Secreted aspartic proteinase family of Candida tropicalis

• Published in: Infection and immunity Vol. 69; no. 1; pp. 405 - 412
• Main Authors: ZAUGG, Christophe, BORG-VON ZEPELIN, Margarete, REICHARD, Utz, SANGLARD, Dominique, MONOD, Michel
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 2001
• Subjects: Amino Acid Sequence; Aspartic Acid Endopeptidases - chemistry; Aspartic Acid Endopeptidases - genetics; Aspartic Acid Endopeptidases - physiology; Aspartic proteinase; Biological and medical sciences; Candida - enzymology; Candida - genetics; Candida - pathogenicity; Candida albicans; Candida tropicalis; Cloning, Molecular; Fundamental and applied biological sciences. Psychology; Fungal and Parasitic Infections; Growth, nutrition, metabolism, transports, enzymes. Molecular biology; Microbiology; Molecular Sequence Data; Mycology; Pathogenicity, host-agent relations, miscellaneous strains, epidemiology; Pichia pastoris; Recombinant Proteins - chemistry; Reverse Transcriptase Polymerase Chain Reaction; SAPT1 gene; SAPT2 gene; Sapt2 protein; SAPT3 gene; Sapt3 protein; SAPT4 gene; Sapt4 protein; Candida albicans; Candidiasis; Yeast; Sap; Mycosis; Virulence; Probe; Fungi; Gene; Candida tropicalis; Serum; Fungi Imperfecti; Ungulata; Thallophyta; Bovine; Enzyme; Secretion; Albumin; Serum albumin; Nitrogen; Medium containing; In vitro; Infection; Peptidases; Vertebrata; Mammalia; Hydrolases; Artiodactyla
• ISSN: 0019-9567; 1098-5522
• DOI: 10.1128/IAI.69.1.405-412.2001

Medically important yeasts of the genus Candida secrete aspartic proteinases (Saps), which are of particular interest as virulence factors. Like Candida albicans, Candida tropicalis secretes in vitro one dominant Sap (Sapt1p) in a medium containing bovine serum albumin (BSA) as the sole source of nitrogen. Using the gene SAPT1 as a probe and under low-stringency hybridization conditions, three new closely related gene sequences, SAPT2 to SAPT4, encoding secreted proteinases were cloned from a C. tropicalis lambdaEMBL3 genomic library. All bands identified by Southern blotting of EcoRI-digested C. tropicalis genomic DNA with SAPT1 could be assigned to a specific SAP gene. Therefore, the SAPT gene family of C. tropicalis is likely to contain only four members. Interestingly, the SAPT2 and SAPT3 gene products, Sapt2p and Sapt3p, which have not yet been detected in C. tropicalis cultures in vitro, were produced as active recombinant enzymes with the methylotrophic yeast Pichia pastoris as an expression system. As expected, reverse transcriptase PCR experiments revealed a strong SAPT1 signal with RNA extracted from cells grown in BSA medium. However, a weak signal was obtained with all other SAPT genes under several conditions tested, showing that these SAPT genes could be expressed at a basic level. Together, these experiments suggest that the gene products Sapt2p, Sapt3p, and Sapt4p could be produced under conditions yet to be described in vitro or during infection.