PDBsum entry 2mg5

Metal binding protein/target peptide

PDB id: 2mg5

Contents

Protein chains

148 a.a.

16 a.a.

PDB id:

2mg5

Name:

Metal binding protein/target peptide

Title:

Solution structure of calmodulin bound to the target peptide of endothelial nitrogen oxide synthase phosphorylated at thr495

Structure:

Calmodulin. Chain: a. Fragment: unp residues 2-149. Synonym: cam. Engineered: yes. Target peptide. Chain: b. Engineered: yes

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. Synthetic: yes

NMR struc:

20 models

Authors:

M.Piazza,T.Dieckmann

Key ref:

M.Piazza et al. (2014). Solution structure of calmodulin bound to the target peptide of endothelial nitric oxide synthase phosphorylated at Thr495. Biochemistry, 53, 1241-1249. PubMed id: 24495081 DOI: 10.1021/bi401466s

Date:

28-Oct-13 Release date: 05-Mar-14

Protein chain

P0DP23  (CALM1_HUMAN) -  Calmodulin-1 from Homo sapiens

Seq: 149 a.a.

Struc: 148 a.a.

Protein chain

P29474  (NOS3_HUMAN) -  Nitric oxide synthase 3 from Homo sapiens

Seq: 1203 a.a.

Struc: 16 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: Chain B: E.C.1.14.13.39 - nitric-oxide synthase (NADPH).
• Reaction: 2 L-arginine + 3 NADPH + 4 O2 + H⁺ = 2 L-citrulline + 2 nitric oxide + 3 NADP⁺ + 4 H2O

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1021/bi401466s

Biochemistry 53:1241-1249 (2014)

PubMed id: 24495081

Solution structure of calmodulin bound to the target peptide of endothelial nitric oxide synthase phosphorylated at Thr495.

M.Piazza, V.Taiakina, S.R.Guillemette, J.G.Guillemette, T.Dieckmann.

ABSTRACT

Nitric oxide synthase (NOS) plays a major role in a number of key physiological and pathological processes, and it is important to understand how this enzyme is regulated. The small acidic calcium binding protein, calmodulin (CaM), is required to fully activate the enzyme. The exact mechanism of how CaM activates NOS is not fully understood at this time. Studies have shown CaM to act like a switch that causes a conformational change in NOS to allow for the transfer of an electron between the reductase and oxygenase domains through a process that is thought to be highly dynamic and at least in part controlled by several possible phosphorylation sites. We have determined the solution structure of CaM bound to a peptide that contains a phosphorylated threonine corresponding to Thr495 in full size endothelial NOS (eNOS) to investigate the structural and functional effects that the phosphorylation of this residue may have on nitric oxide production. Our biophysical studies show that phosphorylation of Thr495 introduces electrostatic repulsions between the target sequence and CaM as well as a diminished propensity for the peptide to form an α-helix. The calcium affinity of the CaM-target peptide complex is reduced because of phosphorylation, and this leads to weaker binding at low physiological calcium concentrations. This study provides an explanation for the reduced level of NO production by eNOS carrying a phosphorylated Thr495 residue.