Thermal Enhancement of Ultraviolet Mutability in a dnaB uvrA Derivative of Escherichia coli B/r: Evidence for Inducible Error-Prone Repair
DNA damage triggers coordinate expression of a cluster of diverse functions in Escherichia coli, including prophage induction, filamentous growth, and “aberrant” reinitiation of DNA replication at the chromosomal origin. The “SOS repair” hypothesis proposes that one of these coordinately inducible functions is an error-prone system of DNA repair (“SOS repair”) which is responsible for ultraviolet mutagenesis. In dnaB strains, incubation at 42°C stops DNA synthesis and induces lambda prophage and should, therefore, also induce the postulated error-prone repair activity. Thermal posttreatment of a dnaB uvrA derivative of E. coli B/r is found to enhance the yield of ultraviolet-light-induced mutations as much as 50-fold, while having no such effect in the dnaB + parent strain. The results support the SOS repair hypothesis. The possibility is discussed that the inducible repair system is a mutagenic DNA polymerase.
KeywordsPyrimidine Dimer Filamentous Growth Inducible Function polA Strain Thermal Enhancement
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- Radman, M. (1974). In Molecular and Environmental Aspects of Mutagenesis (Prakash, L., Sherman, F., Miller, M., Lawrence, C. and Tabor, H. W., eds.), Thomas, Springfield, Ill., pp. 128–142.Google Scholar