title: Evidence for the presence of proteolytically active secreted aspartic proteinase 1 of Candida parapsilosis in the cell wall.
abstract: Pathogenic yeasts of the genus Candida produce secreted aspartic proteinases, which are known to enhance virulence. We focused on Sapp1p proteinase secreted by Candida parapsilosis and studied the final stage of its passage through the cell wall and release into the extracellular environment. We found that Sapp1p displays enzyme activity prior to secretion, and therefore, it is probably fully folded within the upper layer of the cell wall. The positioning of cell surface-associated Sapp1p was detected by cell wall protein labeling using biotinylation agents, extraction of cell wall proteins by β-mercaptoethanol, immunochemical detection, and mass spectrometry analysis. All lysine residues present in the structure of soluble, purified Sapp1p were labeled with biotin. In contrast, the accessibility of individual lysines in cell wall-associated Sapp1p varied with the exception of four lysine residues that were biotinylated in all experiments performed, suggesting that Sapp1p has a preferred orientation in the cell wall. As the molecular weight of this partially labeled Sapp1p did not differ among the experiments, we can assume that the retaining of Sapp1p in the cell wall is not a totally random process and that pathogenic yeasts might use this cell-associated proteinase activity to enhance degradation of appropriate substrates.
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, vvi, Prague, Czech Republic.
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Vinterová
authors.forename: Miloslav
authors.initials: M
authors.lastname: Sanda
authors.forename: Jiří
authors.initials: J
authors.lastname: Dostál
authors.forename: Olga
authors.initials: O
authors.lastname: Hrušková-Heidingsfeldová
authors.forename: Iva
authors.initials: I
authors.lastname: Pichová
mesh_terms: D000595:Amino Acid Sequence; D057055:Aspartic Acid Proteases / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism*; D019921:Biotinylation; D002175:Candida / Q000737:chemistry / Q000201:enzymology*; D002473:Cell Wall / Q000737:chemistry / Q000201:enzymology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D059748:Proteolysis
chemical_list: D057055:Aspartic Acid Proteases