The immunomodulatory lipoglycans, lipoarabinomannan and lipomannan, are exposed at the mycobacterial cell surface.
By labeling surface carbohydrates, we found that a pool of lipoglycans, cell wall associated, is exposed at the cell surface of mycobacteria and thus, most probably, inserted in the outer leaflet of the outer membrane. In contrast, plasma membrane anchored lipoglycans are not accessible to surface labeling. This result supports the role of lipoglycans as key immunomodulatory molecules but raises the question of their transport from the plasma membrane, where they are synthesized, to the outermost layers of the envelope, where they can act as modulins. The data are discussed in terms of consequences for cell envelope organization.
Institut de Pharmacologie et de Biologie Structurale, CNRS UMR 5089, Département Mécanismes Moléculaires des Infections Mycobactériennes, 205 Route de Narbonne, 31077 Toulouse Cedex 4, France.
Sylvain
S
Pitarque
Gérald
G
Larrouy-Maumus
Bruno
B
Payré
Mary
M
Jackson
Germain
G
Puzo
Jérôme
J
Nigou
D001710:Biotin / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry; D006801:Humans; D008070:Lipopolysaccharides / Q000032:analysis* / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000032:analysis* / Q000378:metabolism; D009169:Mycobacterium tuberculosis / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism; D014803:Vitamin B Complex / Q000378:metabolism
D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; C050016:lipoarabinomannan; C064351:lipomannan; D014803:Vitamin B Complex; D001710:Biotin