Center for Biofilm Engineering
Abstract:
"Discrete Protein Determinant Directs the Species-Specific Adherence of
Porphyromonas gingivalis to Oral Streptococci"
01-030 For pathogens to survive in the human oral cavity, they must identify a suitable niche in the complex multispecies biofilm that exists on oral tissues. The periodontal pathogen
Porphyromonas gingivalis adheres to Streptococcus gordonii by interacting with a specific region of the streptococcal SspB polypeptide, designated BAR. However, it does not adhere to
Streptococcus mutans, which expresses SpaP, a highly conserved homolog of SspB. Comparison of the predicted secondary structure of BAR with the corresponding region of SpaP suggested that the substitution of Asn for
Gly1182 and Val for Pro1185 in SspB may confer a unique local structure
that is not conserved in SpaP. A synthetic peptide of 26 amino acids that encompassed residues 1167 to 1193 of SspB
promoted avid adherence of P. gingivalis, whereas a peptide derived from the region corresponding to BAR in SpaP was
inactive. Substitution of Gly1182 and Pro1185 for Asn1182 and
Val1185 in SspB by site-specific mutation generated proteins that were predicted to assume an SpaP-like secondary structure, and the purified proteins did not
promote P. gingivalis adherence. Furthermore, Enterococcus faecalis
strains expressing the site-specific mutants did not support adherence of P. gingivalis cells. In contrast,
P. gingivalis adhered efficiently to E. faecalis strains expressing intact SspB or SspB-SpaP chimeric proteins
containing BAR. These results suggest that a region of SspB consisting of 26 amino acids is sufficient to mediate the
adherence of P. gingivalis to S. gordonii and that the species specificity of adherence arises from its interaction
with a discrete structural determinant of SspB that is not conserved in SpaP.
Demuth, D.R., D.C. Irvine, J.W. Costerton, G.S. Cook, and R.J. Lamont,
"Discrete Protein Determinant Directs the Species-Specific Adherence of Porphyromonas
gingivalis to Oral Streptococci," Infect. Immun., 69(9):5736-5741
(2001).
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