title: Identification and functional characterization of EseH, a new effector of the type III secretion system of Edwardsiella piscicida.
abstract: Edwardsiella piscicida, a bacterial pathogen in fish and humans, expresses a type III secretion system (T3SS) that is critical for pathogen virulence and disease development. However, little is known about the associated effectors and their functional importance. In this study, we identified the ETAE_1757 encoded protein, termed here E. piscicida secretion effector H (EseH) as a novel T3SS effector. We found that upon infection with E. piscicida, EseH is translocated into nucleus of host cells which required the T3SS. Homology modelling analysis suggests that EseH is an enzyme that belongs to the family of phosphothreothine lyases. Consistently, EseH inhibited phosphorylation of ERK1/2, p38α and JNK MAPK pathways in host cells, but had no effect on the NF-kB pathway. Furthermore, mutation of the critical amino acid residues predicted to confer phosphothreonine lyase activity abolished the ability of EseH to inhibit phosphorylation of ERK1/2, p38α and JNK MAPK pathways in host cells. In addition, we found an increase in transcript levels of TNF-α, IL-12, IL-10 and IFN-γ in zebrafish infected with the eseH mutant when compared with the wild type bacterium. Importantly, the virulence of E. piscicida deficient in EseH was highly attenuated in the zebrafish infection model which correlated with decreased loads of the mutant bacterium in both liver and kidney. Complementation of the E. piscicida mutant strain with EseH restored virulence in zebrafish. These results identified EseH as a critical T3SS effector that contributes to virulence by targeting MAPK signalling during E. piscicida infection.
authors.affiliation: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China.
authors.forename: Mingyu
authors.initials: M
authors.lastname: Hou
authors.affiliation: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China.
authors.forename: Ran
authors.initials: R
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China.|Shanghai Engineering Research Center of Marine Cultured Animal Vaccines, Shanghai, 200237, China.|Shanghai Collaborative Innovation Center for Biomanufacturing, Shanghai, 200237, China.
authors.forename: Dahai
authors.initials: D
authors.lastname: Yang
authors.affiliation: Department of Pathology and Comprehensive Cancer Center, University of Michigan, Ann Arbor, MI, 48109, USA.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Núñez
authors.affiliation: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China.
authors.forename: Zhuang
authors.initials: Z
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China.|Shanghai Engineering Research Center of Marine Cultured Animal Vaccines, Shanghai, 200237, China.|Shanghai Collaborative Innovation Center for Biomanufacturing, Shanghai, 200237, China.
authors.forename: Qiyao
authors.initials: Q
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China.|Shanghai Engineering Research Center of Marine Cultured Animal Vaccines, Shanghai, 200237, China.|Shanghai Collaborative Innovation Center for Biomanufacturing, Shanghai, 200237, China.
authors.forename: Yuanxing
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China.|Shanghai Engineering Research Center of Marine Cultured Animal Vaccines, Shanghai, 200237, China.|Shanghai Collaborative Innovation Center for Biomanufacturing, Shanghai, 200237, China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Liu
mesh_terms: D021581:Active Transport, Cell Nucleus; D019943:Amino Acid Substitution; D000818:Animals; D058491:Bacterial Load; D019757:Carbon-Oxygen Lyases / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000737:chemistry; D016207:Cytokines / Q000032:analysis; D004252:DNA Mutational Analysis; D004195:Disease Models, Animal; D020594:Edwardsiella / Q000235:genetics* / Q000472:pathogenicity*; D004756:Enterobacteriaceae Infections / Q000382:microbiology / Q000473:pathology; D055786:Gene Knockout Techniques; D005816:Genetic Complementation Test; D054884:Host-Pathogen Interactions; D057131:Immune Evasion; D007668:Kidney / Q000382:microbiology; D008099:Liver / Q000382:microbiology; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D000069296:Type III Secretion Systems / Q000378:metabolism*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*; D015027:Zebrafish
chemical_list: D016207:Cytokines; D000069296:Type III Secretion Systems; D037521:Virulence Factors; D020929:Mitogen-Activated Protein Kinase Kinases; D019757:Carbon-Oxygen Lyases