title: Relationship of growth temperature and thermotropic lipid phase changes in cytoplasmic and outer membranes from Escherichia coli K12.
abstract: Purified cytoplasmic and outer membranes isolated from cells of wild type Escherichia coli grown at 12, 20, 37 and 43 degrees C were labelled with the fatty acid spin probe 5-doxyl stearate. Electron spin resonance spectroscopy revealed broad thermotropic phase changes. The inherent viscosity of both membranes was found to increase as a function of elevated growth temperature. The lipid order to disorder transition in the outer membrane but not the cytoplasmic membrane was dramatically affected by the temperature of growth. As a result, the cytoplasmic membrane presumably existed in a gel + liquid crystalline state during cellular growth at 12 and 20 degrees C, but in a liquid crystalline state when cells were grown at 37 and 43 degrees C. In contrast, the outer membrane apparently existed in a gel + liquid crystalline state at all incubation temperatures. Data presented here indicate that the temperature range over which the cell can maintain the outer membrane phospholipids in a mixed (presumedly gel + liquid crystalline) state correlates with the temperature range over which growth occurs.
mesh_terms: D002462:Cell Membrane / Q000648:ultrastructure*; D004578:Electron Spin Resonance Spectroscopy; D004926:Escherichia coli / Q000254:growth & development / Q000648:ultrastructure*; D008563:Membrane Lipids / Q000032:analysis*; D013696:Temperature; D014783:Viscosity
chemical_list: D008563:Membrane Lipids