Investigation of the structure and dynamic of calmodulin-nitric oxide synthase complexes using NMR spectroscopy.

Abstract

NMR spectroscopy allows for the determination of high resolution structures, as well as being an efficient method for studying the dynamics of protein-protein and protein-peptide complexes. 15N relaxation and H/D exchange experiments allow for the analysis of these structural dynamics at a residue specific level. Calmodulin (CaM) is a small cytosolic Ca2+ binding protein that serves as a control element for many enzymes. An important target of CaM are the nitric oxide synthase (NOS) enzymes that play a major role in a number of key physiological and pathological processes. Studies have shown CaM facilitates a conformational shift in NOS allowing for efficient electron transfer through a process thought to be highly dynamic and at least in part controlled by several possible phosphorylation sites. This review highlights recent work performed on the CaM-NOS complexes using NMR spectroscopy and shows remarkable differences in the dynamic properties of CaM-NOS complexes at physiologically relevant Ca2+ concentrations. It also shows key structural changes that affect the activity of NOS when interacting with apoCaM mutants and NOS posttranslational modifications are present.