Restructuring Biologically Assembled Binding Protein-Biopolymer Conjugates toward Advanced Materials

Bacterial cell factories have been successfully engineered to efficiently assemble spherical polyhydroxybutyrate inclusions coated with functional proteins of interest. In these submicrometer-sized core-shell assemblies, proteins are bioconjugated to the polymer core, enabling bioengineering for uses as bioseparation resins, enzyme carriers, diagnostic reagents, and particulate vaccines. Here, we explore whether these functional protein-polymer assemblies could be restructured via dissolution and subsequent precipitation while retaining the functionality of the conjugated protein. Polymer core-protein shell assemblies were completely dissolved in chloroform. Subsequent reconstitution into different formats such as hollow spheres, fibers, and films was achieved. Different proteins such as the green fluorescent protein or IgG binding domains GB1 or Z derived from protein G or protein A, respectively, were implemented to monitor the retention of protein function upon generation of reformatted materials. Materials were characterized and the retention of protein functionality was studied by assessing the fluorescence or IgG binding capacity. Since the Z domain protein functionality is retained, it suggests that protein refolding properties are critical parameters for restructuring these functional materials. This study shows that bioengineered biologically assembled protein-coated biopolymer particles can be completely dissolved and reformed into fibers, films, and hollow spheres retaining the original protein function.