Chemical shift perturbations induced by residue specific mutations of CaM interacting with NOS peptides

Abstract

The regulation of Nitric oxide synthase (NOS) by calmodulin (CaM) plays a major role in a number of key physiological and pathological processes. A detailed molecular level picture of how this regulation is achieved is critical for drug development and for our understanding of protein regulation in general.CaM is a small acidic calcium binding protein and is required to fully activate NOS. 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. The interaction of CaM with NOS is modified by a number of post-translation modifications including phosphorylation. Here we present backbone and sidechain 1 H, 15 N NMR assignments of modified CaM interacting with NOS peptides which provides the basis for a detailed study of CaM-NOS interaction dynamics using 15 N relaxation methods.

Novel regulation of equlibrative nucleoside transporter 1 (ENT1) by receptor-stimulated Ca2+-dependent calmodulin binding

“…15 N-labeled CaM was titrated with the ubiquitin-hENT1 loop construct, and the limited amount of line broadening confirmed that the hENT1 loop binds to CaM (Fig. 4A) in the presence of calcium, similar to other studies that have examined the interaction of a protein domain with CaM (44).…”