(283g) Uncovering Sequence-Structure Relationships for Engineering Coassembled Peptide Nanofibers

Peptide coassembly expands the design space of tunable peptide-based functional biomaterials for applications such as tissue engineering, drug delivery, and photoactive material design. Peptide coassembly occurs when two distinct peptide sequences A and B are engineered to spontaneously co-organize into nanofibers in solution. Many coassembling peptide pairs rely on complementary electrostatic interactions between positively charged peptide A and negatively charged peptide B to confer coassembly behavior. As a result, these coassembling pairs were originally thought to arrange into ideal coassembled antiparallel β-sheets with perfect alternation of peptides A and B. However, our solid-state NMR measurements and computational simulations on two existing coassembling systems, King-Webb peptides and CATCH peptides, revealed significant deviations from the ideal nanofiber structure. These deviations highlight a knowledge gap in the sequence-structure relationships underpinning peptide coassembly. In recent studies, we have altered the peptide’s net charge and the charged residue sidechain group to generate CATCH peptide variants. The coassembled β-sheet nanostructure and fiber morphology differed systematically with peptide charge as observed by solid-state NMR and TEM measurements. In another approach, we designed a computational screening algorithm to identify new coassembling peptide pairs. Analysis of 1D ¹³C spectra of each newly identified pair suggest that these new sequences form more highly ordered and more stoichiometrically even (peptide A: peptide B) nanofibers than previous human-designed pairs. Analysis of the computationally derived sequences point towards design rules that promote coassembled antiparallel β-sheet nanofibers. Through our solid-state NMR measurements and computational simulations, we have begun to identify sequence design rules which manipulate nanofiber structure and fiber morphology. An understanding of the sequence-to-structure relationships underpinning binary peptide systems will allow us to finely control coassembled peptide nanofiber structure and properties for desired applications.