This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Mooney, C. Articles by Elsbach, P. Search for Related Content PubMed PubMed Citation Articles by Mooney, C. Articles by Elsbach, P.

 Previous Article  |  Next Article 

Infect Immun. 1975 June; 11(6): 1269-1277
Copyright © 1975 American Society for Microbiology. All Rights Reserved.

Altered Phospholipid Metabolism in Escherichia coli Accompanying Killing by Disrupted Granulocytes

¹ Department of Medicine, New York University School of Medicine, New York, New York 10016

ABSTRACT

The effect of bactericidal concentrations of disrupted rabbit granulocytes and of partially purified granulocyte fractions on phospholipid metabolism by Escherichia coli has been investigated. Previous studies in this laboratory have shown that, during and after killing of E. coli by granulocytes, bacterial macromolecular synthesis continues. Similarly, despite almost complete loss of viability within 15 min, incorporation of [1-¹⁴C]palmitate, [2-¹⁴C]glycerol, and [1-¹⁴C]acetate into E. coli phospholipids, in the presence of granulocyte preparations, remains the same as in control E. coli populations for at least 1 h. Incorporation of [1-¹⁴C]oleate into E. coli phospholipids is actually stimulated during the first 60 min of incubation in the presence of granulocyte preparations (more than twofold at 30 min and 40% at 60 min). With all labeled lipid precursors, bactericidal granulocyte preparations cause a relative increase in the labeling of E. coli cardiolipin, with a corresponding drop in labeled phosphatidyl-glycerol. Labeled lyso-compounds accumulate in the presence of granulocyte preparations when [1-¹⁴C]palmitate, but not when [1-¹⁴C]oleate is the labeled precursor. Since oleate occurs mainly in the 2-acyl position of E. coli phospholipids, whereas at least 50% of palmitate occurs in the 1 position, it appears that a phospholipase A₂ acts on the E. coli phospholipids. These various effects are also seen when E. coli are exposed to highly purified granulocyte preparations that possess potent bactericidal and phospholipase A₂ activities. We speculate that this phospholipase A₂ in the granulocyte preparations stimulates oleate but not palmitate incorporation by initiating increased turnover of the fatty acid in the 2-acyl position of E. coli phospholipids, causing formation of 1-acyl lyso-compounds likely to be preferentially reacylated with unsaturated fatty acids.