DNA polymerase I acts in translesion synthesis mediated by the Y-polymerases in Bacillus subtilis.
Translesion synthesis (TLS) across damaged DNA bases is most often carried out by the ubiquitous error-prone DNA polymerases of the Y-family. Bacillus subtilis encodes two Y-polymerases, Pol Y1 and Pol Y2, that mediate TLS resulting in spontaneous and ultraviolet light (UV)-induced mutagenesis respectively. Here we show that TLS is a bipartite dual polymerase process in B. subtilis, involving not only the Y-polymerases but also the A-family polymerase, DNA polymerase I (Pol I). Both the spontaneous and the UV-induced mutagenesis are abolished in Pol I mutants affected solely in the polymerase catalytic site. Physical interactions between Pol I and either of the Pol Y polymerases, as well as formation of a ternary complex between Pol Y1, Pol I and the beta-clamp, were detected by yeast two- and three-hybrid assays, supporting the model of a functional coupling between the A- and Y-family polymerases in TLS. We suggest that the Pol Y carries the synthesis across the lesion, and Pol I takes over to extend the synthesis until the functional replisome resumes replication. This key role of Pol I in TLS uncovers a new function of the A-family DNA polymerases.
Duigou
Stéphane
S
Laboratoire de Génétique Microbienne, Domaine de Vilvert, INRA, 78352 Jouy en Josas Cedex, France.
Ehrlich
S Dusko
SD
Noirot
Philippe
P
Noirot-Gros
Marie-Françoise
MF
D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics / Q000528:radiation effects; D004249:DNA Damage; D004256:DNA Polymerase I / Q000378:metabolism*; D004260:DNA Repair; D004261:DNA Replication; D004269:DNA, Bacterial / Q000096:biosynthesis* / Q000235:genetics; D004259:DNA-Directed DNA Polymerase / Q000145:classification / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D016296:Mutagenesis; D020798:Two-Hybrid System Techniques; D014466:Ultraviolet Rays
D004269:DNA, Bacterial; D004256:DNA Polymerase I; D004259:DNA-Directed DNA Polymerase