ИСТИНА

Neuronal calcium sensor (NCS) proteins are expressed in CNS and retinal neurons, where they are involved in regulation of cell growth, function and survival in response to intracellular calcium signals. Here, we report that NCSs are redox-sensitive proteins and their structure and function are affected by the oxidation. The majority of NCSs are capable of disulfide dimerization in vitro in the presence of physiological concentrations of an oxidant. Notably, the susceptibility to dimerization varies among these proteins, depending on the presence of calcium and magnesium. Furthermore, NCSs are capable of binding zinc, and their oxidation is enhanced in the presence of Zn2+. Disulfide dimerization of NCS proteins requires their tertiary structure, which allows increased surface accessibility of redox-sensitive cysteine ​​residues. Using macromolecular docking simulations and site-directed mutagenesis, it was found that dimer of each NCS is stabilized by a disulfide bond involving a distinct pair of cysteines and is characterized by unique overall structure, intermolecular interface and energetics. The dimerization alters NCS stability and functional properties, such as interaction with cellular membranes and recognition of binding partners, like scaffolding protein caveolin-1 and G-protein-coupled receptor kinases. Using animal and cellular models of oxidative stress, dimerization of certain NCS proteins was demonstrated to occur under physiological conditions. We propose that an increase in zinc concentration, characteristic of advanced oxidative stress, will result in NCS dimerization and, subsequently, aberrant function and aggregation, which could trigger neuronal apoptosis and neurodegeneration. This study was supported by Russian Foundation for Basic Research grant #18-04-01250.