Affixing N-terminal α-Helix to the Wall of the Voltage-dependent Anion Channel Does Not Prevent Its Voltage Gating
2012 (English)In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 287, no 14, 11437-11445 p.Article in journal (Refereed) Published
The voltage-dependent anion channel (VDAC) governs the free exchange of ions and metabolites between the mitochondria and the rest of the cell. The three-dimensional structure of VDAC1 reveals a channel formed by 19 beta-strands and an N-terminal alpha-helix located near the midpoint of the pore. The position of this alpha-helix causes a narrowing of the cavity, but ample space for metabolite passage remains. The participation of the N-terminus of VDAC1 in the voltage-gating process has been well established, but the molecular mechanism continues to be debated; however, the majority of models entail large conformational changes of this N-terminal segment. Here we report that the pore-lining N-terminal alpha-helix does not undergo independent structural rearrangements during channel gating. We engineered a double Cys mutant in murine VDAC1 that cross-links the alpha-helix to the wall of the beta-barrel pore and reconstituted the modified protein into planar lipid bilayers. The modified murine VDAC1 exhibited typical voltage gating. These results suggest that the N-terminal alpha-helix is located inside the pore of VDAC in the open state and remains associated with beta-strand 11 of the pore wall during voltage gating.
Place, publisher, year, edition, pages
2012. Vol. 287, no 14, 11437-11445 p.
Biochemistry and Molecular Biology
IdentifiersURN: urn:nbn:se:uu:diva-174580DOI: 10.1074/jbc.M111.314229ISI: 000302780100072OAI: oai:DiVA.org:uu-174580DiVA: diva2:529250