3AA6

Crystal structure of Actin capping protein in complex with the Cp-binding motif derived from CD2AP


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.9 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.184 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Two distinct mechanisms for actin capping protein regulation--steric and allosteric inhibition

Takeda, S.Minakata, S.Koike, R.Kawahata, I.Narita, A.Kitazawa, M.Ota, M.Yamakuni, T.Maeda, Y.Nitanai, Y.

(2010) Plos Biol. 8: e1000416-e1000416

  • DOI: 10.1371/journal.pbio.1000416
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • The actin capping protein (CP) tightly binds to the barbed end of actin filaments, thus playing a key role in actin-based lamellipodial dynamics. V-1 and CARMIL proteins directly bind to CP and inhibit the filament capping activity of CP. V-1 complet ...

    The actin capping protein (CP) tightly binds to the barbed end of actin filaments, thus playing a key role in actin-based lamellipodial dynamics. V-1 and CARMIL proteins directly bind to CP and inhibit the filament capping activity of CP. V-1 completely inhibits CP from interacting with the barbed end, whereas CARMIL proteins act on the barbed end-bound CP and facilitate its dissociation from the filament (called uncapping activity). Previous studies have revealed the striking functional differences between the two regulators. However, the molecular mechanisms describing how these proteins inhibit CP remains poorly understood. Here we present the crystal structures of CP complexed with V-1 and with peptides derived from the CP-binding motif of CARMIL proteins (CARMIL, CD2AP, and CKIP-1). V-1 directly interacts with the primary actin binding surface of CP, the C-terminal region of the alpha-subunit. Unexpectedly, the structures clearly revealed the conformational flexibility of CP, which can be attributed to a twisting movement between the two domains. CARMIL peptides in an extended conformation interact simultaneously with the two CP domains. In contrast to V-1, the peptides do not directly compete with the barbed end for the binding surface on CP. Biochemical assays revealed that the peptides suppress the interaction between CP and V-1, despite the two inhibitors not competing for the same binding site on CP. Furthermore, a computational analysis using the elastic network model indicates that the interaction of the peptides alters the intrinsic fluctuations of CP. Our results demonstrate that V-1 completely sequesters CP from the barbed end by simple steric hindrance. By contrast, CARMIL proteins allosterically inhibit CP, which appears to be a prerequisite for the uncapping activity. Our data suggest that CARMIL proteins down-regulate CP by affecting its conformational dynamics. This conceptually new mechanism of CP inhibition provides a structural basis for the regulation of the barbed end elongation in cells.


    Organizational Affiliation

    Structural Biology Research Center, Graduate School of Science, Nagoya University, Nagoya, Japan. takeda.shuichi@f.mbox.nagoya-u.ac.jp




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
F-actin-capping protein subunit alpha-1
A
286Gallus gallusMutation(s): 0 
Gene Names: CAPZA1
Find proteins for P13127 (Gallus gallus)
Go to Gene View: CAPZA1
Go to UniProtKB:  P13127
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
F-actin-capping protein subunit beta isoforms 1 and 2
B
244Gallus gallusMutation(s): 0 
Gene Names: CAPZB
Find proteins for P14315 (Gallus gallus)
Go to Gene View: CAPZB
Go to UniProtKB:  P14315
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
23mer peptide from CD2-associated protein
C
23Homo sapiensMutation(s): 0 
Gene Names: CD2AP
Find proteins for Q9Y5K6 (Homo sapiens)
Go to Gene View: CD2AP
Go to UniProtKB:  Q9Y5K6
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
BA
Query on BA

Download SDF File 
Download CCD File 
B
BARIUM ION
Ba
XDFCIPNJCBUZJN-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.9 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.184 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 59.119α = 90.00
b = 63.871β = 90.00
c = 141.089γ = 90.00
Software Package:
Software NamePurpose
HKL-2000data reduction
MOLREPphasing
REFMACrefinement
HKL-2000data collection
HKL-2000data scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2010-08-04
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance