The intrinsic structural and chemical diversity of proteins makes them highly attractive as self-assembling bio-bricks or ‘tectons’ for fabrication of materials. Supramolecular engineering allows protein quaternary structure and function to be manipulated to generate biocompatible materials with new or improved properties.

I am exploiting self-assembling ring-forming proteins to construct novel tubule and array nanostructures.  The Lsm family of proteins comprise the core of the ribonucleoprotein (RNP) complexes crucial to RNA metabolism. They naturally assemble into oligomeric rings of six to eight protein chains to generate an RNA-binding scaffold.

I have engineered synthetic rings composed of fused Lsm sequences, so creating simplified structures with (AB)₄ symmetry. In solution, these recombinant Lsm self-organise into overlaid ring pairs through electrostatic interactions. Their crystallisation is being pursed to detail the ring-ring interactions involved, required for future smart engineering. Currently, crystals of Lsm [4+1]₄ have been obtained in magnesium acetate and calcium chloride conditions and are being further optimised for synchrotron data collection.

Using chemical modification, I have driven further oligomerisation of Lsm ring tectons into new coherent architectures. Engineering Cys residues into ring faces to promote covalent stacking generates disulfide-bonded Lsm clusters that are readily disengaged by reduction. Conjugation between Lsm rings is also achieved with M ²⁺ metal-binding via engineered His-tags, resulting in cages that are controllable with EDTA. The cluster architecture of these large, pore-containing complexes has been visualised by electron microscopy (EM). Ultimately, these novel nanomaterials will have applications in RNA housing and delivery capsules or as next-generation bio-inspired nanosensors.