title: Lipid and protein composition of membranes of Bacillus megaterium variants in the temperature range 5 to 70 degrees C.
abstract: Membranes were prepared from four temperature range variants of Bacillus megaterium: one obligate thermophile, one facultative thermophile, one mesophile, and one facultative psychrophile, covering the temperature interval between 5 and 70 degrees C. The following changes in membrane composition were apparent with increasing growth temperatures: (i) the relative amount of iso fatty acids increased and that of anteiso acids decreased, the ratio of iso acids to anteiso acids being 0.34 at 5 degrees C and 3.95 at 70 degrees C, and the pair iso/anteiso acids thus seemed to parallel the pair saturated/unsaturated acids in their ability to regulate membrane fluidity; (ii) the relative/unsaturated acids in their ability to regulate membrane fluidity; (ii) the relative amount of long-chain acids (C16 to C18) increased fivefold over that of short-chain acids (C14 and C15) between 5 and 70 degrees C; (iii) the relative amount of phosphatidylethanolamine increased, and this phospholipid accordingly dominated in the thermophilic strains, whereas diphosphatidylglycerol was predominant in the two other strains; and (iv) the ratio of micromoles of phospholipid to milligrams of membrane protein increased three-fold between 5 and 70 degrees C. Moreover, a quantitative variation in membrane proteins was evident between the different strains. Briefly, membrane phospholipids with higher melting points and packing densities appeared to be synthesized at elevated growth temperatures.
mesh_terms: D001410:Bacillus megaterium / Q000032:analysis / Q000648:ultrastructure*; D001426:Bacterial Proteins / Q000032:analysis*; D002308:Cardiolipins / Q000032:analysis; D002462:Cell Membrane / Q000032:analysis; D005227:Fatty Acids / Q000032:analysis*; D008565:Membrane Proteins / Q000032:analysis*; D010714:Phosphatidylethanolamines / Q000032:analysis; D010743:Phospholipids / Q000032:analysis*; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D002308:Cardiolipins; D005227:Fatty Acids; D008565:Membrane Proteins; D010714:Phosphatidylethanolamines; D010743:Phospholipids