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Biophys J. 2019 Mar 5;116(5):847-859. doi: 10.1016/j.bpj.2019.01.031. Epub 2019 Feb 1.

A Cholesterol Analog Induces an Oligomeric Reorganization of VDAC.

Author information

1
Departments of Chemistry, University of Manitoba, Winnipeg, Manitoba, Canada; Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada.
2
Alberta RNA Research and Training Institute, Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, Canada; Li Ka Shing Institute of Virology and Discovery Lab, University of Alberta, Edmonton, Alberta, Canada; Department of Microbiology, Immunology & Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
3
Departments of Chemistry, University of Manitoba, Winnipeg, Manitoba, Canada.
4
Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada.
5
Departments of Chemistry, University of Manitoba, Winnipeg, Manitoba, Canada; Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Manitoba, Canada. Electronic address: jorg.stetefeld@umanitoba.ca.

Abstract

The oligomeric organization of the voltage-dependent anion-selective channel (VDAC) and its interactions with hexokinase play integral roles in mitochondrially mediated apoptotic signaling. Various small to large assemblies of VDAC are observed in mitochondrial outer membranes, but they do not predominate in detergent-solubilized VDAC samples. In this study, a cholesterol analog, cholesteryl-hemisuccinate (CHS), was shown to induce the formation of detergent-soluble VDAC multimers. The various oligomeric states of VDAC induced by the addition of CHS were deciphered through an integrated biophysics approach using microscale thermophoresis, analytical ultracentrifugation, and size-exclusion chromatography small angle x-ray scattering. Furthermore, CHS stabilizes the interaction between VDAC and hexokinase (Kd of 27 ± 6 μM), confirming the biological relevance of oligomers generated. Thus, sterols such as cholesterol in higher eukaryotes or ergosterol in fungi may regulate the VDAC oligomeric state and may provide a potential target for the modulation of apoptotic signaling by effecting VDAC-VDAC and VDAC-hexokinase interactions. In addition, the integrated biophysical approach described provides a powerful platform for the study of membrane protein complexes in solution.

PMID:
30777305
DOI:
10.1016/j.bpj.2019.01.031

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