Molecular dissection of Salmonella-induced membrane ruffling versus invasion |
| |
Authors: | Jan Hä nisch,Julia Ehinger,Markus Ladwein,Manfred Rohde,Emmanuel Derivery,Tanja Bosse,Anika Steffen,Dirk Bumann,Benjamin Misselwitz,Wolf-Dietrich Hardt,Alexis Gautreau,Theresia E. B. Stradal, Klemens Rottner |
| |
Affiliation: | Signalling and Motility Group,;Cytoskeleton Dynamics Group, and;Department of Microbial Pathogenesis, Helmholtz Centre for Infection Research, Inhoffen Strasse 7, D-38124 Braunschweig, Germany.; Laboratoire d'Enzymologie et Biochimie Structurales, UPR3082 CNRS –Bat 34, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France.; Institute of Virology, OE 5230, Hannover Medical School, Carl-Neuberg-Strasse 1, D-30625 Hannover, Germany.; Faculty of Medicine, Biochemistry I, University of Cologne, Joseph-Stelzmann Strasse 52, D-50931 Cologne, Germany.; Infection Biology, Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH-4056 Basel, Switzerland.; Institute of Microbiology, ETH Zürich, Wolfgang-Pauli-Strasse 10, CH-8093 Zürich, Switzerland. |
| |
Abstract: | Type III secretion system-mediated injection of a cocktail of bacterial proteins drives actin rearrangements, frequently adopting the shape of prominent protuberances of ruffling membrane, and culminating in host cell invasion of Gram-negative pathogens like Salmonella typhimurium . Different Salmonella effectors are able to bind actin and activate Rho-family GTPases, which have previously been implicated in mediating actin-dependent Salmonella entry by interacting with N-WASP or WAVE-complex, well-established activators of the actin nucleation machine Arp2/3-complex. Using genetic deletion and RNA interference studies, we show here that neither individual nor collective removal of these Arp2/3- complex activators affected host cell invasion as efficiently as Arp2/3-complex knock-down, although the latter was also not essential. However, interference with WAVE-complex function abrogated Salmonella -induced membrane ruffling without significantly affecting entry efficiency, actin or Arp2/3-complex accumulation. In addition, scanning electron microscopy images captured entry events in the absence of prominent membrane ruffles. Finally, localization and RNA interference studies indicated a relevant function in Salmonella entry for the novel Arp2/3-complex regulator WASH. These data establish for the first time that Salmonella invasion is separable from bacteria-induced membrane ruffling, and uncover an additional Arp2/3-complex activator as well as an Arp2/3-complex-independent actin assembly activity that contribute to Salmonella invasion. |
| |
Keywords: | |
|
|