PROTEIN NANOCAGES AS TEMPLATE SCAFFOLDS FOR BIOMINERALIZATION

Protein nanocages, prevalent throughout nature as vessels for transportation and/or protection, are a fascinating group of assemblies presently receiving a significant amount of research focus. The main question regarding these repeating, symmetrical constructs is, if nature can use them for these functions, why cannot we? We have found that a mutant form of MamA, a magnetosome-associated protein from magnetotactic bacteria, will assemble into a perfectly spherical, hollow, 24-meric protein cage under specific crystallisation conditions. Assembled from eight trimeric rings, this novel architecture possesses eight ~1.5 nm pores evenly distributed across the protein surface. Using the crystal structure as a guide, we are applying mutations to this protein in an attempt to strengthen existing or create new molecular interactions to enable this protein to self-assemble in solution. Thus far, a soluble nanocage assembly has yet to be achieved, though SAXS analysis indicates a highly ordered, hierarchical repeating structure is forming. In addition, X-ray crystallography shows that the mutations have resulted in a tightening of the crystal cage structure. As such, we attempt to explore applications utilising the crystal-form of this fascinating assembly.