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J. Bacteriol., 01 1998, 303-316, Vol 180, No. 2
KE Klose and JJ Mekalanos
Vibrio cholerae, the causative agent of the human diarrheal disease
cholera, is a motile bacterium with a single polar flagellum. Motility has
been implicated as a virulence determinant in some animal models of
cholera, but the relationship between motility and virulence has not yet
been clearly defined. We have begun to define the regulatory circuitry
controlling motility. We have identified five V. cholerae flagellin genes,
arranged in two chromosomal loci, flaAC and flaEDB; all five genes have
their own promoters. The predicted gene products have a high degree of
homology to each other. A strain containing a single mutation in flaA is
nonmotile and lacks a flagellum, while strains containing multiple
mutations in the other four flagellin genes, including a flaCEDB strain,
remain motile. Measurement of fla promoter-lacZ fusions reveals that all
five flagellin promoters are transcribed at high levels in both wild-type
and flaA strains. Measurement of the flagellin promoter-lacZ fusions in
Salmonella typhimurium indicates that the promoter for flaA is transcribed
by the sigma54 holoenzyme form of RNA polymerase while the flaE, flaD, and
flaB promoters are transcribed by the sigma28 holoenzyme. These results
reveal that the V. cholerae flagellum is a complex structure with multiple
flagellin subunits including FlaA, which is essential for flagellar
synthesis and is differentially regulated from the other flagellins.
Copyright © 1998, American Society for Microbiology
Differential regulation of multiple flagellins in Vibrio cholerae [In Process Citation]
Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.
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