Glucan-Associated Protein Modulations and Ultrastructural Changes of the Cell Wall in Candida albicans Treated with Micafungin, a Water-Soluble, Lipopeptide Antimycotic

Abstract

The composition of glucan-associated proteins (GAP) in the cell wall of Candida albicans was strongly affected by treatment with a sub-MIC yet β-glucan synthesis inhibitory concentration (0.01 μg/ml) of FK463 (micafungin). Namely, a decrease in enzymes of glucose metabolism (mostly enolase and a novel 40 kDaltons component, here identified as the enzyme fructose-1,6-biphosphate aldolase) was observed, and this was coupled with an increase in two β1-3 exo-glucanase isoforms (34 and 44 kDa, respectively). No GAP changes were detected in the same strain of the fungus made resistant to the drug, attesting to the specificity of the observed cell wall protein modulation. In addition, GAP changes were accompanied by marked ultrastructural alterations upon treatment with the sub-MIC dose of the drug, the majority of which was an aberrant cell surface morphology and a derangement of the normal layering of the cell wall. Our data demonstrate that sub-MIC doses of micafungin do critically affect not only the β-glucan synthetic machinery but also protein composition and the whole cell wall structure of Candida albicans.