Living cells have evolved sophisticated intracellular organization strategies that are challenging to reproduce synthetically. Biomolecular function depends on both the structure of the molecule itself and the properties of the surrounding medium. The ability to simulate the in vivo environment and isolate biological networks for study in an artificial milieu without sacrificing the crowding, structure, and compartmentalization of a cellular environment, represent engineering challenges with tremendous potential to impact both biological studies and biomedical applications. Emerging experience has shown that polypeptide-based complex coacervation (electrostatically-driven liquid-liquid phase separation) produces a biomimetic microenvironment capable of tuning protein biochemical activity. We have investigated the effect of polypeptide-based coacervates on the dynamic self-assembly of cytoskeletal actin filaments. Coacervate materials are able to directly affect the nucleation and assembly dynamics. Utilizing fluorescence confocal microscopy and fluorescence-based filament growth assays, we have observed the impact of macromolecular crowding, polymer chain length, and chemical specificity of the encapsulating polypeptides-based coacervate phase. These results are supported by similar observations made using specific actin-binding proteins. Moving forward, we are looking to determine the potential impact of specific chemical interactions through the incorporation of sequence-specific motifs into our polypeptide-based coacervate materials. Such systems may prove particularly useful for biochemical assays because of the potential for free transport of molecules across the coacervate phase boundary. *This work is supported by the University of Chicago and the U.S. Department of Energy Office of Science program in Basic Energy Sciences and the Materials Sciences and Engineering Division, and the University of Chicago NSF-MRSEC.

Biomimetic effects on actin cytoskeletal filament growth

250th National Meeting (2015)

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