Engineering a Fusion Protein Biomaterial Based on SpyTag/SpyCatcher Bioconjugation of Elastin and Collagen Synthetic Proteins

Bioconjugation enables the precise control of structural and functional properties in the development of biomaterials by facilitating the covalent linkage of functional biomolecules. In this study, we developed and optimized a bioconjugation strategy to fuse recombinant proteins resembling collagen and elastin using the SpyTag/SpyCatcher system. The proteins were successfully expressed in <i>Escherichia coli</i> strain JM109(DE3) and efficiently purified via histidine affinity chromatography, attaining concentrations of 146.6 μg/mL for Scl2-ST and 124.3 μg/mL for ELP-SC. Following this, we optimized the in vitro bioconjugation process by adjusting the molar ratio of Scl2-ST to ELP-SC to 2:1, maximizing the yield of the fusion protein through the application of diafiltration. Morphological characterization of the fusion and its components was conducted using scanning electron microscopy, confirming that Scl2-ST retained its triple-helical structure, elastin-like polypeptide exhibited self-aggregation, and the fused protein formed a porous network. Our results indicate promising opportunities for scalability innovations, particularly through bioreactor-based production of the bioconjugation, which could allow for the full characterization and further development of this novel biomaterial.