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Purification of Pathogen Vacuoles from Legionella-infected Phagocytes
Published on: June 19, 2012
Legionella pneumophila promotes functional interactions between plasma membrane syntaxins and Sec22b
1Section of Microbial Pathogenesis, Yale University School of Medicine, Boyer Center for Molecular Medicine, New Haven, CT 06536, USA.
Traffic (Copenhagen, Denmark)
|February 19, 2010
Summary
Legionella pneumophila hijacks host cell machinery by manipulating SNARE proteins. This interaction promotes the fusion of bacterial phagosomes with endoplasmic reticulum-derived vesicles for pathogen replication.
Area of Science:
- Cell Biology
- Microbiology
- Molecular Biology
Background:
- Legionella pneumophila replication requires a specialized organelle formed by vesicle fusion.
- Secretory vesicles from the endoplasmic reticulum (ER) fuse with pathogen-containing phagosomes.
Purpose of the Study:
- To investigate the role of host plasma membrane SNARE proteins in Legionella pneumophila vacuole trafficking.
- To determine if SNARE proteins mediate the fusion of ER-derived vesicles with phagosomes.
Main Methods:
- RNA interference was used to deplete plasma membrane syntaxins.
- Localization of SNARE proteins and host factors (calnexin, Rab1) on L. pneumophila phagosomes was assessed.
- Protein interactions between ER- and plasma membrane-localized SNAREs were analyzed.
Main Results:
- Depletion of plasma membrane syntaxins delayed calnexin acquisition and increased Rab1 retention on phagosomes.
- Specific plasma membrane SNAREs (syntaxin 2, 3, 4, SNAP23) and ER-localized Sec22b localized to L. pneumophila vacuoles.
- Virulent L. pneumophila induced a non-canonical interaction between plasma membrane t-SNAREs and v-SNARE Sec22b.
Conclusions:
- Host plasma membrane SNAREs are crucial for L. pneumophila vacuole biogenesis.
- L. pneumophila subverts the host secretory pathway by promoting non-canonical SNARE complex formation.
- This mechanism facilitates phagosome-ER vesicle fusion, supporting bacterial replication.
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