The intrinsically disordered N-terminus of the voltage-dependent anion channel

PLoS Comput Biol. 2021 Feb 12;17(2):e1008750. doi: 10.1371/journal.pcbi.1008750. eCollection 2021 Feb.

Abstract

The voltage-dependent anion channel (VDAC) is a critical β-barrel membrane protein of the mitochondrial outer membrane, which regulates the transport of ions and ATP between mitochondria and the cytoplasm. In addition, VDAC plays a central role in the control of apoptosis and is therefore of great interest in both cancer and neurodegenerative diseases. Although not fully understood, it is presumed that the gating mechanism of VDAC is governed by its N-terminal region which, in the open state of the channel, exhibits an α-helical structure positioned midway inside the pore and strongly interacting with the β-barrel wall. In the present work, we performed molecular simulations with a recently developed force field for disordered systems to shed new light on known experimental results, showing that the N-terminus of VDAC is an intrinsically disordered region (IDR). First, simulation of the N-terminal segment as a free peptide highlighted its disordered nature and the importance of using an IDR-specific force field to properly sample its conformational landscape. Secondly, accelerated dynamics simulation of a double cysteine VDAC mutant under applied voltage revealed metastable low conducting states of the channel representative of closed states observed experimentally. Related structures were characterized by partial unfolding and rearrangement of the N-terminal tail, that led to steric hindrance of the pore. Our results indicate that the disordered properties of the N-terminus are crucial to properly account for the gating mechanism of VDAC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algorithms
  • Animals
  • Anions
  • Apoptosis*
  • Computer Simulation
  • Crystallography, X-Ray
  • Cysteine / chemistry
  • Intrinsically Disordered Proteins / chemistry*
  • Lipid Bilayers / chemistry
  • Mice
  • Mitochondria / metabolism
  • Mitochondrial Membranes
  • Models, Molecular
  • Molecular Dynamics Simulation
  • Mutation
  • Neoplasms / metabolism
  • Peptides / chemistry
  • Protein Conformation*
  • Protein Denaturation
  • Protein Domains
  • Software
  • Voltage-Dependent Anion Channel 1 / chemistry*

Substances

  • Anions
  • Intrinsically Disordered Proteins
  • Lipid Bilayers
  • Peptides
  • Vdac1 protein, mouse
  • Voltage-Dependent Anion Channel 1
  • Cysteine

Associated data

  • Dryad/10.5061/dryad.zw3r2286m

Grants and funding

This work was supported by the Ligue contre le cancer, Comité de la Haute-Savoie (IK). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.