Taxonomic group: bacteria / Actinobacteria
(Phylum: Actinobacteria)
Associated disease: infection due to Mycobacterium tuberculosis [ICD11:
XN1N2 
]
The structure was elucidated in this paperNCBI PubMed ID: 8297342Journal NLM ID: 2984726RPublisher: London, UK : Published by Portland Press on behalf of the Biochemical Society
Institutions: Département des Glycoconjugués et Biomembranes, LPTF du CNRS, Toulouse, France
The cell envelope which surrounds pathogenic mycobacteria is postulated to be a defence barrier against phagocytic cells and its outermost constituents have a tendency to accumulate in the culture medium. The present work demonstrates that the exocellular material of Mycobacterium tuberculosis contains large amounts of polysaccharides with only traces, if any at all, of lipids. Three types of polysaccharides were purified by anion-exchange and gel-filtration chromatography; all were found to be neutral compounds devoid of acyl substituents. They consisted of D-glucan, D-arabino-D-mannan and D-mannan, which were eluted from gel-filtration columns in positions corresponding to molecular masses of 123, 13 and 4 kDa respectively. Their predominant structural features were determined by the characterization of the per-O-methyl derivatives of enzymic, acetolysis and Smith-degradation products and by 1H- and 13C-n.m.r. spectroscopy of the purified polysaccharides, using mono- and two-dimensional homonuclear chemical-shift correlated spectroscopy and two-dimensional heteronuclear (1H/13C) spectroscopy. The glucan which represented up to 90% of the polysaccharides was composed of repeating units of five or six →4-α-D-Glcp-1→ residues and a →4-α-D-Glcp substituted at position 6 with an α-D-Glcp, indicating a glycogen-like highly branched structure not related to the so-called polysaccharide-II previously identified in tuberculin. The arabinomannan consisted of a mannan segment composed of a →6-α-D-Man-1→ core substituted at some positions 2 with an α-D-Manp. The arabinan termini of the arabinomannan were found to be extensively capped with mannosyl residues. The possibility that these polysaccharides contribute to the persistence of the tubercle bacillus in the macrophage by molecular mimicry is discussed.
Structure type: homopolymer
Trivial name: methyl glucose lipopolysaccharide, glucan, maltosaccharide, α-1,4-D-glucan, amylose, α-glucan, glycogen backbone, α-(1,4)-glucan, starch, α-(1-4)-glucan, starch, glycogen
Compound class: CPS, EPS, O-polysaccharide, cell wall polysaccharide, glucan, polysaccharide, methyl glucose lipopolysaccharide
Contained glycoepitopes: IEDB_140629,IEDB_142488,IEDB_144998,IEDB_146664,IEDB_420417,IEDB_420418,IEDB_420421,IEDB_857742,IEDB_983931,SB_192
Methods: 13C NMR, 1H NMR, GLC-MS
Comments, role: linked to -4)[aDGlcp(1-6)]aDGlcp(1- disaccharide
Related record ID(s): 913, 8387, 10122, 22727, 23997, 102751, 106370
NCBI Taxonomy refs (TaxIDs): 1773Reference(s) to other database(s): GTC:G05740LL, GlycomeDB:
12100, CCSD:
4943, CBank-STR:819
Show glycosyltransferases
There is only one chemically distinct structure:
Found 
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