Structure of clathrin coat with bound Hsc70 and auxilin: mechanism of Hsc70-facilitated disassembly

EMBO J. 2010 Feb 3;29(3):655-65. doi: 10.1038/emboj.2009.383. Epub 2009 Dec 24.

Abstract

The chaperone Hsc70 drives the clathrin assembly-disassembly cycle forward by stimulating dissociation of a clathrin lattice. A J-domain containing co-chaperone, auxilin, associates with a freshly budded clathrin-coated vesicle, or with an in vitro assembled clathrin coat, and recruits Hsc70 to its specific heavy-chain-binding site. We have determined by electron cryomicroscopy (cryoEM), at about 11 A resolution, the structure of a clathrin coat (in the D6-barrel form) with specifically bound Hsc70 and auxilin. The Hsc70 binds a previously analysed site near the C-terminus of the heavy chain, with a stoichiometry of about one per three-fold vertex. Its binding is accompanied by a distortion of the clathrin lattice, detected by a change in the axial ratio of the D6 barrel. We propose that when Hsc70, recruited to a position close to its target by the auxilin J-domain, splits ATP, it clamps firmly onto its heavy-chain site and locks in place a transient fluctuation. Accumulation of the local strain thus imposed at multiple vertices can then lead to disassembly.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Auxilins / chemistry
  • Auxilins / metabolism*
  • Cattle
  • Clathrin / chemistry
  • Clathrin / metabolism*
  • Clathrin-Coated Vesicles / chemistry*
  • Clathrin-Coated Vesicles / metabolism
  • Clathrin-Coated Vesicles / ultrastructure
  • Cryoelectron Microscopy
  • HSC70 Heat-Shock Proteins / chemistry
  • HSC70 Heat-Shock Proteins / metabolism*
  • Models, Biological
  • Models, Molecular
  • Multiprotein Complexes / chemistry
  • Multiprotein Complexes / metabolism
  • Protein Binding
  • Protein Multimerization / physiology*
  • Protein Structure, Quaternary
  • Protein Structure, Secondary

Substances

  • Auxilins
  • Clathrin
  • HSC70 Heat-Shock Proteins
  • Multiprotein Complexes