Selective Elimination of the Key Subunit Interfaces Facilitates Conversion of Native 24-mer Protein Nanocage into 8‑mer Nanorings

Living
systems utilize proteins as building blocks to construct
a large variety of self-assembled nanoscale architectures. Yet, creating
protein-based assemblies with specific geometries in the laboratory
remains challenging. Here, we present a new approach that completely
eliminates one natural intersubunit interface of multisubunit protein
architecture with high symmetry, resulting in reassembly of the protein
architecture into one with lower symmetry. We have applied this approach
to the conversion of the 24-mer cage-like ferritin into non-native
8-mer protein nanorings in solution. In the crystal structure, such
newly formed nanorings connect with each other through hydrogen bonding
in a repeating head-to-tail pattern to form nanotubes, and adjacent
nanotubes are staggered relative to one another to create three-dimensional
porous protein assemblies. The above strategy allows the study of
conversion between protein architectures with different geometries
by adjusting the interactions at the intersubunit interfaces, and
the fabrication of novel bio-nanomaterials with different geometries.