Mismatch repair inhibits homeologous recombination via coordinated directional unwinding of trapped DNA structures.
Mol Cell
; 51(3): 326-37, 2013 Aug 08.
Article
in En
| MEDLINE
| ID: mdl-23932715
ABSTRACT
Homeologous recombination between divergent DNA sequences is inhibited by DNA mismatch repair. In Escherichia coli, MutS and MutL respond to DNA mismatches within recombination intermediates and prevent strand exchange via an unknown mechanism. Here, using purified proteins and DNA substrates, we find that in addition to mismatches within the heteroduplex region, secondary structures within the displaced single-stranded DNA formed during branch migration within the recombination intermediate are involved in the inhibition. We present a model that explains how higher-order complex formation of MutS, MutL, and DNA blocks branch migration by preventing rotation of the DNA strands within the recombination intermediate. Furthermore, we find that the helicase UvrD is recruited to directionally resolve these trapped intermediates toward DNA substrates. Thus, our results explain on a mechanistic level how the coordinated action between MutS, MutL, and UvrD prevents homeologous recombination and maintains genome stability.
Full text:
1
Collection:
01-internacional
Health context:
3_ND
Database:
MEDLINE
Main subject:
DNA, Bacterial
/
Adenosine Triphosphatases
/
DNA Helicases
/
Escherichia coli Proteins
/
MutS DNA Mismatch-Binding Protein
/
DNA Mismatch Repair
/
Homologous Recombination
Language:
En
Journal:
Mol Cell
Year:
2013
Document type:
Article