title: Novel type-specific lipooligosaccharides from Mycobacterium tuberculosis.
abstract: Mycobacterium tuberculosis (strain Canetti) is characterized by the presence of two novel glycolipids of the alkali-labile, trehalose-containing lipooligosaccharide class. Their structures were established by permethylation, partial acid hydrolysis, infrared and high-field NMR spectroscopy, and electron-impact and fast atom bombardment mass spectrometry of the native glycolipids and hydrolysis products. The trehalose substituent is unique in that it is methylated at the 6'-position. The structure of the simpler of the two glycolipids is 2-O-Me-alpha-L-Fucp(1----3)-beta-D-Glcp(1----3)-2-O-Me- alpha-L-Rhap(1----3)-2-O-Me-alpha-L- Rhap(1----3)-beta-D-Glcp(1----3)-4-O-Me-alpha-L-Rhap(1----3) -6-O-Me-alpha-D- Glc. Further glycosylation of the octaglycosyl unit of this nonantigenic glycolipid by an incompletely defined N-acyl derivative of a 4-amino-4,6-dideoxy-Galp residue results in the second, highly antigenic nonasaccharide-containing glycolipid. Application of two-dimensional proton correlation spectroscopy demonstrated that the fatty acyl substituents are located on the 2,3,6 and 3,4,6 hydroxyl groups of the terminal glucosyl unit in the proportions of 2:3. Gas chromatography/mass spectrometry and optical rotation measurement allowed identification of the fatty acyl esters as primarily 2L-, 4L-dimethylhexadecanoate, 2L-,4L-,6L-,8L-tetramethyloctadecanoate, and 2-methyl-3-hydroxyeicosanoate. The relationship of these glycolipids to different morphological forms of M. tuberculosis and to virulence is discussed.
authors.affiliation: Department of Microbiology, Colorado State University, Fort Collins 80523.
authors.forename: M
authors.initials: M
authors.lastname: Daffe
authors.forename: M
authors.initials: M
authors.lastname: McNeil
authors.forename: P J
authors.initials: PJ
authors.lastname: Brennan
mesh_terms: D000942:Antigens, Bacterial / Q000737:chemistry; D002240:Carbohydrate Sequence; D006017:Glycolipids / Q000737:chemistry / Q000276:immunology; D008070:Lipopolysaccharides / Q000737:chemistry* / Q000276:immunology / Q000302:isolation & purification; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000032:analysis* / Q000276:immunology; D013055:Spectrophotometry, Infrared; D014199:Trehalose / Q000737:chemistry
chemical_list: D000942:Antigens, Bacterial; D006017:Glycolipids; D008070:Lipopolysaccharides; C023023:lipid-linked oligosaccharides; D014199:Trehalose