Effects of Sequence Composition and Patterning on the Structure and Dynamics of Intrinsically Disordered Proteins

Unlike the well defined structures of classical natively folded proteins, Intrinsically Disordered Proteins (IDP) and Intrinsically Disordered Regions (IDR) dynamically span large conformational and structural ensembles. This dynamic disorder impedes the study of the relationship between the amino acid sequences of the IDPs and their spatial structures, dynamics, and function. Multiple experimental and theoretical evidence points in many cases to the overall importance of the general properties of the amino acid sequence of the IPDs rather than their precise atomistic details. However, while different experimental techniques can probe aspects of the IDP conformations, often different techniques or conditions offer seemingly contradictory results. Using coarse-grained polymer models informed by experimental observations, we investigate the effects of several key variables on the dimensions and the dynamics of IDPs. The coarse-grained simulations are in a good agreement with the results of atomistic MD. We show that the sequence composition and patterning are well reflected in the global conformational variables such as the radius of gyration and hydrodynamic radius, while the end-to-end distance and dynamics are highly sequence specific. We identify the conditions that allow mapping of highly heterogeneous sequences of IDPs onto averaged minimal polymer models. We discuss the implications of these results for the interpretation of the recent experimental measurements, and for further development of appropriate mesoscopic models of IDPs.