Fig. 1.

Schematic illustration of the covalent assembly of triangle and square protein nanostructures. a By genetically fusing cognate SI pairs to the N- and C-termini, three copies of 3HB (PDB:4TQL) can be linked together to form triangular nanostructures. b Using constructs with a different combination of the same orthogonal SI pairs, square nanostructures containing four copies of 3HB can also be made