Structural basis of actin filament nucleation by tandem W domains

Cell Rep. 2013 Jun 27;3(6):1910-20. doi: 10.1016/j.celrep.2013.04.028. Epub 2013 May 30.


Spontaneous nucleation of actin is very inefficient in cells. To overcome this barrier, cells have evolved a set of actin filament nucleators to promote rapid nucleation and polymerization in response to specific stimuli. However, the molecular mechanism of actin nucleation remains poorly understood. This is hindered largely by the fact that actin nucleus, once formed, rapidly polymerizes into filament, thus making it impossible to capture stable multisubunit actin nucleus. Here, we report an effective double-mutant strategy to stabilize actin nucleus by preventing further polymerization. Employing this strategy, we solved the crystal structure of AMPPNP-actin in complex with the first two tandem W domains of Cordon-bleu (Cobl), a potent actin filament nucleator. Further sequence comparison and functional studies suggest that the nucleation mechanism of Cobl is probably shared by the p53 cofactor JMY, but not Spire. Moreover, the double-mutant strategy opens the way for atomic mechanistic study of actin nucleation and polymerization.

Publication types

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

MeSH terms

  • Actin Cytoskeleton / chemistry*
  • Actin Cytoskeleton / genetics
  • Actin Cytoskeleton / metabolism*
  • Actins / chemistry
  • Actins / genetics
  • Actins / metabolism
  • Amino Acid Sequence
  • Animals
  • Crystallography, X-Ray
  • Drosophila
  • Humans
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Conformation
  • Protein Structure, Quaternary
  • Protein Structure, Tertiary


  • Actins

Associated data

  • PDB/4JHD