title: Candida guilliermondii isolated from HIV-infected human secretes a 50 kDa serine proteinase that cleaves a broad spectrum of proteinaceous substrates.
abstract: Non-albicans Candida species cause 35-65% of all candidemias in the general population, especially in immunosuppressed individuals. Here, we describe a case of a 19-year-old HIV-infected man with pneumonia due to a yeast-like organism. This clinical yeast isolate was identified as Candida guilliermondii through mycological tests. C. guilliermondii was cultivated in brain heart infusion medium for 48 h at 37 degrees C. After sequential centrifugation and concentration steps, the free-cell culture supernatant was obtained and extracellular proteolytic activity was assayed firstly using gelatin-SDS-PAGE. A 50 kDa proteolytic enzyme was detected with activity at physiological pH. This activity was completely blocked by 10 mM phenylmethylsulphonyl fluoride (PMSF), a serine proteinase inhibitor, suggesting that this extracellular proteinase belongs to the serine proteinase class. E-64, a strong cysteine proteinase inhibitor, and pepstatin A, a specific aspartic proteolytic inhibitor, did not interfere with the 50 kDa proteinase. Conversely, a zinc-metalloproteinase inhibitor (1,10-phenanthroline) restrained the proteinase activity released by C. guilliermondii by approximately 50%. Proteinases are a well-known class of enzymes that participate in a vast context of yeast-host interactions. In an effort to establish a functional implication for this extracellular serine-type enzyme, we investigated its capacity to hydrolyze some serum proteins and extracellular matrix components. We demonstrated that the 50 kDa exocellular serine proteinase cleaved human serum albumin, non-immune human immunoglobulin G, human fibronectin and human placental laminin, generating low molecular mass polypeptides. Collectively, these results showed for the first time the ability of an extracellular proteolytic enzyme other than aspartic-type proteinases in destroying a broad spectrum of relevant host proteins by a clinical species of non-albicans Candida.
authors.affiliation: Departamento de Microbiologia Geral, Laboratório de Biologia de Protistas, Instituto de Microbiologia Professor Paulo de Góes, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, RJ, Brazil. andre@micro.ufrj.br
authors.forename: André Luis Souza
authors.initials: AL
authors.lastname: Dos Santos
authors.forename: Rosangela Maria de Araújo
authors.initials: RM
authors.lastname: Soares
mesh_terms: D017088:AIDS-Related Opportunistic Infections / Q000382:microbiology*; D000328:Adult; D001798:Blood Proteins / Q000378:metabolism; D001938:Brazil; D002175:Candida / Q000145:classification / Q000201:enzymology* / Q000302:isolation & purification*; D002177:Candidiasis / Q000150:complications / Q000382:microbiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D005780:Gelatin / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007930:Leucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008172:Lung Diseases, Fungal / Q000150:complications / Q000382:microbiology*; D008297:Male; D008970:Molecular Weight; D010436:Pepstatins / Q000494:pharmacology; D010618:Phenanthrolines / Q000494:pharmacology; D010664:Phenylmethylsulfonyl Fluoride / Q000494:pharmacology; D011014:Pneumonia / Q000150:complications / Q000382:microbiology*; D012697:Serine Endopeptidases / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism
chemical_list: D001798:Blood Proteins; D004791:Enzyme Inhibitors; D016326:Extracellular Matrix Proteins; D010436:Pepstatins; D010618:Phenanthrolines; D010664:Phenylmethylsulfonyl Fluoride; D005780:Gelatin; D012697:Serine Endopeptidases; D007930:Leucine; C024974:E 64; C031375:pepstatin; C025205:1,10-phenanthroline