Diverging Liquid-Liquid Phase Separation Behavior of Different Recombinant Major Ampullate Spidroins

Spider silk fibers show exceptional mechanical properties, based on their underlying spider silk proteins (spidroins) as well as a highly developed spinning process, involving the transition of soluble high-molecular-weight spidroins into a hierarchically structured solid fiber. Liquid-liquid-phase separation is crucial for the transition of the liquid to the solid state. Here, the assembly properties of a newly designed recombinant major ampullate spidroin 1 derivative based on an Araneus sequence have been investigated. Interestingly, the protein phase-separates at slightly chaotropic conditions in contrast to respective MaSp2-derived variants from Araneus. Fibers spun from the MaSp1-derivative as well as MaSp1-MaSp2-mixtures provide a deeper insight into the assembly process of the spidroins and how hierarchical architectures of spider silk fibers could be achieved.