PDBsum entry 4hex

Calcium binding protein

PDB id: 4hex

Contents

Protein chains

139 a.a.

Metals

_ZN ×6

_CA ×4

Waters ×78

PDB id:

4hex

Name:

Calcium binding protein

Title:

A novel conformation of calmodulin

Structure:

Calmodulin. Chain: a, b. Synonym: cam. Engineered: yes

Source:

Mus musculus. Mouse. Organism_taxid: 10090. Gene: cam. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.00Å R-factor: 0.211 R-free: 0.237

Authors:

V.Kumar,V.P.R.Chichili,J.Sivaraman

Key ref:

V.Kumar et al. (2013). A novel trans conformation of ligand-free calmodulin. Plos One, 8, e54834. PubMed id: 23382982

Date:

04-Oct-12 Release date: 06-Mar-13

Protein chains

P0DP26  (CALM1_MOUSE) -  Calmodulin-1 from Mus musculus

Seq: 149 a.a.

Struc: 139 a.a.

Plos One 8:e54834 (2013)

PubMed id: 23382982

A novel trans conformation of ligand-free calmodulin.

V.Kumar, V.P.Chichili, X.Tang, J.Sivaraman.

ABSTRACT

Calmodulin (CaM) is a highly conserved eukaryotic protein that binds specifically to more than 100 target proteins in response to calcium (Ca(2+)) signal. CaM adopts a considerable degree of structural plasticity to accomplish this physiological role; however, the nature and extent of this plasticity remain to be fully understood. Here, we report the crystal structure of a novel trans conformation of ligand-free CaM where the relative disposition of two lobes of CaM is different, a conformation to-date not reported. While no major structural changes were observed in the independent N- and C-lobes as compared with previously reported structures of Ca(2+)/CaM, the central helix was tilted by ∼90° at Arg75. This is the first crystal structure of CaM to show a drastic conformational change in the central helix, and reveals one of several possible conformations of CaM to engage with its binding partner.