The host GTPase Dynamin 2 modulates apical junction structure to control cell-to-cell spread of Listeria monocytogenes
The food-borne pathogen Listeria monocytogenes 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 Listeria 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 L. monocytogenes protrusion formation and spread. Tuba contains five SH3 domains apart from the domain that interacts with InlC. Here we show that the human GTPase Dynamin 2 associates with two SH3 domains in the amino terminus of Tuba and acts together with this scaffolding protein to control spread of L. monocytogenes. 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 inlC gene ({Delta}inlC). Dynamin 2 localized to apical junctions in uninfected human cells and to protrusions in cells infected with Listeria. 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. Collectively, our results show that Dynamin 2 cooperates with Tuba to promote intercellular tension that restricts spread of {Delta}inlC Listeria. By expressing InlC, wild-type L. monocytogenes overcomes this restriction.