(S)-2-AMINO-1,3-PROPANEDIOL-3-PHOSPHATE-CARRYING DIRADYLGLYCEROGLYCOLIPIDS - NOVEL MAJOR MEMBRANE-LIPIDS OF CLOSTRIDIUM-INNOCUUM

Two novel aminophosphoglycolipids (I, II) were isolated from Clostridium innocuum which constitute 51% (I) and 15% (II) of total polar membrane lipids. The structures, established by quantitative and methylation analyses, fast-atom-bombardment mass spectrometry, and one- and two-dimensional NMR spectroscopy, are (I) S-2-amino-1,3-propanediol-3-phospho-6-alpha-D-galactopyranosyl(1-2)alpha-D-glucopyranosyl(1-3)dir and (II) an acylated derivative of (I) that carries an additional fatty acid ester on 06 of the glucosyl moiety. The stereochemical configuration of the 2-amino-1,3-propanediol 3-phosphate residue was elucidated by conversion to N-acetylserine 3-phosphate, with subsequent release and identification of L-serine by HPLC. In addition to diacylglycerol species, both aminophosphoglycolipids contain 15-32% 1-O-(alk-1-enyl)-2-O-acyl-glycerol species in which C-14, C-16, and C-18 vinyl ether are combined predominantly with unsaturated C-16 and C-18 fatty acid ester. Hydrogenation of the vinyl ether was required to desorb the alkyl, acyl-substituted species in fast-atom-bombardment mass spectrometry. Hydrogenation made it further possible to release the alkyl glycerols by acid hydrolysis and to locate the ether bond at 01 of the glycerol moiety. In contrast to the glycerophosphoglycolipids of other Gram-positive bacteria, the aminophosphoglycolipids are metabolically not related to the lipoteichoic acid of C. innocuum and serve, therefore, exclusively as major membrane components. Their large abundance among membrane lipids suggests bilayer-forming physicochemical properties.