title: Tuberculosis toxin blocking phagosome maturation inhibits a novel Ca2+/calmodulin-PI3K hVPS34 cascade.
abstract: The capacity of Mycobacterium tuberculosis to infect latently over one billion people and cause two million fatalities annually rests with its ability to block phagosomal maturation into the phagolysosome in infected macrophages. Here we describe how M. tuberculosis toxin lipoarabinomannan (LAM) causes phagosome maturation arrest, interfering with a new pathway connecting intracellular signaling and membrane trafficking. LAM from virulent M. tuberculosis, but not from avirulent mycobacteria, blocked cytosolic Ca2+ increase. Ca2+ and calmodulin were required for a newly uncovered Ca2+/calmodulin phosphatidylinositol (PI)3 kinase hVPS34 cascade, essential for production of PI 3 phosphate (PI3P) on liposomes in vitro and on phagosomes in vivo. The interference of the trafficking toxin LAM with the calmodulin-dependent production of PI3P described here ensures long-term M. tuberculosis residence in vacuoles sequestered away from the bactericidal and antigen-processing organelles in infected macrophages.
authors.affiliation: Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, 915 Camino de Salud, NE, Albuquerque, NM 87131, USA.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Vergne
authors.forename: Jennifer
authors.initials: J
authors.lastname: Chua
authors.forename: Vojo
authors.initials: V
authors.lastname: Deretic
mesh_terms: D000942:Antigens, Bacterial / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology; D002147:Calmodulin / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000378:metabolism; D006801:Humans; D008070:Lipopolysaccharides / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism; D008264:Macrophages / Q000166:cytology / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D009169:Mycobacterium tuberculosis / Q000378:metabolism; D010588:Phagosomes / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D033921:Vesicular Transport Proteins
chemical_list: D000942:Antigens, Bacterial; D002147:Calmodulin; D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D008081:Liposomes; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D033921:Vesicular Transport Proteins; C093846:early endosome antigen 1; C050016:lipoarabinomannan; D019869:Phosphatidylinositol 3-Kinases; D002118:Calcium