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Journal of Bacteriology, May 1999, p. 3087-3095, Vol. 181, No. 10
Department of Microbiology,
Received 28 December 1998/Accepted 12 March 1999
It has been shown previously that inactivation of the
cshA gene, encoding a major cell surface polypeptide (259 kDa) in the oral bacterium Streptococcus gordonii,
generates mutants that are markedly reduced in hydrophobicity,
deficient in binding to oral Actinomyces species and to
human fibronectin, and unable to colonize the oral cavities of mice. We
now show further that surface fibrils 60.7 ± 14.5 nm long, which
are present on wild-type S. gordonii DL1 (Challis) cells,
bind CshA-specific antibodies and are absent from the cell surfaces of
cshA mutants. To more precisely determine the structural
and functional properties of CshA, already inferred from
insertional-mutagenesis experiments, we have cloned the entire
cshA gene into the replicative plasmid pAM401 and expressed
full-length CshA polypeptide on the cell surface of heterologous
Enterococcus faecalis JH2-2. Enterococci expressing CshA
exhibited a 30-fold increase in cell surface hydrophobicity over
E. faecalis JH2-2 carrying the pAM401 vector alone and
2.4-fold-increased adhesion to human fibronectin. CshA expression in
E. faecalis also promoted cell-cell aggregation and
increased the ability of enterococci to bind Actinomyces
naeslundii cells. Electron micrographs of negatively stained
E. faecalis cells expressing CshA showed peritrichous
surface fibrils 70.3 ± 9.1 nm long that were absent from control
E. faecalis JH2-2(pAM401) cells. The fibrils bound
CshA-specific antibodies, as detected by immunoelectron microscopy, and
the antibodies inhibited the adhesion of E. faecalis cells
to fibronectin. The results demonstrate that the CshA polypeptide is
the structural and functional component of S. gordonii
adhesive fibrils, and they provide a molecular basis for past
correlations of surface fibril production, cell surface hydrophobicity,
and adhesion in species of oral "sanguis-like" streptococci.
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Cell Wall-Anchored CshA Polypeptide (259 Kilodaltons) in Streptococcus gordonii Forms Surface Fibrils
That Confer Hydrophobic and Adhesive Properties
*
Corresponding author. Mailing address: Department of
Oral and Dental Science, University of Bristol Dental Hospital and
School, Lower Maudlin St., Bristol, BS1 2LY, United Kingdom. Phone:
(44) 117 928 4358. Fax: (44) 117 928 4428. E-mail:
howard.jenkinson{at}bristol.ac.uk.
Journal of Bacteriology, May 1999, p. 3087-3095, Vol. 181, No. 10
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
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