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Role of DnaB Helicase in UV-Induced Illegitimate Recombination in Escherichia coli
To study the involvement of DNA replication in UV-induced illegitimate recombination, we examined the effect of temperature-sensitive dnaB mutations on illegitimate recombination and found that the frequency of illegitimate recombination was reduced by an elongation-deficient mutation, dnaB14, but n...
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| Hoofdauteurs: | , , , |
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| Formaat: | Artikel |
| Taal: | en |
| Gepubliceerd in: |
American Society for Microbiology
2001
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| Onderwerpen: | |
| Online toegang: | https://ncbi.nlm.nih.gov/pmc/articles/PMC95370/ https://ncbi.nlm.nih.gov/pubmed/11489847 https://ncbi.nlm.nih.govhttp://dx.doi.org/10.1128/JB.183.17.4964-4969.2001 |
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| Samenvatting: | To study the involvement of DNA replication in UV-induced illegitimate recombination, we examined the effect of temperature-sensitive dnaB mutations on illegitimate recombination and found that the frequency of illegitimate recombination was reduced by an elongation-deficient mutation, dnaB14, but not by an initiation-deficient mutation, dnaB252. This result indicates that DNA replication is required for UV-induced illegitimate recombination. In addition, the dnaB14 mutation also affected spontaneous or UV-induced illegitimate recombination enhanced by the recQ mutation. Nucleotide sequence analyses of the recombination junctions showed that DnaB-mediated illegitimate recombination is short homology dependent. Previously, Michel et al. (B. Michel, S. Ehrlich, and M. Uzest, EMBO J. 16:430–438, 1997) showed that thermal treatment of the temperature-sensitive dnaB8 mutant induces double-stranded breaks, implying that induction of illegitimate recombination occurs. To explain the discrepancy between the observations, we propose a model for DnaB function, in which the dnaB mutations may exhibit two types of responses, early and late responses, for double-stranded break formation. In the early response, replication forks stall at damaged DNA, resulting in the formation of double-stranded breaks, and the dnaB14 mutation reduces the double-stranded breaks shortly after temperature shift-up. On the other hand, in the late response, the arrested replication forks mediated by the dnaB8 mutation may induce double-stranded breaks after prolonged incubation. |
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