Trichosporon asahii secretes a 30-kDa aspartic peptidase

Publication date: Available online 30 August 2017 Source:Microbiological Research Author(s): Roberta S. Valle, Lívia S. Ramos, Vanessa J. Reis, Mariangela Ziccardi, Marcos Dornelas-Ribeiro, Cátia L. Sodré, Marta H. Branquinha, André L.S. Santos Trichosporon asahii is a fungal opportunistic pathogen that causes superficial and deep-seated infections presenting high mortality. Very little is known about the virulence attributes produced by this fungus. Herein, aspartic peptidase production was identified in Brazilian clinical isolates of T. asahii by different methodologies. Initially, T. asahii strain 250 (from skin lesion) was inoculated in both liquid and solid culture media containing bovine serum albumin (BSA) as the sole nitrogenous source. A translucent halo around the fungal colony was observed from the 5th day of culture. The cell-free culture supernatant revealed that soluble BSA was hydrolyzed along the growth, generating low molecular mass polypeptides as observed by electrophoresis. Subsequently, the secretions from four clinical strains of T. asahii were analyzed by BSA-SDS-PAGE and a single proteolytic band of 30-kDa was detected under acidic pH at 37°C. The secreted aspartic peptidase of T. asahii efficiently cleaved the cathepsin D peptide substrate, but not the substrates with specificity to HIV-1 peptidase and rennin. The capability to cleave either cathepsin D substrate in a fluorogenic assay or BSA immobilized within a gel matrix varied accor...
Source: Microbiological Research - Category: Infectious Diseases Source Type: research