title: Proteolytic activity of cultured Pseudoperkinsus tapetis extracellular products.
abstract: Several pathogenic protozoan release proteases are necessary for host invasion and initiation of infection. We have identified proteolytic activities in extracellular proteins secreted by the clam parasite Pseudoperkinsus tapetis (Mesomycetozoa) in vitro. The protein concentration of the P. tapetis extracellular products (ECP) increased only during the first week of culture. The appearance of new proteins of 10 and 157 kDa at the second week sample and of 12 kDa at the third week sample was shown by SDS-PAGE. The protease activity rapidly increased in the first 3 weeks of culture, and five clear bands of 23, 29, 60, 67 and 96 kDa with proteolytic activity were detected in the ECP on gelatin SDS-PAGE. Using inhibitors, the proteases were identified as members of the Ca(2+) dependent, serine protease family. Their optimum pH was higher than pH 9.4. The protease activity of the P. tapetis ECP was different than that described for Perkinsus marinus, an oyster pathogen very similar morphologically to the clam parasite and member of the genus in which P. tapetis had been initially included.
authors.affiliation: Instituto de Investigaciones Marinas, Consejo Superior de Investigaciones Científicas (CSIC), Eduardo Cabello, 6, 36208 Vigo, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Camino Ordás
authors.forename: B
authors.initials: B
authors.lastname: Novoa
authors.forename: M
authors.initials: M
authors.lastname: Faisal
authors.forename: S
authors.initials: S
authors.lastname: McLaughlin
authors.forename: A
authors.initials: A
authors.lastname: Figueras
mesh_terms: D000818:Animals; D049872:Bivalvia / Q000469:parasitology*; D002452:Cell Count; D002470:Cell Survival; D002478:Cells, Cultured; D016895:Culture Media, Serum-Free; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000378:metabolism*; D056890:Eukaryota / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D011480:Protease Inhibitors / Q000494:pharmacology; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D013997:Time Factors
chemical_list: D016895:Culture Media, Serum-Free; D011480:Protease Inhibitors; D015842:Serine Proteinase Inhibitors; D010450:Endopeptidases