Mitochondrial Membrane-Associated Protein Mba1 Confers Antifungal Resistance by Affecting the Production of Reactive Oxygen Species in Aspergillus fumigatus.

Azole resistance in the human fungal pathogen Aspergillus fumigatus is becoming a major threat to global health. To date, mutations in the azole target-encoding gene have been implicated in conferring azole resistance, but a steady increase in the number of A. fumigatus isolates with azole resistance resulting from non- mutations has been recognized. Previous studies have revealed that some isolates with non- mutation-induced azole resistance are related to mitochondrial dysfunction. However, knowledge of the molecular mechanism underlying the involvement of non- mutations is limited. In this study, using next-generation sequencing, we found that nine independent azole-resistant isolates without mutations had normal mitochondrial membrane potential. Among these isolates, a mutation in a mitochondrial ribosome-binding protein, Mba1, conferred multidrug resistance to azoles, terbinafine, and amphotericin B but not caspofungin. Molecular characterization verified that the TIM44 domain of Mba1 was crucial for drug resistance and that the N terminus of Mba1 played a major role in growth. Deletion of had no effect on Cyp51A expression but decreased the fungal cellular reactive oxygen species (ROS) content, which contributed to -mediated drug resistance. The findings in this study suggest that some non- proteins drive drug resistance mechanisms that result from reduced ROS production induced by antifungals.