A Common Structural Principle in the Surface Layers of the Archaeobacteria Haloferax, Halobacterium and Archaeoglobus

Abstract

Our present ability to more readily visualise the three dimensional organisation of the bacterial cell surface, especially in the many cases where S-layers are present, has in recent years allowed a comparative approach to the study of this important cell structure. It has also allowed the integration of this structural knowledge with that derived from molecular biology (Baumeister and Engelhardt, 1987; Baumeister and Lembcke, 1992). The bacterial cell surface, whether or not an S-layer is present, is that element of the cell which comes into direct contact with the milieu in which the cell exists. As such, the cell surface is the site of entry for molecules coming into the cell and the site of exit for molecules leaving the cell. This translocation of molecules through the bacterial cell surface involves a combination of both passive and active processes by the components of the various barriers across which molecules enter and leave the cell.