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Updated: Jul 22, 2026

Purification of Pathogen Vacuoles from Legionella-infected Phagocytes
Published on: June 19, 2012
A bacterial guanine nucleotide exchange factor activates ARF on Legionella phagosomes
Hiroki Nagai1, Jonathan C Kagan, Xinjun Zhu
1Section of Microbial Pathogenesis, Yale University School of Medicine, Boyer Center for Molecular Medicine, 295 Congress Avenue, New Haven, CT 06536, USA.
Abstract:
The intracellular pathogen Legionella pneumophila subverts vesicle traffic in eukaryotic host cells to create a vacuole that supports replication. The dot/icm genes encode a protein secretion apparatus that L. pneumophila require for biogenesis of this vacuole. Here we show that L. pneumophila produce a protein called RalF that functions as an exchange factor for the ADP ribosylation factor (ARF) family of guanosine triphosphatases (GTPases). The RalF protein is required for the localization of ARF on phagosomes containing L. pneumophila. Translocation of RalF protein through the phagosomal membrane is a dot/icm-dependent process. Thus, RalF is a substrate of the Dot/Icm secretion apparatus.
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