Genetic analysis and molecular cloning of the Escherichia coli ruv gene

The genetic organisation of the ruv gene, a component of the SOS system for DNA repair and recombination in Escherichia coli, was investigated. New point mutations as well as insertions and deletions were generated using transposon Tn10 inserted in eda as a linked marker for site specific mutagenesis, or directly as a mutagen. The mutations were ordered with respect to one another and previously isolated ruv alleles by means of transductional crosses. The direction of chromosome mobilization from ruv ::Mud( ApRlac ) strains carrying F42lac + established that ruv is transcribed in a counterclockwise direction. Recombinant lambda phages able to restore UV resistance to ruv mutants were identified,and the ruv + region was subcloned into a low copy number plasmid. The ruv + plasmid was able to correct the extreme radiation sensitivity and recombination deficiency of ruv recBC sbcB strains.