title: ExsE Is a Negative Regulator for T3SS Gene Expression inVibrio alginolyticus.
abstract: Type III secretion systems (T3SSs) contribute to microbial pathogenesis ofVibriospecies, but the regulatory mechanisms are complex. We determined if the classic ExsACDE protein-protein regulatory model fromPseudomonas aeruginosaapplies toVibrio alginolyticus. Deletion mutants inV. alginolyticusdemonstrated that, as expected, the T3SS is positively regulated by ExsA and ExsC and negatively regulated by ExsD and ExsE. Interestingly, deletion ofexsEenhanced the ability ofV. alginolyticusto induce host-cell death while cytotoxicity was inhibited byin transcomplementation of this gene in a wild-type strain, a result that differs from a similar experiment withVibrio parahaemolyticusExsE. We further showed that ExsE is a secreted protein that does not contribute to adhesion to Fathead minnow epithelial cells. Anin vitroco-immunoprecipitation assay confirmed that ExsE binds to ExsC to exert negative regulatory effect on T3SS genes. T3SS inV. alginolyticuscan be activated in the absence of physical contact with host cells and a separate regulatory pathway appears to contribute to the regulation of ExsA. Consequently, like ExsE fromP. aeruginosa, ExsE is a negative regulator for T3SS gene expression inV. alginolyticus. Unlike theV. parahaemolyticusorthologue, however, deletion ofexsEfromV. alginolyticusenhancedin vitrocytotoxicity.
authors.affiliation: Institute of Marine Biology, College of Oceanography, Hohai UniversityNanjing, China; Paul G. Allen School for Global Animal Health, Washington State UniversityPullman, WA, USA.
authors.forename: Jinxin
authors.initials: J
authors.lastname: Liu
authors.affiliation: Paul G. Allen School for Global Animal Health, Washington State University Pullman, WA, USA.
authors.forename: Shao-Yeh
authors.initials: SY
authors.lastname: Lu
authors.affiliation: Paul G. Allen School for Global Animal Health, Washington State University Pullman, WA, USA.
authors.forename: Lisa H
authors.initials: LH
authors.lastname: Orfe
authors.affiliation: Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences Guangzhou, China.
authors.forename: Chun-Hua
authors.initials: CH
authors.lastname: Ren
authors.affiliation: Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences Guangzhou, China.
authors.forename: Chao-Qun
authors.initials: CQ
authors.lastname: Hu
authors.affiliation: Paul G. Allen School for Global Animal Health, Washington State University Pullman, WA, USA.
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Call
authors.affiliation: Paul G. Allen School for Global Animal Health, Washington State University Pullman, WA, USA.
authors.forename: Johannetsy J
authors.initials: JJ
authors.lastname: Avillan
authors.affiliation: Institute of Marine Biology, College of Oceanography, Hohai UniversityNanjing, China; Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of SciencesGuangzhou, China.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Zhao
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D002470:Cell Survival; D002478:Cells, Cultured; D003530:Cyprinidae; D004847:Epithelial Cells / Q000382:microbiology; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D047468:Immunoprecipitation; D011485:Protein Binding; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D000069296:Type III Secretion Systems / Q000378:metabolism*; D044149:Vibrio alginolyticus / Q000235:genetics* / Q000378:metabolism*
chemical_list: D012097:Repressor Proteins; D000069296:Type III Secretion Systems
keywords: ExsACDE; ExsE; T3SS; Vibrio alginolyticus; gene expression; negative regulator