Modulation des retrograden Vesikeltransports durch Legionellen
Zusammenfassung der Projektergebnisse
The causative agent of Legionnaires´ pneumonia, Legionella pneumophila, replicates intracellularly in protozoa and macrophages within a distinct membrane-bound compartment, the “Legionella-containing vacuole” (LCV). To form LCVs, the bacteria translocate a plethora of “effector proteins” by means of the Icm/Dot type IV secretion system (T4SS) into eukaryotic host cell, where some of them subvert host signaling and vesicle trafficking by targeting PI lipids or small GTPases. We identified and characterized novel Icm/Dot substrates that (i) bind to the retromer and inhibit retrograde trafficking (RidL), (ii) act as a phytase and protect the bacteria from bacteriostatic phytate (LppA), or (iii) activate the small GTPase Ran and stabilize microtubules (LegG1). Moreover, we (iv) analyzed by real-time microscopy the LCV PI pattern, and (v) identified by proteomics a number of novel small GTPases as LCV components. Collectively, these results substantially contribute to a mechanistic understanding of LCV formation and virulence of L. pneumophila. Furthermore, the discovery of a bacterial phytase that counteracts intracellular bacteriostatic phytate implies that this family of enzymes might represent therapeutic targets to combat intracellular pathogens. The publication in Cell Host Microbe was covered by the press bureau of the Ludwig-Maximilians University (http://www.uni-muenchen.de/forschung/news/2013/f-41-13.html) and other media (http://www.aerztezeitung.de/medizin/krankheiten/infektionskrankheiten/article/ 843033/infektiologie-legionellen-wachsen-fressfeind.html; http://www.vitanet.de/aktuelles/ infektionen-immunsystem/20130719-listige-legionellen). Finally, the leading author of this study, Ivo Finsel, received the PhD prize of the DZIF (Deutsches Zentrum für Infektionsforschung) at the annual assembly of the DGHM and VAAM 2014 in Leipzig.
Projektbezogene Publikationen (Auswahl)
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(2013) Activation of Ran GTPase by a Legionella effector promotes microtubule polymerization, pathogen vacuole motility and infection. PLoS Pathog. 9: e1003598
Rothmeier, E., Pfaffinger, G., Hoffmann, C., Harrison, C. F., Grabmayr, H., Repnik, U., Hannemann, M., Wölke, S., Bausch, A., Griffith, G., Müller-Taubenberger, A., Itzen, A. & Hilbi, H.
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(2013) The Legionella effector RidL inhibits retrograde trafficking to promote intracellular replication. Cell Host Microbe 14: 38-50
Finsel, I., Ragaz, C., Hoffmann, C., Harrison, C. F., Weber, S., van Rahden, V. A., Johannes, L. & Hilbi, H.
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(2014) Functional analysis of novel small GTPases identified in the proteome of purified Legionella-containing vacuoles from macrophages. Cell. Microbiol. 16, 1034-1052
Hoffmann, C., Finsel, I., Otto, A., Pfaffinger, G., Rothmeier, E., Hecker, M., Becher, D. & Hilbi, H.
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(2014) Icm/Dot-dependent inhibition of phagocyte migration by Legionella is antagonized by a translocated Ran GTPase activator. Cell. Microbiol. 16, 977-992
Simon, S., Wagner, M., Rothmeier, E., Müller-Taubenberger, A. & Hilbi, H.
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(2014) Live cell imaging of phosphoinositide dynamics and membrane architecture during Legionella infection. mBio 5: e00839-13
Weber, S., Wagner, M. & Hilbi, H.
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(2014) The Legionella longbeachae Icm/Dot substrate SidC selectively binds PtdIns(4)P with nanomolar affinity and promotes pathogen vacuole-endoplasmic reticulum interactions. Infect. Immun. 82: 4021-4033
Dolinsky, S., Haneburger, I., Hannemann, M, Cichy, A., Itzen, A. & Hilbi, H.
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A type IV-translocated Legionella cysteine phytase counteracts intracellular growth restriction by phytate. J. Biol. Chem., 2014 Dec 5;289(49):34175-88
Weber, S., Stirnimann, C. U., Wieser, M., Frey, D., Meier, R., Engelhardt, S., Li, X., Capitani, G., Kammerer, R. A. & Hilbi, H.
