title: Mechanism of phagolysosome biogenesis block by viable Mycobacterium tuberculosis.
abstract: Live Mycobacterium tuberculosis persists in macrophage phagosomes by interfering with phagolysosome biogenesis. Here, using four-dimensional microscopy and in vitro assays, we report the principal difference between phagosomes containing live and dead mycobacteria. Phosphatidylinositol 3-phosphate (PI3P), a membrane trafficking regulatory lipid essential for phagosomal acquisition of lysosomal constituents, is retained on phagosomes harboring dead mycobacteria but is continuously eliminated from phagosomes with live bacilli. We show that the exclusion of PI3P from live mycobacterial phagosomes can be only transiently reversed by Ca2+ fluxes, and that live M. tuberculosis secretes a lipid phosphatase, SapM, that hydrolyzes PI3P, inhibits phagosome-late endosome fusion in vitro, and contributes to inhibition of phagosomal maturation.
authors.affiliation: Department of Molecular Genetics and Microbiology , University of New Mexico School of Medicine, Albuquerque, NM 87131, USA.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Vergne
authors.forename: Jennifer
authors.initials: J
authors.lastname: Chua
authors.forename: Hwang-Ho
authors.initials: HH
authors.lastname: Lee
authors.forename: Megan
authors.initials: M
authors.lastname: Lucas
authors.forename: John
authors.initials: J
authors.lastname: Belisle
authors.forename: Vojo
authors.initials: V
authors.lastname: Deretic
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D008264:Macrophages / Q000382:microbiology / Q000502:physiology*; D051379:Mice; D009169:Mycobacterium tuberculosis / Q000472:pathogenicity / Q000502:physiology*; D010588:Phagosomes / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism
chemical_list: D018129:Phosphatidylinositol Phosphates; C055525:phosphatidylinositol 3-phosphate; D019869:Phosphatidylinositol 3-Kinases; D002118:Calcium