Premium
Clp upregulates transcription of engA gene encoding a virulence factor in Xanthomonas campestris by direct binding to the upstream tandem Clp sites
Author(s) -
Hsiao Yi-Min,
Liao Hsiu-Ying,
Lee Mong-Chuan,
Yang Tsuey-Ching,
Tseng Yi-Hsiung
Publication year - 2005
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2005.05.023
Subject(s) - xanthomonas campestris , microbiology and biotechnology , binding site , electrophoretic mobility shift assay , biology , transcription (linguistics) , mutant , dna , site directed mutagenesis , promoter , gene , transcription factor , chemistry , genetics , gene expression , linguistics , philosophy
In Xanthomonas campestris , the causative agent of black rot in crucifers, the endoglucanase level is greatly decreased in the mutant deficient in Clp, a homologue of cyclic AMP receptor protein (CRP). It is established that Clp has the same DNA binding specificity as CRP at positions 5, 6, and 7 (GTG motif) of the DNA half site. In this study, the engA transcription initiation site was determined by the 5′ RACE method, and two consensus Clp‐binding sites, site I and site II centered at −69.5 and −42.5, respectively, were located. Transcriptional fusion assays indicated that Clp greatly activates engA transcription. Site‐directed mutagenesis indicated that position 5 of GTG motif in site II is essential for both DNA‐protein complex formation in electrophoretic mobility shift assays and engA transcription in vivo. In addition, mutation at position 5 of site I drastically reduces the promoter activity, indicating that binding of Clp to site I exerts a synergistic effect on the transcription activation by site II. engA appears to be the first X. campestris gene known to be activated by Clp via a direct binding to the promoter.