PMID:6343804
| Citation |
Lieberman, HB and Witkin, EM (1983) DNA degradation, UV sensitivity and SOS-mediated mutagenesis in strains of Escherichia coli deficient in single-strand DNA binding protein: effects of mutations and treatments that alter levels of Exonuclease V or recA protein. Mol. Gen. Genet. 190:92-100 |
|---|---|
| Abstract |
Certain strains suppress the temperature-sensitivity caused by ssb-1, which encodes a mutant ssDNA binding protein (SSB). At 42 degrees C, such strains are extremely UV-sensitive, degrade their DNA extensively after UV irradiation, and are deficient in UV mutability and UV induction of recA protein synthesis. We transduced recC22, which eliminates Exonuclease V activity, and recAo281, which causes operator-constitutive synthesis of recA protein, into such an ssb-1 strain. Both double mutants degraded their DNA extensively at 42 degrees C after UV irradiation, and both were even more UV-sensitive than the ssb-1 single mutant. We conclude that one or more nucleases other than Exonuclease V degrades DNA in the ssb recC strain, and that recA protein, even if synthesized copiously, can function efficiently in recombinational DNA repair and in control of post-UV DNA degradation only if normal SSB is also present. Pretreatment with nalidixic acid at 30 degrees C restored normal UV mutability at 42 degrees C, but did not increase UV resistance, in an ssb-1 strain. Another ssb allele, ssb-113, which blocks SOS induction at 30 degrees C, increases spontaneous mutability more than tenfold. The ssb-113 allele was transduced into the SOS-constitutive recA730 strain SC30. This double mutant expressed the same elevated spontaneous and UV-induced mutability at 30 degrees C as the ssb+ recA730 strain, and was three times more UV-resistant than its ssb-113 recA+ parent. We conclude that ssb-1 at 42 degrees C and ssb-113 at 30 degrees C block UV-induced activation of recA protease, but that neither allele interferes with subsequent steps in SOS-mediated mutagenesis. |
| Links | |
| Keywords |
Bacterial Proteins/metabolism; Carrier Proteins/genetics; DNA Repair; DNA Replication; DNA, Bacterial/metabolism; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli/radiation effects; Escherichia coli Proteins; Exodeoxyribonuclease V; Exodeoxyribonucleases/metabolism; Mutation; Nalidixic Acid/pharmacology; Rec A Recombinases; Ultraviolet Rays |
| edit table |
Significance
You can help EcoliWiki by summarizing why this paper is useful
Useful Materials and Methods
You can help Ecoliwiki by describing the useful materials (strains, plasmids, antibodies, etc) described in this paper.
Annotations
<annotationlinks/>
EcoliWiki Links
Add links to pages that link here (e.g. gene, product, method pages)
See also
References
See Help:References for how to manage references in EcoliWiki.