Inactivation of recG stimulates the RecF pathway during lesion-induced recombination in E. coli.
Lesions that transiently block DNA synthesis generate replication intermediates with recombinogenic potential. In order to investigate the mechanisms involved in lesion-induced recombination, we developed an homologous recombination assay involving the transfer of genetic information from a plasmid donor molecule to the Escherichia coli chromosome. The replication blocking lesion used in the present assay is formed by covalent binding of the carcinogen N-2-acetylaminofluorene to the C8 position of guanine residues (G-AAF adducts). The frequency of recombination events was monitored as a function of the number of lesions present on the donor plasmid. These DNA adducts are found to trigger high levels of homologous recombination events in a dose-dependent manner. Formation of recombinants is entirely RecA-dependent, the RecF and RecBCD sub-pathways accounting for about 2/3 and 1/3, respectively. Inactivation of recG stimulates recombinant formation about five-fold. In a recG background, the RecF pathway is stimulated about four-fold, while the contribution of the RecBCD pathway remains constant. In addition, in the recG strain, a recombination pathway that accounts for about 30% of the recombinants and requires genes that belong to both RecF and RecBCD pathways is revealed.
Bichara
Marc
M
Departement Intégrité du Génome, UMR 7100, CNRS, Ecole Supérieure de Biotechnologie de Strasbourg, Boulevard Sebastien Brant, BP 10413, 67412 Illkirch-Cedex, France. bichara@esbs.u-strasbg.fr
Pinet
Isabelle
I
Origas
Mélanie
M
Fuchs
Robert P P
RP
D015073:2-Acetylaminofluorene / Q000494:pharmacology; D004249:DNA Damage / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D043211:Exodeoxyribonuclease V / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006147:Guanine / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D011938:Rec A Recombinases / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D015398:Signal Transduction
D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C489340:recF protein, E coli; C071446:RecG protein, E coli; D006147:Guanine; D015073:2-Acetylaminofluorene; D011938:Rec A Recombinases; D043211:Exodeoxyribonuclease V; C468322:exodeoxyribonuclease V, E coli