Macromolecule Content

• Total Structure Weight: 21.43 kDa 
• Atom Count: 1500 
• Residue Count: 186 
• Unique protein chains: 2

2K3S

HADDOCK-derived structure of the CH-domain of the smoothelin-like 1 complexed with the C-domain of apocalmodulin

• DOI: 10.2210/pdb2K3S/pdb

• Classification: PROTEIN BINDING
• Organism(s): Mus musculus, Xenopus laevis
• Expression System: Escherichia coli
• Mutation(s): No 


• Deposited: 2008-05-15 Released: 2008-05-27 
• Deposition Author(s): Ishida, H., Borman, M.A., Ostrander, J., Vogel, H.J., MacDonald, J.A.

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Experimental Data Snapshot

• Method: SOLUTION NMR
• Conformers Calculated: 1000 
• Conformers Submitted: 15 
• Selection Criteria: structures with the lowest energy 

Literature

Solution structure of the calponin homology (CH) domain from the smoothelin-like 1 protein: a unique apocalmodulin-binding mode and the possible role of the C-terminal type-2 CH-domain in smooth muscle relaxation.

Ishida, H., Borman, M.A., Ostrander, J., Vogel, H.J., MacDonald, J.A.

(2008) J Biol Chem 283: 20569-20578

• PubMed: 18477568 
• DOI: 10.1074/jbc.M800627200
• Primary Citation of Related Structures:  
  2K3S, 2JV9


• PubMed Abstract: 
  

The SMTNL1 protein contains a single type-2 calponin homology (CH) domain at its C terminus that shares sequence identity with the smoothelin family of smooth muscle-specific proteins. In contrast to the smoothelins, SMTNL1 does not associate with F-actin in vitro, and its specific role in smooth muscle remains unclear. In addition, the biological function of the C-terminal CH-domains found in the smoothelin proteins is also poorly understood. In this work, we have therefore determined the solution structure of the CH-domain of mouse SMTNL1 (SMTNL1-CH; residues 346-459). The secondary structure and the overall fold for the C-terminal type-2 CH-domain is very similar to that of other CH-domains. However, two clusters of basic residues form a unique surface structure that is characteristic of SMTNL1-CH. Moreover, the protein has an extended C-terminal alpha-helix, which contains a calmodulin (CaM)-binding IQ-motif, that is also a distinct feature of the smoothelins. We have characterized the binding of apo-CaM to SMTNL1-CH through its IQ-motif by isothermal titration calorimetry and NMR chemical shift perturbation studies. In addition, we have used the HADDOCK protein-protein docking approach to construct a model for the complex of apo-CaM and SMTNL1-CH. The model revealed a close interaction of SMTNL1-CH with the two Ca(2+) binding loop regions of the C-terminal domain of apo-CaM; this mode of apo-CaM binding is distinct from previously reported interactions of apo-CaM with IQ-motifs. Finally, we comment on the putative role of the CH-domain in the biological function of SMTNL1.

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Organizational Affiliation: 

Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Smoothelin-like protein 1	A	119	Mus musculus	Mutation(s): 0  Gene Names: Smtnl1
Find proteins for Q99LM3 (Mus musculus) Explore Q99LM3  Go to UniProtKB:  Q99LM3

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details	Image
Calmodulin	B	67	Xenopus laevis	Mutation(s): 0  Gene Names: calm1
Find proteins for P0DP33 (Xenopus laevis) Explore P0DP33  Go to UniProtKB:  P0DP33

Experimental Data & Validation

Experimental Data

• Method: SOLUTION NMR
• Conformers Calculated: 1000 
• Conformers Submitted: 15 
• Selection Criteria: structures with the lowest energy 
• OLDERADO: 2K3S Olderado

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2008-05-15 
• Released Date: 2008-05-27 
Deposition Author(s): Ishida, H., Borman, M.A., Ostrander, J., Vogel, H.J., MacDonald, J.A.

Revision History 

• Version 1.0: 2008-05-27
  Type: Initial release
  
• Version 1.1: 2011-07-13
  Changes: Version format compliance