A controlled co-assembly approach to tune temperature responsiveness of biomimetic proteins.

The controlled co-assembly of biomacromolecules through tuneable interactions offers a simple and fascinating opportunity to assemble multiple molecules into a single entity with enhanced complexity and unique properties. Herein, our study presents a dynamic co-assembled system using the multistimuli responsive intrinsically disordered protein Rec1-resilin and the adhesive hydrophilic protein silk sericin (SS). We utilized advanced characterization techniques including circular dichroism (CD) spectroscopy, dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and small/ultra-small angle neutron scattering (SANS/USANS) to elucidate the detailed co-assembly behavior of the system and its evolution over time and temperature. To achieve sufficient neutron contrast, we successfully biosynthesised deuterium-labeled Rec1-resilin (D-Rec1). Our research demonstrates that this co-assembly allows the formation of a robust entity with dynamic conformational assembly and disassembly, exhibiting both the upper critical solution temperature (UCST) and lower critical solution temperature (LCST) with reversibility. The assembly and disassembly dynamics of the co-assembled entity at UCST are very fast, while the process is kinetically controlled at LCST. This study provides significant new insights into the interplay of a hydrophilic, multi-responsive IDP and a highly hydrophilic protein, shaping the thermoresponsive and stable properties of the co-assembled entity.