Biosensor-Enabled Discovery of CaERG6 Inhibitors and Their Antifungal Mode of Action against Candida albicans

Fungal infections caused by opportunistic pathogens, such as Candida albicans, are generally underappreciated by the public in spite of their high mortality rates. Antifungal arsenals are extremely limited. Herein, based on biosynthetic pathway comparison and functional characterization, CaERG6, a crucial sterol 24-C-methyltransferase involved in the biosynthesis of ubiquitous ergosterol in C. albicans, was set up as an antifungal target. CaERG6 inhibitors were identified from the in-house small-molecule library by a biosensor-based high-throughput screening. The CaERG6 inhibitor NP256 (palustrisoic acid E) is a potential antifungal natural product that acts by inhibiting ergosterol biosynthesis, downregulating the gene expression level in hyphal formation, blocking biofilm formation, and disrupting morphological transition in C. albicans. NP256 enhances C. albicans susceptibility to some known antifungals significantly. The present study demonstrated the CaERG6 inhibitor NP256 as a potential class of antifungal compound for monotherapy or combinatory therapy.