Septin 11 restricts InlB-mediated invasion by Listeria.
Septins are filament-forming GTPases implicated in several cellular functions, including cytokinesis. We previously showed that SEPT2, SEPT9, and SEPT11 colocalize with several bacteria entering into mammalian non-phagocytic cells, and SEPT2 was identified as essential for this process. Here, we investigated the function of SEPT11, an interacting partner of SEPT9 whose function is still poorly understood. In uninfected HeLa cells, SEPT11 depletion by siRNA increased cell size but surprisingly did not affect actin filament formation or the colocalization of SEPT9 with actin filaments. SEPT11 depletion increased Listeria invasion, and incubating SEPT11-depleted cells with beads coated with the Listeria surface protein InlB also led to increased entry as compared with control cells. Strikingly, as shown by fluorescence resonance energy transfer, the InlB-mediated stimulation of Met signaling remained intact in SEPT11-depleted cells. Taken together, our results show that SEPT11 is not required for the bacterial entry process and rather restricts its efficacy. Because SEPT2 is essential for the InlB-mediated entry of Listeria, but SEPT11 is not, our findings distinguish the roles of different mammalian septins.
Mostowy
Serge
S
Unité des Interactions Bactéries-Cellules, Institut Pasteur, Paris F-75015, France.
Danckaert
Anne
A
Tham
To Nam
TN
Machu
Christophe
C
Guadagnini
Stéphanie
S
Pizarro-Cerdá
Javier
J
Cossart
Pascale
P
D001426:Bacterial Proteins / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism* / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D020558:GTP Phosphohydrolases / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D008089:Listeria monocytogenes / Q000378:metabolism / Q000472:pathogenicity*; D008565:Membrane Proteins / Q000378:metabolism*; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence / Q000379:methods; D008954:Models, Biological; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D058112:Septins; D015398:Signal Transduction
D001426:Bacterial Proteins; D018797:Cell Cycle Proteins; D008565:Membrane Proteins; C095768:inlB protein, Listeria monocytogenes; D010744:Phosphoric Monoester Hydrolases; D020558:GTP Phosphohydrolases; C496549:SEPTIN11 protein, human; C474315:SEPTIN9 protein, human; D058112:Septins