title: Single-nucleotide base excision repair DNA polymerase activity in C. elegans in the absence of DNA polymerase β.
abstract: The base excision DNA repair (BER) pathway known to occur in Caenorhabditis elegans has not been well characterized. Even less is known about the DNA polymerase (pol) requirement for the gap-filling step during BER. We now report on characterization of in vitro uracil-DNA initiated BER in C. elegans. The results revealed single-nucleotide (SN) gap-filling DNA polymerase activity and complete BER. The gap-filling polymerase activity was not due to a DNA polymerase β (pol β) homolog, or to another X-family polymerase, since computer-based sequence analyses of the C. elegans genome failed to show a match for a pol β-like gene or other X-family polymerases. Activity gel analysis confirmed the absence of pol β in the C. elegans extract. BER gap-filling polymerase activity was partially inhibited by both dideoxynucleotide and aphidicolin. The results are consistent with a combination of both replicative polymerase(s) and lesion bypass/BER polymerase pol θ contributing to the BER gap-filling synthesis. Involvement of pol θ was confirmed in experiments with extract from pol θ null animals. The presence of the SN BER in C. elegans is supported by these results, despite the absence of a pol β-like enzyme or other X-family polymerase.
authors.affiliation: Laboratory of Structural Biology, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA.
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Asagoshi
authors.forename: Wade
authors.initials: W
authors.lastname: Lehmann
authors.forename: Elena K
authors.initials: EK
authors.lastname: Braithwaite
authors.forename: Lucas
authors.initials: L
authors.lastname: Santana-Santos
authors.forename: Rajendra
authors.initials: R
authors.lastname: Prasad
authors.forename: Jonathan H
authors.initials: JH
authors.lastname: Freedman
authors.forename: Bennett
authors.initials: B
authors.lastname: Van Houten
authors.forename: Samuel H
authors.initials: SH
authors.lastname: Wilson
mesh_terms: D000818:Animals; D016590:Aphidicolin / Q000494:pharmacology; D017173:Caenorhabditis elegans / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D004247:DNA / Q000096:biosynthesis; D019951:DNA Polymerase beta / Q000235:genetics; D004260:DNA Repair; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D023281:Genomics; D016366:Open Reading Frames; D000097462:DNA Polymerase theta
chemical_list: D016590:Aphidicolin; D004247:DNA; D019951:DNA Polymerase beta; D004259:DNA-Directed DNA Polymerase; D000097462:DNA Polymerase theta