Structure of membrane lipids and physico-biochemical properties of the plasma membrane from Thermoplasma acidophilum, adapted to growth at 37 degrees C.
Thermoplasma acidophilum, a mycoplasma-like organism, grows optimally at 56 degrees C and pH2. The low temperature extreme of growth is 37 degrees C. The plasma membrane of cells grown at 37 degrees C was isolated and characterized physicobiochemically. Membrane lipids which comprise 25% of the membrane dry weight consist mainly of two repetitively methyl-branched C40 side chains that were ether-linked to two glycerol molecules. The lipid structures were elucidated by combined gas chromatography-mass spectroscopy, direct probe mass spectroscopy and 13C NMR. 37 degrees C-grown cells contained lipids with 42% more pentane cyclization than the 56 degrees C-grown cells. In 37 degrees C-grown cells, phospholipid and serine content decreased by about 10% each, carbohydrate content increased by 5%. EPR studies demonstrated an increase in membrane lipid fluidity of 37 degrees C-grown cells with an upper transition temperature at 35 degrees C which was shifted down by 10 degrees C compared with cells grown at 56 degrees C. Membrane-bound ATPase activities also indicated similar changes upon adaptation. There is a close correlation between membrane fluidity and physiological functioning of this membrane-bound enzyme.
D000255:Adenosine Triphosphate / Q000032:analysis; D002462:Cell Membrane / Q000032:analysis / Q000502:physiology*; D004578:Electron Spin Resonance Spectroscopy; D005227:Fatty Acids / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008560:Membrane Fluidity; D008563:Membrane Lipids / Q000032:analysis; D013696:Temperature; D013822:Thermoplasma / Q000502:physiology* / Q000648:ultrastructure
D005227:Fatty Acids; D008563:Membrane Lipids; D000255:Adenosine Triphosphate