Effects of temperature variation and phenethyl alcohol addition on acyl chain order and lipid organization in Escherichia coli derived membrane systems. A 2H- and 31P-NMR study.
Using 2H- and 31P-NMR techniques the effects of temperature variation and phenethyl alcohol addition were investigated on lipid acyl chain order and on the macroscopic lipid organization of membrane systems derived from cells of the Escherichia coli fatty acid auxotrophic strain K1059, which was grown in the presence of [11,11-2H2]oleic acid. Membranes of intact cells showed a gel to liquid-crystalline phase transition in the range of 4-20 degrees C, which was similar to that observed for the total lipid extract and for the dominant lipid species phosphatidylethanolamine (PE). Phosphatidylglycerol (PG) remained in a fluid bilayer throughout the whole temperature range (4-70 degrees C). At 30 degrees C acyl chain order was highest in PE, followed by the total lipid extract, PG, intact cells, and isolated inner membrane vesicles. Acyl chain order in E. coli PE and PG was much higher than in the corresponding dioleoylphospholipids. E. coli PE was found to maintain a bilayer organization up to about 60 degrees C, whereas in the total lipid extract as well as in intact E. coli cells bilayer destabilization occurred already at about 42 degrees C. It is proposed that the regulation of temperature at which the bilayer-to-non-bilayer transition occurs may be important for membrane functioning in E. coli. Addition of phenethyl alcohol did not affect the macroscopic lipid organization in E. coli cells or in the total lipid extract, but caused a large reduction in chain order of about 70% at 1 mol% of the alcohol in both membrane systems. It is concluded that while both increasing temperature and addition of phenethyl alcohol can affect membrane integrity, in the former case this is due to the induction of non-bilayer lipid structures, whereas in the latter case this is caused by an increase in membrane fluidity.
Killian
J A
JA
Department of Biochemistry of Membranes, University of Utrecht, Netherlands.
Fabrie
C H
CH
Baart
W
W
Morein
S
S
de Kruijff
B
B
D004926:Escherichia coli / Q000737:chemistry* / Q000187:drug effects / Q000235:genetics; D005227:Fatty Acids / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy; D008563:Membrane Lipids / Q000737:chemistry*; D009154:Mutation; D010626:Phenylethyl Alcohol / Q000494:pharmacology*; D010743:Phospholipids / Q000032:analysis; D013696:Temperature
D005227:Fatty Acids; D008563:Membrane Lipids; D010743:Phospholipids; D010626:Phenylethyl Alcohol