Deduction of upstream sequences of Xanthomonas campestris flagellar genes responding to transcription activation by FleQ.
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.
Hu
Rouh-Mei
RM
Department of Biotechnology and Bioinformatics, Asia University, Taichung 413, Taiwan.
Yang
Tsuey-Ching
TC
Yang
Shu-Hui
SH
Tseng
Yi-Hsiung
YH
D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D016384:Consensus Sequence / Q000235:genetics; D005407:Flagella / Q000235:genetics*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics; D017422:Sequence Analysis, DNA / Q000379:methods*; D015534:Trans-Activators / Q000235:genetics*; D015533:Transcriptional Activation / Q000235:genetics*; D016959:Xanthomonas campestris / Q000235:genetics*
D001426:Bacterial Proteins; C108098:FleQ protein, Pseudomonas aeruginosa; D015534:Trans-Activators