Icm/Dot‐dependent inhibition of phagocyte migration by Legionella is antagonized by a translocated Ran GTPase activator. (27th January 2014)

• Record Type: Journal Article
• Authors: Simon, Sylvia; Wagner, Maria A.; Rothmeier, Eva; Müller‐Taubenberger, Annette; Hilbi, Hubert
• Is Part Of: Cellular microbiology. Volume 16:Number 7(2014:Jul.)
• Page Start: 977
• Page End: 992
• Publication Date: 2014-01-27
• Subjects: Microbiology -- Periodicals; Cytology -- Periodicals; Host-parasite relationships -- Periodicals; Microbiology -- Periodicals; Cells -- Periodicals; Microbiologie -- Périodiques; Microbiologie; Relation hôte-parasite; Cytologie; Cellule; Réponse cellulaire; Ressource Internet (Descripteur de forme); Périodique électronique (Descripteur de forme); 579.05
• DOI: 10.1111/cmi.12258
• Languages: English
• ISSNs: 1462-5814

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>The environmental bacterium <italic>L</italic><italic>egionella pneumophila</italic> causes a severe pneumonia termed Legionnaires' disease. <italic>L</italic><italic>. pneumophila</italic> employs a conserved mechanism to replicate within a specific vacuole in macrophages or protozoa such as the social soil amoeba <italic>D</italic><italic>ictyostelium discoideum</italic>. Pathogen–host interactions depend on the Icm/Dot type IV secretion system (T4SS), which translocates approximately 300 different effector proteins into host cells. Here we analyse the effects of <italic>L</italic><italic>. pneumophila</italic> on migration and chemotaxis of amoebae, macrophages or polymorphonuclear neutrophils (PMN). Using under‐agarose assays, <italic>L</italic><italic>. pneumophila</italic> inhibited in a dose‐ and T4SS‐dependent manner the migration of <italic>D</italic><italic>. discoideum</italic> towards folate as well as starvation‐induced aggregation of the social amoebae. Similarly, <italic>L</italic><italic>. pneumophila</italic> impaired migration of murine RAW 264.7 macrophages towards the cytokines CCL5 and TNFα, or of primary human PMN towards the peptide fMLP respectively. <italic>L</italic><italic>. pneumophila</italic> lacking the T4SS‐translocated activator of the small eukaryotic GTPase Ran, Lpg1976/LegG1, hyper‐inhibited the migration of <italic>D</italic><italic>. discoideum</italic>, macrophages or PMN. The phenotype was reverted by plasmid‐encoded LegG1 to an extent observed for mutant bacteria lacking a functional Icm/Dot T4SS.Similarly, LegG1 promoted random migration of <italic>L</italic><italic>. pneumophila</italic>‐infected macrophages and A549 epithelial cells in a Ran‐dependent manner, or upon 'microbial microinjection' into HeLa cells by a <italic>Y</italic><italic>ersinia</italic> strain lacking endogenous effectors. Single‐cell tracking and real‐time analysis of <italic>L</italic><italic>. pneumophila</italic>‐infected phagocytes revealed that the velocity and directionality of the cells were decreased, and cell motility as well as microtubule dynamics was impaired. Taken together, these findings indicate that the <italic>L</italic><italic>. pneumophila</italic> Ran activator LegG1 and consequent microtubule polymerization are implicated in Icm/Dot‐dependent inhibition of phagocyte migration.</p> </abstract>