Please use this identifier to cite or link to this item: https://doi.org/10.1074/jbc.M111.295188
Title: Two-component PhoB-PhoR regulatory system and ferric uptake regulator sense phosphate and iron to control virulence genes in type III and VI secretion systems of Edwardsiella tarda
Authors: Chakraborty, S. 
Sivaraman, J. 
Leung, K.Y.
Mok, Y.-K. 
Issue Date: 11-Nov-2011
Citation: Chakraborty, S., Sivaraman, J., Leung, K.Y., Mok, Y.-K. (2011-11-11). Two-component PhoB-PhoR regulatory system and ferric uptake regulator sense phosphate and iron to control virulence genes in type III and VI secretion systems of Edwardsiella tarda. Journal of Biological Chemistry 286 (45) : 39417-39430. ScholarBank@NUS Repository. https://doi.org/10.1074/jbc.M111.295188
Abstract: Inorganic phosphate (P i) and iron are essential nutrients that are depleted by vertebrates as a protective mechanism against bacterial infection. This depletion, however, is sensed by some pathogens as a signal to turn on the expression of virulence genes. Here, we show that the PhoB-PhoR two-component system senses changes in P i concentration, whereas the ferric uptake regulator (Fur) senses changes in iron concentration in Edwardsiella tarda PPD130/91 to regulate the expression of type III and VI secretion systems (T3SS and T6SS) through an E. tarda secretion regulator, EsrC. In sensing low P i concentration, PhoB-PhoR autoregulates and activates the phosphate-specific transport operon, pstSCAB-phoU, by binding directly to the Pho box in the promoters of phoB and pstS. PhoB also binds with EsrC simultaneously on the promoter of an E. tarda virulence protein, evpA, to regulate directly the transcription of genes from T6SS. In addition, PhoB requires and interacts with PhoU to activate esrC and suppress fur indirectly through unidentified regulators. Fur, on the other hand, senses high iron concentration and binds directly to the Fur box in the promoter of evpP to inhibit EsrC binding to the same region. In addition, Fur suppresses transcription of phoB, pstSCAB-phoU, and esrC indirectly via unidentified regulators, suggesting negative cross-talk with the Pho regulon. Physical interactions exist between Fur and PhoU and between Fur and EsrC. Our findings suggest that T3SS and T6SS may carry out distinct roles in the pathogenicity of E. tarda by responding to different environmental factors. © 2011 by The American Society for Biochemistry and Molecular Biology, Inc.
Source Title: Journal of Biological Chemistry
URI: http://scholarbank.nus.edu.sg/handle/10635/102102
ISSN: 00219258
DOI: 10.1074/jbc.M111.295188
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