Geometric Lessons and Design Strategies for Nanoscale Protein Cages

Abstract

Protein molecules bring a rich functionality to the field of designed nanoscale architectures. High-symmetry protein cages are rapidly finding diverse applications in biomedicine, nanotechnology, and imaging, but methods for their reliable and predictable construction remain challenging. In this study we introduce an approach for designing protein assemblies that combines ideas and favorable elements adapted from recent work. Cubically symmetric cages can be created by combining two simpler symmetries, following recently established principles. Here, two different oligomeric protein components are brought together in a geometrically specific arrangement by their separate genetic fusion to individual components of a heterodimeric coiled-coil polypeptide motif of known structure. Fusions between components are made by continuous α-helices to limit flexibility. After a computational design, we tested 10 different protein cage constructions experimentally, two of which formed larger assemblies. One produced the intended octahedral cage, ∼26 nm in diameter, while the other appeared to produce the intended tetrahedral cage as a minor component, crystallizing instead in an alternate form representing a collapsed structure of lower stoichiometry and symmetry. Geometric distinctions between the two characterized designs help explain the different degrees of success, leading to clearer principles and improved prospects for the routine creation of nanoscale protein architectures using diverse methods.

Programming interchangeable and reversible heterooligomeric protein self-assembly using a bifunctional ligand

“…Alternatively, self-assembly of two protein components can be achieved through gene fusion, 18,19 disulphide bond, 20 gene fusion and covalent linkage, 21 host-guest interaction, 22 and computational design. [23][24][25][26] However, their components are not easily interchangeable unless their gene constructs or PPIs are redesigned from scratch.…”

Design of Ligand-Operable Protein-Cages That Open Upon Specific Protein Binding

“…Advances in rational protein design methods have made it possible to create novel proteins, enzymes, and higher-order complexes. − Exploiting principles of symmetric self-assembly, sophisticated supramolecular architectures in the shapes of cubes and other polyhedra can be produced from much simpler protein building blocks. − Comparable supramolecular structures are ubiquitous throughout nature, as exemplified by microtubules, polyhedral viruses, S-layer proteins, etc. − Recent design studies have led to wholly new sets of novel protein architectures, opening vast avenues of exploration for synthetic biology.…”

Hierarchical peroxiredoxin assembly through orthogonal pH-response and electrostatic interactions

“…Highly-ordered protein assemblies have received growing interest as bottom-up strategy to yield biodegradable and biocompatible materials. [6][7][8][9] Their well-defined structure, presenting precisely positioned building blocks and regular pore sizes enables technologies such as metamaterial preparation, [10][11][12][13][14][15][16] catalytic systems, 17,18 templated (porous)materials, 19,20 biomedical applications, 21 and waste-water treatment. 22 The potential Prx have not been missed in this approach.…”