Premium
Regulation of endothelial nitric oxide synthase phosphorylated at Thr495 by interaction with calmodulin (769.8)
Author(s) -
Piazza Michael,
Guillemette J. Guy,
Dieckmann Thorsten
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.769.8
Subject(s) - phosphorylation , calmodulin , chemistry , nitric oxide , peptide , enos , biochemistry , nitric oxide synthase , nitric oxide synthase type iii , microbiology and biotechnology , biophysics , enzyme , biology , organic chemistry
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. Calmodulin (CaM), a small acidic calcium binding protein, 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 electron transfer 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 of eNOS that contains a phosphorylated threonine corresponding to Thr495 in order 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 due to phosphorylation and this leads to weaker binding under low physiological calcium concentrations. This study provides an explanation for the reduced NO production by eNOS carrying a phosphorylated Thr495 residue. Grant Funding Source : National Science and Engineering Research Council (NSERC)