Very short patch mismatch repair activity associated with gene dcm is not conferred by a plasmid coding for EcoRII methylase
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Very short patch mismatch repair activity associated with gene dcm is not conferred by a plasmid coding for EcoRII methylase.
The only cytosine methylase in Escherichia coli K-12 methylates the second cytosine in the sequence CC (A/T)GG and is encoded by gene dcm. Methylation and very short patch mismatch repair activities lacking in a dcm mutant of E. coli were restored by a plasmid containing the cloned dcm gene. In contrast, plasmids with the gene for EcoRII methylase, which is a homolog of dcm, restored only cytos...
متن کاملSpontaneous mutation at a 5-methylcytosine hotspot is prevented by very short patch (VSP) mismatch repair.
In many strains of Escherichia coli, the product of gene dcm methylates the internal cytosines in the sequence 5'CC(A or T)GG. Spontaneous deamination of 5-methylcytosine produces thymine which, if not corrected, can result in a transition mutation. 5-Methylcytosines in the lacI gene are hotspots for spontaneous C to T mutations. dcm is linked to vsr, a gene required for very short patch (VSP) ...
متن کاملVery-short-patch repair in Escherichia coli requires the dam adenine methylase.
Strains of Escherichia coli which lack the dam-encoded adenine methylase are mutators due to a reduction in the efficiency of postreplication mismatch repair. In this study, we show that Dam(-) strains are also defective in very-short-patch repair, the system which corrects T/G mismatches arising from the deamination of 5-methylcytosine. This defect is associated with decreased levels of Vsr, t...
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The crystal structure of very short patch repair (Vsr) endonuclease, in complex with Mg2+ and with duplex DNA containing a TG mismatch, has been determined at 2.3 A resolution. In E. coli, the enzyme recognizes a TG mismatched base pair, generated after spontaneous deamination of methylated cytosines, and cleaves the phosphate backbone on the 5' side of the thymine. Extensive interactions betwe...
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Tsaalbi-Shtylik et al. reveal that DNA mismatch repair (MMR) proteins suppress UV-induced mutagenesis by removing nucleotides introduced by error-prone DNA polymerases. The MMR pathway is best known for its role in correcting the rare mistakes of replicative DNA polymerases. However, the MMR proteins Msh2 and Msh6 have also been implicated in preventing the introduction of DNA mutations followi...
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ژورنال
عنوان ژورنال: Journal of Bacteriology
سال: 1988
ISSN: 0021-9193,1098-5530
DOI: 10.1128/jb.170.10.4967-4968.1988