A Bacterial Guanine Nucleotide Exchange Factor Activates ARF on Legionella Phagosomes

• Published in: Science (American Association for the Advancement of Science) 2002-01, Vol.295 (5555), p.679-682
• Main Authors: Nagai, Hiroki, Kagan, Jonathan C., Zhu, Xinjun, Kahn, Richard A., Roy, Craig R.
• Format: Article
• Language: English
• Subjects: Acanthamoeba - microbiology; ADP ribosylation factor; ADP-Ribosylation Factor 1 - genetics; ADP-Ribosylation Factor 1 - metabolism; ADP-Ribosylation Factors - metabolism; Amino Acid Sequence; Animals; Antibodies; ARF protein; Bacteria; Bacterial genetics; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Biological and medical sciences; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cell Line; Cell lines; DNA; dot gene; Fundamental and applied biological sciences. Psychology; Genes, Bacterial; Guanine nucleotide exchange factor; Guanine Nucleotide Exchange Factors - chemistry; Guanine Nucleotide Exchange Factors - genetics; Guanine Nucleotide Exchange Factors - metabolism; Humans; icm gene; Legionella; Legionella - genetics; Legionella pneumophila; Legionella pneumophila - genetics; Legionella pneumophila - growth & development; Legionella pneumophila - metabolism; Legionellosis; Legionnaires' disease; Macrophages; Macrophages - microbiology; Mice; Mice, Inbred A; Microbiology; Molecular biology; Molecular Sequence Data; Pathogenicity, virulence, toxins, bacteriocins, pyrogens, host-bacteria relations, miscellaneous strains; Pathology; Phagosomes; Phagosomes - metabolism; Phagosomes - microbiology; Prevention; Protein Structure, Tertiary; Protein Transport; Proteins; RalF protein; Ralfs; Recombinant Fusion Proteins - metabolism; Recruitment; Rickettsia; RNA, Bacterial - genetics; RNA, Bacterial - metabolism; RNA, Messenger - genetics; RNA, Messenger - metabolism; Sequence Homology, Amino Acid; Steepest descent method
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1067025

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.