Tailor-made crystalline structures of truncated S-layer proteins

Two surface (S-)layer proteins, both binding specifically to a heteropolysaccharide and one with the additional ability to self-assemble into crystalline arrays, and mixtures of them, form nanometre-thick layers on heteropolysaccharides differing in morphology and viscoelasticity. Pure S-layer proteins formed unstructured and crystalline layers, respectively, whereas a mixture formed fractal-like, patchy structures. This finding provides essential information for the self-assembly of S-layer proteins on heteropolysaccharides and constitutes the starting point for the investigation of these patchy structures as tethering layers for functional lipid membranes.