The Proteolytic System of Candida dubliniensis

Proteases of Candida dubliniensis have been scarcely studied, these enzymes may play an important role in nitrogen metabolism, post-translational processing, nutritional stress, dimorphism, virulence, etc. In this work, we report the presence of five different intracellular proteases and one extracellular proteolytic activity. The intracellular proteases are: aminopeptidase ycdAPE, carboxypeptidase ycdCP, dipeptidyl aminopeptidase ycdDAP, proteinases ycdPrA and ycdPrB, and extracellular protease Sap activity, measured under several nutritional conditions. C. dubliniensis produced the highest level of intracellular proteolytic enzymes, i.e., ycdAPE, ycdCP, ycdDAP, ycdPrA and ycdPrB in media with peptone during stationary growth phase. Chelating agents affected mainly APE activity; whereas ycdCp, ycdDAP, and ycdPrB were affected by serine protease inhibitors; ycdPrA was affected by pepstatin, an aspartyl protease inhibitor. We found Sap activity in C. dubliniensis in YCB-SBA medium, this activity was inhibited by pepstatin inhibitor. Southern analysis revealed the presence of at least four genes encoding Sap in the C. dublinienisis genome (using as probes SAP1, SAP2, SAP3, and SAP4-6 genes from C. albicans).