The expression of the secreted aspartyl proteinases Sap4 to Sap6 from Candida albicans in murine macrophages

Mol Microbiol. 1998 May;28(3):543-54. doi: 10.1046/j.1365-2958.1998.00815.x.


Medically important yeasts of the genus Candida secrete aspartyl proteinases (Sap), which are of particular interest as virulence factors. Six closely related gene sequences, SAP1 to SAP6, for secreted proteinases are present in Candida albicans. The methylotrophic yeast Pichia pastoris was chosen as an expression system for preparing substantial amounts of each Sap isoenzyme. Interestingly, Sap4, Sap5 and Sap6, which have not yet been detected in C. albicans cultures in vitro, were produced as active recombinant enzymes. Different Sap polyclonal antibodies were raised in rabbits and tested before further application by enzyme-linked immunosorbent assay (ELISA) against each recombinant Sap. Two antisera recognized only Sap4 to Sap6. Using these antisera, together with sap null mutants obtained by targeted mutagenesis, we could demonstrate a high production of Sap4, Sap5 and Sap6 by C. albicans cells after phagocytosis by murine peritoneal macrophages. Furthermore, a delta sap4,5,6 null mutant was killed 53% more effectively after contact with macrophages than the wild-type strain. These results support a role for Sap4 to Sap6 in pathogenicity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Fungal / immunology
  • Antigens, Fungal / analysis
  • Aspartic Acid Endopeptidases / genetics
  • Aspartic Acid Endopeptidases / immunology
  • Aspartic Acid Endopeptidases / isolation & purification
  • Aspartic Acid Endopeptidases / metabolism*
  • Candida albicans / enzymology*
  • Candida albicans / genetics
  • Candida albicans / growth & development
  • Candida albicans / pathogenicity
  • Cross Reactions
  • Enzyme-Linked Immunosorbent Assay
  • Fluorescent Antibody Technique
  • Fungal Proteins*
  • Hydrogen-Ion Concentration
  • Isoenzymes / metabolism
  • Macrophages, Peritoneal / microbiology*
  • Mice
  • Phagocytosis
  • Pichia / enzymology
  • Plasmids / genetics
  • Rabbits
  • Recombinant Fusion Proteins / isolation & purification
  • Recombinant Fusion Proteins / metabolism


  • Antibodies, Fungal
  • Antigens, Fungal
  • Fungal Proteins
  • Isoenzymes
  • Recombinant Fusion Proteins
  • Aspartic Acid Endopeptidases
  • SAP4 protein, Candida albicans
  • SAP5 protein, Candida albicans