Maturation of Rhodococcus equi-containing vacuoles is arrested after completion of the early endosome stage.
Rhodococcus equi is a facultative intracellular bacterium that can cause bronchopneumonia in foals and AIDS patients. Here, we have analyzed R. equi-containing vacuoles (RCVs) in murine macrophages by confocal laser scanning microscopy, by transmission electron microscopy and by immunochemistry upon purification. We show that RCVs progress normally through the early stages of phagosome maturation acquiring PI3P, early endosome antigen-1, and Rab5, and loosing all or much of them within minutes. Although mature RCVs possess the normally late endocytic markers, lysosome-associated membrane proteins, lysobisphosphatidic acid and Rab7, they lack other hallmark features of late endocytic organelles such as possession of cathepsin D, acid beta-glucuronidase, proton-pumping ATPase and the ability to fuse with prelabeled lysosomes. Bacterial strains possessing a virulence-associated plasmid maintain a nonacidified compartment for 48 h, whereas isogenic strains lacking such plasmids acidify progressively. In summary, RCVs represent a novel phagosome maturation stage positioned after completion of the early endosome stage and before reaching a fully mature late endosome compartment. In addition, vacuole biogenesis can be influenced by bacterial plasmids.
Institut für Zellbiologie and Bonner Forum Biomedizin, University of Bonn, Ulrich-Haberland-Str. 61a, 53121 Bonn, Germany.
Eugenia
E
Fernandez-Mora
Marco
M
Polidori
Anja
A
Lührmann
Ulrich E
UE
Schaible
Albert
A
Haas
D000818:Animals; D015703:Antigens, CD / Q000032:analysis; D001854:Bone Marrow Cells / Q000382:microbiology / Q000502:physiology; D002460:Cell Line; D002478:Cells, Cultured; D005260:Female; D005455:Fluorescent Antibody Technique; D049452:Green Fluorescent Proteins / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D008246:Lysophospholipids / Q000032:analysis; D051907:Lysosomal Membrane Proteins; D008264:Macrophages / Q000382:microbiology* / Q000502:physiology* / Q000648:ultrastructure; D051379:Mice; D008810:Mice, Inbred C57BL; D046529:Microscopy, Electron, Transmission; D050178:Monoglycerides; D010588:Phagosomes / Q000382:microbiology* / Q000502:physiology* / Q000648:ultrastructure; D018129:Phosphatidylinositol Phosphates / Q000032:analysis / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000032:analysis; D016929:Rhodococcus equi / Q000235:genetics / Q000472:pathogenicity; D014162:Transfection; D014617:Vacuoles / Q000382:microbiology* / Q000502:physiology* / Q000648:ultrastructure; D014774:Virulence; D001616:beta-Galactosidase / Q000032:analysis / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000032:analysis / Q000235:genetics; D000090802:rab7 GTP-Binding Proteins
D015703:Antigens, CD; D008246:Lysophospholipids; D051907:Lysosomal Membrane Proteins; D050178:Monoglycerides; D018129:Phosphatidylinositol Phosphates; D011993:Recombinant Fusion Proteins; C012786:bis(monoacylglyceryl)phosphate; C485184:enhanced green fluorescent protein; C055525:phosphatidylinositol 3-phosphate; D000090802:rab7 GTP-Binding Proteins; C000716465:rab7 GTP-binding proteins, mouse; D049452:Green Fluorescent Proteins; D001616:beta-Galactosidase; D020691:rab GTP-Binding Proteins