Isolation and characterization of a receptor for type 1 fimbriae of Escherichia coli from guinea pig erythrocytes

The adhesion of Escherichia coli to eukaryotic cells is mediated by proteinaceous surface appendages called fimbriae and complementary receptors on host cells. Although type 1 fimbriae, which contain a D-mannose-reactive lectin, have been well studied little is known about the binding mechanism of isolated fimbriae to individual cell receptors. This report describes the isolation and purification of a guinea pig erythrocyte receptor for type 1 fimbriae. Erythrocyte membranes were dissolved in 0.5% Triton X-100 and the receptor isolated and purified by affinity chromatography using type 1 fimbriae immobilized on Sepharose. The 65-kDa receptor, which inhibits the agglutination of guinea pig erythrocytes by type 1 fimbriated E. coli, has a pI of 8.5-8.7, and binds concanavalin A and type 1 fimbriae in a dose-dependent and saturable manner. The fimbrial binding activity of the receptor was reduced when treated with sodium metaperiodate, endoglycosidase H, trypsin, and V8 protease, suggesting the isolated receptor is a glycoprotein with N-linked carbohydrate units. Isolated type 1 fimbriae inhibited the binding of fimbriated E. coli to purified receptor in a dose- and time-related fashion. The calculated binding affinity was 6 X 10(6) M-1, a value consistent with the low binding affinity expected from previous studies of the agglutination of guinea pig erythrocytes by isolated type 1 fimbriae.