title: Trehalose-containing lipooligosaccharides of Mycobacterium gordonae: presence of a mono-O-methyltetra-O-acyltrehalose "core" and branching in the oligosaccharide backbone.
abstract: Past evidence has indicated that Mycobacterium gordonae, as isolated from soil and as an occasional opportunistic pathogen, exists as a serocomplex. We now demonstrate that the basis of seroreactivity and diversity is a novel series of alkali-labile, trehalose-containing lipooligosaccharides (LOS). The structures from two strains were established by per-O-methylation, partial acid hydrolysis, infrared and high-field NMR spectroscopy, electron-impact MS, and fast atom bombardment/mass spectrometry of the native lipooligosaccharides and hydrolysis products. The structure of the major lipooligosaccharide, LOS-I, of M. gordonae strain 989 was defined as 2-O-CH3-4-O-CH3CO-alpha-L-Fucp-(1-->3)- beta-D-Glcp-(1-->3)-2-O-CH3-alpha-L-Rhap-(1-->3)-[beta-D-Xylp++ +-(1-->2)-]- alpha-L-Rhap-(1-->3)-beta-D-Glcp-(1-->3)-alpha-L-Rhap-(1-->3 )-6-O- CH3-alpha-D-Glcp-(1<-->1)-2,3,4,6-tetra-O-acyl-alpha-D-Glcp, which was further glycosylated at C-3 of the terminal 2-O-CH3-4-O-CH3CO-alpha-L-Fucp by an incompletely defined N-acyl derivative of 4-amino-4,6-dideoxy-2,3-di-O-CH3-Galp. The structure of the major lipooligosaccharide, LOS-I, of a second strain of M. gordonae (strain 990) was defined as alpha-L-Rhap-(1-->2)-3-O-CH3-alpha-L-Rhap- (1-->3)-[beta-D-Xylp-(1-->2)-]-alpha-L-Rhap-(1-->3)-beta-D-G lcp- (1-->3)[beta-D-Xylp-(1-->2)-]-alpha-L-Rhap- (1-->3)-beta-D-Glcp-(1-->3)-beta-D-Glcp-(1-->3)-alpha-L-Rhap-(1--> 3)-6-O-CH3- alpha-D-Glcp-(1<-->1)-2,3,4,6-tetra-O-acyl-alpha-D-Glcp. The other minor LOSs from both strains were also defined. Both families of LOSs from the two strains contain a novel mono-6'-O-CH3-2,3,4,6-tetra-O-acyltrehalose unit, representing the first example of such a unit among the LOSs isolated to date from mycobacteria. Also, the more polar antigenic products, LOS-I, -II', -II", and -III from M. gordonae 989 and LOS-I, -II, and -II' from M. gordonae 990, are characterized by branching of the oligosaccharide backbone, the first instance of sugar branching in these products. In the case of LOS-I and -III from M. gordonae 989, the branch consists of a terminal (t)-beta-D-Xylp unit, whereas in LOS-II' and -II", they are (t)-3-O-CH3-beta-D-Xylp and (t)-alpha-D-Araf, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)
authors.affiliation: Department of Microbiology, Colorado State University, Fort Collins 80523.
authors.forename: G S
authors.initials: GS
authors.lastname: Besra
authors.forename: M R
authors.initials: MR
authors.lastname: McNeil
authors.forename: K H
authors.initials: KH
authors.lastname: Khoo
authors.forename: A
authors.initials: A
authors.lastname: Dell
authors.forename: H R
authors.initials: HR
authors.lastname: Morris
authors.forename: P J
authors.initials: PJ
authors.lastname: Brennan
mesh_terms: D000215:Acylation; D000942:Antigens, Bacterial / Q000737:chemistry; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D003429:Cross Reactions; D006027:Glycosides / Q000737:chemistry; D006868:Hydrolysis; D007536:Isomerism; D008070:Lipopolysaccharides / Q000737:chemistry* / Q000276:immunology; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009161:Mycobacterium / Q000737:chemistry* / Q000276:immunology; D009844:Oligosaccharides / Q000737:chemistry*; D016339:Spectrometry, Mass, Fast Atom Bombardment; D014199:Trehalose / Q000737:chemistry*
chemical_list: D000942:Antigens, Bacterial; D006027:Glycosides; D008070:Lipopolysaccharides; D009844:Oligosaccharides; C023023:lipid-linked oligosaccharides; D014199:Trehalose