Development and characterization of LipoCatch: a bacterial lipoprotein-based biomaterial that self-assembles into...

Genetically encoded nanomaterials enable the control of molecular composition and function, yet the use of the biosynthetic bacterial lipidation pathway to build hybrid protein/lipid nanostructures has not been reported. Here, we designed a versatile bacterial lipoprotein, named LipoCatch, for modular nanostructure formation. Lipidation was achieved by appending a signal peptide to the protein-encoding gene of SpyCatcher from the SpyCatcher/SpyTag protein/peptide binding pair. This protein was biosynthetically produced in E. coli and purified in the presence of detergent. LC-MS, SEC, DLS, and TEM confirmed site-specific lipidation and formation of nanoparticles with an average diameter of 13 nm. We show that LipoCatch supports two orthogonal functionalization strategies: (1) covalent modification through the SpyCatcher/SpyTag system and (2) the non-covalent incorporation of phospholipids that permits the tuning of particle size and compositions. Finally, stability studies show LipoCatch and hybrid LipoCatch/phospholipid nanostructures are tolerant to lyophilization, in contrast to phospholipid-only liposomes. Together, this proof-of-principle study establishes an engineered bacterial lipoprotein, LipoCatch, as a genetically encoded platform for building customizable bacterial lipoprotein-based biomaterials.