Candida albicans exhibits a pepstatin A‐insensitive secreted aspartic protease as a virulence factor

Abstract

Candida albicans exists in most people, but opportunistically causes severe diseases. One of the major virulence factors is secreted aspartic protease family, encoded by 10 SAP genes (1). Sap isozymes are suggested to contribute to many virulence processes. However, there is a controversy whether Sap family is really a major virulence factor or not, because use of pepstatin A showed little protective effect. In this study, we found Sap7 was a pepstatin A‐insensitive protease and tried to determine the mechanism of pepstatin A‐insensitivity. SAP7 gene was cloned from C. albicans and heterogeneously produced by Pichia pastoris. Proteolytic activity of wild type Sap7 and alanine‐substituted mutants was measured using FRETS‐25Ala library. As a result, we found that Sap7 was pepstatin A‐insensitive and that the M242A and T467A mutants had sensitivity to pepstatin A. M242 and T467 were located in the entrance to an active site, and the substitution of alanine made the entrance wider. This alteration might enable pepstatin A accessibility to the center (2). Grants; JSPS for Young Scientists and Regional Innovation Creation R&D Programs.