Error-free recombinational repair predominates over mutagenic translesion replication in E. coli.
Tolerance mechanisms are important in the ability of cells to cope with DNA damage. In E. coli, the two main damage tolerance mechanisms are recombinational repair (RR) and translesion replication (TLR). Here we show that RR effectively repairs gaps opposite DNA lesions. When both mechanisms are functional, RR predominates over TLR, being responsible for 86% of the repair events. This predominance of RR is determined by the high concentration of RecA present under SOS conditions, which causes a differential inhibition of TLR. Further inhibition of TLR is caused by the RecA-catalyzed strand exchange reaction of RR. This molecular hierarchy in the tolerance of DNA lesions ensures that the nonmutagenic RR predominates over the mutagenic TLR, thereby contributing to genetic stability.
Berdichevsky
Ala
A
Department of Biological Chemistry, The Weizmann Institute of Science, 76100, Rehovot, Israel.
Izhar
Lior
L
Livneh
Zvi
Z
D001426:Bacterial Proteins / Q000378:metabolism; D004249:DNA Damage / Q000235:genetics*; D004260:DNA Repair / Q000235:genetics*; D004261:DNA Replication / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000378:metabolism; D016296:Mutagenesis; D011938:Rec A Recombinases / Q000378:metabolism; D011995:Recombination, Genetic / Q000235:genetics*; D013014:SOS Response, Genetics
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D011938:Rec A Recombinases; C120926:DNA polymerase V, E coli; D004259:DNA-Directed DNA Polymerase; C055218:UmuD protein, E coli