BACTERIAL S-LAYERS

S-layers are paracrystalline planar assemblies of protein (or glycoprotein) which coat the surfaces of some gram-negative and gram-positive bacteria (eubacteria) and archaea (archaeobacteria). Over the past three to tour years, high resolution three-dimensional structures of several S-layers have been obtained by transmission electron microscopy and, now, scanning probe microscopy (both atomic force and scanning tunneling microscopies) is providing topographical detail. Molecular approaches on select S-layer producing bacteria are helping to define the synthetic and translocative pathways necessary before surface self-assembly can commence. In an industrial sense, S-layers are contributing to a new application science, nanotechnology, where they are being used as molecular filters, immobilization and affinity matrices, and biosensors.