Isolation and expression in Escherichia coli of a Xanthomonas oryzae recA-like gene

The recA gene from the bacterium Xanthomonas oryzae pv. oryzae (Xoo), a rice pathogen, was cloned based on its ability to complement DNA repair defects of Escherichia coli recA − mutants. The Xoo recA was localized to a 1.3-kb Sau3AI- XhoI fragment and, when cloned into pBR322, specifies increased methylmethanesulfonate and mitomycin C resistance to E. coli recA mutants and allows λ red − gam − to plaque on an E. coli recA − host. An E. coli recA − strain harboring a plasmid containing the Xoo recA-like gene was shown to produce a 40-kDa protein which cross-reacted with an anti- E. coli RecA antibody. A similar molecular mass protein to RecA has been detected in several Xanthomonas pathovars using an anti- E. coli RecA antibody. Furthermore, the cloned Xoo recA was shown to hybridize to genomic DNA from various Xanthomonas pathovars, but not to genomic DNA from other bacteria species under high-stringency hybridization conditions. These results indicate the isolation of the Xoo recA gene.