F-actin binding is essential for coronin 1B function in vivo

J Cell Sci. 2007 May 15;120(Pt 10):1779-90. doi: 10.1242/jcs.007641. Epub 2007 Apr 24.


Coronins are conserved F-actin binding proteins that have been implicated in a variety of processes including fibroblast migration, phagocytosis, and chemotaxis. Recent data from our lab indicate that coronin 1B coordinates Arp2/3-dependent actin filament nucleation and cofilin-mediated filament turnover at the leading edge of migrating fibroblasts. Analysis of coronin function has been hampered by the lack of a clear understanding of how coronin interacts with F-actin. Here, we identify a surface-exposed conserved arginine residue at position 30 (R30), which is crucial for coronin 1B binding to F-actin both in vitro and in vivo. Using actin co-sedimentation, we demonstrate that coronin 1B binds with high affinity to ATP/ADP-P(i)-F-actin (170 nM) and with 47-fold lower affinity to ADP-F-actin (8 microM). In contrast to a previous study, we find no evidence for enhanced cofilin binding to F-actin in the presence of either coronin 1B or coronin 1A. Instead, we find that coronin 1B protects actin filaments from cofilin-induced depolymerization. Consistent with an important role for interactions between coronin 1B and F-actin in vivo, an R30D coronin mutant that does not bind F-actin localizes inefficiently to the leading edge. Furthermore, our analysis indicates that F-actin binding is absolutely required for coronin 1B to exert its effects on whole-cell motility and lamellipodial dynamics.

Publication types

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

MeSH terms

  • Actin Cytoskeleton / metabolism
  • Actin Cytoskeleton / ultrastructure
  • Actins / metabolism*
  • Actins / ultrastructure
  • Adenosine Diphosphate / metabolism
  • Adenosine Triphosphate / metabolism
  • Amino Acid Sequence / physiology
  • Animals
  • Arginine / metabolism
  • Binding Sites / physiology
  • Cell Line
  • Cell Movement / physiology
  • Drosophila melanogaster
  • Fibroblasts / metabolism
  • Fibroblasts / ultrastructure
  • Humans
  • Microfilament Proteins / chemistry
  • Microfilament Proteins / metabolism*
  • Microscopy, Electron
  • Models, Molecular
  • Protein Binding / physiology
  • Protein Structure, Tertiary / physiology
  • Pseudopodia / metabolism
  • Pseudopodia / ultrastructure
  • Rats


  • Actins
  • Microfilament Proteins
  • coronin proteins
  • Adenosine Diphosphate
  • Adenosine Triphosphate
  • Arginine