PDBsum entry 5e1k

Metal binding protein

PDB id: 5e1k

Contents

Protein chain

145 a.a.

Ligands

MPD ×2

Metals

_CA ×5

Waters ×176

PDB id:

5e1k

Name:

Metal binding protein

Title:

Selenomethionine ca2+-calmodulin from paramecium tetraurelia sad data

Structure:

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

Source:

Paramecium tetraurelia. Organism_taxid: 5888. Gene: cam, gspatt00015825001. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.00Å R-factor: 0.144 R-free: 0.165

Authors:

J.Lin,H.Van Den Bedem,A.T.Brunger,M.A.Wilson

Key ref:

J.Lin et al. (2016). Atomic resolution experimental phase information reveals extensive disorder and bound 2-methyl-2,4-pentanediol in Ca(2+)-calmodulin. Acta Crystallogr D Struct Biol, 72, 83-92. PubMed id: 26894537 DOI: 10.1107/S2059798315021609

Date:

29-Sep-15 Release date: 25-Nov-15

Protein chain

P07463  (CALM_PARTE) -  Calmodulin from Paramecium tetraurelia

Seq: 149 a.a.

Struc: 145 a.a.

DOI no: 10.1107/S2059798315021609

Acta Crystallogr D Struct Biol 72:83-92 (2016)

PubMed id: 26894537

Atomic resolution experimental phase information reveals extensive disorder and bound 2-methyl-2,4-pentanediol in Ca(2+)-calmodulin.

J.Lin, H.van den Bedem, A.T.Brunger, M.A.Wilson.

ABSTRACT

Calmodulin (CaM) is the primary calcium signaling protein in eukaryotes and has been extensively studied using various biophysical techniques. Prior crystal structures have noted the presence of ambiguous electron density in both hydrophobic binding pockets of Ca(2+)-CaM, but no assignment of these features has been made. In addition, Ca(2+)-CaM samples many conformational substates in the crystal and accurately modeling the full range of this functionally important disorder is challenging. In order to characterize these features in a minimally biased manner, a 1.0 Å resolution single-wavelength anomalous diffraction data set was measured for selenomethionine-substituted Ca(2+)-CaM. Density-modified electron-density maps enabled the accurate assignment of Ca(2+)-CaM main-chain and side-chain disorder. These experimental maps also substantiate complex disorder models that were automatically built using low-contour features of model-phased electron density. Furthermore, experimental electron-density maps reveal that 2-methyl-2,4-pentanediol (MPD) is present in the C-terminal domain, mediates a lattice contact between N-terminal domains and may occupy the N-terminal binding pocket. The majority of the crystal structures of target-free Ca(2+)-CaM have been derived from crystals grown using MPD as a precipitant, and thus MPD is likely to be bound in functionally critical regions of Ca(2+)-CaM in most of these structures. The adventitious binding of MPD helps to explain differences between the Ca(2+)-CaM crystal and solution structures and is likely to favor more open conformations of the EF-hands in the crystal.