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Multiple pathways for SOS-induced mutagenesis in Escherichia coli: An overexpression of dinB/dinP results in strongly enhancing mutagenesis in the absence of any exogenous treatment to damage DNA

par Kim, Su Ryang;Maenhaut, Geneviève ;Yamada, Masami;Yamamoto, Yoshihiro;Matsui, Keiko;Sofuni, Toshio;Nohmi, Takehiko;Ohmori, Haruo
Référence Proceedings of the National Academy of Sciences of the United States of America, 94, 25, page (13792-13797)
Publication Publié, 1997-12

Article révisé par les pairs

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Résumé :

dinP is an Escherichia coli gene recently identified at 5.5 min of the genetic map, whose product shows a similarity in amino acid sequence to the E. coli UmuC protein involved in DNA damage-induced mutagenesis. In this paper we show that the gene is identical to dinB, an SOS gene previously localized near the lac locus at 8 min, the function of which was shown to be required for mutagenesis of nonirradiated λ phage infecting UV- preirradiated bacterial cells (termed λUTM for λ untargeted mutagenesis). A newly constructed dinP null mutant exhibited the same defect for λUTM as observed previously with a dinB::Mu mutant, and the defect was complemented by plasmids carrying dinP as the only intact bacterial gene. Furthermore, merely increasing the dinP gene expression, without UV irradiation or any other DNA-damaging treatment, resulted in a strong enhancement of mutagenesis in F'lac plasmids; at most, 800-fold increase in the G6-to-G5 change. The enhanced mutagenesis did not depend on recA, uvrA, or umuDC. Thus, our results establish that E. coli has at least two distinct pathways for SOS- induced mutagenesis: one dependent on umuDC and the other on dinB/P.