The Als3 Cell Wall Adhesin Plays a Critical Role in Human Serum Amyloid A1-Induced Cell Death and Aggregation in Candida albicans.

Antimicrobial peptides and proteins play critical roles in the host defense against invading pathogens. We recently discovered that recombinantly expressed human and mouse serum amyloid A1 (rhSAA1 and rmSAA1, respectively) proteins have potent antifungal activities against the major human fungal pathogen At high concentrations, rhSAA1 disrupts membrane integrity and induces rapid fungal cell death. In the present study, we find that rhSAA1 promotes cell aggregation and targets the cell wall adhesin Als3. Inactivation of in leads to a striking decrease in cell aggregation and cell death upon rhSAA1 treatment, suggesting that Als3 plays a critical role in SAA1 sensing. We further demonstrate that deletion of the transcriptional regulators controlling the expression of , such as , , and , in results in similar effects to that of the mutant upon rhSAA1 treatment. Global gene expression profiling indicates that rhSAA1 has a discernible impact on the expression of cell wall- and metabolism-related genes, suggesting that rhSAA1 treatment could lead to a nutrient starvation effect on cells.