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Deduction of upstream sequences of Xanthomonas campestris flagellar genes responding to transcription activation by FleQ.

Authors
  • Hu, Rouh-Mei
  • Yang, Tsuey-Ching
  • Yang, Shu-Hui
  • Tseng, Yi-Hsiung
Type
Published Article
Journal
Biochemical and biophysical research communications
Publication Date
Oct 07, 2005
Volume
335
Issue
4
Pages
1035–1043
Identifiers
PMID: 16111660
Source
Medline
License
Unknown

Abstract

Xanthomonas campestris pv. campestris (Xcc), a close relative to Pseudomonas aeruginosa, is the pathogen causing black rot in cruciferous plants. In P. aeruginosa, FleQ serves as a cognate activator of sigma54 in transcription from several sigma54-dependent promoters of flagellar genes. These P. aeruginosa promoters have been analyzed for FleQ-binding sequences; however, no consensus was deduced. Xcc, although lacks fleSR, has a fleQ homologue residing among over 40 contiguously clustered flagellar genes. A fleQ mutant, Xc17fleQ, constructed by insertional mutation is deficient in FleQ protein, non-flagellated, and immobile. Transcriptional fusion assays on six putative sigma54-dependent promoters of the flagellar genes, fliE, fliQ, fliL, flgG, flgB, and flhF, indicated that each of them is also FleQ dependent. Each of these promoters has a sequence with weak consensus to 5'-gaaacCCgccgCcgctTt-3', immediately upstream of the predicted sigma54-binding site, with an imperfect inverted repeat containing a GC-rich center flanked by several A and T at 5'- and 3'-ends, respectively. Replacing this region in fliE promoter with a HindIII recognition sequence abolished the transcription, indicating that this region responds to transcription activation by FleQ.

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