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Infect. Immun., Mar 1996, 756-762, Vol 64, No. 3
M Kontani, H Ono, H Shibata, Y Okamura, T Tanaka, T Fujiwara, S Kimura and S Hamada
It has been shown that Porphyromonas gingivalis 381, a suspected
periodontopathogen, possesses fimbriae on its cell surface. The organism is
also known to produce proteases which can degrade the host cell surface
matrix proteins. In this study, we investigated the effect of protease on
the binding of the purified P. gingivalis fimbriae to cultured fibroblasts
or matrix proteins. A protease that can hydrolyze benzoyl-L-arginine
p-nitroanilide was obtained from P. gingivalis 381 cells by sonication in
phosphate-buffered 0.2% Triton X-100 and was purified by column
chromatography. The molecular size of the protease was estimated to be 55
kDa by gel filtration or 47 kDa by sodium dodecyl sulfate-polyacrylamide
gel electrophoresis analysis. The enzyme activity was markedly inhibited by
sulfhydryl reagents, antipain, and leupeptin. The protease degraded various
host proteins, including collagen and fibronectin, and cleaved the COOH
terminus of the arginine residue in peptides such as benzoyl-L-arginine
p-nitroanilide. However, P. gingivalis fimbriae were not degraded by
protease activity. The enzyme activity was enhanced in the presence of
reducing agents or CaCl2. When cultured fibroblasts were partially treated
with the protease, the binding of the purified P. gingivalis fimbriae to
the fibroblast monolayer was increased significantly. However, this
enhancing effect was suppressed upon the addition of antipain and
leupeptin. Similarly, binding of the fimbriae to the collagen or
fibronectin immobilized on the microtiter wells was also enhanced. Addition
of these host matrix proteins efficiently inhibited the binding of fimbriae
to the fibroblast monolayer. The binding assay of fimbriae using dipeptidyl
ligand affinity column chromatography demonstrated a clear interaction
between fimbriae and the arginine residue. Taken together, these results
indicate that the P. gingivalis protease at least partially degrades the
host matrix proteins, which, in turn, may lead to an increased exposure of
the cryptic ligands that can result in enhanced fimbria-mediated binding of
this organism to periodontal tissues.
Copyright © 1996, American Society for Microbiology
Cysteine protease of Porphyromonas gingivalis 381 enhances binding of fimbriae to cultured human fibroblasts and matrix proteins
Department of Oral Microbiology, Osaka University Faculty of Dentistry, Japan.
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