PDBsum entry 1j7o

Metal binding protein

PDB id: 1j7o

Contents

Protein chain

76 a.a. *

Metals

_CA ×2

* Residue conservation analysis

PDB id:

1j7o

Name:

Metal binding protein

Title:

Solution structure of calcium-calmodulin n-terminal domain

Structure:

Calmodulin. Chain: a. Fragment: n-terminal domain. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Expressed in: escherichia coli. Expression_system_taxid: 562.

NMR struc:

3 models

Authors:

J.J.Chou,C.B.Klee,A.Bax

Key ref:

J.J.Chou et al. (2001). Solution structure of Ca(2+)-calmodulin reveals flexible hand-like properties of its domains. Nat Struct Biol, 8, 990-997. PubMed id: 11685248 DOI: 10.1038/nsb1101-990

Date:

17-May-01 Release date: 07-Nov-01

Protein chain

P0DP23  (CALM1_HUMAN) -  Calmodulin-1 from Homo sapiens

Seq: 149 a.a.

Struc: 76 a.a.

DOI no: 10.1038/nsb1101-990

Nat Struct Biol 8:990-997 (2001)

PubMed id: 11685248

Solution structure of Ca(2+)-calmodulin reveals flexible hand-like properties of its domains.

J.J.Chou, S.Li, C.B.Klee, A.Bax.

ABSTRACT

The solution structure of Ca(2+)-ligated calmodulin is determined from residual dipolar couplings measured in a liquid crystalline medium and from a large number of heteronuclear J couplings for defining side chains. Although the C-terminal domain solution structure is similar to the X-ray crystal structure, the EF hands of the N-terminal domain are considerably less open. The substantial differences in interhelical angles correspond to negligible changes in short interproton distances and, therefore, cannot be identified by comparison of NOEs and X-ray data. NOE analysis, however, excludes a two-state equilibrium in which the closed apo conformation is partially populated in the Ca(2+)-ligated state. The difference between the crystal and solution structures of Ca(2+)-calmodulin indicates considerable backbone plasticity within the domains of calmodulin, which is key to their ability to bind a wide range of targets. In contrast, the vast majority of side chains making up the target binding surface are locked into the same chi(1) rotameric states as in complexes with target peptide.

Selected figure(s)

Figure 3.
Figure 3. Normalized average difference, D, between the measured dipolar couplings and those predicted by the refined NMR structure as a function of residue number. D = ((( 1D[NH])2 + ( 1D[C H ])2 + ( 1D[C'C ])2 + ( 1D[C'N])2 + ( 2D[C'H ] measure and best-fit couplings, where all couplings have been normalized relative to 1D[NH]. No couplings were measured for Asn 42 because residue 43 is a Pro and Asn 42 HN is broadened by rapid solvent exchange at pH 7.0. Residues Met 76 -Asp 81 are highly flexible and excluded from the structure calculation. The symbols correspond to apo CaM (square), parvalbumin (triangle) and Ca^2+ -CaM (circle) starting structures.

Figure 4.
Figure 4. Ribbon diagrams of the backbone of the Ca^2+ -CaM solution structure, shown in red, and the 1 Å crystal structure (1EXR) in blue. a, For the N-terminal domain, the superposition is optimized for residues 29 -54 (helices II and III), revealing the large difference in the orientation of helix I (26°) and IV (22°). b, For the C-terminal domain, residues 102 -127 (helices VI and VII) are superimposed, showing much smaller orientation differences of 15° and 10° for helix V and VIII, respectively. c,d, Solution structures including side chains, color coded according to their mobility as determined by 3J[CC] and 3J[CN] couplings. Red indicates extensive rotameric [1] averaging; blue, single [1] rotamers; and gray, residues with insufficient data for accurately defining [1] distributions. Eight Met residues (yellow) have unique [1] angles but exhibit extensive [3] averaging. Figures generated using MOLMOL49.

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nat Struct Biol (2001, 8, 990-997) copyright 2001.

Figures were selected by an automated process.