Voltage-Dependent Anion Channel Transports Calcium Ions through Biomimetic Membranes

Abstract

The mitochondrial outer membrane channel (VDAC), a central player in mitochondria and cell death, was reconstituted in polymer-supported phospholipid bilayers. Highly purified VDAC was first reconstituted in vesicles; channel properties and NADH-ferricyanide reductase activity were ascertained before deposition onto solid substrates. 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine/1,2-distearoyl-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol)-N-hydroxysuccinimide mixed vesicles containing VDAC were linked onto amine-grafted surfaces (glass and gold) and disrupted to form a VDAC-containing polymer-tethered planar bilayer. Surface plasmon spectroscopy, fluorescence microscopy, and atomic force microscopy measurements ascertained the membrane thickness, fluidity, and continuity. VDAC reconstituted in bilayers efficiently transported calcium ions and was modulable by two channel blockers, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid and l-glutamate. The novel setup may allow the study of the assembly of a polyprotein complex centered on VDAC and its role in mitochondrial biology, calcium fluxes, and apoptosis.

Physiological Roles of the Permeability Transition Pore

“…134 At a more integrated level, mitochondria are interconnected within the so-called mitochondrial network, undergo fusion and fission events to adapt to stress, 135 and communicate with other organelles such as the endoplasmic/sarcoplasmic reticulum via microdomains to transfer Ca 2+ and trigger some proapoptotic signaling cascade in case of stress. 63,[136][137][138] For instance, in the heart, a partial loss of optic atrophy type 1 (OPA1), an IM protein involved in mitochondrial fusion, affects the mitochondrial network morphology, PTP sensitivity to Ca 2+ , and cardiac adaptation to pressure overload. 139 But the links among mitochondrial dynamics, PTP, and pathology remain largely unknown and have to be further explored.…”

Novel Engineered Ion Channel Provides Controllable Ion Permeability for Polyelectrolyte Microcapsules Coated with a Lipid Membrane

“…An easier and proven way to ensure that the microcapsules do not stimulate an immune response is coating the polyelectrolyte with phospholipid membranes. [4][5][6][7][8] A further advantage of this approach is the possibility to incorporate biomolecules such as membrane transport proteins in the supported phospholipid membranes, as has been explored recently by several groups [9,10] and reported in this paper. The…”

Voltage-dependent structural changes of the membrane-bound anion channel hVDAC1 probed by SEIRA and electrochemical impedance spectroscopy

“…In this respect, electrode-supported bilayer lipid membranes (BLMs) represent ideal model systems as they allow embedment of the protein within the membrane and the generation of a transmembrane potential. Reconstitution of the VDAC in BLMs has in fact already been demonstrated, 23 but such devices have not yet been coupled to in situ IR spectroscopic measurements. Recently, we demonstrated that the construction of a tethered bilayer lipid membrane (tBLM) on nanostructured Au film electrodes meets the requirements for potential-controlled IR spectroscopy since the metallic support allows for applying surface-enhanced infrared absorption (SEIRA) spectroscopy.…”