title: RGD motif of lipoprotein T, involved in adhesion of Mycoplasma conjunctivae to lamb synovial tissue cells.
abstract: Lipoprotein T (LppT), a membrane-located 105-kDa lipoprotein of Mycoplasma conjunctivae, the etiological agent of infectious keratoconjunctivitis (IKC) of domestic sheep and wild Caprinae, was characterized. LppT was shown to promote cell attachment to LSM 192 primary lamb joint synovial cells. Adhesion of M. conjunctivae to LSM 192 cells is inhibited by antibodies directed against LppT. The RGD (Arg-Gly-Asp) motif of LppT was found to be a specific site for binding of M. conjunctivae to these eukaryotic host cells. Recombinant LppT fixed to polymethylmethacrylate slides binds LSM 192 cells, whereas LppT lacking the RGD site is deprived of binding capacity to LSM 192, and LppT containing RGE rather than RGD shows reduced binding. Synthetic nonapeptides derived from LppT containing RGD competitively inhibit binding of LSM 192 cells to LppT-coated slides, whereas nonapeptides containing RAD rather than RGD do not inhibit. RGD-containing, LppT-derived nonapeptides are able to directly inhibit binding of M. conjunctivae to LSM 192 cells by competitive inhibition, whereas the analogous nonapeptide containing RAD rather than RGD or the fibronectin-derived RGD hexapeptide has no inhibitory effect. These results reveal LppT as the first candidate of a RGD lectin in Mycoplasma species that is assumed to bind to beta integrins.
authors.affiliation: Institute of Veterinary Bacteriology, University of Bern, Länggass-Strasse 122, CH-3012 Bern, Switzerland.
authors.forename: Liza
authors.initials: L
authors.lastname: Zimmermann
authors.forename: Ernst
authors.initials: E
authors.lastname: Peterhans
authors.forename: Joachim
authors.initials: J
authors.lastname: Frey
mesh_terms: D020816:Amino Acid Motifs / Q000502:physiology; D000818:Animals; D001422:Bacterial Adhesion / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D002460:Cell Line; D003001:Cloning, Molecular; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D008074:Lipoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D045684:Mycoplasma conjunctivae / Q000502:physiology*; D012756:Sheep; D013583:Synovial Membrane / Q000166:cytology*
chemical_list: D001426:Bacterial Proteins; D008074:Lipoproteins