2MG5

Solution Structure of Calmodulin bound to the target peptide of Endothelial Nitrogen Oxide Synthase phosphorylated at Thr495

Summary for 2MG5

• Entry DOI: 10.2210/pdb2mg5/pdb
• NMR Information: BMRB: 19586
• Descriptor: Calmodulin, target peptide (2 entities in total)
• Functional Keywords: calmodulin, nitric oxide synthase, enos, metal binding protein-target peptide complex, metal binding protein/target peptide
• Biological source: Homo sapiens (human)
• Cellular location: Cytoplasm, cytoskeleton, spindle: P62158
• Total number of polymer chains: 2
• Total formula weight: 18512.36

Authors

Piazza, M.,Dieckmann, T. (deposition date: 2013-10-28, release date: 2014-03-05, Last modification date: 2024-11-06)

Primary citation

Piazza, M.,Taiakina, V.,Guillemette, S.R.,Guillemette, J.G.,Dieckmann, T.
Solution structure of calmodulin bound to the target Peptide of endothelial nitric oxide synthase phosphorylated at thr495.
Biochemistry, 53:1241-1249, 2014

PubMed 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.

PubMed: 24495081
DOI: 10.1021/bi401466s

Experimental method

SOLUTION NMR