Deletion of PMP3 increases ketoconazole resistance by affecting plasma membrane potential in Candida albicans.

Ketoconazole is a classical antifungal drug commonly used in the clinic. With the increased use of ketoconazole in recent years, an increasing number of drug-resistant strains have emerged during clinical treatment. It is well known that fungi acquire drug resistance in multiple ways, while the molecular mechanisms underlying ketoconazole resistance remain for comprehensive exploration. In this study, we found that the expression of the small plasma membrane protein-encoding gene PMP3 was significantly down-regulated in several clinically isolated ketoconazole-resistant strains, indicating the relationship between PMP3 expression and ketoconazole resistance. By knocking out the PMP3, we found that the absence of the Pmp3 resulted in a significant increase in resistance of Candida albicans to ketoconazole, which was also confirmed in a systemic infection model in mice. We further demonstrated that various physiological properties, such as cell membrane fluidity, plasma membrane potential, permeability and ergosterol distribution were altered in the pmp3Δ/Δ mutant, which is associated with the enhanced cellular resistance to ketoconazole. In addition, overexpression rather than deletion of PMP3 alters the hyphal development and biofilm formation capacity in C. albicans. This study reveals the contribution of Pmp3 to alteration of drug resistance in fungal pathogens, which may guide the development of novel antifungal strategies.