Flagellin gene fliC of Xanthomonas campestris is upregulated by transcription factor Clp.
Clp, a homologue of cyclic AMP receptor protein (CRP), of Xanthomonas campestris regulates the expression of many genes. In this study, proteomic analysis showed the amounts of several extracellular proteins in a clp mutant to be reduced, including the flagellin encoded by fliC. Transcriptional fusion assay showed that activity of fliC promoter is reduced by 2.3-fold in clp mutant compared to the wild-type, coincident with the protein levels. The clp mutant is slightly reduced in motility; however, electron microscopy showed no significant change in the monotrichous flagellation. A fleQ homologue with conserved Clp-binding site in the upstream region is present in the fully sequenced X. campestris genome, suggesting that regulation of the flagellar genes is similar to that of Pseudomonas aeruginosa in involving Vfr, the CRP homologue, and FleQ in a cascade manner except that Vfr downregulates fleQ. Concomitant loss of flagellum and motility in fliC mutant and absence of a second homologue in the genome sequence suggest that X. campestris possesses a single flagellin gene, fliC. In addition, mutation of this gene does not affect virulence.
Lee
Mong-Chuan
MC
Institute of Molecular Biology, National Chung Hsing University, Taichung 402, Taiwan.
Weng
Shu-Fen
SF
Tseng
Yi-Hsiung
YH
D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001483:Base Sequence; D005407:Flagella / Q000648:ultrastructure; D005408:Flagellin / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D008969:Molecular Sequence Data; D009068:Movement; D009154:Mutation; D011401:Promoter Regions, Genetic; D020543:Proteome / Q000737:chemistry; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D015854:Up-Regulation; D014774:Virulence; D016959:Xanthomonas campestris / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity
D001426:Bacterial Proteins; C436751:Clp protein, Xanthomonas campestris; D020543:Proteome; D014157:Transcription Factors; D005408:Flagellin