3Q4A

Crystal structure of the TPR domain of CHIP complexed with phosphorylated Smad1 peptide


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.542 Å
  • R-Value Free: 0.208 
  • R-Value Work: 0.168 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Molecular Mechanism of the Negative Regulation of Smad1/5 Protein by Carboxyl Terminus of Hsc70-interacting Protein (CHIP).

Wang, L.Liu, Y.T.Hao, R.Chen, L.Chang, Z.Wang, H.R.Wang, Z.X.Wu, J.W.

(2011) J.Biol.Chem. 286: 15883-15894

  • DOI: 10.1074/jbc.M110.201814
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • The transforming growth factor-β (TGF-β) superfamily of ligands signals along two intracellular pathways, Smad2/3-mediated TGF-β/activin pathway and Smad1/5/8-mediated bone morphogenetic protein pathway. The C terminus of Hsc70-interacting protein (C ...

    The transforming growth factor-β (TGF-β) superfamily of ligands signals along two intracellular pathways, Smad2/3-mediated TGF-β/activin pathway and Smad1/5/8-mediated bone morphogenetic protein pathway. The C terminus of Hsc70-interacting protein (CHIP) serves as an E3 ubiquitin ligase to mediate the degradation of Smad proteins and many other signaling proteins. However, the molecular mechanism for CHIP-mediated down-regulation of TGF-β signaling remains unclear. Here we show that the extreme C-terminal sequence of Smad1 plays an indispensable role in its direct association with the tetratricopeptide repeat (TPR) domain of CHIP. Interestingly, Smad1 undergoes CHIP-mediated polyubiquitination in the absence of molecular chaperones, and phosphorylation of the C-terminal SXS motif of Smad1 enhances the interaction and ubiquitination. We also found that CHIP preferentially binds to Smad1/5 and specifically disrupts the core signaling complex of Smad1/5 and Smad4. We determined the crystal structures of CHIP-TPR in complex with the phosphorylated/pseudophosphorylated Smad1 peptides and with an Hsp70/Hsc70 C-terminal peptide. Structural analyses and subsequent biochemical studies revealed that the distinct CHIP binding affinities of Smad1/5 or Smad2/3 result from the nonconservative hydrophobic residues at R-Smad C termini. Unexpectedly, the C-terminal peptides from Smad1 and Hsp70/Hsc70 bind in the same groove of CHIP-TPR, and heat shock proteins compete with Smad1/5 for CHIP interaction and concomitantly suppress, rather than facilitate, CHIP-mediated Smad ubiquitination. Thus, we conclude that CHIP inhibits the signaling activities of Smad1/5 by recruiting Smad1/5 from the functional R-/Co-Smad complex and further promoting the ubiquitination/degradation of Smad1/5 in a chaperone-independent manner.


    Organizational Affiliation

    MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, China.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
STIP1 homology and U box-containing protein 1
B
137Mus musculusMutation(s): 0 
Gene Names: Stub1 (Chip)
EC: 2.3.2.27
Find proteins for Q9WUD1 (Mus musculus)
Go to UniProtKB:  Q9WUD1
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Smad1 peptide
C
10Homo sapiensMutation(s): 0 
Gene Names: SMAD1 (BSP1, MADH1, MADR1)
Find proteins for Q15797 (Homo sapiens)
Go to Gene View: SMAD1
Go to UniProtKB:  Q15797
Small Molecules
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
SEP
Query on SEP
C
L-PEPTIDE LINKINGC3 H8 N O6 PSER
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.542 Å
  • R-Value Free: 0.208 
  • R-Value Work: 0.168 
  • Space Group: P 21 21 2
Unit Cell:
Length (Å)Angle (°)
a = 46.132α = 90.00
b = 77.444β = 90.00
c = 36.456γ = 90.00
Software Package:
Software NamePurpose
MAR345dtbdata collection
PHASERphasing
HKL-2000data scaling
HKL-2000data reduction
PHENIXrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2011-03-16
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance