-DNA glycosylase (MutM) and endonuclease VIII (Nei), excise Gh and Sp, when paired with C or G in DNA, although Nth is less active than the other two. MutM prefers Sp and Gh paired with C (kcat/K(m) of 0.24-0.26 min(-1) x nM(-1)), while Nei prefers G over C as the complementary base (k(cat)/K(m) - 0.15-0.17 min(-1) x nM(-1)). However, only Nei efficiently excises these paired with A. MutY, a 8-oxoG.A(G)-specific A(G)-DNA glycosylase, is inactive with Gh(Sp).A/G-containing duplex oligonucleotide, in spite of specific affinity. It inhibits excision of lesions by MutM from the Gh.G or Sp.G pair, but not from Gh.C and Sp.C pairs. In contrast, MutY does not significantly inhibit Nei for any Gh(Sp) base pair. These results suggest a protective function for MutY in preventing mutation as a result of A (G) incorporation opposite Gh(Sp) during DNA replication.
authors.affiliation: Sealy Center for Molecular Science and Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, 6.136 Medical Research Building, Route 1079, Galveston, TX 77555, USA.
authors.forename: T K
authors.initials: TK
authors.lastname: Hazra
authors.forename: J G
authors.initials: JG
authors.lastname: Muller
authors.forename: R C
authors.initials: RC
authors.lastname: Manuel
authors.forename: C J
authors.initials: CJ
authors.lastname: Burrows
authors.forename: R S
authors.initials: RS
authors.lastname: Lloyd
authors.forename: S
authors.initials: S
authors.lastname: Mitra
mesh_terms: D045647:DNA Glycosylases; D004260:DNA Repair; D043382:DNA-Formamidopyrimidine Glycosylase; D043224:Deoxyribonuclease (Pyrimidine Dimer); D004583:Electrons; D004706:Endodeoxyribonucleases / Q000737:chemistry / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins; D006146:Guanidines / Q000737:chemistry / Q000378:metabolism*; D006147:Guanine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism*; D006151:Guanosine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism*; D006827:Hydantoins / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D009699:N-Glycosyl Hydrolases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D010084:Oxidation-Reduction; D011485:Protein Binding; D012545:Schiff Bases / Q000737:chemistry; D013141:Spiro Compounds / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D004791:Enzyme Inhibitors; D029968:Escherichia coli Proteins; D006146:Guanidines; D006827:Hydantoins; D012545:Schiff Bases; D013141:Spiro Compounds; C467338:guanidinohydantoin; C408822:spiroiminodihydantoin; D006151:Guanosine; C024829:8-hydroxyguanine; D006147:Guanine; D004706:Endodeoxyribonucleases; D043224:Deoxyribonuclease (Pyrimidine Dimer); C106403:NTH protein, E coli; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; C061738:mutY adenine glycosylase; D043382:DNA-Formamidopyrimidine Glycosylase; C468610:DNA-formamidopyrimidine glycosylase, E coli