Designer Nanorings with Functional Cavities from Self-Assembling [beta]-Sheet Peptides

[beta]-Barrel proteins that take the shape of a ring are common in many types of water-soluble enzymes and water-insoluble transmembrane pore-forming proteins. Since [beta]-barrel proteins perform diverse functions in the cell, it would be a great step towards developing artificial proteins if we can control the polarity of artificial [beta]-barrel proteins at will. Here, we describe a rational approach to construct [beta]-barrel protein mimics from the self-assembly of peptide-based building blocks. With this approach, the direction of the self-assembly process toward the formation of water-soluble [beta]-barrel nanorings or water-insoluble transmembrane [beta]-barrel pores could be controlled by the simple but versatile molecular manipulation of supramolecular building blocks. This study not only delineates the basic driving force that underlies the folding of [beta]-barrel proteins, but also lays the foundation for the facile fabrication of [beta]-barrel protein mimics, which can be developed as nanoreactors, ion- and small-molecule-selective pores, and novel antibiotics. [PUBLICATION ABSTRACT]