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Differential secretion of Sap4-6 proteins in Candida albicans during hyphae formation
Yee-Chun Chen1,2, Chi-Chen Wu3,1, Wei-Lian Chung3,1
1Department of Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan2.
Abstract:
Secreted aspartyl proteinases (Saps) from Candida albicans are encoded by a multi-gene family and are considered to be putative virulence factors for candidiasis. SAP4-6 mRNAs were first detected during hyphae formation and were assumed to play roles in the development of disseminated candidiasis. Recombinant Sap proteins (Sap2-6) were prepared and specific antibodies were generated against Sap2-6. The presence of Sap4, Sap5 and Sap6, but not Sap2 or Sap3, was demonstrated in culture supernatants of C. albicans after induction of hyphae formation. In parallel to hyphae formation, Sap5 (approximately 40 kDa) was detected as early as approximately 6 h after induction at neutral pH, and Sap4/6 (approximately 43 kDa) were detected after approximately 24 h when the culture medium became acidic. The differential secretion of Sap5 and Sap4/6 was affected when the culture medium pH was buffered at pH 6.5 or pH 4.5. In addition, intracellular pools of Sap4-6 seem to exist, and protein is not necessary for Sap4-6 induction. This study provides the first evidence that Sap4-6 proteins in C. albicans are differentially produced and secreted during hyphae formation.
Insights
Secreted aspartyl proteinases (Saps) from Candida albicans, specifically Sap4-6, are differentially produced and secreted during hyphae formation. This finding offers new insights into the virulence factors contributing to candidiasis.
Area of Science:
- Mycology
- Molecular Biology
- Biochemistry
Background:
- Secreted aspartyl proteinases (Saps) are key virulence factors in Candida albicans infections.
- SAP4-6 gene expression is linked to hyphae formation, suggesting a role in disseminated candidiasis.
Purpose of the Study:
- To investigate the differential production and secretion of Sap4-6 proteins during Candida albicans hyphae formation.
- To determine the influence of pH on Sap4-6 secretion.
Main Methods:
- Generation of recombinant Sap proteins (Sap2-6) and specific antibodies.
- Detection of Sap proteins in culture supernatants using Western blotting.
- Induction of hyphae formation and manipulation of culture medium pH.
Main Results:
- Sap4, Sap5, and Sap6 were detected in supernatants after hyphae induction, while Sap2 and Sap3 were not.
- Sap5 was secreted early (6h) at neutral pH, whereas Sap4/6 appeared later (24h) in acidic conditions.
- Culture medium pH significantly affected the differential secretion of Sap5 and Sap4/6.
- Intracellular pools of Sap4-6 exist, and protein is not required for their induction.
Conclusions:
- Candida albicans differentially produces and secretes Sap4-6 proteins during hyphae formation.
- The timing and pH-dependent secretion of Sap4-6 suggest distinct roles in the pathogenesis of candidiasis.