title: Organelle membrane proteomics reveals differential influence of mycobacterial lipoglycans on macrophage phagosome maturation and autophagosome accumulation.
abstract: The mycobacterial cell wall component lipoarabinomannan (LAM) has been described as one of the key virulence factors of Mycobacterium tuberculosis. Modification of the terminal arabinan residues of this lipoglycan with mannose caps in M. tuberculosis or with phosphoinositol caps in Mycobacterium smegmatis results in distinct host immune responses. Given that M. tuberculosis typically persists in the phagosomal vacuole after being phagocytosed by macrophages, we performed a proteomic analysis of that organelle after treatment of macrophages with LAMs purified from the two mycobacterial species. The quantitative changes in phagosomal proteins suggested a distinct role for mannose-capped LAM in modulating protein trafficking pathways that contribute to the arrest of phagosome maturation. Enlightened by our proteomic data, we performed further experiments to show that only the LAM from M. tuberculosis inhibits accumulation of autophagic vacuoles in the macrophage, suggesting a new function for this virulence-associated lipid.
authors.affiliation: College of Life Sciences, Nankai University, Tianjin 300071, China.
authors.forename: Wenqing
authors.initials: W
authors.lastname: Shui
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Petzold
authors.forename: Alyssa
authors.initials: A
authors.lastname: Redding
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Austin
authors.initials: A
authors.lastname: Pitcher
authors.forename: Leslie
authors.initials: L
authors.lastname: Sheu
authors.forename: Tsung-Yen
authors.initials: TY
authors.lastname: Hsieh
authors.forename: Jay D
authors.initials: JD
authors.lastname: Keasling
authors.forename: Carolyn R
authors.initials: CR
authors.lastname: Bertozzi
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000494:pharmacology; D001343:Autophagy / Q000187:drug effects*; D015151:Immunoblotting; D007425:Intracellular Membranes / Q000737:chemistry*; D007553:Isotope Labeling; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D008856:Microscopy, Fluorescence; D009169:Mycobacterium tuberculosis / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D010588:Phagosomes / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects; D040901:Proteomics / Q000379:methods; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry; D014357:Trypsin / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000378:metabolism
chemical_list: D000942:Antigens, Bacterial; D008070:Lipopolysaccharides; D010446:Peptide Fragments; D010716:Phosphatidylinositols; D033921:Vesicular Transport Proteins; C093846:early endosome antigen 1; C050016:lipoarabinomannan; D014357:Trypsin