title: Cytolysin-dependent delay of vacuole maturation in macrophages infected with Listeria monocytogenes.
abstract: The bacterial pathogen Listeria monocytogenes (Lm) evades the antimicrobial mechanisms of macrophages by escaping from vacuoles to the cytosol, through the action of the cytolysin listeriolysin O (LLO). Because of heterogeneities in the timing and efficiency of escape, important questions about the contributions of LLO to Lm vacuole identity and trafficking have been inaccessible. Expression of cyan fluorescent protein (CFP)-labelled endocytic membrane markers in macrophages along with a yellow fluorescent protein (YFP)-labelled indicator of Lm entry to the cytosol identified compartments lysed by bacteria. Lm escaped from Rab5a-negative, lysosome-associated membrane protein-1 (LAMP1)-negative, Rab7-positive, phosphatidylinositol 3-phosphate [PI(3)P]-positive vacuoles. Lm vacuoles did not label with YFP-Rab5a unless the bacteria were first opsonized with IgG. Wild-type Lm delayed vacuole fusion with LAMP1-positive lysosomes, relative to LLO-deficient Lm. Bacteria prevented from expressing LLO until their arrival into LAMP1-positive lysosomes escaped inefficiently. Thus, the LLO-dependent delay of Lm vacuole fusion with lysosomes affords Lm a competitive edge against macrophage defences by providing bacteria more time in organelles they can penetrate.
authors.affiliation: Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109-0620, USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Henry
authors.forename: Lee
authors.initials: L
authors.lastname: Shaughnessy
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Loessner
authors.forename: Christine
authors.initials: C
authors.lastname: Alberti-Segui
authors.forename: Darren E
authors.initials: DE
authors.lastname: Higgins
authors.forename: Joel A
authors.initials: JA
authors.lastname: Swanson
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D001427:Bacterial Toxins; D002451:Cell Compartmentation; D003600:Cytosol / Q000378:metabolism; D010450:Endopeptidases / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000235:genetics; D006360:Heat-Shock Proteins / Q000502:physiology*; D006460:Hemolysin Proteins; D007425:Intracellular Membranes / Q000378:metabolism; D008089:Listeria monocytogenes / Q000378:metabolism / Q000502:physiology*; D008164:Luminescent Proteins / Q000235:genetics; D051907:Lysosomal Membrane Proteins / Q000378:metabolism; D008247:Lysosomes / Q000382:microbiology / Q000502:physiology; D008264:Macrophages / Q000382:microbiology / Q000502:physiology*; D051379:Mice; D008856:Microscopy, Fluorescence; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014617:Vacuoles / Q000382:microbiology / Q000502:physiology*; D020691:rab GTP-Binding Proteins / Q000378:metabolism; D020696:rab5 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D000090802:rab7 GTP-Binding Proteins; D052118:Lysosomal-Associated Membrane Protein 1
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D010450:Endopeptidases; D049452:Green Fluorescent Proteins; D006360:Heat-Shock Proteins; D006460:Hemolysin Proteins; D008164:Luminescent Proteins; D051907:Lysosomal Membrane Proteins; D018129:Phosphatidylinositol Phosphates; D011993:Recombinant Fusion Proteins; D020691:rab GTP-Binding Proteins; D020696:rab5 GTP-Binding Proteins; D000090802:rab7 GTP-Binding Proteins; C485182:Cyan Fluorescent Protein; C052255:Lamp1 protein, mouse; D052118:Lysosomal-Associated Membrane Protein 1; C055525:phosphatidylinositol 3-phosphate; C000716465:rab7 GTP-binding proteins, mouse; C054562:yellow fluorescent protein, Bacteria; C001143:endolysin; C038705:hlyA protein, Listeria monocytogenes