Effector proteins function to alter host cell physiology and promote bacterial survival in host tissues. This protease targets the host cell ubiquitin pathway by acting as a deubiquitinase in infected host cells. Specifically hydrolyzes mono- and polyubiquitin substrates in vitro with a preference for 'Lys-63'-linked ubiquitin chains, suggesting that it interferes with a signaling pathway rather than inhibiting proteasomal-dependent degradation of its targets. Does not possess desumoylating activity. Is required for the Salmonella-induced delayed cytotoxicity in macrophages and full virulence. Is not required for intracellular bacterial replication. The Vmax of the reaction with ubiquitin-1-amido methyl coumarin (Ub-AMC) as substrate is 2354 pM/sec/uM enzyme. Secreted via type III secretion system 2 (SPI-2 TTSS), and delivered into the host cytoplasm. In phagocytic cells localizes to the Salmonella-containing vacuole (SCV). In epithelial cells localizes to the Salmonella-containing vacuole (SCV) and to the Salmonella-induced filaments (Sifs), which are tubular membrane extensions from the SCV that are formed at late stages of infection. Expression of the gene is induced inside phagocytic cells and is dependent on the SsrA/SsrB system. Belongs to the peptidase C79 family.