Sites and functional consequence of VDAC–alkylphenol anesthetic interactions

• Propofol enhances closure of mammalian VDAC.
• Propofol does not affect gramicidin A, which is sensitive to membrane environment.
• Modulation of VDAC by propofol likely occurs through direct protein binding.
• Alkylphenol general anesthetics bind Gly56 and Val184 on rat VDAC1.

General anesthetics have previously been shown to bind mitochondrial VDAC. Here, using a photoactive analog of the anesthetic propofol, we determined that alkylphenol anesthetics bind to Gly56 and Val184 on rat VDAC1. By reconstituting rat VDAC into planar bilayers, we determined that propofol potentiates VDAC gating with asymmetry at the voltage polarities; in contrast, propofol does not affect the conductance of open VDAC. Additional experiments showed that propofol also does not affect gramicidin A properties that are sensitive to lipid bilayer mechanics. Together, this suggests propofol affects VDAC function through direct protein binding, likely at the lipid-exposed channel surface, and that gating can be modulated by ligand binding to the distal ends of VDAC β-strands where Gly56 and Val184 are located.