title: Deletion of β-strands 9 and 10 converts VDAC1 voltage-dependence in an asymmetrical process.
abstract: Voltage-dependent anion selective channel isoform1 maintains the permeability of the outer mitochondrial membrane. Its voltage-gating properties are relevant in bioenergetic metabolism and apoptosis. The N-terminal domain is suspected to be involved in voltage-gating, due to its peculiar localization. However this issue is still controversial. In this work we exchanged or deleted the β-strands that take contact with the N-terminal domain. The exchange of the whole hVDAC1 β-barrel with the homologous hVDAC3 β-barrel produces a chimeric protein that, in reconstituted systems, loses completely voltage-dependence. hVDAC3 β-barrel has most residues in common with hVDAC1, including V143 and L150 considered anchor points for the N-terminus. hVDAC1 mutants completely lacking either the β-strand 9 or both β-strands 9 and 10 were expressed, refolded and reconstituted in artificial bilayers. The mutants formed smaller pores. Molecular dynamics simulations of the mutant structure supported its ability to form smaller pores. The mutant lacking both β-strands 9 and 10 showed a new voltage-dependence feature resulting in a fully asymmetric behavior. These data indicate that a network of β-strands in the pore-walls, and not single residues, are required for voltage-gating in addition to the N-terminus.
authors.affiliation: Department of Biological, Geological and Environmental Sciences, University of Catania, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Reina
authors.forename: Andrea
authors.initials: A
authors.lastname: Magrì
authors.forename: Marco
authors.initials: M
authors.lastname: Lolicato
authors.forename: Francesca
authors.initials: F
authors.lastname: Guarino
authors.forename: Agata
authors.initials: A
authors.lastname: Impellizzeri
authors.forename: Elke
authors.initials: E
authors.lastname: Maier
authors.forename: Roland
authors.initials: R
authors.lastname: Benz
authors.forename: Matteo
authors.initials: M
authors.lastname: Ceccarelli
authors.forename: Vito
authors.initials: V
authors.lastname: De Pinto
authors.forename: Angela
authors.initials: A
authors.lastname: Messina
mesh_terms: D000595:Amino Acid Sequence; D008564:Membrane Potentials; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D016415:Sequence Alignment; D050995:Voltage-Dependent Anion Channel 1 / Q000737:chemistry* / Q000502:physiology
chemical_list: D011993:Recombinant Fusion Proteins; D050995:Voltage-Dependent Anion Channel 1