Recapitulating native aculeate silk structure enables enhanced mechanical performance in recombinant protein materials

Abstract

Recombinant structural proteins offer powerful and versatile platforms for the rational design of advanced functional materials, as their molecular architectures are genetically programmable and amenable to precise engineering. Among these systems, the coiled coil silk proteins of aculeate insects represent a distinctive class of polymers that combine efficient recombinant production with substantial sequence and structural design flexibility. While previous studies have demonstrated that materials fabricated from individual recombinant silk proteins can support diverse functional behaviours including nitric oxide sensing, oxygen reduction catalysis, photodynamic activity, and hydrogen evolution, their mechanical properties fall well short of those of native aculeate silk. Here, we show that recapitulating key features of the native silk architecture, specifically multi protein assembly and covalent cross linking, enables the formation of recombinant materials with enhanced mechanical performance relative to single protein recombinant silk materials. Materials incorporating all four silk proteins present in native aculeate silk (F1–F4) were rapidly stabilised using short, dry thermal treatments that induce intermolecular isopeptide cross links while preserving the underlying coiled coil secondary structure. Compared with materials formed from single proteins and stabilised primarily by β sheet interactions, these multi component silk assemblies exhibit substantial but sample dependent increases in strength up to 200% and extensibility of up to 150%. Although the magnitude of improvement varies across samples, directly linking protein composition, cross linking chemistry, and mechanical performance, this work demonstrates that cooperative multi protein assembly and covalent network formation are critical determinants of native like stability and resilience in aculeate silk. These findings establish recombinant multi component aculeate silk materials as a robust and tunable platform for the development of mechanically resilient, multifunctional protein based materials.