Coiled-coil intermediate filament stutter instability and molecular unfolding

Comput Methods Biomech Biomed Engin. 2011 May;14(5):483-9. doi: 10.1080/10255842.2011.560147.

Abstract

Intermediate filaments (IFs) are the key components of cytoskeleton in eukaryotic cells and are critical for cell mechanics. The building block of IFs is a coiled-coil alpha-helical dimer, consisting of several domains that include linkers and other structural discontinuities. One of the discontinuities in the dimer's coiled-coil region is the so-called 'stutter' region. The stutter is a region where a variation of the amino acid sequence pattern from other parts of the alpha-helical domains of the protein is found. It was suggested in earlier works that due to this sequence variation, the perfect coiled-coil arrangement ceases to exist. Here, we show using explicit water molecular dynamics and well-tempered metadynamics that for the coil2 domain of vimentin IFs the stutter is more stable in a non-alpha-helical, unfolded state. This causes a local structural disturbance in the alpha helix, which has a global effect on the nanomechanics of the structure. Our analysis suggests that the stutter features an enhanced tendency to unfolding even under the absence of external forces, implying a much greater structural instability than previously assumed. As a result it features a smaller local bending stiffness than other segments and presents a seed for the initiation of molecular bending and unfolding at large deformation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Computer Simulation
  • Dimerization
  • Humans
  • Hydrogen Bonding
  • Intermediate Filament Proteins / chemistry*
  • Intermediate Filaments / chemistry*
  • Models, Molecular*
  • Molecular Dynamics Simulation
  • Protein Stability
  • Protein Structure, Quaternary
  • Protein Structure, Tertiary
  • Unfolded Protein Response
  • Vimentin / chemistry

Substances

  • Intermediate Filament Proteins
  • Vimentin