Isolation and characterization of the Rickettsia prowazekii recA gene

The recA gene has been isolated from Rickettsia prowazekii, an obligate intracellular bacterium. Comparison of the amino acid sequence of R. prowazekii RecA with that of Escherichia coli RecA revealed that 62% of the residues were identical. The highest identity was found with RecA of Legionella pneumophila, in which 69% of the residues were identical. Amino acid residues of E. coli RecA associated with functional activities are conserved in rickettsial RecA, and the R. prowazekii recA gene complements E. coli recA mutants for UV light and methyl methanesulfonate sensitivities as well as recombinational deficiencies. The characterized region upstream of rickettsial recA did not contain a sequence homologous to an E. coli LexA binding site (SOS box), suggesting differences in the regulation of the R. prowazekii recA gene.