Protein vesicles incorporating functional, globular proteins have enormous potential in a number of bio-applications such as drug delivery systems, micro bioreactors, and mimicking artificial cells. We have designed globule-zipper-polypeptide protein complexes (mCherry-ZE/ZR-ELP), consisting of a model fluorescent globular protein (mCherry), high affinity leucine zipper pair (ZE/ZR), and thermo-responsive elastin-like polypeptide (ELP). The fusion protein complexes at a constant concentration undergo the phase transition from soluble monomers, through dynamic coacervates, to stable hollow vesicles as operating temperature (To) increases over transition temperature (Tt). Since the Tt is decreased with increasing protein concentration, diverse self-assembled structures from spherical particles to vesicles form with the increased average sizes as protein concentration increases at the same To. Also, the protein complexes can self-assemble into either single-layered or bi-layered vesicles according to the hydrophobic conformation of ELP domain. Furthermore, we have investigated the effects of coacervate aging below the Tt and rate of warming on vesicle size and structure. Combined, this work helps understand the phase transition of mCherry-ZE/ZR-ELP complexes and reveals the effect of difference in the To and Tt and warming dynamics on the self-assembled protein vesicle size and structures. This information provides a simple design rule to engineer the functional, globular domain-containing protein vesicles with desired size and structure for target applications.

Self-assembled recombinant globular protein vesicles

254th National Meeting (2017)

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