2O9V

The second SH3 domain from Ponsin in complex with the paxillin proline rich region


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.63 Å
  • R-Value Free: 0.177 
  • R-Value Work: 0.143 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Paxillin and ponsin interact in nascent costameres of muscle cells

Gehmlich, K.Pinotsis, N.Hayess, K.van der Ven, P.F.Milting, H.El Banayosy, A.Wilmanns, M.Ehler, E.

(2007) J.Mol.Biol. 369: 665-682

  • DOI: 10.1016/j.jmb.2007.03.050
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Muscle differentiation requires the transition from motile myoblasts to sessile myotubes and the assembly of a highly regular contractile apparatus. This striking cytoskeletal remodelling is coordinated with a transformation of focal adhesion-like ce ...

    Muscle differentiation requires the transition from motile myoblasts to sessile myotubes and the assembly of a highly regular contractile apparatus. This striking cytoskeletal remodelling is coordinated with a transformation of focal adhesion-like cell-matrix contacts into costameres. To assess mechanisms underlying this differentiation process, we searched for muscle specific-binding partners of paxillin. We identified an interaction of paxillin with the vinexin adaptor protein family member ponsin in nascent costameres during muscle differentiation, which is mediated by an interaction of the second src homology domain 3 (SH3) domain of ponsin with the proline-rich region of paxillin. To understand the molecular basis of this interaction, we determined the structure of this SH3 domain at 0.83 A resolution, as well as its complex with the paxillin binding peptide at 1.63 A resolution. Upon binding, the paxillin peptide adopts a polyproline-II helix conformation in the complex. Contrary to the charged SH3 binding interface, the peptide contains only non-polar residues and for the first time such an interaction was observed structurally in SH3 domains. Fluorescence titration confirmed the ponsin/paxillin interaction, characterising it further by a weak binding affinity. Transfection experiments revealed further characteristics of ponsin functions in muscle cells: All three SH3 domains in the C terminus of ponsin appeared to synergise in targeting the protein to force-transducing structures. The overexpression of ponsin resulted in altered muscle cell-matrix contact morphology, suggesting its involvement in the establishment of mature costameres. Further evidence for the role of ponsin in the maintenance of mature mechanotransduction sites in cardiomyocytes comes from the observation that ponsin expression was down-regulated in end-stage failing hearts, and that this effect was reverted upon mechanical unloading. These results provide new insights in how low affinity protein-protein interactions may contribute to a fine tuning of cytoskeletal remodelling processes during muscle differentiation and in adult cardiomyocytes.


    Organizational Affiliation

    Institute of Biochemistry and Biology, University of Potsdam, Germany. k.gehmlich@ucl.ac.uk




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Ponsin
A
67Homo sapiensMutation(s): 0 
Gene Names: SORBS1 (KIAA0894, KIAA1296, SH3D5)
Find proteins for Q9BX66 (Homo sapiens)
Go to Gene View: SORBS1
Go to UniProtKB:  Q9BX66
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Paxillin
B
10Homo sapiensMutation(s): 0 
Gene Names: PXN
Find proteins for P49023 (Homo sapiens)
Go to Gene View: PXN
Go to UniProtKB:  P49023
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.63 Å
  • R-Value Free: 0.177 
  • R-Value Work: 0.143 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 24.490α = 90.00
b = 41.852β = 90.00
c = 58.790γ = 90.00
Software Package:
Software NamePurpose
SCALEPACKdata scaling
DENZOdata reduction
MOLREPphasing
MAR345data collection
REFMACrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2007-10-30
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance
  • Version 1.2: 2017-10-18
    Type: Refinement description