Zap1 is required for Candida glabrata response to fluconazole.

The increasing prevalence of fluconazole-resistant clinical isolates of Candida spp. strongly hinders the widespread use of the drug. To tackle this problem, great efforts have been made to fully understand the fungal response to fluconazole. In this work, we show that the role of Zap1 in Candida glabrata goes beyond regulating yeast adaptation to zinc deficiency. In line with our previous observation that deletion of ZAP1 makes yeast cells more sensitive to fluconazole, we found that the mutant CgΔzap1 accumulates higher levels of the drug, which correlates well with its lower levels of ergosterol. Surprisingly, Zap1 is a negative regulator of the drug efflux transporter gene CDR1 and of its regulator, PDR1. The apparent paradox of drug accumulation in cells where genes encoding transporters relevant for drug extrusion are being overexpressed led us to postulate that their activity could be impaired. In agreement, Zap1-depleted cells present, in addition to decreased ergosterol levels, an altered composition of membrane phospholipids, which together should impact membrane function and impair the detoxification of fluconazole. Overall, our study brings to light Zap1 as an important hub in Candida glabrata response to fluconazole.

A copper(II)-binding triazole derivative with ionophore properties is active against Candida spp.

Invasive fungal infections (IFIs) are life threatening and existing antifungal drugs are not completely effective due to undesirable side effects and resistance emergence. Azoles are often the treatment of choice for IFIs and growing evidence suggests that copper can act synergistically with these drugs. In this work, we designed a compound bringing together azole and copper(II)-binding groups and studied the molecular mechanisms underlying its biological toxicity. Our results show that both the compound, 4, and its copper(II) complex, Cu.4, are active against Candida spp. We found that Cu.4 acts as a copper(II) ionophore, which results in the intracellular accumulation of reactive oxygen species (ROS), whereas compound 4 is an iron chelator and exerts its toxicity by decreasing iron bioavailability. Interestingly, while 4 is not very toxic to macrophages or HeLa cells, Cu.4 significantly affects their viability. Overall, this work provides evidence of how copper can be combined with azoles to deregulate copper homeostasis, opening new horizons for the development of bifunctional antifungals.