Near-atomic resolution for one state of F-actin

Structure. 2015 Jan 6;23(1):173-182. doi: 10.1016/j.str.2014.11.006. Epub 2014 Dec 18.


Actin functions as a helical polymer, F-actin, but attempts to build an atomic model for this filament have been hampered by the fact that the filament cannot be crystallized and by structural heterogeneity. We have used a direct electron detector, cryo-electron microscopy, and the forces imposed on actin filaments in thin films to reconstruct one state of the filament at 4.7 Å resolution, which allows for building a reliable pseudo-atomic model of F-actin. We also report a different state of the filament where actin protomers adopt a conformation observed in the crystal structure of the G-actin-profilin complex with an open ATP-binding cleft. Comparison of the two structural states provides insights into ATP-hydrolysis and filament dynamics. The atomic model provides a framework for understanding why every buried residue in actin has been under intense selective pressure.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Actin Cytoskeleton / chemistry*
  • Actin Cytoskeleton / metabolism
  • Actin Cytoskeleton / ultrastructure
  • Actins / chemistry*
  • Actins / metabolism
  • Animals
  • Cryoelectron Microscopy
  • Models, Molecular
  • Nucleotides / chemistry
  • Nucleotides / metabolism
  • Phosphates / chemistry
  • Phosphates / metabolism
  • Protein Multimerization
  • Protein Structure, Quaternary
  • Rabbits


  • Actins
  • Nucleotides
  • Phosphates