Previous Article | Next Article ![]()
Infect. Immun., 06 1997, 2041-2051, Vol 65, No. 6
HF Heinzerling, M Olivares and RA Burne
Oral spirochetes possess many potential virulence factors, including the
capacity for tissue invasion and persistence despite a vigorous host immune
response. In an attempt to identify treponemal immunoreactive components,
sera derived from individuals with advanced periodontal disease were used
as a reagent to isolate recombinant bacteriophage lambda clones expressing
antigens of the oral spirochete Treponema denticola ATCC 35405. Nucleotide
sequence analysis of a clone expressing three immunoreactive products has
revealed seven T. denticola genes which appear to encode homologs of
flagellar basal body constituents, FlgB, FlgC, FliE, and FliF, a flagellar
switch component, FliG, and the putative flagellar export proteins, FliH
and FliI, initially characterized in Salmonella typhimurium. Also
identified was a gene resembling fliJ. Primer extension analysis identified
a transcriptional start site 5' to the treponemal flgB gene. Appropriately
spaced with respect to this start site was a sigma28 binding motif. The
absence of additional identifiable sigma factor binding motifs within the
treponemal sequence and the proximity of adjacent genes suggested operonic
arrangement, and reverse transcriptase PCR provided evidence of
cotranscription. Supporting the identification of these genes as flagellar
components, heterologous expression in enteric bacteria of the putative
switch basal body genes from T. denticola interfered with motility.
Specifically, the presence of a plasmid expressing treponemal fliG reduced
swarming motility in S. typhimurium, while in Escherichia coli, this
plasmid conferred a nonmotile phenotype and a reduction in flagellar
number. Thus, while spirochetal flagella are subject to unique synthetic
and functional constraints, the organization of flagellar genes and the
presence of sigma28-like elements are reminiscent of the flagellar systems
of other bacteria, and there appears to be sufficient conservation of
constituent proteins to allow interaction between T. denticola switch-
basal body proteins and the flagellar machinery of gram-negative bacteria.
Copyright © 1997, American Society for Microbiology
Genetic and transcriptional analysis of flgB flagellar operon constituents in the oral spirochete Treponema denticola and their heterologous expression in enteric bacteria
Department of Dental Research, University of Rochester, New York 14642, USA.
This article has been cited by other articles:
| J. Bacteriol. | J. Virol. | Eukaryot. Cell |
|---|
| Microbiol. Mol. Biol. Rev. | Clin. Vaccine Immunol. | All ASM Journals |
|---|