Identification and characterization of an aspartyl protease from Cryptococcus neoformans

Cryptococcosis, caused by Cryptococcus neoformans, is an invasive infection often occurring in AIDS patients. Potent therapy against HIV, which includes protease inhibitors (PIs), has beneficial effects also on opportunistic infections by pathogens such as C. neoformans and C. albicans. PIs inhibit growth of C. albicans by affecting the activity of its aspartyl proteases. We identified, cloned and sequenced a cDNA from C. neoformans encoding for a putative aspartyl protease (CnAP1), and the corresponding genomic region. The gene cnap1 codifies for a protein of 505 aa, with a canonical aspartyl protease structure. We purified the recombinant protein and analyzed its activity in the presence of PIs (Indinavir, Lopinavir, Ritonavir), but did not evidence any inhibition of protease activity. The transcriptional level of cnap1 in C. neoformans is constant in different media. The absence of any inhibition activity by PIs suggests that other targets for PIs might exist in C. neoformans.