(575c) Multicomplex Formation in the Presence of Polymer Crowders Mimicking in-Cell Environment

Macromolecular crowding experienced by biomolecules inside the milieu of a cell can have a significant impact on biological processes such as protein folding, binding, and aggregation. Most previous work had focused on rigid spherical crowders that are devoid of intramolecular conformational fluctuations that are commonly present in cellular biomolecules acting as crowding agents. A more faithful representation of in-cell crowding agents will be polymeric chains that can interconvert between a wide variety of conformations. To Identify the effects of such crowding agents on protein binding thermodynamics and kinetics, we use polymer crowders that can adopt compact as well as extended conformations. We find that the effect of such crowders is qualitatively different from spherical crowders. We also present a simple theoretical model that can semi-quantitatively explain our simulation results.