S-Layer Proteins as Basic Building Blocks in a Biomolecular Construction Kit

Uwe B. Sleytr, Dietmar Pum, and Margit Sára

Center for Ultrastructure Research and Ludwig Boltzmann Institute for Molecular Nanotechnology, University of Agricultural Sciences, Vienna, Gregor Mendel Str. 33, A-1180 Wien, Austria

e-mail: sleytr@edv1.boku.ac.at
 

Diatoms are eucaryotic, unicellular algae thaMany species of bacteria and archaea possess a crystalline surface layer (S-layer) as the outermost component of their cell envelopes. S-layers are composed of a single protein or glycoprotein species with molecular weights ranging from 40.000 to 200.000. The crystalline arrays exhibit either oblique (p1, p2), square (p4) or hexagonal (p3, p6) spacegroup symmetry. The center-to-center spacing of the morphological units is in the range of 3 to 35nm and the thickness of most S-layer lattices is in the 5 to 10nm range. Pores in the crystalline protein meshwork are of well defined size and morphology with a mean diameter of 2 to 6nm [1, 2].

The most relevant features exploited in applied S-layer research are: (i) isolated S-layer subunits are capable of recrystallizing into differently shaped self-assembly products in suspension and as closed monolayers onto solid supports (e.g. silicon wafers, metals, polymers), at the air/water interface, and on Langmuir lipid films and liposomes, (ii) repetitive physicochemical properties of S-layers down to the subnanometer scale enable functionalization of surfaces and interfaces. The remarkable supramolecular principles of S-layers are presently exploited in the fields of molecular nanotechnology, nanobiotechnology, biomimetic and nanoelectronics [2, 3, 4].

Literature

[1] M. Sára and U. B. Sleytr, S-layer proteins. J. Bacteriol. (in press).

[2] U. B. Sleytr, P. Messner, D. Pum and M. Sára, Crystalline bacterial cell surface layers (S-layers): from supramolecular cell structure to biomimetics and nanotechnology. Angew. Chem. Int. Ed. 38, 1034-1054 (1999).

[3] D. Pum and U. B. Sleytr, The application of bacterial S-layers in molecular nanotechnology. Trends Biotechnol. 17 8-12 (1999).

[4] U. B. Sleytr, M. Sára and D. Pum, Crystalline bacterial cell surface layers (S-layers): a versatile self-assembly system. In: Supramolecular Polymerization, Alberto Ciferri (ed.), Marcel Dekker (in press).