The ability of proteins to self-assemble into ordered nanoscale architectures makes biomolecules ideal templates for bio-responsive nanodevices and materials. I am currently working with the ring-forming Lsm protein system to develop tubule-based nanostructures with the capacity to bind and sequester RNA. Lsm proteins form the core of the ribonucleoprotein (RNP) complexes crucial to RNA metabolism. They assemble as oligomeric rings via the association of seven distinct Lsm protomers to generate an RNA-binding scaffold.

I have engineered Lsm polyprotein pairs fused via linker sequences in order to generate novel low symmetry ring forms. These Lsm modules readily repeat into tetrameric rings that occur singly in solution, or as asymmetrical overlaid pairs. In addition, cysteine-containing Lsm mutants have been generated to promote disulfide-bonded fusion of ring pairs. These new organisations offer the possibility for conjugation of fluorescent probes and other bio-reactive molecules.

Size exclusion chromatography (SEC) analysis has proved essential to monitor the solution-state polymeric organisations of Lsm rings. I will outline biophysical characterisation of single, stacked and higher order Lsm polyprotein assemblies. This includes investigation of quaternary structure by electron microscopy (EM), atomic force microscopy (AFM) and the behaviour of Lsm polyprotein variants in solution.