Regulation and Pathways of Membrane Lipid Biosynthesis in Bacilli
For cogent reasons, studies on the regulation of membrane fluidity and on the consequences to the cell of perturbations in this property are often carried out in bacteria. In contrast to eukaryotic organisms which contain a complex variety of internal membranous organelles in addition to the plasma membrane, bacterial membranes are external and restricted to the cell envelopes. Essentially all of the lipids of bacterial cells are found in these membrane envelopes and therefore the total lipids extracted from bacteria fairly accurately reflect the gross composition of their external membrane systems. In practice, this relative simplicity greatly facilitates attempts to correlate changes in lipid composition on the one hand with alterations in membrane fluidity and function on the other. The absence of sterols and polyunsaturated fatty acids in most bacteria as well as their usually less complex complement of other lipids also eases the technical and interpretative aspects of such studies. Also important, especially for research designed to reveal the biochemical processes involved in the adaptive regulation of membrane fluidity, is the fact that bacteria can be grown in well-defined media under rigorously controlled conditions but are nevertheless usually capable of adjusting to much wider variations from their optimum environment than are eukaryotic organisms.
KeywordsUnsaturated Fatty Acid Membrane Fluidity Fatty Acid Synthesis Fatty Acid Biosynthesis Desaturase Activity
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