title: An inducible and secreted eukaryote-like serine/threonine kinase of Salmonella enterica serovar Typhi promotes intracellular survival and pathogenesis.
abstract: Eukaryote-like serine/threonine kinases (eSTKs) constitute an important family of bacterial virulence factors. Genome analysis had predicted putative eSTKs in Salmonella enterica serovar Typhi, although their functional characterization and the elucidation of their role in pathogenesis are still awaited. We show here that the primary sequence and secondary structure of the t4519 locus of Salmonella Typhi Ty2 have all the signatures of eukaryotic superfamily kinases. t4519 encodes a ∼39-kDa protein (T4519), which shows serine/threonine kinase activities in vitro. Recombinant T4519 (rT4519) is autophosphorylated and phosphorylates the universal substrate myelin basic protein. Infection of macrophages results in decreased viability of the mutant (Ty2Δt4519) strain, which is reversed by gene complementation. Moreover, reactive oxygen species produced by the macrophages signal to the bacteria to induce T4519, which is translocated to the host cell cytoplasm. That T4519 may target a host substrate(s) is further supported by the activation of host cellular signaling pathways and the induction of cytokines/chemokines. Finally, the role of T4519 in the pathogenesis of Salmonella Typhi is underscored by the significantly decreased mortality of mice infected with the Ty2Δt4519 strain and the fact that the competitive index of this strain for causing systemic infection is 0.25% that of the wild-type strain. This study characterizes the first eSTK of Salmonella Typhi and demonstrates its role in promoting phagosomal survival of the bacteria within macrophages, which is a key determinant of pathogenesis. This, to the best of our knowledge, is the first study to describe the essential role of eSTKs in the in vivo pathogenesis of Salmonella spp.
authors.affiliation: Division of Clinical Medicine, National Institute of Cholera and Enteric Diseases, Kolkata, India.
authors.forename: Nagaraja
authors.initials: N
authors.lastname: Theeya
authors.affiliation: Division of Clinical Medicine, National Institute of Cholera and Enteric Diseases, Kolkata, India.
authors.forename: Atri
authors.initials: A
authors.lastname: Ta
authors.affiliation: Division of Clinical Medicine, National Institute of Cholera and Enteric Diseases, Kolkata, India.
authors.forename: Sayan
authors.initials: S
authors.lastname: Das
authors.affiliation: Biomedical Informatics Centre, National Institute of Cholera and Enteric Diseases, Kolkata, India.
authors.forename: Rahul S
authors.initials: RS
authors.lastname: Mandal
authors.affiliation: Biophysics and Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, India.
authors.forename: Oishee
authors.initials: O
authors.lastname: Chakrabarti
authors.affiliation: Structural Biology and Bio-Informatics Division, Indian Institute of Chemical Biology, Kolkata, India.
authors.forename: Saikat
authors.initials: S
authors.lastname: Chakrabarti
authors.affiliation: Division of Electron Microscopy, National Institute of Cholera and Enteric Diseases, Kolkata, India.
authors.forename: Amar N
authors.initials: AN
authors.lastname: Ghosh
authors.affiliation: Division of Clinical Medicine, National Institute of Cholera and Enteric Diseases, Kolkata, India Biomedical Informatics Centre, National Institute of Cholera and Enteric Diseases, Kolkata, India dasss@icmr.org.in.
authors.forename: Santasabuj
authors.initials: S
authors.lastname: Das
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D016207:Cytokines / Q000096:biosynthesis; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008264:Macrophages / Q000276:immunology* / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D010587:Phagocytosis; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D017382:Reactive Oxygen Species / Q000276:immunology; D012485:Salmonella typhi / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity*; D017384:Sequence Deletion / Q000235:genetics; D015398:Signal Transduction / Q000276:immunology; D014435:Typhoid Fever / Q000276:immunology / Q000401:mortality / Q000473:pathology*; D037521:Virulence Factors
chemical_list: D016207:Cytokines; D017382:Reactive Oxygen Species; D037521:Virulence Factors; D017346:Protein Serine-Threonine Kinases