Team:Slovenia/Coiled-coil polyhedra Results.html

Summary

We set to prepare complex polyhedra as well as two-dimensional lattice; both can be constructed from interacting rigid polypeptide rods, assuming the polypeptide being equivalent of DNA origami. This could produce structures that do not exist in nature. Coiled-coil interactions represent the best candidate for this type of assembly as their sequence dictates the selectivity and orientation for interactions with other coiled-coil segments. In the section on modeling we analyzed the potentials of this approach and designed amino acid sequences of their building blocks.
We tested experimentally the feasibility of manufacturing this type of structures as nothing similar had been shown before. We designed, prepared and characterized a polypeptide composed of designed pair of complementary parallel coiled-coil-forming segments and a parallel homodimeric coiled-coil-forming segment in between. This polypeptide could, depending on its concentration, assemble a box or cover the surface with hexagonal packing. We designed a procedure for slow chemical annealing of the assembly and confirmed that the designed polypeptide forms the expected secondary structure. At low concentrations of the polypeptide small assemblies with nanometer dimensions were observed by AFM. Self-assembly based on slow annealing at higher polypeptide concentration moreover produced a two dimensional polypeptide lattice with edges below 10 nm, which was detected by a TEM (Figure 1). Results confirm our design and that it is indeed possible to manufacture this type of polypeptide assemblies. This opens exciting prospects for even more complex assemblies and a whole new range of potential applications.

Figure 1: TEM image of the self-assembled nanostructure made of K2