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Titolo:
ESCHERICHIA-COLI MUTY PROTEIN HAS A GUANINE-DNA GLYCOSYLASE THAT ACTSON 7,8-DIHYDRO-8-OXOGUANINE-GUANINE MISPAIR TO PREVENT SPONTANEOUS G-C-]C-G TRANSVERSIONS
Autore:
ZHANG QM; ISHIKAWA N; NAKAHARA T; YONEI S;
Indirizzi:
KYOTO UNIV,GRAD SCH SCI,RADIAT BIOL LAB,SAKYO KU,KITASHIRAKAWA OIWAKECHO KYOTO 6068502 JAPAN KYOTO UNIV,GRAD SCH SCI,RADIAT BIOL LAB,SAKYO KU KYOTO 6068502 JAPAN
Titolo Testata:
Nucleic acids research
fascicolo: 20, volume: 26, anno: 1998,
pagine: 4669 - 4675
SICI:
0305-1048(1998)26:20<4669:EMPHAG>2.0.ZU;2-F
Fonte:
ISI
Lingua:
ENG
Soggetto:
GENERATES G.C->T.A TRANSVERSIONS; G-A MISPAIRS; MISMATCH REPAIR; MUTATOR LOCUS; DAMAGED BASE; MUTATIONS; GENE; 8-HYDROXYGUANINE; 8-OXOGUANINE; MUTAGENESIS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
56
Recensione:
Indirizzi per estratti:
Citazione:
Q.M. Zhang et al., "ESCHERICHIA-COLI MUTY PROTEIN HAS A GUANINE-DNA GLYCOSYLASE THAT ACTSON 7,8-DIHYDRO-8-OXOGUANINE-GUANINE MISPAIR TO PREVENT SPONTANEOUS G-C-]C-G TRANSVERSIONS", Nucleic acids research, 26(20), 1998, pp. 4669-4675

Abstract

Low rates of spontaneous G:C-->C:G transversions would be achieved not only by the correction of base mismatches during DNA replication butalso by the prevention and removal of oxidative base damage in DNA. Escherichia coli must have several pathways to repair such mismatches and DNA modifications. In this study, we attempted to identify mutator loci leading to G:C-->C:G transversions in E.coli. The strain CC103 carrying a specific mutation in lacZ was mutagenized by random miniTn10 insertion mutagenesis, In this strain, only the G:C-->C:G change can revert the glutamic acid at codon 461, which is essential for sufficient beta-galactosidase activity to allow growth on lactose, Mutator strains were detected as colonies with significantly increased rates of papillae formation on glucose minimal plates containing P-Gal and X-Gal. We screened similar to 40 000 colonies and selected several mutator strains. The strain GC39 showed the highest mutation rate to Lac(+). The gene responsible for the mutator phenotypes, mut39, was mapped at around 67 min on the E.coli chromosome. The sequencing of the miniTn10-flanking DNA region revealed that the mut39 was identical to the mutY gene of E.coli. The plasmid carrying the mutY(+) gene reduced spontaneous G:C-->T:A and G:C-->C:G mutations in both mutY and mut39 strains. purified MutY protein bound to the oligonucleotides containing 7,8-dihydro-8-oxo-guanine (8oxoG):G and 8-oxoG:A, Furthermore, we found that the MutY protein had a DNA glycosylase activity which removes unmodified guanine from the 8-oxoG:G mispair. These results demonstrate that the MutY protein prevents the generation of G:C-->C:G transversions by removing guanine from the 8-oxoG:G mispair in E.coli.

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Documento generato il 28/09/20 alle ore 11:43:03