Coronin-1A stabilizes F-actin by bridging adjacent actin protomers and stapling opposite strands of the actin filament

J Mol Biol. 2008 Feb 22;376(3):607-13. doi: 10.1016/j.jmb.2007.12.007. Epub 2007 Dec 8.


Coronins are F-actin-binding proteins that are involved, in concert with Arp2/3, Aip1, and ADF/cofilin, in rearrangements of the actin cytoskeleton. An understanding of coronin function has been hampered by the absence of any structural data on its interaction with actin. Using electron microscopy and three-dimensional reconstruction, we show that coronin-1A binds to three protomers in F-actin simultaneously: it bridges subdomain 1 and subdomain 2 of two adjacent actin subunits along the same long-pitch strand, and it staples subdomain 1 and subdomain 4 of two actin protomers on different strands. Such a mode of binding explains how coronin can stabilize actin filaments in vitro. In addition, we show which residues of F-actin may participate in the interaction with coronin-1A. Human nebulin and Xin, as well as Salmonella invasion protein A, use a similar mechanism to stabilize actin filaments. We suggest that the stapling of subdomain 1 and subdomain 4 of two actin protomers on different strands is a common mechanism for F-actin stabilization utilized by many actin-binding proteins that have no homology.

Publication types

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

MeSH terms

  • Actins / chemistry
  • Actins / metabolism*
  • Animals
  • Humans
  • Microfilament Proteins / chemistry
  • Microfilament Proteins / metabolism*
  • Models, Molecular
  • Muscle Proteins
  • Protein Interaction Mapping


  • Actins
  • Microfilament Proteins
  • Muscle Proteins
  • nebulin
  • coronin proteins