Impact of calcium binding and thionylation of S100A1 protein on its NMR derived structure and backbone dynamics

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Abstract

S100 proteins play a crucial role in multiple important biological processes in vertebrate organisms acting predominantly as calcium signal transmitters. S100A1 is a typical representative of this family of proteins. Upon binding of four Ca2+ ions it undergoes a dramatic conformational change, resulting in exposure, in each of its two identical subunits, a large hydrophobic cleft that binds to target proteins. It has been shown that abnormal expression of S100A1 is strongly correlated with a number of severe human diseases: cardiomyopathy and neurodegenerative disorders. A few years ago we have found that thionylation of Cys 85 - the unique cysteine in two identical S100A1 subunits – leads to a drastic increase of the protein affinity for calcium. We postulated that the protein activated by thionylation becomes a more efficient calcium signal transmitter. Therefore, we decided to undertake, using NMR methods, a comparative study of structure and dynamics of native and thionylated human S100A1 in its apo and holo states. In this paper we present the results obtained for the both forms of this protein in its holo state and compare them with the previously published structure of native apo S100. The main conclusion that we draw from these results is that the increased calcium binding affinity of S100A1 upon thionylation arises, most probably, from rearrangement of the hydrophobic core in its apo form.

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• Impact of calcium binding and thionylation of S100A1 protein on its NMR derived structure and backbone dynamics. (deposited 14 Apr 2014 12:20)
  • Impact of calcium binding and thionylation of S100A1 protein on its NMR derived structure and backbone dynamics. (deposited 15 Apr 2014 11:52) [Currently Displayed]