Force-dependent conformational switch of α-catenin controls vinculin binding

Nat Commun. 2014 Jul 31;5:4525. doi: 10.1038/ncomms5525.

Abstract

Force sensing at cadherin-mediated adhesions is critical for their proper function. α-Catenin, which links cadherins to actomyosin, has a crucial role in this mechanosensing process. It has been hypothesized that force promotes vinculin binding, although this has never been demonstrated. X-ray structure further suggests that α-catenin adopts a stable auto-inhibitory conformation that makes the vinculin-binding site inaccessible. Here, by stretching single α-catenin molecules using magnetic tweezers, we show that the subdomains MI vinculin-binding domain (VBD) to MIII unfold in three characteristic steps: a reversible step at ~5 pN and two non-equilibrium steps at 10-15 pN. 5 pN unfolding forces trigger vinculin binding to the MI domain in a 1:1 ratio with nanomolar affinity, preventing MI domain refolding after force is released. Our findings demonstrate that physiologically relevant forces reversibly unfurl α-catenin, activating vinculin binding, which then stabilizes α-catenin in its open conformation, transforming force into a sustainable biochemical signal.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton / chemistry
  • Actin Cytoskeleton / metabolism
  • Animals
  • Binding Sites
  • Gene Expression Regulation
  • Magnetic Fields
  • Mechanotransduction, Cellular
  • Mice
  • Optical Tweezers
  • Protein Binding
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Recombinant Fusion Proteins / chemistry*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Stress, Mechanical
  • Vinculin / chemistry*
  • Vinculin / genetics
  • Vinculin / metabolism
  • alpha Catenin / chemistry*
  • alpha Catenin / genetics
  • alpha Catenin / metabolism

Substances

  • Recombinant Fusion Proteins
  • alpha Catenin
  • Vinculin