Cloned truncated recA genes in E. coli

Publisher Website
Google Scholar
Abstract
The ability of plasmids carrying truncated recA genes to sensitize recA + cells to UV-irradiation was dependent upon the size of the cloned recA gene fragment. Radiosensitization correlated with the inhibition of recombinational repair, and the in vivo reduction of recA protein recombinase activity, as measured by λbio11 plating efficiency. W-reactivation was also abolished by the radiosensitizing plasmids, whilst DNA degradation control, naladixic acid induced filamentation and λ induction were unaffected. UV-induced mutagenesis in excision proficient E. coli was unaffected, whilst excision deficient strains were hypermutable. It is suggested that these effects of plasmids bearing 22% or more of the recA gene are the result of the interaction of full-sized and truncated protien subunits to generate multimers unable to catalyze recombination.