Principles Governing the Self-Assembly of Coiled-Coil Protein Nanoparticles

Abstract

Self-assembly refers to the spontaneous organization of individual building blocks into higher order structures. It occurs in biological systems such as spherical viruses, which utilize icosahedral symmetry as a guiding principle for the assembly of coat proteins into a capsid shell. In this study, we characterize the self-assembling protein nanoparticle (SAPN) system, which was inspired by such viruses. To facilitate self-assembly, monomeric building blocks have been designed to contain two oligomerization domains. An N-terminal pentameric coiled-coil domain is linked to a C-terminal coiled-coil trimer by two glycine residues. By combining monomers with inherent propensity to form five- and threefold symmetries in higher order agglomerates, the supposition is that nanoparticles will form that exhibit local and global symmetry axes of order 3 and 5. This article explores the principles that govern the assembly of such a system. Specifically, we show that the system predominantly forms according to a spherical core-shell morphology using a combination of scanning transmission electron microscopy and small angle neutron scattering. We introduce a mathematical toolkit to provide a specific description of the possible SAPN morphologies, and we apply it to characterize all particles with maximal symmetry. In particular, we present schematics that define the relative positions of all individual chains in the symmetric SAPN particles, and provide a guide of how this approach can be generalized to nonspherical morphologies, hence providing unprecedented insights into their geometries that can be exploited in future applications.

Harnessing self-assembled peptide nanoparticles in epitope vaccine design

“…The concept of self-assembly Self-assembly is defined as the ability of some molecules to spontaneously arrange themselves into well-ordered structures (Whitesides and Grzybowski, 2002). In nature, this common phenomenon results in the production of a variety of ensembles using finite building blocks (Indelicato et al, 2016;Whitesides and Grzybowski, 2002). Natural self-assembled molecules are primarily composed of DNA, polypeptides, and proteins and are found in a wide variety of living organisms, such as virus capsids, cell membranes, enzymes, and the cellular cytoskeleton.…”

“…In chemical methods, the building blocks sequences and buffer conditions may affect the molecular weight of the produced SAPN and its polymorphism (Indelicato et al, 2016). The nanoscale assembly is based on a fundamental parameter: the peptide solution concentration.…”

Vaccine technologies: From whole organisms to rationally designed protein assemblies

“…SAPNs are rationally designed repetitive antigen displays that can function for a diverse array of antigens. Disease antigens can be added to either the C or the N terminus of each SAPN monomer, and in the prototypical SAPN 60 monomers will self-assemble into a particle with regular symmetry [187][188][189][190]. Each assembled SAPN is decorated on its surface with 60 copies of an antigen, making them excellent repetitive antigen displays (Fig.…”

The use of a P. falciparum specific coiled-coil domain to construct a self-assembling protein nanoparticle vaccine to prevent malaria

“…In a standard icosahedral structure four LCMs can further self-assemble into a full SAPN structure, meaning that 60 monomers make up each SAPN. However, recent biophysical studies combined with an analysis using viral tiling theory has shown that the SAPNs can possibly also assemble into higher order assemblies containing multiples of 60 chains per particle [27]. Each SAPN is predicted to contain 60 copies (or a multiple thereof ) of P27A and P27-NC epitopes (Fig.…”