PDBsum entry 1exr

Metal transport

PDB id: 1exr

Contents

Protein chain

146 a.a. *

Metals

_CA ×5

Waters ×178

* Residue conservation analysis

PDB id:

1exr

Name:

Metal transport

Title:

The 1.0 angstrom crystal structure of ca+2 bound calmodulin

Structure:

Calmodulin. Chain: a. Engineered: yes

Source:

Paramecium tetraurelia. Organism_taxid: 5888. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.00Å R-factor: 0.136 R-free: 0.163

Authors:

M.A.Wilson,A.T.Brunger

Key ref:

M.A.Wilson and A.T.Brunger (2000). The 1.0 A crystal structure of Ca(2+)-bound calmodulin: an analysis of disorder and implications for functionally relevant plasticity. J Mol Biol, 301, 1237-1256. PubMed id: 10966818 DOI: 10.1006/jmbi.2000.4029

Date:

03-May-00 Release date: 20-Sep-00

Protein chain

P07463  (CALM_PARTE) -  Calmodulin from Paramecium tetraurelia

Seq: 149 a.a.

Struc: 146 a.a.

DOI no: 10.1006/jmbi.2000.4029

J Mol Biol 301:1237-1256 (2000)

PubMed id: 10966818

The 1.0 A crystal structure of Ca(2+)-bound calmodulin: an analysis of disorder and implications for functionally relevant plasticity.

M.A.Wilson, A.T.Brunger.

ABSTRACT

Calmodulin (CaM) is a highly conserved 17 kDa eukaryotic protein that can bind specifically to over 100 protein targets in response to a Ca(2+) signal. Ca(2+)-CaM requires a considerable degree of structural plasticity to accomplish this physiological role; however, the nature and extent of this plasticity remain poorly characterized. Here, we present the 1.0 A crystal structure of Paramecium tetraurelia Ca(2+)-CaM, including 36 discretely disordered residues and a fifth Ca(2+) that mediates a crystal contact. The 36 discretely disordered residues are located primarily in the central helix and the two hydrophobic binding pockets, and reveal correlated side-chain disorder that may assist target-specific deformation of the binding pockets. Evidence of domain displacements and discrete backbone disorder is provided by translation-libration-screw (TLS) analysis and multiconformer models of protein disorder, respectively. In total, the evidence for disorder at every accessible length-scale in Ca(2+)-CaM suggests that the protein occupies a large number of hierarchically arranged conformational substates in the crystalline environment and may sample a quasi-continuous spectrum of conformations in solution. Therefore, we propose that the functionally distinct forms of CaM are less structurally distinct than previously believed, and that the different activities of CaM in response to Ca(2+) may result primarily from Ca(2+)-mediated alterations in the dynamics of the protein.

Selected figure(s)

Figure 1.
Figure 1. Ribbon and ADP representations of CaM. (a) A ribbon representation of CaM, with Ca^2+ represented as yellow spheres. The protein adopts the extended dumbell conformation seen in previous studies. (b) A C^a trace of CaM, with thermal ellipsoids for the C^a atoms represented at the 90 % probability level. The ellipsoids are colored according to U[eq], ranging from blue (lowest U[eq]) to red (highest U[eq]). The largest values of U[eq] are found in the central helix and the hydrophobic binding pockets, as well as the two termini. Panel (a) was made with MOLSCRIPT [Kraulis 1991] and RENDER [Merritt and Murphy 1994]. Figure (b) made with MOLSCRIPT and RASTEP [Merritt and Murphy 1994].

Figure 3.
Figure 3. Two views of discrete side-chain disorder in the hydrophobic binding pockets of CaM. In (a) and (b), the major conformation is represented with a darker line. (a) Pro43 and Met36 illustrate the clustering of discretely disordered residues that is typical in both hydrophobic binding pockets (here the N-terminal binding pocket). (b) An example of clearly resolved discrete disorder for Ile136 in the C-terminal binding pocket. Approximately 25 % of the 36 disordered residues in CaM show comparably well-resolved disorder. This Figure was generated by OPLOT [Jones et al 1991].

The above figures are reprinted by permission from Elsevier: J Mol Biol (2000, 301, 1237-1256) copyright 2000.

Figures were selected by the author.