title: Replisome-mediated translesion synthesis and leading strand template lesion skipping are competing bypass mechanisms.
abstract: A number of different enzymatic pathways have evolved to ensure that DNA replication can proceed past template base damage. These pathways include lesion skipping by the replisome, replication fork regression followed by either correction of the damage and origin-independent replication restart or homologous recombination-mediated restart of replication downstream of the lesion, and bypass of the damage by a translesion synthesis DNA polymerase. We report here that of two translesion synthesis polymerases tested, only DNA polymerase IV, not DNA polymerase II, could engage productively with the Escherichia coli replisome to bypass leading strand template damage, despite the fact that both enzymes are shown to be interacting with the replicase. Inactivation of the 3' → 5' proofreading exonuclease of DNA polymerase II did not enable bypass. Bypass by DNA polymerase IV required its ability to interact with the β clamp and act as a translesion polymerase but did not require its "little finger" domain, a secondary region of interaction with the β clamp. Bypass by DNA polymerase IV came at the expense of the inherent leading strand lesion skipping activity of the replisome, indicating that they are competing reactions.
authors.affiliation: From the Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065.
authors.forename: Carolina B
authors.initials: CB
authors.lastname: Gabbai
authors.affiliation: From the Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065.
authors.forename: Joseph T P
authors.initials: JT
authors.lastname: Yeeles
authors.affiliation: From the Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065 kmarians@sloankettering.edu.
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Marians
mesh_terms: D055162:Biocatalysis; D004249:DNA Damage; D004257:DNA Polymerase II / Q000378:metabolism; D019951:DNA Polymerase beta / Q000378:metabolism; D004260:DNA Repair / Q000235:genetics*; D004261:DNA Replication / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism; D008957:Models, Genetic; D009841:Oligonucleotides / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D018741:Replication Origin / Q000235:genetics*; D013698:Templates, Genetic
chemical_list: D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D009841:Oligonucleotides; D004257:DNA Polymerase II; D019951:DNA Polymerase beta
keywords: DNA Damage; DNA Polymerase; DNA Repair; DNA Replication; Genomic Instability