title: Characterization of two cysteine proteases secreted by Blastocystis ST7, a human intestinal parasite.
abstract: Blastocystis spp. are unicellular anaerobic intestinal parasites of both humans and animals and the most prevalent ones found in human stool samples. Their association with various gastrointestinal disorders raises the questions of its pathogenicity and of the molecular mechanisms involved. Since secreted proteases are well-known to be implicated in intestinal parasite virulence, we intended to determine whether Blastocystis spp. possess such pathogenic factors. In silico analysis of the Blastocystis subtype 7 (ST7) genome sequence highlighted 22 genes coding proteases which were predicted to be secreted. We characterized the proteolytic activities in the secretory products of Blastocystis ST7 using specific protease inhibitors. Two cysteine proteases, a cathepsin B and a legumain, were identified in the parasite culture supernatant by gelatin zymographic SDS-PAGE gel and MS/MS analysis. These proteases might act on intestinal cells and disturb gut function. This work provides serious molecular candidates to link Blastocystis spp. and intestinal disorders.
authors.affiliation: Clermont Université, Université Blaise Pascal, Laboratoire Microorganismes: Génome et Environnement, BP 10448, F-63000 Clermont-Ferrand, France.
authors.forename: Ivan
authors.initials: I
authors.lastname: Wawrzyniak
authors.forename: Catherine
authors.initials: C
authors.lastname: Texier
authors.forename: Philippe
authors.initials: P
authors.lastname: Poirier
authors.forename: Eric
authors.initials: E
authors.lastname: Viscogliosi
authors.forename: Kevin S W
authors.initials: KS
authors.lastname: Tan
authors.forename: Frédéric
authors.initials: F
authors.lastname: Delbac
authors.forename: Hicham
authors.initials: H
authors.lastname: El Alaoui
mesh_terms: D000595:Amino Acid Sequence; D016844:Blastocystis / Q000166:cytology / Q000201:enzymology* / Q000235:genetics*; D002401:Cathepsin B / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D057056:Cysteine Proteases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D016054:DNA, Protozoan / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007422:Intestines / Q000469:parasitology; D008969:Molecular Sequence Data; D011480:Protease Inhibitors / Q000378:metabolism; D040901:Proteomics; D053719:Tandem Mass Spectrometry; D037521:Virulence Factors / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D000099240:Asparaginyl Endopeptidase
chemical_list: D002401:Cathepsin B; D003546:Cysteine Endopeptidases; D057056:Cysteine Proteases; D016054:DNA, Protozoan; D011480:Protease Inhibitors; D037521:Virulence Factors; D000099240:Asparaginyl Endopeptidase