Adhesion Molecule of Borrelia burgdorferi ; Its Function and Application

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The binding activities of Borrelia burgdorferi to glycosphingolipid which are present in various types of cells were examined. B.burgdorferi bound specifically to galactosylceramide (GalCer) and glucosylceramide (GicCer), but not to other glycosphingolipids. The binding specificity of B.burgdorferi to various glycosphingolipid suggested that the binding receptor in the species is ceramide monohexoside. The necessity of the sugar and N-acyl moieties in galactosylceramide for the binding of Borre1ia was shown using chemically modified GalCer. The binding activities of the low-passage virulent strains to GalCer on TLC plates and to CHO-K1 cells in vitro were threefold higher than those of high-passage avirulent strains. Binding was no affected by pretreatment of Borrelia with monospecific anti-outer surface protein C (OspC) serum. These results indicated that the binding of Borrelia to glycosphingolipid expressed cell surface play an essential role in infection of mammalian hosts, but that OspC is not associated with binding. Two proteins, 37kDa and 67kDa, were involved in binding of B.burgdorferi to galactosylceramide as shown by blotting assay using biotinylated GalCer as a probe. 37kDa and 67kDa proteins reactive were determined as glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and homologue of heat shock protein 62, respectively. Recombinant GAPDH expressed by E.coli were bound with GalCer on TLC plate. The finding obtained in this study indicated that GAPDH is one of adhesion factor of B.burgdorferi.