The design of symmetric protein nanomaterials comes of age in theory and practice

In nature, protein molecules have evolved as building blocks for the assembly of diverse and complex structures, many of which exhibit a high degree of symmetry. This observation has motivated a number of recent engineering efforts in which the advantages of symmetry have been exploited to design novel self-assembling protein structures of great size. Materials ranging from cages to extended two and three-dimensional arrays have been demonstrated. Especially for extended arrays, a vast number of geometrically different design types are possible. A table of geometric rules is provided for designing a universe of novel materials by combining two component symmetries.