The Salmonella effector SptP dephosphorylates host AAA+ ATPase VCP to promote development of its intracellular replicative niche.

Virulence effectors delivered into intestinal epithelial cells by Salmonella trigger actin remodeling to direct pathogen internalization and intracellular replication in Salmonella-containing vacuoles (SCVs). One such effector, SptP, functions early during pathogen entry to deactivate Rho GTPases and reverse pathogen-induced cytoskeletal changes following uptake. SptP also harbors a C-terminal protein tyrosine phosphatase (PTPase) domain with no clear host substrates. Investigating SptP's longevity in infected cells, we uncover a late function of SptP, showing that it associates with SCVs, and its PTPase activity increases pathogen replication. Direct SptP binding and specific dephosphorylation of the AAA+ ATPase valosin-containing protein (VCP/p97), a facilitator of cellular membrane fusion and protein degradation, enhanced pathogen replication in SCVs. VCP and its adaptors p47 and Ufd1 were necessary for generating Salmonella-induced filaments on SCVs, a membrane fusion event characteristic of the pathogen replicative phase. Thus, Salmonella regulates the biogenesis of an intracellular niche through SptP-mediated dephosphorylation of VCP.

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