title: Trichomonas vaginalis: the adhesins AP51 and AP65 bind heme and hemoglobin.
abstract: Trichomonas vaginalis is the cause of human trichomoniasis, the most common non-viral sexually transmitted disease worldwide. Although acquisition of iron by binding to host hemoglobin through distinct receptor(s) has been described, no specific heme- or hemoglobin-binding site has been reported in this parasite. To determine the presence of hemoglobin-binding protein(s), membrane proteins were subjected to hemoglobin-affinity chromatography. Eluted proteins were analysed by SDS-PAGE. Two protein bands of 48 and 63 kDa were detected. Competition assay with an excess amount of hemoglobin or hemin in hemoglobin-affinity chromatography could block the 63- and 48-kDa bands, respectively. Further analysis by mass spectrometry indicated that the 48- and 63-kDa proteins had identity with two T. vaginalis adhesins: AP51 and AP65, respectively. This study confirms the existence of multifunctional proteins in T. vaginalis, and suggested that AP51 and AP65, besides serving as adhesion molecules, could also act as heme- and hemoglobin-binding proteins.
authors.affiliation: Division of Infectious Diseases, Department of Medicine, University of Ottawa, The Ottawa Health Research Institute, The Ottawa Hospital, 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6.
authors.forename: Shahed
authors.initials: S
authors.lastname: Ardalan
authors.forename: B Craig
authors.initials: BC
authors.lastname: Lee
authors.forename: Gary E
authors.initials: GE
authors.lastname: Garber
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D019921:Biotinylation; D015153:Blotting, Western; D015815:Cell Adhesion Molecules / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002846:Chromatography, Affinity; D004591:Electrophoresis, Polyacrylamide Gel; D020868:Gene Silencing; D006418:Heme / Q000378:metabolism*; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D007501:Iron / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014246:Trichomonas vaginalis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: C110980:AP51 adhesin, Trichomonas vaginalis; C096723:AP65-1 protein, Trichomonas vaginalis; D015815:Cell Adhesion Molecules; D006454:Hemoglobins; D008565:Membrane Proteins; D015800:Protozoan Proteins; D006418:Heme; D007501:Iron