Influence of Membrane Lipid Composition and Organization on Radio-and Thermosensitivity of Bacteria
Numerous investigators have studied and reported on the effects of ionizing radiation on cellular membranes. The effects reported range from inactivation of membrane-bound enzymes to increased ion permeability. This review concerns radiation effects on bacterial membranes and related structures such as “DNA- membrane complexes.” In addition, the relationship of composition and organization of the Escherichia coli membrane to hyperthermic cell killing is considered. In particular, evidence for the role played by fatty acids on the movement of proteins to the outer membrane and the relevance of such protein redistribution on cell survival in heat-stressed cells are discussed.
Bacteria, especially auxotrophs of Escherichia coli, provide powerful tools for study of the role of the membrane in radiation sensitivity (1–5) and hyperthermic sensitivity (6–9). The non-auxotrophic strains most studied by radiobiologists have been the radiation-resistant strain, B/r, and the radiation-sensitive strain, Bs™1. The unsaturated fatty acid-requiring auxotroph, K1060, has provided a cell whose membrane composition can be controlled in a predictable manner. Simply by varying the growth temperature and the unsaturated fatty acid provided during growth, one can control the biophysical properties of the membrane. Such modified cells are important tools for researchers interested in studying the influence of membrane composition on cell killing by radiation and heat.
KeywordsMembrane Fluidity Membrane Composition Phospholipid Composition Elaidic Acid Osmotic Fragility
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