Bacterial envelope

The biogenesis of a gram-negative bacterial envelope requires subsequent sorting mechanisms for its component proteins after their translocation across the inner membrane (Duong et al., 1997 Danese and Silhavy, 1998). In addition, some proteins such as proteases and toxins are secreted through the outer membrane to the extracellular space. Three major secretion pathways have been characterized (Salmond and Reeves, 1993). 

Duong, F., Eichler J., Price, A., Leonard, M., and Wickner W. (1997). Biogenesis of the gram-negative bacterial envelope. Cell 91, 567-573. 

An interesting exception to the absolute validity of the tifth postulate is the considerable activity of chloramphenicol derivatives in cell-free model systems of protein synthesis when these derivatives are substituted with amino acyl residues instead of with dichloroacetyl as is the antibiotic itself (rev. in 2°)). This has been traced to the necessity of the dichloroacetyl grouping in aiding in the permeation of the antibiotic through the bacterial envelope 21 The amino acyl derivatives have very low antibacterial activity 20. Permeation failures of actinomycin D, macrolides and distamycin A with respect to certain families of bacteria occlude the action of these antibiotics on their intracellular drug receptors and target reactions but can be overcome experimentally by measures which render test organisms permeable. 

Garcia, D., Gomez, N., Manas, P, Raso, J., and Pagan, R. 2007. Pulsed electric fields cause bacterial envelopes permeabilization depending on the treatment intensity, the treatment medium pH and the microorganism investigated. International Journal of Food Microbiology 113 219-227. 

Barak, R. and Eisenbach, M. (1992). Fumarate or a fumarate metabolite restores switching ability to rotating flagella of bacterial envelopes. J. Bacterial. 174, 643-645. 

Ravid, S., Matsumura, E and Eisenbach, M. (1986). Restoration of flagellar clockwise rotation in bacterial envelopes by insertion of the chemotaxis protein CheY. Proc. Natl. Acad. Sci. U.S.A. 83, 7157-7161. 

A typical example of covalently linked lipoprotein is a small protein in the outer membrane of gram-negative bacterial envelopes that contributes to the mechanical stability of the cell envelope. This lipoprotein contains only 58 amino acid residues containing three covalently attached fatty acids, all joined to the amino-terminal cysteine [18], In the cell envelope, the amino group of the carboxyl-terminal lysine is linked to a carboxyl group of peptidoglycan. Thus, the lipoprotein ties the outer membrane to the peptidoglycan layer and thereby contributes to the mechanical stability of the cell membrane. 

It is hoped that a better understanding of the role of bacterial envelope components as determinants of pathogenicity will lead to the development of improved vaccines. Careful selection and combination of antigens... 

Some Problems in Organelle and Bacterial Envelope Biogenesis... 

The substantial amount of current information about the chemistry, morphology, and function of bacterial envelopes makes it possible to integrate this information into a meaningful view of this important cellular structure. It is obvious, however, that the technical complexity and the breadth of the subject matter makes it necessary to emphasize a particular approach and to describe the available data from the perspective of the individual investigator and his model of study. 

The chemical treatment of macromolecular synthesis in bacterial membranes has been treated in a number of excellent reviews.The morphology of the bacterial envelopes has also been described in previous reviews. ... 

Fig. 5. Diagram showing the various cleavage planes of the bacterial envelope. OM Outer membrane, cleaving in plane I. IM Inner membrane, cleaving in plane II. The filled circles in OM represent proteins of the rigid layer. The open circles in IM represent particles typical of plane II.

The bacterial envelope contains a variety of pili, among which the F- provide the adsorption sites for two general classes of pilus-specific... 

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