Development of peptide inhibitor screening platform utilizing unnatural amino acid as a warhead

Abstract

Peptide library technology is one of the most important tools for discovering new drugs, especially many peptide sequences have been discovered to bind along the surface of proteins and inhibit the function of target proteins. However, most of the active sites of target proteins, such as enzymes, consist of deep and narrow cleft, has been considered as a field of small molecule compounds. It has been difficult to target these narrow gaps only with the 21 amino acids in nature that make up the peptide library. We conducted a research on combining between functional groups of small molecule compounds and the peptide library using the Genetic Code Expansion technology, and through this, we tried to achieve the advantages of peptides and small molecule compounds. First, based on the structural information of the active site of the protein, unnatural amino acid that can specifically bind to the target protein was designed. Unnatural amino acid was designed with knowledge to the known structure of natural products and post-translational modification (PTM), and a designed unnatural amino acid synthesis was performed, and an aminoacyl-tRNA synthetase (ARS) was developed. Through this, a peptide containing unnatural amino acid was biosynthesized inside model organisms, and genetic circuit engineering was performed for a development of yeast 2-hybrid screening platform for peptide inhibitors. As a result, the peptide sequence containing unnatural amino acid was successfully discovered, and its function as an inhibitor was confirmed using an enzyme activity assay and SPR experiment.