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Structure type: oligomer
Aglycon: polymer of -5)aDAraf(1-
Trivial name: lipoarabinomannan
Contained glycoepitopes: IEDB_130701,IEDB_1309625,IEDB_134619,IEDB_136104,IEDB_143632,IEDB_144983,IEDB_152206,IEDB_857717,IEDB_857718,IEDB_857722,IEDB_857723,IEDB_857726,IEDB_857727,IEDB_983930,SB_136,SB_196,SB_44,SB_67,SB_72

• Article ID: 742
  Khoo KH, Tang JB, Chatterjee D "Variation in mannose-capped terminal arabinan motifs of lipoarabinomannans from clinical isolates of Mycobacterium tuberculosis and Mycobacterium avium complex" - Journal of Biological Chemistry 276(6) (2001) 3863-3871
  

  The unique terminal arabinan motifs of mycobacterial lipoarabinomannan (LAM), which are mannose-capped to different extents, probably constitute the single most important structural entity engaged in receptor binding and subsequent immunopathogenesis. We have developed a concerted approach of endoarabinanase digestion coupled with chromatography and mass spectrometry analysis to rapidly identify and quantitatively map the complement of such terminal units among the clinical isolates of different virulence and drug resistance profiles. In comparison with LAM from laboratory strains of Mycobacterium tuberculosis, an ethambutol (Emb) resistant clinical isolate was shown to have a significantly higher proportion of nonmannose capped arabinan termini. More drastically, the mannose capping was completely inhibited when an Emb-susceptible strain was grown in the presence of subminimal inhibitory concentration of Emb. Both cases resulted in an increase of arabinose to mannose ratio in the overall glycosyl composition of LAM. Emb, therefore, not only could affect the complete elaboration of the arabinan as found previously for LAM from Mycobacterium smegmatis resistant mutant but also could inhibit the extent of mannose capping and hence its associated biological functions in M. tuberculosis. Unexpectedly, an intrinsically Emb-resistant Mycobacterium avium isolate of smooth transparent colony morphology was found to have most of its arabinan termini capped with a single mannose residue instead of the more common dimannoside as established for LAM from M. tuberculosis. This is the first report on the LAM structure from M. avium complex, an increasingly important opportunistic infectious agent afflicting AIDS patients

  structure, virulence, lipoarabinomannan, Mycobacterium tuberculosis, tuberculosis, Mycobacterium avium Complex

  NCBI PubMed ID: 11073941
  Journal NLM ID: 2985121R
  Publisher: Baltimore, MD: American Society for Biochemistry and Molecular Biology
  Correspondence: delphi@lamar.colostate.edu
  Institutions: Department of Microbiology, Colorado State University, Fort Collins, Colorado 80523, USA
  Methods: HPAEC, MS, enzymatic digestion
  
   
  
  Mycobacterium tuberculosis CSU19, Mycobacterium avium 2151
  CSDB ID 880 (all data & tools)

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Structure type: fragment of a bigger structure
Trivial name: arabinan in LAM
Compound class: cell wall polysaccharide
Contained glycoepitopes: IEDB_130701,IEDB_1309625,IEDB_134619,IEDB_136104,IEDB_143632,IEDB_144983,IEDB_152206,IEDB_857717,IEDB_857718,IEDB_857722,IEDB_857723,IEDB_857726,IEDB_857727,IEDB_983930,SB_136,SB_196,SB_44,SB_67,SB_72

• Article ID: 1449
  Chatterjee D, Khoo K "Mycobacterial lipoarabinomannan: an extraordinary lipoheteroglycan with profound physiological effects" - Glycobiology 8(2) (1998) 113-120
  

  Detailed structural and functional studies over the last decade have led to current recognition of the mycobacterial lipoarabinomannan (LAM) as a phosphatidylinositol anchored lipoglycan with diverse biological activities. Fatty acylation has been demonstrated to be essential for LAM to maintain its functional integrity although the focus has largely been on the arabinan motifs and the terminal capping function. It has recently been shown that the mannose caps may be involved not only in attenuating host immune response, but also in mediating the binding of mycobacteria to and subsequent entry into macrophages. This may further be linked to an intracellular trafficking pathway through which LAM is thought to be presented by CD1 to subsets of T-cells. The implication of LAM as major histocompatibility complex (MHC)-independent T-cell epitope and the ensuing immune response is an area of intensive studies. Another recent focus of research is the biosynthesis of arabinan which has been shown to be inhibitable by the anti-tuberculosis drug, ethambutol. The phenomenon of truncated LAM as synthesized by ethambutol resistant strains provides an invaluable handle for dissecting the array of arabinosyltransferases involved, as well as generating much needed structural variants for further structural and functional studies. It is hoped that with more systematic investigations based on clinical isolates and human cell lines, the true significance of LAM in the immunopathogenesis of tuberculosis and leprosy can eventually be explained.

  structure, Mycobacteria, lipoarabinomannan, lipoglycan, tuberculosis, CD1, phosphatidylinositol, ethambutol, lipomannan, phosphatidylinositol mannosides

  NCBI PubMed ID: 9451020
  Journal NLM ID: 9104124
  Publisher: IRL Press at Oxford University Press
  Institutions: Department of Microbiology, Colorado State University, Fort Collins, CO 80523, USA and Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
  
   
  
  Mycobacterium
  CSDB ID 1216 (all data & tools)