Evidence that the major outer membrane protein of Chlamydia trachomatis is glycosylated

Abstract

The major outer membrane protein (MOMP) of Chiamydia trachomatis was determined to be a glycoprotein on the basis of susceptibility to glycosidase digestion and the presence of carbohydrate by staining and radiolabeling. The MOMP of the serovar L2 organisms was isolated by electroelution from the protein band excised from the gel after sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The incubation of MOMP with N-glycosidase F, an endoglycosidase that cleaves the N-glycan, and periodate resulted in two new molecular weight species. While MOMP treated with N-glycosidase F showed a lower-molecular-weight mobility, the periodate-treated MOMP increased in molecular weight. Both treatments abolished the ability of the MOMP to bind to HeLa cell components. In the immunoblot, the reactivity to the monoclonal antibody specific against the C. trachomatis species was preserved. The endoglycosidase specific to 0-linked glycan, endo-aN -acetylgalactosaminidase, had no visible effect on the isolated MOMP. Carbohydrate was detected in the MOMP by p-phenylenediamine staining of the protein band in the gel following SDS-PAGE. Autoradiograms of proteins of chlamydial organisms metabolically labeled with [3H]galactose or * Corresponding author.

Characterization of glycoproteins fromChlamydia trachomatisusing lectins

“…The MOMP is reported to have a molecular mass of about 40 kDa, which fits well with the gp40 in our blots. Also the binding of ConA, PNA and DBA, and the lack of binding to UEA-I and RCA in the gp40, agrees with previous studies of different MOMP preparations (3,12,14). Conflicting results on the binding of…”

“…WGA to gp40 have been published. In our blots WGA binding was not convincing (3,14). Chlamydial infection of mammalian cells requires attachment, endocytosis and inhibition of phagolysosomal fusion (10).…”

“…Lectinbinding might be used for identifying different serotypes of C. trachomatis. The outer membrane proteins (MOMP) of C. trachomutis serotypes B, E and L2, as well as of C. pneumoniue, have been characterized using different lectins (3,12,14). Modulation of the carbohydrates of the MOMP abolished the binding of iodinated components from the target cell, indicating an important role of the sugar structures of chlamydial organisms (14).…”

Pathogenic Puppetry: Manipulation of the Host Actin Cytoskeleton by Chlamydia trachomatis

“…The host component of this GAG-mediated bridge between EB and the host has remained elusive; however, recent work suggests an alternative, GAG-independent OmcB/MOMP attachment mechanism. Mounting evidence indicates that both proteins are post-translationally modified via glycosylation, as OmcB/MOMP recovered from EBs shows evidence of modification by N-linked high-mannose oligosaccharides [52][53][54]. Furthermore, both proteins exhibit reactivity to Erythrina crista-galli lectin, which binds to sites of N-acetyllactosamine glycosylation [54].…”

The 32-kDa glycoprotein of Chlamydia trachomatis is an acidic protein that may be involved in the attachment process

“…The speclficItles of monoclonal antibodies (mAbs) and rabbit antlsera against C trachomatts used in this study have been described previously mAbs KK-12 recognizes the C trachomatts species-specific ep~tope on the 40-kDa major outer membrane protein (MOMP) and CF-2 reacts against the Chlamydla genus-specific llpopolysaccharlde [7] Rabbit immune sera were produced against whole EBs [8], isolated MOMP [9], and affinity purified 155-kDa protein [10] of the 434 strata of the L2 serovar In addition, mAbs against anti di-and trlfucosylated type 2 glycohpld (ATCC HB 8775) and anti-human A associated H blood group antigen (ATCC HB 9298) were produced from clones obtained from the American Type Culture Collection…”