PDBsum entry 2m0j

Metal binding protein/metal transport

PDB id: 2m0j

Contents

Protein chains

148 a.a.

28 a.a.

Metals

_CA ×4

PDB id:

2m0j

Name:

Metal binding protein/metal transport

Title:

3d structure of calmodulin and calmodulin binding domain of olfactory cyclic nucleotide-gated ion channel complex

Structure:

Calmodulin. Chain: a. Synonym: cam. Engineered: yes. Peptide from cyclic nucleotide-gated olfactory channel. Chain: b. Fragment: unp residues 60-87. Synonym: cyclic nucleotide-gated cation channel 2, cyclic nucleotide- gated channel alpha-2, cng channel alpha-2, cng-2, cng2, cyclic

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: calm1, calm, cam, cam1, calm2, cam2, camb, calm3, calml2, cam3, camc, camiii. Expressed in: escherichia coli. Expression_system_taxid: 562. Rattus norvegicus. Rat.

NMR struc:

20 models

Authors:

I.Deli,C.Chyan

Key ref:

D.Irene et al. (2013). Binding orientation and specificity of calmodulin to rat olfactory cyclic nucleotide-gated ion channel. J Biomol Struct Dyn, 31, 414-425. PubMed id: 22877078 DOI: 10.1080/07391102.2012.703069

Date:

29-Oct-12 Release date: 30-Oct-13

Protein chain

P0DP23  (CALM1_HUMAN) -  Calmodulin-1 from Homo sapiens

Seq: 149 a.a.

Struc: 148 a.a.

Protein chain

Q00195  (CNGA2_RAT) -  Cyclic nucleotide-gated channel alpha-2 from Rattus norvegicus

Seq: 664 a.a.

Struc: 28 a.a.

DOI no: 10.1080/07391102.2012.703069

J Biomol Struct Dyn 31:414-425 (2013)

PubMed id: 22877078

Binding orientation and specificity of calmodulin to rat olfactory cyclic nucleotide-gated ion channel.

D.Irene, J.W.Huang, T.Y.Chung, F.Y.Li, J.T.Tzen, T.H.Lin, C.L.Chyan.

ABSTRACT

Calmodulin (CaM), the primary intracellular Ca(2+) receptor, regulates a large number of key enzymes and controls a wide spectrum of important biological responses. Recognition between CaM and its target sequence in rat olfactory cyclic nucleotide-gated ion channel (OLFp) was investigated by circular dichroism (CD), fluorescence, and NMR spectroscopy. Fluorescence data showed the OLFp tightly bound to CaM with a dissociation constant of 12 nM in a 1:1 stoichiometry. Far-UV CD data showed that approximately 60% of OLFp residues formed α-helical structures when associated with CaM. NMR data showed that most of the (15)N-(1)H HSQC cross-peaks of the (15)N-labeled CaM not only shifted but also split into two sets of peaks upon association with the OLFp. Our data indicated that the two distinct CaM/OLFp complexes existed simultaneously with stable structures that were not interexchangeable within the NMR time scale. In light of the palindromic sequence of OLFp (FQRIVRLVGVIRDW) for CaM targeting, we proposed that the helical OLFp with C2 symmetry may bind to CaM in two orientations. This hypothesis is supported by the observation that only one set of (15)N-(1)H HSQC cross-peaks of the (15)N-labeled CaM was detected upon association with OLFp-M13 chimeric peptide (OLFMp), a mutated OLFp lacking the palindromic feature. The binding specificity of OLFMp to CaM was restored when the palindromic feature was destroyed. Binding modes of CaM/OLFp and CaM/OLFMp simulated by molecular docking were in accord with their distinct patterns observed in HSQC spectra. Our studies suggest that the palindromic residues in OLFp are crucial for the orientation-specific recognition by CaM.