The Escherichia coli enzoskeleton.

The nature of the structure of the bacterial cell is becoming clearer. The envelope contains periseptal annuli, a discontinuous periplasm and adhesion sites, whilst the cytoplasmic membrane is probably organized into distinct proteolipid domains by the coupled transcription-translation-insertion (transertion) of membrane proteins. The structure of the nucleoid is determined by proteins which self-associate and by attachment to membrane, which is achieved in part by transertion. Metabolic pathways form multi-enzyme complexes which channel substrates and which connect membranes and nucleic acids to create the extensive, cross-linked, intracellular structure we term the 'enzoskeleton'. This enzoskeleton includes eukaryotic-like cytoskeletal structures and elements such as the MukB and FtsZ proteins. We propose that the enzoskeleton is regulated by calcium and by protein phosphorylation during adaptation to different environments and during the cell cycle.