Genetic organization of the lexA, recA and recX genes in Xanthomonas campestris.
A gene cluster containing lexA, recA and recX genes was previously identified and characterized in Xanthomonas campestris pathovar citri (X. c. pv. citri). We have now cloned and sequenced the corresponding regions in the Xanthomonas campestris pv. campestris (X. c. pv. campestris) and Xanthomonas oryzae pathovar oryzae (X. o. pv. oryzae) chromosome. Sequence analysis of these gene clusters showed significant homology to the previously reported lexA, recA and recX genes. The genetic linkage and the deduced amino acid sequences of these genes displayed very high identity in different pathovars of X. campestris as well as in X. oryzae. Immunoblot analysis revealed that the over-expressed LexA protein of X. c. pv. citri functioned as a repressor of recA expression in X. c. pv. campestris, indicating that the recombinant X. c. pv. citri LexA protein was functional in a different X. campestris pathovar. The abundance of RecA protein was markedly increased upon exposure of X. c. pv. campestris to mitomycin C, and an upstream region of this gene was shown to confer sensitivity to positive regulation by mitomycin C on a luciferase reporter gene construct. A symmetrical sequence of TTAGTAGTAATACTACTAA present within all three Xanthomonas lexA promoters and a highly conserved sequence of TTAGCCCCATACCGAA present in the three regulatory regions of recA indicate that the SOS box of Xanthomonas strains might differ from that of Escherichia coli.
Yang
Yen-Chun
YC
Department of Life Science, Fu Jen University, 510 Chun-Chen Road, Taipei 242, Taiwan, ROC.
Hsu
Chien-Hsiu
CH
Chou
Chun-Ping
CP
Yang
Mei-Kwei
MK
D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D016680:Genome, Bacterial; D008969:Molecular Sequence Data; D005810:Multigene Family; D009875:Operator Regions, Genetic / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011938:Rec A Recombinases / Q000235:genetics*; D012697:Serine Endopeptidases / Q000235:genetics*; D016959:Xanthomonas campestris / Q000235:genetics*; D000099160:LexA Repressor Protein
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D011938:Rec A Recombinases; D012697:Serine Endopeptidases; D000099160:LexA Repressor Protein; C099195:RecA protein, Xanthomonas campestris; C430523:RecX protein, Xanthomonas campestris