Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/60385
標題: Two non-consensus Clp binding sites are involved in upregulation of the gum operon involved in xanthan polysaccharide synthesis in Xanthomonas campestris pv. campestris
作者: Chen, C.H.
楊秋英
Lin, N.T.
Hsiao, Y.M.
Yang, C.Y.
Tseng, Y.H.
關鍵字: Clp;Clp binding site;CRP homologue;Transcription activation;Xanthan;polysaccharide;Xanthomonas campestris;transcription factor clp;amp receptor protein;phage phi-lf;escherichia-coli;gene;virulence;dna;biosynthesis;specificity;activation
Project: Research in Microbiology
期刊/報告no:: Research in Microbiology, Volume 161, Issue 7, Page(s) 583-589.
摘要: 
Biosynthesis of xanthan polysaccharide, a virulence factor of phytopathogenic Xanthomonas campestris pv. campestris (Xcc), involves the gum operon and the cyclic AMP receptor protein (CRP) homologue Clp. Clp was shown to have the same DNA binding specificity as the CRP at positions 5, 6, and 7 (GTG motif) of the left arm. Therefore, Clp binding sites (CBSs) have typically been identified by pattern searching of the Xcc genome using the consensus CRP binding sequence. Here, results of a reporter assay and electrophoretic mobility shift assay suggest that Clp upregulates the gum operon by binding to two non-consensus sites, in which a more conserved right arm may compensate for the lack of conservation in the left arm, a high GC content in the central region (6 bp) may be important for binding, and binding may be enhanced if the GC-rich central region is palindromic. These suggest that atypical CBSs exist in Xcc promoters and that Clp, while retaining the capacity to bind typical CBSs, has evolved to bind atypical CBS because: 1) Clp shares only moderate homology with the CRP and is modulated by cyclic di-GMP; and 2) Xcc has a higher GC content (65%) than Escherichia coli (50%). (C) 2010 Elsevier Masson SAS. All rights reserved.
URI: http://hdl.handle.net/11455/60385
ISSN: 0923-2508
DOI: 10.1016/j.resmic.2010.05.012
Appears in Collections:分子生物學研究所

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