Possible role of secreted proteinases in Candida albicans infections.

Extracellular proteolytic activity of the human pathogen Candida albicans is due to the activity of at least nine secreted aspartyl proteinase (Sap) isoenzymes. SAP1-9 genes are differentially regulated both in vitro and in vivo at the transcriptional level. All SAP genes are translated into preproenzymes, which are processed by a signal peptidase and a Kex2-like proteinase. In vitro experiments using purified Saps suggested that active Saps may play a role in attachment, colonization, penetration of host tissues and immune evasion. In vivo expression of SAP1-6 during oral candidosis was established. Using sap mutants, produced by targeted gene disruption, a prominent role for SAP1-6 during murine disseminated infections and for SAP1-3 during rat vaginal infections could be demonstrated. These data underline the general importance of extracellular proteinases for the pathogenesis in C. albicans infections.