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Maturation of Rhodococcus equi ‐Containing Vacuoles is Arrested After Completion of the Early Endosome Stage
Author(s) -
FernandezMora Eugenia,
Polidori Marco,
Lührmann Anja,
Schaible Ulrich E.,
Haas Albert
Publication year - 2005
Publication title -
traffic
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.677
H-Index - 130
eISSN - 1600-0854
pISSN - 1398-9219
DOI - 10.1111/j.1600-0854.2005.00304.x
Subject(s) - endosome , biology , vacuole , endocytic cycle , phagosome , microbiology and biotechnology , phagolysosome , organelle , lysosome , endocytosis , intracellular , biochemistry , cell , cytoplasm , enzyme
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 PI(3)P, 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 β‐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.