title: Nascent DNA processing by RecJ favors lesion repair over translesion synthesis at arrested replication forks in Escherichia coli.
abstract: DNA lesions that arrest replication can lead to rearrangements, mutations, or lethality when not processed accurately. After UV-induced DNA damage in Escherichia coli, RecA and several recF pathway proteins are thought to process arrested replication forks and ensure that replication resumes accurately. Here, we show that the RecJ nuclease and RecQ helicase, which partially degrade the nascent DNA at blocked replication forks, are required for the rapid recovery of DNA synthesis and prevent the potentially mutagenic bypass of UV lesions. In the absence of RecJ, or to a lesser extent RecQ, the recovery of replication is significantly delayed, and both the recovery and cell survival become dependent on translesion synthesis by polymerase V. The RecJ-mediated processing is proposed to restore the region containing the lesion to a form that allows repair enzymes to remove the blocking lesion and DNA synthesis to resume. In the absence of nascent DNA processing, polymerase V can synthesize past the lesion to prevent lethality, although this occurs with slower kinetics and a higher frequency of mutagenesis.
authors.affiliation: Department of Biology, Portland State University, Box 751, Portland, OR 97207-0751, USA. charmc@pdx.edu
authors.forename: Charmain T
authors.initials: CT
authors.lastname: Courcelle
authors.forename: Kin-Hoe
authors.initials: KH
authors.lastname: Chow
authors.forename: Andrew
authors.initials: A
authors.lastname: Casey
authors.forename: Justin
authors.initials: J
authors.lastname: Courcelle
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis* / Q000528:radiation effects; D004249:DNA Damage; D004265:DNA Helicases / Q000378:metabolism; D004260:DNA Repair; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005090:Exodeoxyribonucleases / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D053484:RecQ Helicases; D014466:Ultraviolet Rays
chemical_list: D029968:Escherichia coli Proteins; D004247:DNA; C120926:DNA polymerase V, E coli; D004259:DNA-Directed DNA Polymerase; D005090:Exodeoxyribonucleases; C489467:RecJ protein, E coli; D000251:Adenosine Triphosphatases; C506724:RecQ protein, E coli; D004265:DNA Helicases; D053484:RecQ Helicases