PMID: 8509382Jun 15, 1993

Polymorphic regulation of membrane phospholipid composition in Escherichia coli

The Journal of Biological Chemistry
A G RietveldB de Kruijff


To investigate whether the phase preference of Escherichia coli membrane lipids is regulated by adjustment of the ratio of bilayer to non-bilayer lipids, the lipid biosynthetic mutant AD93 was used. This strain lacks the ability to synthesize phosphatidylethanolamine, a non-bilayer lipid which normally accounts for 70-80% of the phospholipids in the E. coli membrane. The lack of phosphatidylethanolamine is compensated by a large increase in the levels of phosphatidylglycerol and cardiolipin. This strain has an absolute requirement for high concentrations of divalent cations. Since divalent cations are known to induce HII phase formation in cardiolipin model systems, this suggests that cardiolipin in combination with divalent cations replaces phosphatidylethanolamine in the membrane and that it is the non-bilayer forming property of the latter which is important for membrane functioning. The growth of the mutant strain was found to be dependent on the type and concentration of divalent cations present in the growth medium. In media supplemented with MgCl2 and CaCl2, growth was maximal at concentrations of 30-50 mM. In the presence of SrCl2 a growth optimum was observed at 15 mM. The cells did not grow in the presence of BaCl2 or...Continue Reading

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