Artificial Lipidation of Antifungal Proteins and Antifungal Behavior: A Case Study with Cholesterylation

Lipid-based formulation of antifungal small drugs is used to mitigate drug toxicity while retaining effective antifungal activity. Herein, the effect of artificial cholesterylation of is studied, both of which were site-specifically modified using a microbial transglutaminase-reactive Q-tag (LysM-Q and CatD-Q). This produced protein-lipid conjugates (LysM-cholesteryl [Chol] or -palmitoyl [Pal] and CatD-Chol or -Pal). Although lipidation of these chitinase domains enhances the antifungal activity against Trichoderma viride, palmitoylated proteins (LysM-Pal and CatD-Pal) show stronger antifungal effects than cholesterylated proteins (LysM-Chol and CatD-Chol) both in the absence and presence of amphotericin B. Further characterization with lipidated LysM-fused green fluorescent protein (LysM-muGFP-Pal and -Chol) shows that the cholesterylation of proteins promotes distribution to dextran-rich phase in an aqueous two-phase system consisting of polyethylene glycol and dextran. Fluorescence microscopic analyses of the phase-separated giant unilamellar vesicles reveal a distinct anchoring behavior between LysM-muGFP-Pal and -Chol to lipid membranes, which is possibly correlated with aggregate formation. These results highlight that the chemical properties of the lipid moiety are crucial to achieve effective enhancement of antifungal activity through artificial lipidation.