Fig. 1: Protein monomer design lattice matched to the mica surface and assembly outcome.
a The Rosetta design model of a DHR10-mica18 protein nanorod with dimensions 3.6 nm × 20 nm adsorbed on mica surface. The protein consists of 18 tandem repeat units shown in green with alpha-helices rendered as cylinders. An aluminosilicate layer of the mica substrate is shown with the K+ sublattice (shown as purple spheres). Scale bar is 5 nm. b Side view of the protein-mica interface showing negatively charged glutamate side chains (green and red sticks, respectively) extending from the protein with a periodicity that forms a 2-to-1 lattice match with the mica surface. c, d AFM images of the final assembly states of DHR-mica18 on f-mica and m-mica in 100 mM and e, f 3 M KCl, respectively. Scale bars are 100 nm. The FFT is shown in the inset. The FFT scale bars are 0.5 nm-1. Note that the observed phases are observed both during in situ imaging and after extraction from solution. In addition, the same orientation of the rods in (f) is observed everywhere across the surface. g–i Illustrations of 2D phases of hard rods possible at high concentrations in a three-fold potential: g 2D high-density disordered (HDD) phase, h nematic phase, and i smectic phase. Note that the smectic phase is not predicted when the rods are non-interacting21.
