The chemical structure of a phosphoglucolipid from the membrane of the bacterium Acholeplasma laidlawii strain B-PG9 has been determined by high resolution NMR to be 1,2-diacyl-3-O-[glycerophosphoryl-6-O-(α-D-glucopyranosyl-(1 → 2)-O-α-D-glucopyranosyl)]-sn-glycerol (GPDGlcDAG). It was concluded that this lipid has exactly the same structure as one of the phosphoglucolipids from A. laidlawii strain A-EF22. By cryo transmission electron microscopy (cryo-TEM) and NMR diffusion techniques it was shown that, in highly diluted aqueous solutions, this membrane lipid forms long thread-like micelles in equilibrium with lipid vesicles. The cause of the occurrence of these different aggregates is discussed in terms of the varying molecular shapes of the lipid because of a heterogeneous composition of the acyl chains. A second membrane phosphoglucolipid from the bacterium, namely 1,2-diacyl-3-O[glycerophosphoryl-6-O-(α-D-glucopyranosyl-(1 → 2)-monoacylglycerophosphoryl-6-O-α-D-glucopyranosyl)]-sn-glycerol (MABGPDGlcDAG), was found to form only a lamellar liquid crystalline phase coexisting with water.
- Acholeplasma laidlawii
- Lipid structure