Related Experiment Video
Updated: May 17, 2025
Fluorescence Live-cell Imaging of the Complete Vegetative Cell Cycle of the Slow-growing Social Bacterium Myxococcus xanthus
Published on: June 20, 2018
Xanthomonas oryzae Orphan Response Regulator EmvR Is Involved in Virulence, Extracellular Polysaccharide Production
Pei-Dong Ren1,2, Zeng-Feng Ma3, Qing-Qing Liu2
1Plant Protection Research Institute, Guangxi Academy of Agricultural Science, Key Laboratory of Green Prevention and Control on Fruits and Vegetables in South China Ministry of Agriculture and Rural Affairs, Guangxi Key Laboratory of Biology for Crop Diseases and Insect Pests, Nanning, China.
The orphan response regulator EmvR influences Xanthomonas oryzae pv. oryzicola virulence and motility by regulating type IV pilus synthesis and interacting with two-component systems.
Area of Science:
- Bacterial Pathogenesis
- Molecular Microbiology
- Two-Component Signaling Systems
Background:
- Bacteria utilize two-component systems (TCSs), comprising histidine sensor kinases (HKs) and response regulators (RRs), to adapt to environmental cues.
- Xanthomonas oryzae pv. oryzicola (Xoc) is a significant pathogen causing bacterial leaf streak in rice, primarily infecting through stomata and wounds.
Purpose of the Study:
- To investigate the role of the orphan single-domain response regulator EmvR in Xoc virulence, extracellular polysaccharide (EPS) production, and cell motility.
- To elucidate the molecular mechanisms underlying EmvR's function, including its interactions with other cellular components.
Main Methods:
- Genetic manipulation of Xoc to create emvR deletion mutants and overexpression strains.
- Virulence assays using spraying and infiltration inoculation methods.
- Analysis of bacterial motility (spreading and twitching) and EPS production.
- Biochemical assays to determine interactions between EmvR, PilB, and TCS components (ColS/ColR).
Main Results:
- Deletion of emvR reduced Xoc virulence under spraying inoculation and significantly altered cell motility, weakening spreading and enhancing twitching.
- EmvR overexpression significantly increased EPS production, while deletion did not significantly affect it.
- EmvR directly interacts with PilB, repressing its ATPase activity, and thereby modulating type IV pilus (T4P) biogenesis.
- EmvR also interacts with the TCS components ColS/ColR, influencing Xoc spreading and twitching.
Conclusions:
- EmvR is a crucial regulator of Xoc virulence and motility, particularly in the early stages of infection via rice stomata, through its control of T4P synthesis.
- A novel 'one-to-two' TCS working model is proposed involving ColS/ColR and EmvR in regulating Xoc motility.
- EmvR integrates environmental signals to coordinate bacterial adaptation and infection processes.
