Secretion of serine peptidase by a clinical strain of Candida albicans: influence of growth conditions and cleavage of human serum proteins and extracellular matrix components

• Published in: FEMS immunology and medical microbiology Vol. 46; no. 2; pp. 209 - 220
• Main Authors: Dos Santos, André Luis Souza, De carvalho, Isabela Miller, Da silva, Bianca Alcântara, Portela, Maristela Barbosa, Alviano, Celuta Sales, De araújo Soares, Rosangela Maria
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-03-2006; Blackwell
• Subjects: Adult; Biological and medical sciences; Blood Proteins - metabolism; Candida albicans; Candida albicans - enzymology; Candida albicans - growth & development; Candida albicans - pathogenicity; Candidiasis - microbiology; Culture Media; extracellular matrix; Extracellular Matrix - metabolism; extracellular proteolytic activity; Female; Fundamental and applied biological sciences. Psychology; Fungal Proteins - metabolism; Humans; metallopeptidase; Metalloproteases - metabolism; Microbiology; Miscellaneous; Mycology; Serine Endopeptidases - secretion; serine peptidases; serum proteins; Urinary Tract Infections - microbiology; serine peptidases; extracellular proteolytic activity; metallopeptidase; serum proteins; extracellular matrix; Candida albicans; Human; Yeast; Microbiology; Enzyme; Secretion; Serine; Serum protein; Strain; Fungi; Peptidases; Immunology; Hydrolases; Extracellular matrix; Fungi Imperfecti; Thallophyta
• ISSN: 0928-8244; 1574-695X
• DOI: 10.1111/j.1574-695X.2005.00023.x

Abstract
Candida albicans expresses a vast number of hydrolytic enzymes, playing roles in several phases of yeast–host interactions. Here, we identified two novel extracellular peptidase classes in C. albicans. Using gelatin–sodium dodecyl sulfate polyacrylamide gel electrophoresis two gelatinolytic activities were detected at physiological pH: a 60-kDa metallopeptidase, completely blocked by 1,10-phenanthroline, and a 50-kDa serine peptidase inhibited by phenylmethylsulfonyl fluoride. In an effort to establish a probable functional implication for these novel peptidase classes, we demonstrated that the 50-kDa secretory serine peptidase was active over a broad pH range (5.0–7.2) and was capable to hydrolyze some soluble human serum proteins and extracellular matrix components. Conversely, when this isolate was grown in yeast carbon base supplemented with bovine serum albumin, a secretory aspartyl peptidase activity was measured, instead of metallo- and serine peptidases, suggesting that distinct medium composition induces different expression of released peptidases in C. albicans. Additionally, we showed by quantitative proteolytic measurement, flow cytometry and immunoblotting assays that the brain heart infusion medium might repress the Sap1–3 production. Collectively, our results showed for the first time the capability of an extracellular proteolytic enzyme other than aspartic-type peptidases to cleave a broad spectrum of relevant host proteinaceous substrates by the human pathogen C. albicans.