This project aims to advance understanding of the mode of action of the clinically vital but also highly toxic antifungal drug amphotericin B (AmB). Alternative to the classic ion channel model, preliminary studies in this proposal show that AmB forms large extramembranous aggregates that extract sterols from lipid bilayers and thereby kill cells. This novel sterol sponge model illuminates a new and more actionable roadmap to an improved therapeutic index, i.e., maximize the relative binding affinity of the AmB sterol sponge for the sterol found in fungi (ergosterol) vs. humans (cholesterol).
Aim 1 is to determine the structure of the AmB sterol sponge, assembled in the presence of physiologically relevant lipid bilayers.
Aim 2 is to determine the structures of the complexes of the AmB sponge with ergosterol and cholesterol.
Aim 3 is to determine the structure of the sterol sponge and corresponding ergosterol complex derived from a new derivative of AmB, AmBMU, which was recently discovered and shown to bind ergosterol but not cholesterol, to be non-toxic to human cells, and to retain potent antifungal activity in vitro and in mice. Collectively, these studies wll provide a high-resolution picture of the atomistic interactions that underlie the biological activities of AmB and thus powerfully enable the rational development of less toxic derivatives of this clinically vital natural product. These studies will also further illuminate the fundamental features of how clinically validated resistance-refractory antimicrobial action can be achieved and lay the foundation for the frontier pursuit of other biologically relevant small molecule-small molecule interactions. Relevance to Human Health. Amphotericin B is the powerful but unfortunately highly toxic gold standard therapy for treatment of systemic fungal infections, and this drug has uniquely evaded the emergence of microbial resistance despite more than half a century of widespread clinical utilization. Better understanding how AmB exerts its biological activities is thus critical for guiding the rational development of derivatives with an improved therapeutic index as well as other resistance-refractory antimicrobial agents.

Public Health Relevance

Amphotericin B is the powerful but unfortunately highly toxic gold standard therapy for treatment of systemic fungal infections, and this drug has uniquely evaded the emergence of microbial resistance despite more than half a century of widespread clinical utilization. Better understanding how AmB exerts its biological activities is thus critica for guiding the rational development of derivatives with an improved therapeutic index as well as other resistance-refractory antimicrobial agents.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM112845-04
Application #
9384755
Study Section
Macromolecular Structure and Function C Study Section (MSFC)
Program Officer
Wehrle, Janna P
Project Start
2015-01-15
Project End
2018-11-30
Budget Start
2017-12-01
Budget End
2018-11-30
Support Year
4
Fiscal Year
2018
Total Cost
Indirect Cost
Name
University of Illinois Urbana-Champaign
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
041544081
City
Champaign
State
IL
Country
United States
Zip Code
61820
Greenwood, Alexander I; Clay, Mary C; Rienstra, Chad M (2017) 31P-dephased, 13C-detected REDOR for NMR crystallography at natural isotopic abundance. J Magn Reson 278:8-17
Ghosh, Manali; Rienstra, Chad M (2017) 1H-Detected REDOR with Fast Magic-Angle Spinning of a Deuterated Protein. J Phys Chem B 121:8503-8511
Shi, Xiangyan; Rienstra, Chad M (2016) Site-Specific Internal Motions in GB1 Protein Microcrystals Revealed by 3D ²H-¹³C-¹³C Solid-State NMR Spectroscopy. J Am Chem Soc 138:4105-19
Courtney, Joseph M; Rienstra, Chad M (2016) Efficient dipolar double quantum filtering under magic angle spinning without a (1)H decoupling field. J Magn Reson 269:152-156
Hisao, Grant S; Harland, Michael A; Brown, Robert A et al. (2016) An efficient method and device for transfer of semisolid materials into solid-state NMR spectroscopy rotors. J Magn Reson 265:172-6
Davis, Stephen A; Della Ripa, Lisa A; Hu, Lingbowei et al. (2015) C3-OH of Amphotericin B Plays an Important Role in Ion Conductance. J Am Chem Soc 137:15102-4