DNA Mismatch Repair in Bacteria

摘要: There are two major DNA mismatch-repair (MMR) systems in bacteria to correct biosynthetic errors. Long-patch repair involve a long-patch excision and resynthesis (up 1000 nucleotides) specific particular strand. Short-patch have tract shorter than 15 nucleotides, dictated by the nature of mismatches. The methyl-directed MMR distinguishes daughter strand from parental hemi-methylated state enhances fidelity replication genetic recombination. Cells defective several hundred-fold higher spontaneous mutation frequencies transitions short nucleotide insertion/deletion mutations. MMR-defective strains resistant some types alkylating agents. also has an anti-recombination function limiting recombination between divergent sequences preventing gross chromosomal rearrangement. short-patch MutY base pathway is independent methylation. MutY, adenine glycosylase, responsible for reduction errors caused oxidized guanines (8-oxoGs). may be coupled with cooperate mismatch achieve anti-mutagenic functions.