Coassembly of a New Insect Cuticular Protein and Chitosan via Liquid-Liquid Phase Separation

Insect cuticle is a fiber-reinforced composite material that consists of polysaccharide chitin fibers and a protein matrix. The molecular interactions between insect cuticle proteins and chitin that govern the assembly and evolution of cuticles are still not well understood. Herein, we report that Ostrinia furnacalis cuticular protein hypothetical-1 (OfCPH-1), a newly discovered and most abundant cuticular protein from Asian corn borer O. furnacalis, can form coacervates in the presence of chitosan. The OfCPH-1-chitosan coacervate microdroplets are initially liquid-like but become gel-like with increasing time or salt concentration. The liquid-to-gel transition is driven by hydrogen-bonding interactions, during which an induced beta-sheet structure of OfCPH-1 is observed. Given the abundance of OfCPH-1 in the cuticle of O. furnacalis, this liquid-liquid phase separation process and its aging behavior could play critical roles in the formation of the cuticle.

Automated summary

This study reports that a highly abundant cuticular protein OfCPH-1 from the Asian corn borer has the ability to form gel-like droplets in the presence of chitosan. The transition from liquid-like to gel-like state is driven by hydrogen-bonding interactions and is associated with the induced beta-sheet structure of OfCPH-1. This liquid-liquid phase separation process and its aging behavior may play critical roles in the formation of the insect cuticle.