Inhibiting mitochondrial phosphate transport as an unexploited antifungal strategy

The development of effective antifungal therapeutics remains a formidable challenge due to the close evolutionary relationship between humans and fungi. Mitochondrial function may present an exploitable vulnerability due to its differential utilization in fungi and its pivotal roles in fungal morphogenesis, virulence, and drug resistance already demonstrated by others. We now report mechanistic characterization of ML316, a thiohydantoin which kills drug-resistant Candida species at nanomolar concentrations through fungal-selective inhibition of the mitochondrial phosphate carrier Mir1. We established ML316 as the first Mir1 inhibitor using genetic, biochemical, and metabolomic approaches. Inhibition of Mir1 by ML316 in respiring yeast diminished mitochondrial oxygen consumption resulting in an unusual metabolic catastrophe marked by citrate accumulation, and death. In a mouse model of azole-resistant oropharyngeal candidiasis, ML316 reduced fungal burden and enhanced azole activity. Targeting Mir1 could provide a new, much needed therapeutic strategy to address the rapidly rising burden of drug-resistant fungal infection.