title: Phospholipase C-mediated release of neuraminidase from Tritrichomonas foetus cell surface.
abstract: The release of the Tritrichomonas foetus plasma-membrane ectoenzyme neuraminidase by exogenous specific phospholipase C (PI-PLC) was investigated. Neuraminidase activity was determined using both the peanut agglutinin (PNA) hemagglutination test and the specific substrate N-acetylneuramin-lactose in a colorimetric assay. The release of the neuraminidase by PI-PLC was dependent on the reaction time and the concentration of PI-PLC. Neuraminidase activity was also detected in supernatant of untreated T. foetus. Spontaneous or PI-PLC-induced release of neuraminidase from protozoan cells was markedly decreased by 10 mM ZnCl2, suggesting the occurrence of an endogenous PI-PLC in the parasite. After T. foetus lysis at 37 degrees C with a solution of Triton X-114, neuraminidase activity was preferentially found in the aqueous phase rather than in the detergent phase, again suggesting that the parasite contains an endogenous PI-PLC that converts the hydrophobic form of neuraminidase anchored to the T. foetus cell membrane into a hydrophilic form. These results show that neuraminidase is linked to the T. foetus plasma membrane via a glycosylphosphatidylinositol anchor.
authors.affiliation: Laboratório de Biologia Celular e Tecidual, Universidade Estadual do Norte Fluminense, RJ, Brazil.
authors.forename: B P
authors.initials: BP
authors.lastname: Dias Filho
authors.forename: W
authors.initials: W
authors.lastname: De Souza
authors.forename: A F
authors.initials: AF
authors.lastname: Andrade
authors.forename: M J
authors.initials: MJ
authors.lastname: Esteves
authors.forename: J
authors.initials: J
authors.lastname: Angluster
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D002712:Chlorides / Q000494:pharmacology; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D007700:Kinetics; D009439:Neuraminidase / Q000378:metabolism*; D016835:Tritrichomonas foetus / Q000201:enzymology*; D010738:Type C Phospholipases / Q000494:pharmacology*; D017967:Zinc Compounds / Q000494:pharmacology
chemical_list: D002712:Chlorides; D017261:Glycosylphosphatidylinositols; D017967:Zinc Compounds; C016837:zinc chloride; D010738:Type C Phospholipases; D009439:Neuraminidase