Identification of Multiple Cryptococcal Fungicidal Drug Targets by Combined Gene Dosing and Drug Affinity Responsive Target Stability Screening
Yoon-Dong Park,
Wei Sun,
Antonio Salas,
Avan Antia,
Cindy Carvajal,
Amy Wang,
Xin Xu,
Zhaojin Meng,
Ming Zhou,
Gregory J. Tawa,
Jean Dehdashti,
Wei Zheng,
Christina M. Henderson,
Adrian M. Zelazny,
Peter R. Williamson
Affiliations
Yoon-Dong Park
Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
Wei Sun
National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, Maryland, USA
Antonio Salas
Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
Avan Antia
Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
Cindy Carvajal
Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
Amy Wang
National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, Maryland, USA
Xin Xu
National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, Maryland, USA
Zhaojin Meng
Protein Characterization Laboratory, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
Ming Zhou
Protein Characterization Laboratory, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
Gregory J. Tawa
National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, Maryland, USA
Jean Dehdashti
National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, Maryland, USA
Wei Zheng
National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, Maryland, USA
Christina M. Henderson
Microbiology Service, Department of Laboratory Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland, USA
Adrian M. Zelazny
Microbiology Service, Department of Laboratory Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland, USA
Peter R. Williamson
Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
ABSTRACT Cryptococcus neoformans is a pathogenic fungus that is responsible for up to half a million cases of meningitis globally, especially in immunocompromised individuals. Common fungistatic drugs, such as fluconazole, are less toxic for patients but have low efficacy for initial therapy of the disease. Effective therapy against the disease is provided by the fungicidal drug amphotericin B; however, due to its high toxicity and the difficulty in administering its intravenous formulation, it is imperative to find new therapies targeting the fungus. The antiparasitic drug bithionol has been recently identified as having potent fungicidal activity. In this study, we used a combined gene dosing and drug affinity responsive target stability (GD-DARTS) screen as well as protein modeling to identify a common drug binding site of bithionol within multiple NAD-dependent dehydrogenase drug targets. This combination genetic and proteomic method thus provides a powerful method for identifying novel fungicidal drug targets for further development. IMPORTANCE Cryptococcosis is a neglected fungal meningitis that causes approximately half a million deaths annually. The most effective antifungal agent, amphotericin B, was developed in the 1950s, and no effective medicine has been developed for this disease since that time. A key aspect of amphotericin B’s effectiveness is thought to be because of its ability to kill the fungus (fungicidal activity), rather than just stop or slow its growth. The present study utilized a recently identified fungicidal agent, bithionol, to identify potential fungicidal drug targets that can be used in developing modern fungicidal agents. A combined protein and genetic analysis approach was used to identify a class of enzymes, dehydrogenases, that the fungus uses to maintain homeostasis with regard to sugar nutrients. Similarities in the drug target site were found that resulted in simultaneous inhibition and killing of the fungus by bithionol. These studies thus identify a common, multitarget site for antifungal development.
