Structural Dynamics of IDPs probed by Cross-Correlated NMR Spin Relaxation

The main goal of the proposed research project is to investigate cross-correlated NMR spin relaxation as a novel tool for structural and dynamic studies of intrinsically disordered proteins (IDPs). We plan to establish a NMR methodological framework to elucidate a detailed atomistic picture of their dynamic behavior and the details of structural compaction in IDPs and structural adaptations upon ligand binding. Specifically, we plan to study changes in the structural dynamics of IDPs upon binding to membrane systems, small molecules and cognate protein binding partners on the structural dynamics of IDPs. The two IDPs under investigation are Osteopontin and BASP1, two intrinsically disordered proteins involved in neuronal plasticity and synaptic vesicle fusion, as well as metastasis and tumor outgrowth. IDPs have attracted a lot of attention over the last decade due to both their fascinating structural properties and their involvement in important physiological and pathological processes. These proteins are not only lacking stably folded tertiary structures but also their intrinsic flexibility has significant impact on their biological functionality, therefore challenging the old structure-function paradigm. The efficient sampling of a vast and heterogeneous conformational space endows IDPs with enormous potential to interact with and control multiple binding partners at once making them efficient binding partners in multiple instances. The inherent structural flexibility of IDPs, however, requires the application of appropriate experimental methods, since, by definition, X-Ray crystallography cannot access the distribution of conformational states of disordered proteins. In contrast, NMR spectroscopy has been developed into a powerful structural biology technique that offers unique opportunities for structural and dynamic studies of IDPs and allows to characterize their conformational space and derive dynamic models. Here we will investigate sophisticated experimental NMR spin relaxation methodologies to characterize structural dynamics of intrinsically disordered proteins. The applications to Osteopontin and BASP1 will serve to illustrate the potential of the technique and will provide unprecedented insight into the conformational space of the medically highly relevant IDPs.

The main goal of the proposed research project is to investigate cross-correlated NMR spin relaxation as a novel tool for structural and dynamic studies of intrinsically disordered proteins (IDPs). IDPs are fascinating problems for structural biology as these proteins are lacking stably folded tertiary structures and their intrinsic flexibility has significant impact on their biological functionality. The efficient sampling of a vast and heterogeneous conformational space endows IDPs with enormous potential to interact with and control multiple binding partners at once making them efficient binding partners in multiple instances. The inherent structural flexibility of IDPs, however, requires the application of appropriate experimental methods, since, by definition, X-Ray crystallography cannot access the distribution of conformational states of disordered proteins. In contrast, NMR spectroscopy has been developed into a powerful structural biology technique that offers unique opportunities for structural and dynamic studies of IDPs and allows to characterize their conformational space and derive dynamic models. Within the project we have successfully established a NMR methodological framework to characterize structural dynamics of intrinsically disordered proteins. Specifically, we could show that these sophisticated NMR spin relaxation experiments can be used to probe backbone dihedral angle distributions in IDPs and thus provide unprecedented insight into the conformational space of these medically highly relevant protein systems.