Characterization of glycoproteins from Chlamydia trachomatis using lectins.

Glycoproteins in Chlamydia trachomatis, serotype L1, elementary bodies were studied by lectin blotting. A panel of 23 lectins representing a variety of sugar specificities was used. The pattern of lectin-binding specificities at a peptide band was studied in order to determine the type and structure of its glycoconjugate. To establish chlamydial origin of the glycopeptide bands in the blot, control samples from non-infected host cell membranes were run in parallel. Terminal mannosidic structures were demonstrated in a 72 kDa glycopeptide (gp72) by its selective binding of Galanthus nivalis lectin (GNA). Sialic acids were found in two chlamydial glycopeptides, gp40 and gp64, which appear to carry O-linked glycoconjugates as they bound the peanut agglutinin (PNA, both gp40 and gp64) and jackfruit lectin (Jac, only gp40). Such structures were also present in other chlamydial glycopeptides. Lectins with specificities for fucose in different links, galactose and N-acetyl glucosamine bound to several chlamydial peptides. On the basis of our results we suggest an alternative mechanism for uptake of chlamydial elementary bodies into host cells, namely phagocytosis mediated by eukaryotic cell surface lectins.