The dinB gene encodes a novel E. coli DNA polymerase, DNA pol IV, involved in mutagenesis. |
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Authors: | J Wagner P Gruz S R Kim M Yamada K Matsui R P Fuchs T Nohmi |
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Institution: | Division of Genetics and Mutagenesis, National Institute of Health Sciences, Tokyo, Japan. |
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Abstract: | In Escherichia coli, the dinB gene is required for the SOS-induced lambda untargeted mutagenesis pathway and confers a mutator phenotype to the cell when the gene product is overexpressed. Here, we report that the purified DinB protein is a DNA polymerase. This novel E. coli DNA polymerase (pol IV) is shown to be strictly distributive, devoid of proofreading activity, and prone to elongate bulged (misaligned) primer/template structures. Site-directed mutagenesis experiments of dinB also demonstrate that the polymerase activity of DinB is required for its in vivo mutagenicity. Along with the sequence homologies previously found within the UmuC-like protein family, these results indicate that the uncovered DNA polymerase activity may be a common feature of all these homologous proteins. |
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