DNA polymerases are error-prone at RecA-mediated recombination intermediates

Abstract

G enetic studies have suggested thatY-family translesion DNA polymerase IV (DinB) performs error-prone recombination-directed replication (RDR) under conditions of stress due to its ability to promote mutations during double-strand break (DSB) repair in growth-limited E. coli cells. In recent studies we have demonstrated that pol IV is preferentially recruited to D-loop recombination intermediates at stressinduced concentrations and is highly mutagenic during RDR in vitro. These findings verify longstanding genetic data that have implicated pol IV in promoting stress-induced mutagenesis at D-loops. In this Extra View, we demonstrate the surprising finding that A-family pol I, which normally exhibits high-fidelity DNA synthesis, is highly error-prone at D-loops like pol IV. These findings indicate that DNA polymerases are intrinsically error-prone at RecA-mediated D-loops and suggest that auxiliary factors are necessary for suppressing mutations during RDR in non-stressed proliferating cells.

Stress-Induced Mutagenesis: Implications in Cancer and Drug Resistance

“…Purified Pol IV in solution can load at a D loop HR-intermediate-like structure (Figure 1 c ), catalyze DNA synthesis, and produce errors such as those seen in HR-MBR (Figure 1 d – f ) (Pomerantz et al 2013). These data provide biochemical support for the HR-MBR mechanism.…”

The antioxidant drug N-acetylcysteine abolishes SOS-mediated mutagenesis produced by fluoroquinolones in bacteria

“…Together, these results support the existence of a TLS-independent mutagenic pathway. Pomerantz et al suggested that Pol I can be highly error-prone at RecA-mediated D-loops produced by DSB repair (Pomerantz, Goodman, and O'Donnell 2013). Hence, it is likely that CIP, by generating DSB, can fuel the creation of these RecA-mediated D-loops and the subsequent Pol I mutagenesis.…”

“…Together, these results support the existence of a TLSindependent mutagenic pathway. Pomerantz et al suggested that Pol I can be highly errorprone at RecAmediated Dloops produced by DSB repair(56). Hence, it is likely that…”

DNA double-strand breaks induced by reactive oxygen species promote DNA polymerase IV activity inEscherichia coli

“…These observations suggest that pol IV promotes the formation of DBSs due to the BER-mediated removal of closely spaced 8-oxo-dGTPs incorporated by pol IV (16). Other studies indicate that pol IV has a role in the repair of DSBs (20,21,30,31,22–29): First, pol IV physically interacts with the RecA recombinase and RecA nucleoprotein filaments (RecA*); a key player in DSB repair (DSBR) (26, 32). This interaction might facilitate pol IV to function in strand exchange (33).…”

“…Interestingly, the mutagenic potential of pol IV is modulated by UmuD and the recombinase RecA (26,29–31). UmuD induces error-free synthesis of pol IV (26), promoting long-lived association of pol IV with the DNA (32).…”