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The EMBO Journal
(1999) 18, 3924–3933, doi:10.1093/emboj/18.14.3924
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| A Salmonella virulence protein that inhibits cellular trafficking |
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Kei-ichi Uchiya1, M.Alejandro Barbieri2, Kouichi Funato2, Ankur H Shah1, Philip D. Stahl2 and Eduardo A. Groisman1
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1 Howard Hughes Medical Institute and Department of Molecular Microbiology, 600 South Euclid Avenue, St Louis, MO 63110-1093, USA
2 Department of Cell Biology and Physiology, Washington University School of Medicine, 600 South Euclid Avenue, St Louis, MO 63110-1093, USA
To whom correspondence should be addressed
Eduardo A. Groisman, groisman@borcim.wustl.edu
Received 26 April 1999; Revised 24 May 1999; Accepted 24 May 1999.
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| Abstract |
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| Salmonella enterica requires a type III secretion system, designated Spi/Ssa, to survive and proliferate within macrophages. The Spi/Ssa system is encoded within the SPI-2 pathogenicity island and appears to function intracellularly. Here, we establish that the SPI-2-encoded SpiC protein is exported by the Spi/Ssa type III secretion system into the host cell cytosol where it interferes with intracellular trafficking. In J774 macrophages, wild-type Salmonella inhibited fusion of Salmonella-containing phagosomes with lysosomes and endosomes, and interfered with trafficking of vesicles devoid of the microorganism. These inhibitory activities required living Salmonella and a functional spiC gene. Purified SpiC protein inhibited endosome–endosome fusion in vitro. A Sindbis virus expressing the SpiC protein interfered with normal trafficking of the transferrin receptor in vivo. A spiC mutant was attenuated for virulence, suggesting that the ability to interfere with intracellular trafficking is essential for Salmonella pathogenesis. |
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| Keywords: endosome, intracellular trafficking, phagosome, Salmonella, type III secretion |
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