Studying the reversibility and self-assembly of cephalopod: specific proteins

The colour-changing ability of cephalopods has inspired the development of new technologies. Recently, special attention has been
dedicated to structural proteins (reflectins) found in cephalopods visual systems. In vivo, upon a phosphorylation trigger, reflectins form microstructures that work as Braggreflectors. Recombinantly produced reflectins have shown great potential as biophotonic and protonconductive materials[1]–[3]. In this work, we study the reversible self-assembly properties of two reflectins, one from the light organ of E.scolopes[4] and another from the skin tissue of O.bimaculoides[5]. Both, have different sequence compositions which impact their biophysical properties and self-assembly mechanisms. We firstly optimise the production of these protein sequences by recombinant expression and the downstream purification methods. Secondly, we characterised their biophysical properties, namely by Circular Dichroism to assess protein folding and thermal stability, by Dynamic Light Scattering and Atomic Force Microscopy to study protein organization into particles. Our results indicate that reflectins self-assemble into nano- and microparticles and change dimension by varying the solvent conditions. Finally, we showed that both reflectins have different capacity to reversible self assembly, that is related with their sequence composition. Our results strongly corroborate the idea that reflectins sequence is important for the necessary reversible stimuli-responsive reorganization at the molecular level with impact on the optical phenomena associated with camouflage.