IDENTIFICATION OF BETA-L-GULOSE AS THE SUGAR MOIETY OF THE MAIN POLARLIPID THERMOPLASMA-ACIDOPHILUM

The main polar lipid (MPL) of Thermoplasma acidophilum has been purifi ed and its structure determined. NMR, mass spectrometry, and capillary gas chromatography-mass spectrometry experiments have shown that the previously unidentified sugar moiety of MPL is the rare sugar L-gulose . MPL is thus a tetraether lipid with cyclopentane rings and head grou ps of phosphoglycerol, as previously reported, and beta-L-gulopyranose . Further, MPL is also the dominant lipid found in lipid extracts from another species of the Thermoplasma genus, T. volcanium, suggesting t hat L-gulose may represent a dominant sugar moiety of the polar lipids biosynthesized by this archaeobacterial genus. Minor phospholipids we re tentatively identified as diether and hydroxydiether analogs of pho sphatidylglycerol, and phosphatidylinositol.