Sequence and genetic analysis of multiple flagellin-encoding genes from Proteus mirabilis.
Surface-induced overproduction of flagellin is one of the hallmarks of Proteus mirabilis swarmer cell differentiation. In this study, we analyzed the nucleotide (nt) and amino acid (aa) sequences, and expression of the P. mirabilis flagellin-encoding gene (fliC) region. The nt sequence analysis of a 3567-bp region reveals three ORFs, each with homology to known Escherichia coli flagellar genes. The first ORF corresponds to fliD, the gene encoding the flagellar filament capping protein, FliD (HAP2). The second and third ORFs are highly homologous to each other and to fliC genes from many other Gram- bacteria. To distinguish between the two alleles, we have designated these genes fliC1 and fliC2. Sequences highly homologous to promoter sites for the alternate sigma factor of RNA polymerase, sigma 28, are found 5' to the start of each gene. Additionally, both fliC1 and fliC2 have a conserved direct tandem repeat (DTR) sequence upstream from the sigma 28 promoter that may have functional significance in the transcriptional control of fliC expression during swarmer cell differentiation. Both FliC1 and FliC2 were produced in E. coli, but only FliC1 could complement FliC- mutants of E. coli. Southern hybridization data indicate the presence of fliC1 and fliC2 in six distinct P. mirabilis strains, indicating that multiple flagellin-encoding genes are common in P. mirabilis. Hybridization data also suggest the presence of a third flagellin-encoding gene, fliC3, in all isolates. The possible significance of multiple fliC in swarmer cell differentiation is discussed.
Belas
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Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore 21202.
Flaherty
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D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D005407:Flagella / Q000235:genetics; D005408:Flagellin / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D018628:Gene Dosage; D005798:Genes, Bacterial / Q000235:genetics*; D005816:Genetic Complementation Test; D015698:Genomic Library; D008969:Molecular Sequence Data; D016366:Open Reading Frames / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011513:Proteus mirabilis / Q000235:genetics* / Q000502:physiology; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid
D001426:Bacterial Proteins; D005408:Flagellin; C076733:FlaD protein, Bacteria