Structure determining methods for describing the structures and interactions of intrinsically disordered proteins
Our aim is to combine complex biophysical and functional studies of proteins with the determination of secondary structure by CD spectroscopy. Our results will help to understand better the primary and secondary structural characteristics that determine behavior of the interaction motifs of intrinsically disordered proteins (IDPs). We also work on the improvement of a CD spectrum analysis software in order to develop a program that is suited for the secondary structure characterization of IDPs. This new CD spectroscopy method enables screening of different molecules and circumstances in a fast and cheap way before the expensive and time-consuming NMR experiments.
During our collaboration we studied the p53-mdm2 binding and the secondary structural changes that occur in the TAD region of p53 upon binding. We concluded that although both the wild-type and mutant TAD region are disordered in the free form, the wild type TAD has a higher alpha helical propensity than the mutant TAD, influencing the capability of mdm2 binding.
We also showed that the empty carrier sequence as well as TNFR5 and SF1 is highly disordered in their unbound form, their secondary structural propensity is minimal. Since the bound structure of these recognition motifs is known, we could conclude that in their cases the structural changes occur upon binding, which is to show that it’s induced folding and not conformational selection that drives the formation of the bound structure.
Ágnes Tantos - József Kardos