title: The Salmonella Effector SpvD Is a Cysteine Hydrolase with a Serovar-specific Polymorphism Influencing Catalytic Activity, Suppression of Immune Responses, and Bacterial Virulence.
abstract: Many bacterial pathogens secrete virulence (effector) proteins that interfere with immune signaling in their host. SpvD is a Salmonella enterica effector protein that we previously demonstrated to negatively regulate the NF-κB signaling pathway and promote virulence of S. enterica serovar Typhimurium in mice. To shed light on the mechanistic basis for these observations, we determined the crystal structure of SpvD and show that it adopts a papain-like fold with a characteristic cysteine-histidine-aspartate catalytic triad comprising Cys-73, His-162, and Asp-182. SpvD possessed an in vitro deconjugative activity on aminoluciferin-linked peptide and protein substrates in vitro A C73A mutation abolished SpvD activity, demonstrating that an intact catalytic triad is required for its function. Taken together, these results strongly suggest that SpvD is a cysteine protease. The amino acid sequence of SpvD is highly conserved across different S. enterica serovars, but residue 161, located close to the catalytic triad, is variable, with serovar Typhimurium SpvD having an arginine and serovar Enteritidis a glycine at this position. This variation affected hydrolytic activity of the enzyme on artificial substrates and can be explained by substrate accessibility to the active site. Interestingly, the SpvDG161variant more potently inhibited NF-κB-mediated immune responses in cells in vitro and increased virulence of serovar Typhimurium in mice. In summary, our results explain the biochemical basis for the effect of virulence protein SpvD and demonstrate that a single amino acid polymorphism can affect the overall virulence of a bacterial pathogen in its host.
authors: From the Section of Microbiology and.
authors: Grzegorz J
authors: GJ
authors: Grabe
authors: Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, United Kingdom and.
authors: Yue
authors: Y
authors: Zhang
authors: Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, United Kingdom and.
authors: Michal
authors: M
authors: Przydacz
authors: From the Section of Microbiology and.
authors: Nathalie
authors: N
authors: Rolhion
authors: Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, United Kingdom and.
authors: Yi
authors: Y
authors: Yang
authors: the Division of Protein and Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge CB2 OQH, United Kingdom.
authors: Jonathan N
authors: JN
authors: Pruneda
authors: the Division of Protein and Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge CB2 OQH, United Kingdom.
authors: David
authors: D
authors: Komander
authors: From the Section of Microbiology and d.holden@imperial.ac.uk.
authors: David W
authors: DW
authors: Holden
authors: Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, United Kingdom and s.hare@imperial.ac.uk.
authors: Stephen A
authors: SA
authors: Hare
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002384:Catalysis; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D020125:Mutation, Missense; D012480:Salmonella Infections / Q000235:genetics / Q000378:metabolism; D012477:Salmonella enteritidis / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity; D013045:Species Specificity; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C445368:SpvD protein, Salmonella enterica; D037521:Virulence Factors
keywords: Salmonella enterica; bacterial pathogenesis; crystal structure; cysteine protease; effector; structure-function