Involvement of DnaE, the second replicative DNA polymerase from Bacillus subtilis, in DNA mutagenesis.
2004
Le Chatelier, Emmanuelle, E. | Bécherel, Olivier | d'Alençon, Emmanuelle | Canceill, Danielle | Dusko Ehrlich, S. | Fuchs, Robert P.P. | Jannière, Laurent | Unité de génétique microbienne ; Institut National de la Recherche Agronomique (INRA) | Université de Strasbourg (UNISTRA) | Cancérogenèse et mutagenèse moléculaire et structurale (CMMS) ; Centre National de la Recherche Scientifique (CNRS)
International audience
Show more [+] Less [-]English. In a large group of organisms including low G + C bacteria and eukaryotic cells, DNA synthesis at the replication fork strictly requires two distinct replicative DNA polymerases. These are designated pol C and DnaE in Bacillus subtilis. We recently proposed that DnaE might be preferentially involved in lagging strand synthesis, whereas pol C would mainly carry out leading strand synthesis. The biochemical analysis of DnaE reported here is consistent with its postulated function, as it is a highly potent enzyme, replicating as fast as 240 nucleotides/s, and stalling for more than 30 s when encountering annealed 5'-DNA end. DnaE is devoid of 3' --> 5'-proofreading exonuclease activity and has a low processivity (1-75 nucleotides), suggesting that it requires additional factors to fulfill its role in replication. Interestingly, we found that (i) DnaE is SOS-inducible; (ii) variation in DnaE or pol C concentration has no effect on spontaneous mutagenesis; (iii) depletion of pol C or DnaE prevents UV-induced mutagenesis; and (iv) purified DnaE has a rather relaxed active site as it can bypass lesions that generally block other replicative polymerases. These results suggest that DnaE and possibly pol C have a function in DNA repair/mutagenesis, in addition to their role in DNA replication.
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