title: A type VI secretion system regulated by OmpR in Yersinia pseudotuberculosis functions to maintain intracellular pH homeostasis.
abstract: Type VI secretion systems (T6SSs) which widely distributed in Gram-negative bacteria have been primarily studied in the context of cell interactions with eukaryotic hosts or other bacteria. We have recently identified a thermoregulated T6SS4 in the enteric pathogen Yersinia pseudotuberculosis. Here we report that OmpR directly binds to the promoter of T6SS4 operon and regulates its expression. Further, we observed that the OmpR-regulated T6SS4 is essential for bacterial survival under acidic conditions and that its expression is induced by low pH. Moreover, we showed that T6SS4 plays a role in pumping H(+)  out of the cell to maintain intracellular pH homeostasis. The acid tolerance phenotype of T6SS4 is dependent on the ATPase activity of ClpV4, one of the components of T6SS4. These results not only uncover a novel strategy utilized by Y. pseudotuberculosis for acid resistance, but also reveal that T6SS, a bacteria secretion system known to be functional in protein transportation has an unexpected function in H(+)  extrusion under acid conditions.
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Weipeng
authors.initials: W
authors.lastname: Zhang
authors.forename: Yao
authors.initials: Y
authors.lastname: Wang
authors.forename: Yunhong
authors.initials: Y
authors.lastname: Song
authors.forename: Tietao
authors.initials: T
authors.lastname: Wang
authors.forename: Shengjuan
authors.initials: S
authors.lastname: Xu
authors.forename: Zhong
authors.initials: Z
authors.lastname: Peng
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Lin
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.forename: Xihui
authors.initials: X
authors.lastname: Shen
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D058947:Bacterial Secretion Systems; D006706:Homeostasis / Q000502:physiology*; D006859:Hydrogen / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D042541:Intracellular Space / Q000737:chemistry*; D050296:Microbial Viability; D009876:Operon / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000502:physiology; D011485:Protein Binding; D015534:Trans-Activators / Q000378:metabolism*; D015011:Yersinia pseudotuberculosis / Q000235:genetics / Q000378:metabolism*; D015012:Yersinia pseudotuberculosis Infections / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; D015534:Trans-Activators; C112177:osmolarity response regulator proteins; D006859:Hydrogen