Research Project code：0550030159
Update date：Nov. 02, 2005
The molecular mechanisms by which Porphyromonas gingivalis interacts with oral streptococci and accumulates into biofilms
1999 - 2008
Investigating Researcher (1)：
Porphyromonas gingivalis cells attached to the plaque-forming bacteria such as Streptococcus oralis. This coadhesion event may lead to the development of P. gingivalis biofilms in the periodontal sites. We previously reported that glyceraldehyde-3-phosphate dehydrogenase (GAPDH) of S. oralis ATCC 9811 bound to P. gingivalis 381 major fimbriae. The purpose of this study was to investigate whether GAPDHs of various oral streptococci were involved in binding to P. gingivalis major fimbriae. The GAPDH activities in 16 strains of oral streptococci were measured by incubating a constant number of streptococci with glyceraldehyde-3-phosphate and NAD+. Coaggregation activity between P. gingivalis and streptococci was measured by visual scoring and a turbidimetric assay. GAPDHs of 5 strains of streptococci were extracted with mutanolysin and purified by a Cibacron Blue Sepharose column. Binding ability of GAPDHs to P. gingivalis recombinant fimbriae (rFimA) was examined by Western blot assay. The kinetic interaction of GAPDH with rFimA was measured by a biomolecular interaction analyzing system (BIAcore). The cells of S. oralis ATCC 9811, S. oralis ATCC 10557, Streptococcus sanguinis ATCC 10556, Streptococcus gordonii G9B, and Streptococcus mitis ATCC 15909 showed high activities of coaggregation and GAPDH among the species tested. GAPDH activity on cell surface of streptococci was correlated with coaggregation activity (r=0.832, P<0.01). Purified GAPDHs of 5 strains of streptococci were found to bind to rFimA by Western blot assay. S. oralis recombinant GAPDH inhibited the coaggregation between P. gingivalis and 5 strains of streptococci in a dose-dependent manner, and showed complete inhibition at a concentration of 2.0 ug/ml. The interaction between S. oralis GAPDH and rFimA was specific, and the association constant (Ka) value was 4.34 x 107 M-1.GAPDHs of various oral streptococci may be involved in binding to P. gingivalis major fimbriae. GAPDHs of some plaque-forming streptococci may contribute to the colonization of P. gingivalis.
Return to Previous Page