ANTAGONISTIC EFFECT OF SYNTHETIC PEPTIDES CORRESPONDING TO THE BINDING REGIONS WITHIN FIMBRIAL SUBUNIT PROTEIN FROM PORPHYROMONAS-GINGIVALIS TO HUMAN GINGIVAL FIBROBLASTS

Specific binding region within fumbrial subunit protein (fimbrilin) fr om Porphyromonas gingivalis strain 381 was studied in cultured human g ingival fibroblasts. Fluorescent micrographs visualised FITC-labelled fimbriae of P. gingivalis specifically bound to normal human fibroblas t cell line (Gin-1) along the cell surface. Flow cytometric analysis a lso revealed the binding of FITC-labelled fimbriae to Gin-1 cells. Syn thetic peptides composed of residues 1-20 (AFGVGDDESKVAKLTVMVYM) of th e fimbrilin from P. gingivalis, FP381 (1-20), FP381(69-80; ALTTELTAENQ E) and FP381(171-181; DANYLTGSLTT) definitely inhibited P. gingivalis fimbria-binding to Gin-1 cells by enzyme-linked immunosorbent assay (E LISA). Furthermore, based on the Scatchard plot analysis of the bindin g of I-125-labelled P. gingivalis fimbriae to Gin-1 cells, the apparen t dissociation constant (Kd) was calculated as 15.9 pM, and the number of binding sites (Rt) was estimated as 150 sites/cell. Binding studie s of 125 I-labelled FP381(171-181) also revealed the presence of a non -interacting, single class of affinity binding sites: the apparent Kd and Rt were 29.2 nM and 18440 sites/cell on Gin-1 cells, respectively. These results demonstrate that specific binding regions on P. gingiva lis fimbriae to human gingival fibroblasts are present, and certain co rresponding peptides clearly inhibited the binding of P. gingivalis fi mbriae to human gingival fibroblasts. Copyright (C) 1997 Elsevier Scie nce Ltd.