PDBsum entry 2vaf

Metal binding protein

PDB id: 2vaf

Contents

Protein chain

349 a.a. *

* Residue conservation analysis

PDB id:

2vaf

Name:

Metal binding protein

Title:

Crystal structure of human cardiac calsequestrin

Structure:

Calsequestrin-2. Chain: a. Fragment: residues 22-399. Synonym: calsequestrin, cardiac muscle isoform, human cardiac calsequestrin. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Organ: heart. Expressed in: escherichia coli. Expression_system_taxid: 469008.

Resolution:

3.80Å R-factor: 0.274 R-free: 0.325

Authors:

E.Kim,B.Youn,L.Kemper,C.Campbell,H.Milting,M.Varsanyi,C.Kang

Key ref:

E.Kim et al. (2007). Characterization of human cardiac calsequestrin and its deleterious mutants. J Mol Biol, 373, 1047-1057. PubMed id: 17881003 DOI: 10.1016/j.jmb.2007.08.055

Date:

31-Aug-07 Release date: 11-Sep-07

Supersedes:

2v0q

Protein chain

O14958  (CASQ2_HUMAN) -  Calsequestrin-2 from Homo sapiens

Seq: 399 a.a.

Struc: 349 a.a.

DOI no: 10.1016/j.jmb.2007.08.055

J Mol Biol 373:1047-1057 (2007)

PubMed id: 17881003

Characterization of human cardiac calsequestrin and its deleterious mutants.

E.Kim, B.Youn, L.Kemper, C.Campbell, H.Milting, M.Varsanyi, C.Kang.

ABSTRACT

Mutations of conserved residues of human cardiac calsequestrin (hCSQ2), a high-capacity, low-affinity Ca2+-binding protein in the sarcoplasmic reticulum, have been associated with catecholamine-induced polymorphic ventricular tachycardia (CPVT). In order to understand the molecular mechanism and pathophysiological link between these CPVT-related missense mutations of hCSQ2 and the resulting arrhythmias, we generated three CPVT-causing mutants of hCSQ2 (R33Q, L167H, and D307H) and two non-pathological mutants (T66A and V76M) and investigated the effect of these mutations. In addition, we determined the crystal structure of the corresponding wild-type hCSQ2 to gain insight into the structural effects of those mutations. Our data show clearly that all three CPVT-related mutations lead to significant reduction in Ca2+-binding capacity in spite of the similarity of their secondary structures to that of the wild-type hCSQ2. Light-scattering experiments indicate that the Ca2+-dependent monomer-polymer transitions of the mutants are quite different, confirming that the linear polymerization behavior of CSQ is linked directly to its high-capacity Ca2+ binding. R33Q and D307H mutations result in a monomer that appears to be unable to form a properly oriented dimer. On the other hand, the L167H mutant has a disrupted hydrophobic core in domain II, resulting in high molecular aggregates, which cannot respond to Ca2+. Although one of the non-pathological mutants, T66A, shares characteristics with the wild-type, the other null mutant, V76M, shows significantly altered Ca2+-binding and polymerization behaviors, calling for careful reconsideration of its status.

Selected figure(s)

Figure 1.
Figure 1. A diagram of CSQ polymerization. The CSQ molecule exists as either a monomer or a wide range of high molecular mass clusters, depending on the ionic environment. The extended N terminus of CSQ establishes the front-to-front dimer interface through arm exchange. Following a further increase of the concentration of Ca^2+, the carboxy terminus of CSQ, which is the most negative region, forms tetramer and higher-order linear polymers capturing substantial amounts of Ca^2+ in the back-to-back interface.

Figure 7.
Figure 7. Amino acid sequence comparison of human CSQ1 with human, canine, rabbit, chicken and xenopus CSQ2. Five mutational sites (R33, T66, V76, L167, and D307) are highlighted in green and the mutation was named according to the amino acid number in the unprocessed CSQ. The signal peptides are indicated with the black broken-line box. The secondary structural elements are indicated with colored arrows on top of the corresponding sequences and each domain (I, II and III) is marked with green lines.

The above figures are reprinted by permission from Elsevier: J Mol Biol (2007, 373, 1047-1057) copyright 2007.

Figures were selected by an automated process.