Distribution of phospholipid molecular species in outer and cytoplasmic membrane of Escherichia coli.

The outer membrane of Escherichia coli K-12 contained a smaller proportion of phospholipid molecular species with two unsaturated fatty acyl chains than did the cytoplasmic membrane. Proportions of phospholipid molecular species in the outer and cytoplasmic membranes changed in response to temperature changes. As the temperature increased, the content of 1-palmitoyl-2-cis-9,10-methylenehexadecanoyl species increased. Translocation of phospholipids from the cytoplasmic membrane to the outer membrane and synthesis of various molecular species were observed.