Employing the SpyTag-SpyCatcher Reaction for the Modification of Supramolecular Polymers with Functional Proteins.

Abstract

Supramolecular assemblies hold great potential as biomaterials for several biomedical applications. The modification of supramolecular biomaterials is needed to achieve controlled bioactive functions. Supramolecular ureidopyrimidinone (UPy) monomers have been shown to assemble into long supramolecular polymers that can be functionalized with bioactive peptides and visualized as UPy-fibers. So far, the introduction of biological functionality has been limited to small molecules and peptides. Here, we describe a general method based on SpyTag-SpyCatcher chemistry for conjugating full-length proteins with biologically relevant functions to μm-long UPy fibers via native peptide bond formation, yielding 100% conversion in a 5:95 mol % coassembly of UPy-SpyTag with UPy-glycinamide. The conjugation of monoclonal antibodies is performed using photo-cross-linkable protein G domains. We demonstrate intact fibers and colocalization of antibodies and UPy-fibers using biophysical and imaging methods and achieve recruitment of supramolecular assemblies to the surface of mammalian cells via the EGFR-specific antibody Cetuximab. The approach introduced here represents a robust and widely applicable postassembly modification method that shows promise in the functionalization of future biomaterials.