Clp upregulates transcription of engA gene encoding a virulence factor in Xanthomonas campestris by direct binding to the upstream tandem Clp sites

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Title:	Clp upregulates transcription of engA gene encoding a virulence factor in Xanthomonas campestris by direct binding to the upstream tandem Clp sites
Authors:	(Yi-Min Hsiao);(Hsiu-Ying Liao);(Mong-Chuan Lee);楊翠青(Tsuey-Ching Yang);(Yi-Hsiung Tseng)
Contributors:	健康照護學院醫學檢驗生物技術學系
Date:	2005.06
Issue Date:	2009-08-26 15:59:39 (UTC+8)
Abstract:	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 teh 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 concensus 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 acitvates 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.
Relation:	FEBS LETTERS 579(579 )3525 ~3533
Appears in Collections:	[Department of Medical Laboratory Science and Biotechnology ] Journal articles

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