Figure 1.

Designing well-defined protein-based building blocks for constructing self-assembled nanostructured materials. a) A schematic of (I27₆-SM)₁ building blocks. b) A schematic of the structure of (I27₆-SM)₄ created during protein expression in E.coli through self-assembly of monomeric streptavidin. c) A schematic of 1.5kb single-end biotinylated DNA. d) AFM images of (I27₆-SM)₄ incubated with biotinylated DNA (see also Figure S4). e) High-resolution AFM image of (I27₆-SM)₄ shows a structure that is similar to the schematic illustration in (b). The measured length of ~50 nm from one arm to another matches the expected length of the complex. The total length of the intact 12 I27 and streptavidin tetramer is ~53 nm based on crystal structures of both proteins: a single I27 = ~4 nm (PDB: 1TIT) and a core streptavidin = ~5 nm (PDB: 1MK5).