Internalization of Pseudomonas aeruginosa Strain PAO1 into Epithelial Cells Is Promoted by Interaction of a T6SS Effector with the Microtubule Network

摘要: Invasion of nonphagocytic cells through rearrangement the actin cytoskeleton is a common immune evasion mechanism used by most intracellular bacteria. However, some pathogens modulate host microtubules as well still poorly understood mechanism. In this study, we aim at deciphering mechanisms which opportunistic bacterial pathogen Pseudomonas aeruginosa invades cells, although it considered mainly an extracellular bacterium. Using confo- cal microscopy and immunofluorescence, show that evolved VgrG2b effector P. strain PAO1 delivered into epithelial type VI secretion system, called H2-T6SS, involving VgrG2a component. An in vivo interactome allows identification microtubule components, including -tubulin ring complex (TuRC), multiprotein catalyzing nucleation, major target VgrG2b. This interaction promotes microtubule-dependent internalization bacterium since colchicine nocodazole, two microtubule-destabilizing drugs, prevent VgrG2b-mediated entry even if invasion requires actin. We further validate our findings dem- onstrating injection step can be bypassed ectopic production inside prior to infection. Moreover, such uncoupling between also reveals they constitute inde- pendent steps. With VgrG2b, provide thefirst example protein interacting with TuRC. Our study offers key insight self-promoting human via directed specific effector- interaction. IMPORTANCE Innate immunity specifically professional phagocytic are determinants ability control among various virulence strategies, attack, able avoid clearance triggering its own cells. previously showed secretion/injection machinery, H2 system (H2-T6SS), uptake Here investigate H2-T6SS enables enter machinery where interacts and, more particularly, the-tubulin (TuRC) known microtubule-nucleating center. precedes microtubule- actin-dependent aeruginosa. thus discovered unprecedented for factor constitutes, knowledge,