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Journal of Bacteriology, March 2005, p. 2182-2189, Vol. 187, No. 6
0021-9193/05/$08.00+0 doi:10.1128/JB.187.6.2182-2189.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
Environmental pH Sensing: Resolving the VirA/VirG Two-Component System Inputs for Agrobacterium Pathogenesis
Rong Gao and
David G. Lynn*
Center for Fundamental and Applied Molecular Evolution, Departments of Chemistry and Biology, Emory University, Atlanta, Georgia
Received 21 September 2004/
Accepted 14 December 2004
Agrobacterium tumefaciens stands as one of biotechnology's greatest successes, with all plant genetic engineering building on the strategies of this pathogen. By integrating responses to external pHs, phenols, and monosaccharides, this organism mobilizes oncogenic elements to efficiently transform most dicotyledonous plants. We now show that the complex signaling network used to regulate lateral gene transfer can be resolved as individual signaling modules. While pH and sugar perception are coupled through a common pathway, requiring both low pH and sugar for maximal virulence gene expression, various VirA and ChvE alleles can decouple pH and monosaccharide perception. This VirA and ChvE system may represent a common mechanism that underpins external pH perception in prokaryotes, and the use of these simple genetic elements may now be extended to research on specific responses to changes in environmental pH.
* Corresponding author. Mailing address: Center for Fundamental and Applied Molecular Evolution, Departments of Chemistry and Biology, Emory University, Atlanta, GA 30322. Phone: (404) 727-9348. Fax: (404) 727-6586. E-mail:
dlynn2{at}emory.edu.
Journal of Bacteriology, March 2005, p. 2182-2189, Vol. 187, No. 6
0021-9193/05/$08.00+0 doi:10.1128/JB.187.6.2182-2189.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
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