Reviews

Cytoskeletal Elements in Bacteria Mycoplasma pneumoniae, Thermoanaerobacterium sp., and Escherichia coli as Revealed by Electron Microscopy
Frank Mayer

Institut für Mikrobiologie und Genetik, Georg-August-Universität Göttingen, Göttingen, Germany

Address of Corresponding Author

J Mol Microbiol Biotechnol 2006;11:228-243 (DOI: 10.1159/000094057)

  Key Words

• Bacterial cytoskeletons
• Electron microscopy
• Mycoplasma pneumoniae
• Thermoanaerobacterium sp.
• Escherichia coli
• Elongation factor Tu
• Cytoskeletal web
• Antibacterial drug
• Inducible bacterial lysis

  Abstract

Recently, electron microscopic studies on the eubacteria Mycoplasma pneumoniae, Thermoanaerobacterium sp., and Escherichia coli have revealed the existence of cytoskeletal elements so far unknown in prokaryotes. The wall-less bacterium M. pneumoniae contains, in close vicinity to the inner face of the cytoplasmic membrane, a helically organized lining composed of protein elements that form a regular network of meshes that encloses the entire cytoplasm. Numerous regularly spaced pin-like structural elements, the stalks with terminal knobs, connect the lining with the cytoplasmic membrane. In this bacterium, a specific rod-like structural element is located in the tip region. Occasionally, it is bent or twisted. It consists of two matching blade-like sub-elements. A number of parallel linkers, extending from the edges of the rod, make contact with the lining. The proximal end of the rod is attached to a wheel-like complex. Fibrils originating from the wheel cross the cytoplasm and make contact with the lining. E. coli contains a similar helically organized lining close to the inner face of the cytoplasmic membrane. Groups of ribosomes (polysomes) were seen to be attached to the helical elements of the lining. A feature that is common to both bacteria and to Thermoanaerobacterium sp. appears to be that the lining and the fibrils crossing the cytoplasm contain a high number of copies of the bacterial elongation factor Tu (EF-Tu). This indicates that this protein may play an important role as a structural element in bacterial cytoskeletons. This notion was supported by experiments in which the cytoskeleton in E. coli was destabilized by induced expression of truncated EF-Tu, with the consequence of cell lysis, and by the finding that in vitro polymerization of monomeric EF-Tu into protofilaments was hindered in a mixture of full-size EF-Tu and truncated EF-Tu consisting of domain 3 only. Current research and developmental efforts are aimed at the design of a new class of antibacterial drugs, acting by destabilization of the EF-Tu-containing bacterial cytoskeleton, and of an innovative mode of inducible lysis of recombinant bacteria by controlled destabilization of the EF-Tu-containing cytoskeleton.

Copyright © 2006 S. Karger AG, Basel

  Author Contacts

Prof. Dr. Frank Mayer
Bungenstrasse 29
DE-21682 Stade (Germany)
Tel. +49 4141 45866
E-Mail fmayer12@gmx.de

  Article Information

Number of Print Pages : 16
Number of Figures : 14, Number of Tables : 0, Number of References : 38