PDBsum entry 2k3s

Protein binding

PDB id: 2k3s

Contents

Protein chains

119 a.a. *

67 a.a. *

* Residue conservation analysis

PDB id:

2k3s

Name:

Protein binding

Title:

Haddock-derived structure of the ch-domain of the smoothelin-like 1 complexed with thE C-domain of apocalmodulin

Structure:

Smoothelin-like protein 1. Chain: a. Engineered: yes. Calmodulin. Chain: b. Synonym: cam. Engineered: yes

Source:

Mus musculus. Mouse. Gene: smtnl1. Expressed in: escherichia coli. Xenopus laevis. African clawed frog. Gene: calm1.

NMR struc:

15 models

Authors:

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

Key ref:

H.Ishida et al. (2008). 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. J Biol Chem, 283, 20569-20578. PubMed id: 18477568 DOI: 10.1074/jbc.M800627200

Date:

15-May-08 Release date: 27-May-08

Protein chain

Q99LM3  (SMTL1_MOUSE) -  Smoothelin-like protein 1 from Mus musculus

Seq: 459 a.a.

Struc: 119 a.a.*

Protein chain

P0DP33  (CALM1_XENLA) -  Calmodulin-1 from Xenopus laevis

Seq: 149 a.a.

Struc: 67 a.a.

* PDB and UniProt seqs differ at 4 residue positions (black crosses)

DOI no: 10.1074/jbc.M800627200

J Biol Chem 283:20569-20578 (2008)

PubMed id: 18477568

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.

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

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.

Selected figure(s)

Figure 5.
FIGURE 5. Structural comparison of SMTNL1-CH with other type-2 CH-domains. The lowest energy structure of SMTNL1-CH is superimposed on the CH-domain structure from smoothelin (a), -actinin 1 (b), spectrin (c), and MICAL-1 (d). SMTNL1-CH is colored navy in all panels.

Figure 8.
FIGURE 8. HADDOCK-derived structure of SMTNL1-CH complexed with the C-terminal domain of apo-CaM. a, superposition of 15 models of the complex of SMTNL1-CH (green) with the C-terminal domain of apo-CaM (blue). b, ribbon representation of the lowest energy model. The side chains that contribute to the formation of intermolecular hydrogen bonds are also shown. The acidic and basic side chains are colored in pink and blue, respectively, whereas Tyr is shown in green.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2008, 283, 20569-20578) copyright 2008.

Figures were selected by the author.