OCCURRENCE OF MONOACYL-DIGLUCOSYL-DIACYL-GLYCEROL AND MONOACYL-BIS-GLYCEROPHOSPHORYL-DIGLUCOS IN MEMBRANES OF ACHOLEPLASMA-LAIDLAWII STRAINB-PG9

It is shown by thin-layer and high-performance liquid chromatography t hat the two membrane lipids monoacyl-diglucosyl-diacyl-glycerol (MADGl cDAG) and l-bis-glycerophosphoril-diglucosyl-diacyl-glycerol are synth esized by Acholeplasma laidlawii strain B-PG9 when the cells are grown in two different growth media. The two lipids are also synthesized by A. laidlawii strain A-EF22 and their chemical structures have been de termined previously by NMR spectroscopy. Since a reversed hexagonal ph ase is the only liquid-crystalline phase formed by MADGlcDAG, it is co ncluded that A. laidlawii strain B-PG9, in resemblance to strain A-EF2 2, synthesizes three membrane lipids that are able to form reversed no nlamellar phases. A comparison of the membrane lipids from the two str ains shows that there is essentially one lipid from each strain that d iffers. However, both these lipids have common physico-chemical proper ties, namely the ability to form reversed nonlamellar phases. Finally, it is also shown that novel lipids may be synthesized by A. laidlawii through long-time adaptation to altered growth conditions. (C) 1998 E lsevier Science B.V.