SummaryFungal infections cause millions of deaths annually and are challenging to treat due to limited therapeutic options and rising resistance. Cryptococci are intrinsically resistant to the latest generation of antifungals, echinocandins, while Candida auris , a notorious global threat, is also increasingly resistant. We perform a natural product screen to rescue caspofungin fungicidal activity against Cryptococcus neoformans H99 and identify butyrolactol A, which restores echinocandin efficacy against resistant fungal pathogens, including multidrug-resistant C. auris . Mode of action studies reveal that butyrolactol A inhibits the phospholipid flippase Apt1 Cdc50, blocking phospholipid transport. Cryo-elect... More
SummaryFungal infections cause millions of deaths annually and are challenging to treat due to limited therapeutic options and rising resistance. Cryptococci are intrinsically resistant to the latest generation of antifungals, echinocandins, while Candida auris , a notorious global threat, is also increasingly resistant. We perform a natural product screen to rescue caspofungin fungicidal activity against Cryptococcus neoformans H99 and identify butyrolactol A, which restores echinocandin efficacy against resistant fungal pathogens, including multidrug-resistant C. auris . Mode of action studies reveal that butyrolactol A inhibits the phospholipid flippase Apt1 Cdc50, blocking phospholipid transport. Cryo-electron microscopy analysis of the Apt1 butyrolactol A complex reveals that the flippase is trapped in a dead-end state. Apt1 inhibition disrupts membrane asymmetry, vesicular trafficking, and cytoskeletal organization, thereby enhancing echinocandin uptake and potency. This study identifies lipid flippases as promising antifungal targets and demonstrates the potential of revisiting natural products to expand the antifungal arsenal and combat resistance.Graphical AbstractChen et al. identify the natural product butyrolactol A as an inhibitor of the phospholipid flippase Apt1 Cdc50, which it locks in a nonfunctional state. By disrupting membrane homeostasis and enhancing drug uptake, butyrolactol A restores echinocandin efficacy against intrinsically resistant fungal pathogens, including Cryptococcus and Candida auris .
