The Relevance of S-Layer Fusion Proteins in Nanobiotechnology

Eva M. Egelseer, Christine Völlenkle, Magdalena Pleschberger, Dieter Moll, Nicola Ilk, Carina Huber, Andreas Breitwieser, Uwe B. Sleytr, and Margit Sára Center for Ultrastructure Research, Ludwig-Boltzmann-Institute for Molecular Nanotechnology, University of Agricultural Sciences, Gregor-Mendel-Str. 33, A-1180 Vienna, Austria e-mail: egelseer@edv1.boku.ac.at URL: http://www.boku.ac.at/zuf/nano0.htm

Many bacteria and archaea possess crystalline bacterial cell surface layers (S-layers) as their outermost cell envelope component which show either oblique, square, or hexagonal lattice symmetry. In bacteria, the S-layer subunits are linked to each other and to the underlying cell envelope layer by non covalent interactions and recognize a distinct type of secondary cell wall polymer (SCWP) as the proper anchoring structure in the rigid cell wall layer. Particularly the recrystallization of recombinant S-layer fusion proteins on any type of support coated with the appropriate SCWP should allow the functionalization of surfaces with a porous protein lattice while maintaining the biological properties of the fused peptide. The genes encoding the S-layer proteins SbsA and SbsB of Geobacillus stearothermophilus PV72, SbsC of G. stearothermophilus ATCC 12980 and SbpA of Bacillus sphaericus CCM 2177 have been sequenced and cloned. Based on these S-layer proteins, different S-layer fusion proteins were constructed, carrying either streptavidin, the major birch pollen allergen Bet v1, the hypervariable region of a camel antibody or the Fc-binding domain as the biologically active sequence.