J. Biol. Chem., Vol. 268, Issue 5, 3168-3179, Feb, 1993
Lipooligosaccharidic antigen containing a novel C4-branched 3,6-dideoxy- alpha-hexopyranose typifies Mycobacterium gastri
M Gilleron, J Vercauteren and G Puzo
Laboratoire de Pharmacologie et de Toxicologie Fondamentales, Centre National de la Recherche Scientifique, Toulouse, France.
Lipooligosaccharides (LOSs) have recently been proposed as markers of
mycobacterial avirulence. They have been characterized in Mycobacterium
kansasii cell wall and were investigated in Mycobacterium gastri since the
distinction between the two mycobacterial species remains in some question.
A set of unknown LOSs was isolated from M. gastri W471. The highly
antigenic lipooligosaccharide, LOS-III, was purified and appeared in all
the M. gastri strains investigated regardless of their morphology.
Moreover, by enzyme-linked immunosorbent assay and chromatographic
approaches, it was found that LOS-III unambiguously distinguished M. gastri
from the opportunistic pathogen M. kansasii. The LOS-III structure was
established from its native form using NMR spectroscopy. This strategy
revealed the presence of a supplementary monosaccharide (X) which was not
characterized by routine carbohydrate analysis. Its core structure,
3,6-dideoxy-alpha-hexopyranose, was established from the complete
assignment of the 1H and 13C spectra by two-dimensional homonuclear (COSY,
HOHAHA) and heteronuclear 1H-13C heteronuclear multiple quantum correlation
spectroscopy (HMQC) and HMQC- HOHAHA spectroscopy. Due to the absence of a
proton at C4, the key data of the C4 side chain structure came from the
heteronuclear multiple bond correlation spectroscopy (HMBC) spectrum. It
was revealed to be a C-alkyl chain of partial structure
1,3-dimethoxypropyl. From the HMBC spectrum, this novel C-branched
monosaccharide was located at the nonreducing end of the LOS, while the
putative reducing end was found to consist of a 2',4,6-triacylated
alpha-alpha-trehalose. The following structure, based on the evidence
presented in this paper, is proposed for LOS-III: Xp alpha(1-->3)[L-Xylp
beta(1-->4)](6)3-O-Me-Rhap alpha(1-- >3)D- Galp beta(1-->3)-D-Glcp
beta(1-->4)2-O-acyl-D-Glcp- alpha(1<==>1)alpha 4,6-di-O-
acyl-D-Glcp.