Azole Drugs Are Imported By Facilitated Diffusion in Candida albicans and Other Pathogenic Fungi

PLoS Pathogens

Lizbeth Hedstrom¹  Sarah E. Leyde²  Hanna N. Oltean²  Bryce E. Mansfield²  Brian G. Oliver²  Samantha J. Hoot²  Theodore C. White² 

[1] Brandeis University Department of Biology and Chemistry, Waltham, Massachusetts, United States of America;Seattle Biomedical Research Institute, Seattle, Washington, United States of America

关键词: Azoles;    C;    ida albicans;    Imidazole;    Antimicrobial resistance;    Fungal pathogens;    Saccharomyces cerevisiae;    Fungi;    Glucose;   

DOI  :  10.1371/journal.ppat.1001126

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Despite the wealth of knowledge regarding the mechanisms of action and the mechanisms of resistance to azole antifungals, very little is known about how the azoles are imported into pathogenic fungal cells. Here the in-vitro accumulation and import of Fluconazole (FLC) was examined in the pathogenic fungus, Candida albicans. In energized cells, FLC accumulation correlates inversely with expression of ATP-dependent efflux pumps. In de-energized cells, all strains accumulate FLC, suggesting that FLC import is not ATP-dependent. The kinetics of import in de-energized cells displays saturation kinetics with a Km of 0.64 uM and Vmax of 0.0056 pmol/min/108 cells, demonstrating that FLC import proceeds via facilitated diffusion through a transporter rather than passive diffusion. Other azoles inhibit FLC import on a mole/mole basis, suggesting that all azoles utilize the same facilitated diffusion mechanism. An analysis of related compounds indicates that competition for azole import depends on an aromatic ring and an imidazole or triazole ring together in one molecule. Import of FLC by facilitated diffusion is observed in other fungi, including Cryptococcus neoformans, Saccharomyces cerevisiae, and Candida krusei, indicating that the mechanism of transport is conserved among fungal species. FLC import was shown to vary among Candida albicans resistant clinical isolates, suggesting that altered facilitated diffusion may be a previously uncharacterized mechanism of resistance to azole drugs.

【 授权许可】

CC BY