Archaea contain a novel diether phosphoglycolipid with a polar head group identical to the conserved core of eucaryal glycosyl phosphatidylinositol.
The structure of a major ether polar lipid of the methanogenic archaeon Methanosarcina barkeri was identified as glucosaminyl archaetidylinositol. This lipid had archaeol (2,3-di-O-phytanyl-sn-glycerol) as a core lipid portion, and the polar head group consisted of 1 mol each of phosphate, myo-inositol and D-GlcN. The polar head group was identified by means of chemical degradations, phosphatidylinositol-specific phospholipase C treatment, permethylation analysis, and fast atom bombardment-mass spectrometry as glucosaminylinositol phosphate, which was linked to the glycerol backbone via a phosphodiester bond. The stereochemical configuration of the phospho-myo-inositol residue of glucosaminyl archaetidylinositol was determined to be 1-D-myo-inositol 1-phosphate by measuring optical rotation of phospho-myo-inositol prepared by nitrous acid deamination and alkaline hydrolysis from the lipid. 1H NMR of the intact lipid showed that GlcN was linked to C-6 position of myo-inositol as an alpha-anomer. It is, finally, concluded that the complete structure of this lipid is 2,3-di-O-phytanyl-sn-glycero-1-phospho- 1'[6'-O-(2"-amino-2"-deoxy-alpha-D-glucopyranosyl)]-1'-D-myo-inositol. This lipid has a hybrid nature of an archaeal feature in alkyl glycerol diether core portion and an eucaryal feature in the polar head group identical to the conserved core structure (GlcNp(alpha 1-6)-myo-inositol 1-phosphate) of glycosylated phosphatidylinositol which serves as a membrane protein anchor in eucaryal cells.
Nishihara
M
M
Department of Chemistry, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan.
Utagawa
M
M
Akutsu
H
H
Koga
Y
Y
D002240:Carbohydrate Sequence; D006017:Glycolipids / Q000032:analysis* / Q000737:chemistry; D017261:Glycosylphosphatidylinositols; D009682:Magnetic Resonance Spectroscopy; D017021:Methanosarcina barkeri / Q000737:chemistry*; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010716:Phosphatidylinositols / Q000032:analysis* / Q000737:chemistry
D006017:Glycolipids; D017261:Glycosylphosphatidylinositols; D010716:Phosphatidylinositols