The S100 proteins represent a vertebrate-specific Ca2+sensor protein family with 20 paralog members that exert their function by binding to target proteins. Their physiological function is ill-defined, however they are overexpressed in several pathological conditions such as tumors, fibrosis and inflammations. S100 interactions are rather promiscuous, a partner protein is often able to bind to several S100 proteins. The major goal of our collaboration is to determine the S100 interactome and establish a specificity map within the family. Currently it cannot be performed since based on literature data and our preliminary experiments the binding partner that has been identified so far bind to approximately two-thirds of S100 proteins, while one-third do not have known partners at all. Based on the above only partial and distorted specificity maps can be constructed, therefore we have decided to extend and complete the S100 interactome using mass spectrometry methodology (AP-TAP-MS). Partner protein will be isolated from appropriate cell lysates using affinity chromatography with recombinant S100 protein. The partners will be identified after tryptic digestion, LC-MS/MS sequencing and database search. The novel partner proteins and their S100 complexes will be characterized by biochemical and in-cell experiments, moreover the structure of the interesting partner will be determined as well as we plan to perform further functional studies. On the longer term results from this collaboration could also lead to S100-based drug developments.

László Nyitray, Gitta Schlosser, Lilla Turiák

Result_May 2020