Differential regulation of SAP8 and SAPS, which encode two new members of the secreted aspartic proteinase family in Candida albicans

Abstract

SUMMARY: Secreted aspartic proteinases (Saps) contribute to the virulence of Candida albicans in systemic animal models of infection. Seven genes encoding Saps (SAM-SAP7) have been identified to date but evidence suggested the existence of additional SAP genes. The screening of a C. albicans iZEMBL3 genomic library for the presence of other SAP genes was undertaken. Two new genes, SAP8 and SAPS, were isolated. The N-terminal amino acid sequence deduced from SAP8 downstream of a Kex2plike cleavage site corresponds to the N-terminal amino acid sequence of the 41 kDa Sap isolated and characterized previously. SAP8 mRNA was expressed preferentially in yeasts at 25 "C after 6 and 9 h growth in BSA-containing medium. SAPS encodes an aspartic proteinase with a Kex2pllike cleavage site and contains a putative glycophosphatidylinositol-anchor signal at the C-terminus. Although the SAPS gene product has not yet been isolated from cultures of C. albicans, transcripts of SAPS were observed preferentially in later growth phases when SAP8 expression had decreased.