Studies of flexible systems

Pau Bernadó

Small-angle X-ray Scattering (SAXS) is nowadays a well-established method to structurally characterize biomolecules and macromolecular complexes in solution. Most common modelling strategies of SAXS data relay on the presence of a single family of particles in solution with an identical 3D structure. However, there are very relevant biological systems where this approximation is not valid because they sample a large number of conformational substates with important structural rearrangements that modify the molecular size and shape. Multi-domain proteins, Intrinsically Disordered Proteins (IDPs) and RNA are examples of this situation. For these cases, traditional approaches are no longer valid and new modelling methodologies are required. Several approaches have been developed for the quantitative interpretation of SAXS data of flexible biomolecules in terms of structure and dynamics. These methods include Ensemble Optimization Method (EOM), the Minimal Ensemble Search (MES), and Ensemble Refinement of SAXS (EROS).

In this talk the relevance of protein dynamics and how SAXS can help in its characterization will be presented. The importance of the detection of protein dynamics in order to avoid structural aliasing will be stressed. Additionally, the EOM will be presented with especial emphasis on the advantages, requirements and limitations for its usage. Several examples will be given to exemplify the concepts provided along the presentation.

Date/time: Friday, 31 October 2014, 11:00