Interplay between Replication and Recombination in Escherichia coli: Impact of the Alternative DNA Polymerases
Homologous recombination (HR) and translesion synthesis (TLS) are two pathways involved in the tolerance of lesions that block the replicative DNA polymerase. However, whereas TLS is frequently error-prone and, therefore, can be deleterious, HR is generally error-free. Furthermore, because the recom...
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Published in | Proceedings of the National Academy of Sciences - PNAS Vol. 103; no. 12; pp. 4564 - 4569 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
United States
National Academy of Sciences
21.03.2006
National Acad Sciences |
Subjects | |
Online Access | Get full text |
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Summary: | Homologous recombination (HR) and translesion synthesis (TLS) are two pathways involved in the tolerance of lesions that block the replicative DNA polymerase. However, whereas TLS is frequently error-prone and, therefore, can be deleterious, HR is generally error-free. Furthermore, because the recombination enzymes and alternative DNA polymerases that perform TLS may use the same substrate, their coordination might be important to assure cell fitness and survival. This study aimed to determine whether and how these pathways are coordinated in Escherichia coli cells by using conjugational replication and recombination as a model system. The role of the three alternative DNA polymerases that are regulated by the SOS system was tested in DNA polymerase III holoenzyme-proficient and -deficient mutants. When Pollll is inactive, the alternative DNA polymerases copy DNA in the following order: Polll, PollV, and PolV. The observed hierarchy corresponds to the selective constraints imposed on the genes coding for alternative DNA polymerases observed in natural populations of E. coli, suggesting that this hierarchy depends on the frequency of specific damages encountered during the evolutionary history of E. coli. We also found that DNA replication and HR are in competition and that they can precede each other. Our results suggest that there is probably not an active choice of which pathway to use, but, rather, the nature and concentration of lesions that lead to formation of ssDNA and the level of SOS induction that they engender might determine the outcome of the competition between HR and alternative DNA polymerases. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Author contributions: S.D. and I.M. designed research; S.D. performed research; S.D. contributed new reagents/analytic tools; S.D. and I.M. analyzed data; and S.D. and I.M. wrote the paper. Edited by Philip C. Hanawalt, Stanford University, Stanford, CA, and approved January 23, 2006 |
ISSN: | 0027-8424 1091-6490 |
DOI: | 10.1073/pnas.0509012103 |