The host GTPase Dynamin 2 modulates apical junction structure to control cell-to-cell spread of <i>Listeria monocytogenes</i>

The food-borne pathogen <i>Listeria monocytogenes</i> uses actin-based motility to generate plasma membrane protrusions that mediate the spread of bacteria between host cells. In polarized epithelial cells, efficient protrusion formation by <i>L. monocytogenes</i> requires the secreted bacterial protein InlC, which binds to a carboxyl-terminal Src homology 3 (SH3) domain in the human scaffolding protein Tuba. This interaction antagonizes Tuba, thereby diminishing cortical tension at the apical junctional complex and enhancing <i>L. monocytogenes</i> protrusion formation and spread. Tuba contains five SH3 domains apart from the domain that interacts with InlC. Here, we show that human GTPase Dynamin 2 associates with two SH3 domains in the amino-terminus of Tuba and acts together with this scaffolding protein to control the spread of <i>L. monocytogenes</i>. Genetic or pharmacological inhibition of Dynamin 2 or knockdown of Tuba each restored normal protrusion formation and spread to a bacterial strain deleted for the <i>inlC</i> gene (∆<i>inlC</i>). Dynamin 2 localized to apical junctions in uninfected human cells and protrusions in cells infected with <i>L. monocytogenes</i>. Localization of Dynamin 2 to junctions and protrusions depended on Tuba. Knockdown of Dynamin 2 or Tuba diminished junctional linearity, indicating a role for these proteins in controlling cortical tension. Infection with <i>L. monocytogenes</i> induced InlC-dependent displacement of Dynamin 2 from junctions, suggesting a possible mechanism of antagonism of this GTPase. Collectively, our results show that Dynamin 2 cooperates with Tuba to promote intercellular tension that restricts the spread of ∆<i>inlC Listeria</i>. By expressing InlC, wild-type <i>L. monocytogenes</i> overcomes this restriction.