PDBsum entry 3sui

Calcium-binding protein

PDB id: 3sui

Contents

Protein chains

146 a.a.

15 a.a.

Ligands

SO4

Metals

_CA ×4

Waters ×91

PDB id:

3sui

Name:

Calcium-binding protein

Title:

Crystal structure of ca2+-calmodulin in complex with a trpv1 c- terminal peptide

Structure:

Calmodulin. Chain: a. Synonym: cam. Engineered: yes. Transient receptor potential cation channel subfamily v member 1. Chain: b. Fragment: unp residues 767-801. Synonym: trpv1, capsaicin receptor, osm-9-like trp channel 1, otrpc1,

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: calm, calm1, calm2, calm3, calml2, cam, cam1, cam2, cam3, camb, camc, camiii. Expressed in: escherichia coli. Expression_system_taxid: 469008. Rattus norvegicus. Rat.

Resolution:

1.95Å R-factor: 0.194 R-free: 0.248

Authors:

S.-Y.Lau,R.Gaudet

Key ref:

S.Y.Lau et al. (2012). Distinct properties of Ca2+-calmodulin binding to N- and C-terminal regulatory regions of the TRPV1 channel. J Gen Physiol, 140, 541-555. PubMed id: 23109716 DOI: 10.1085/jgp.201210810

Date:

11-Jul-11 Release date: 12-Sep-12

Protein chain

P0DP23  (CALM1_HUMAN) -  Calmodulin-1 from Homo sapiens

Seq: 149 a.a.

Struc: 146 a.a.

Protein chain

O35433  (TRPV1_RAT) -  Transient receptor potential cation channel subfamily V member 1 from Rattus norvegicus

Seq: 838 a.a.

Struc: 15 a.a.

DOI no: 10.1085/jgp.201210810

J Gen Physiol 140:541-555 (2012)

PubMed id: 23109716

Distinct properties of Ca2+-calmodulin binding to N- and C-terminal regulatory regions of the TRPV1 channel.

S.Y.Lau, E.Procko, R.Gaudet.

ABSTRACT

Transient receptor potential (TRP) vanilloid 1 (TRPV1) is a molecular pain receptor belonging to the TRP superfamily of nonselective cation channels. As a polymodal receptor, TRPV1 responds to heat and a wide range of chemical stimuli. The influx of calcium after channel activation serves as a negative feedback mechanism leading to TRPV1 desensitization. The cellular calcium sensor calmodulin (CaM) likely participates in the desensitization of TRPV1. Two CaM-binding sites are identified in TRPV1: the N-terminal ankyrin repeat domain (ARD) and a short distal C-terminal (CT) segment. Here, we present the crystal structure of calcium-bound CaM (Ca(2+)-CaM) in complex with the TRPV1-CT segment, determined to 1.95-Å resolution. The two lobes of Ca(2+)-CaM wrap around a helical TRPV1-CT segment in an antiparallel orientation, and two hydrophobic anchors, W787 and L796, contact the C-lobe and N-lobe of Ca(2+)-CaM, respectively. This structure is similar to canonical Ca(2+)-CaM-peptide complexes, although TRPV1 contains no classical CaM recognition sequence motif. Using structural and mutational studies, we established the TRPV1 C terminus as a high affinity Ca(2+)-CaM-binding site in both the isolated TRPV1 C terminus and in full-length TRPV1. Although a ternary complex of CaM, TRPV1-ARD, and TRPV1-CT had previously been postulated, we found no biochemical evidence of such a complex. In electrophysiology studies, mutation of the Ca(2+)-CaM-binding site on TRPV1-ARD abolished desensitization in response to repeated application of capsaicin, whereas mutation of the Ca(2+)-CaM-binding site in TRPV1-CT led to a more subtle phenotype of slowed and reduced TRPV1 desensitization. In summary, our results show that the TRPV1-ARD is an important mediator of TRPV1 desensitization, whereas TRPV1-CT has higher affinity for CaM and is likely involved in separate regulatory mechanisms.