Salmonella effector SopB reorganizes cytoskeletal vimentin to maintain replication vacuoles for efficient infection

A variety of intracellular bacteria modulate the host cytoskeleton to establish subcellular niches for replication. However, the role of intermediate filaments, which are crucial for mechanical strength and resilience of the cell, and in bacterial vacuole preservation remains unclear. Here, we show that Salmonella effector SopB reorganizes the vimentin network to form cage-like structures that surround Salmonella-containing vacuoles (SCVs). Genetic removal of vimentin markedly disrupts SCV organization, significantly reduces bacterial replication and cell death. Mechanistically, SopB uses its N-terminal Cdc42-binding domain to interact with and activate Cdc42 GTPase, which in turn recruits vimentin around SCVs. A high-content imaging-based screening identified that MEK1/2 inhibition led to vimentin dispersion. Our work therefore elucidates the signaling axis SopB-Cdc42-MEK1/2 as mobilizing host vimentin to maintain concrete SCVs and identifies a mechanism contributing to Salmonella replication. Importantly, Trametinib, a clinically-approved MEK1/2 inhibitor identified in the screen, displayed significant anti-infection efficacy against Salmonella both in vitro and in vivo, and may provide a therapeutic option for treating drug-tolerant salmonellosis. Vimentin is an intermediate filament protein responsible for maintaining cell shape. Here, the authors characterise the role of the Salmonella effector SopB on the vimentin network and its contribution to infection.

Automated summary

Intracellular bacteria can manipulate the host cytoskeleton to create spaces for replication. The Salmonella effector SopB rearranges the vimentin network to form cage-like structures around the bacteria. Inhibition of MEK1/2 results in vimentin dispersion and disrupts bacterial replication, demonstrating the importance of the SopB-Cdc42-MEK1/2 signaling axis in maintaining stable Salmonella-containing vacuoles.