S-layer-streptavidin fusion proteins and S-layer-specific heteropolysaccharides as part of a biomolecular construction kit for application in nanobiotechnology

Abstract

Crystalline bacterial cell surface layer (S-layer) proteins represent the outermost envelope component of many bacteria and archaea. Isolated S-layer proteins frequently show the ability to recrystallize into monomolecular protein lattices on solid supports, Langmuir lipid films, or liposomes. Many S-layer proteins specifically recognize a distinct type of secondary cell wall polymer (SCWP) as the proper anchoring structure to the rigid cell wall layer. This is the reason why such heteropolysaccharides were exploited as biomimetic linkers to solid supports, which is especially important if S-layer fusion proteins having a foreign sequence incorporated on the outermost surface are used for recrystallization to generate functional monomolecular protein lattices. The latter are currently being exploited as sensing layers for label free detection systems, as affinity matrices for binding immunoglobulins, or in the case of liposomes, as novel targeting and delivery systems.