title: Analyses of binding sequences of the two LexA proteins of Xanthomonas axonopodis pathovar citri.
abstract: Xanthomonas axonopodis pv. citri (X. axonopodis pv. citri) possesses two lexA genes, designated lexA1 and lexA2. Electrophoretic mobility shift data show that LexA1 binds to both lexA1 and lexA2 promoters, but LexA2 does not bind to the lexA1 promoter, suggesting that LexA1 and LexA2 play different roles in regulating the expression of SOS genes. In this study, we have determined that LexA2 binds to a 14-bp dyad-spacer-dyad palindromic sequence, 5'-TGTACAAATGTACA-3', located at nucleotides -41 to -28 relative to the translation start site of lexA2 of X. axonopodis pv. citri. The two spacer nucleotides in this sequence can be changed from AA to TT without affecting LexA2 binding; all other base deletions or substitutions abolish LexA2 binding. The LexA1 binding sequence in the promoter region of lexA2 is TTAGTACTAAAGTTATAA and is located at -133 to -116, and that in the lexA1 gene is AGTAGTAATACTACT located at nucleotides -19 to -5 relative to the translation start site of lexA1. Any base change in the latter sequence abolishes LexA1 binding.
authors.affiliation: Department of Life Science, Fu Jen University, 510 Chun-Chen Road, Taipei 242, Taiwan, ROC. 002327@mail.fju.edu.tw
authors.forename: Mei-Kwei
authors.initials: MK
authors.lastname: Yang
authors.forename: Chien-Hsiu
authors.initials: CH
authors.lastname: Hsu
authors.forename: Vin-Long
authors.initials: VL
authors.lastname: Sung
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D017422:Sequence Analysis, DNA; D012697:Serine Endopeptidases / Q000378:metabolism*; D015533:Transcriptional Activation; D053532:Xanthomonas axonopodis / Q000235:genetics*; D000099160:LexA Repressor Protein
chemical_list: D001426:Bacterial Proteins; D012697:Serine Endopeptidases; D000099160:LexA Repressor Protein