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RecA‐mediated excision repair: a novel mechanism for repairing DNA lesions at sites of arrested DNA synthesis
Author(s) -
Bichara Marc,
Pinet Isabelle,
Lambert Iain B.,
Fuchs Robert P. P.
Publication year - 2007
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2007.05790.x
Subject(s) - biology , homologous recombination , dna repair , plasmid , nucleotide excision repair , dna , replication protein a , microbiology and biotechnology , dna polymerase , dna replication , polymerase , genetics , gene , dna binding protein , transcription factor
Summary In Escherichia coli, bulky DNA lesions are repaired primarily by nucleotide excision repair (NER). Unrepaired lesions encountered by DNA polymerase at the replication fork create a blockage which may be relieved through RecF‐dependent recombination. We have designed an assay to monitor the different mechanisms through which a DNA polymerase blocked by a single AAF lesion may be rescued by homologous double‐stranded DNA sequences. Monomodified single‐stranded plasmids exhibit low survival in non‐SOS induced E. coli cells; we show here that the presence of a homologous sequence enhances the survival of the damaged plasmid more than 10‐fold in a RecA‐dependent way. Remarkably, in an NER proficient strain, 80% of the surviving colonies result from the UvrA‐dependent repair of the AAF lesion in a mechanism absolutely requiring RecA and RecF activity, while the remaining 20% of the surviving colonies result from homologous recombination mechanisms. These results uncover a novel mechanism – RecA‐mediated excision repair – in which RecA‐dependent pairing of the mono‐modified single‐stranded template with a complementary sequence allows its repair by the UvrABC excinuclease.