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Modulation of plant mitochondrial VDAC by phytosterols
Lamia Mlayeh1, Sunita Chatkaew, Marc Léonetti
1Centre de Biologie Structurale et de Bioinformatique, Université Libre de Bruxelles, Brussels, Belgium.
Biophysical Journal
|October 7, 2010
Summary
Cholesterol and phytosterols affect bean seed mitochondrial voltage-dependent anion-selective channel (VDAC) selectivity and gating. Stigmasterol uniquely alters VDAC voltage-dependence, crucial for channel function in vivo.
Area of Science:
- Mitochondrial biophysics
- Plant cell biology
- Membrane protein function
Background:
- Mitochondrial membranes contain sterols that influence protein function.
- Voltage-dependent anion-selective channels (VDACs) are crucial porins in the outer mitochondrial membrane.
- Plant VDACs play roles in metabolite transport and cellular signaling.
Purpose of the Study:
- To investigate the impact of cholesterol and phytosterols (sitosterol, stigmasterol) on bean seed VDAC.
- To determine how sterol type and concentration affect VDAC's electrophysiological properties.
- To elucidate the role of phytosterols in VDAC gating under physiological conditions.
Main Methods:
- Purification of VDAC from Phaseolus coccineus mitochondria.
- Electrophysiological recordings of single VDAC channels in lipid bilayers.
- Modulation of sterol composition and concentration in the membrane.
- Reversible sterol depletion using methyl-β-cyclodextrins.
Main Results:
- VDAC selectivity is modulated by both cholesterol and phytosterols.
- Stigmasterol, but not cholesterol or sitosterol, alters VDAC voltage-dependence.
- Sterol addition does not affect VDAC unitary conductance.
- Sterol effects are reversible upon depletion.
- Phytosterols are essential for VDAC gating at physiological salt concentrations.
Conclusions:
- Sterol composition significantly impacts plant VDAC function, affecting selectivity and voltage-dependence.
- Stigmasterol plays a unique role in regulating VDAC gating.
- Phytosterols are vital for VDAC channel activity in vivo.
- Understanding sterol-VDAC interactions provides insights into mitochondrial regulation in plants.
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