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Ralstonia pseudosolanacearum PhcQ Controls Quorum Sensing-Dependent Phenotypes by Binding PhcA and Maintaining Its
Min Chen1,2, Lili Luo2, Huixin Yang3
1College of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xian, China.
Molecular Plant Pathology
|July 1, 2026
Summary
PhcQ maintains the stability of PhcA protein, a key component in the quorum-sensing (QS) system of Ralstonia solanacearum species complex (RSSC). This interaction is crucial for regulating virulence and QS-dependent gene expression in this plant pathogen.
Area of Science:
- Microbiology
- Plant Pathology
- Molecular Biology
Background:
- The quorum-sensing (QS) system is vital for regulating virulence in the Ralstonia solanacearum species complex (RSSC).
- The phcBSR operon and phcA genes control QS, with PhcQ potentially activating PhcA and regulating QS-dependent genes.
Purpose of the Study:
- To genetically demonstrate PhcQ's role in the QS regulatory pathway.
- To elucidate the mechanism by which PhcQ influences PhcA function and stability.
Main Methods:
- Genetic deletion and overexpression studies in R. pseudosolanacearum OE1-1.
- Proteomic analysis, Western blot, and structural analysis of PhcA.
- Bimolecular fluorescence complementation and GST pull-down assays.
Main Results:
- PhcQ deletion increased type III secretion system gene expression and decreased exopolysaccharide synthesis gene expression, similar to PhcA mutants.
- PhcQ maintains PhcA protein stability, with PhcA levels reduced by ~59% in phcQ mutants.
- PhcQ directly binds to PhcA, stabilizing it via its C-terminal tail, which is critical for protein stability.
Conclusions:
- PhcQ is a key component of the QS regulatory pathway, maintaining PhcA protein stability.
- This interaction ensures proper QS-dependent gene regulation in RSSC.
- A novel regulatory mechanism involving PhcQ-PhcA binding for virulence control in plant pathogens is revealed.
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