5-Fluoroindole Inhibits Its Putative Target Methionine Synthase and Pseudomonas syringae pv. actinidiae Virulence
Chun Zhang1, Kunhong Zhao1, Zilin Wu1,2
1State Key Laboratory of Green Pesticide, Center for R&D of Fine Chemicals, Guizhou University, Huaxi District, Guiyang 550025, China.
Abstract:
Bacterial canker caused by Pseudomonas syringae pv. actinidiae (Psa) severely impacts global kiwifruit production. This study shows that 5-fluoroindole exerts significant bactericidal activity against Psa, with a half-maximal effective concentration (EC50) of 15.34 μg/mL, demonstrating a higher efficacy than the positive control copper hydroxide (EC50 = 58.65 μg/mL). 5-Fluoroindole disrupts membrane integrity, induces oxygen species (ROS) accumulation, and triggers apoptosis in Psa. Transcriptome analysis reveals that 5-fluoroindole treatment increased the expression of the methionine synthase II (MetE) gene by 6.28 fold compared with the expression of this gene in the control (CK) group. Microscale thermophoresis and isothermal titration calorimetry show that the dissociation constants of the binding of 5-fluoroindole to MetE protein are 0.33 and 8.55 μM, respectively. Molecular docking experiments indicate that Asp693 is a key binding site and that there is no specific binding between 5-fluoroindole and the Psa MetED693A mutant. This study provides valuable insights for developing effective agents to control kiwifruit bacterial canker.
Insights
5-Fluoroindole effectively combats kiwifruit bacterial canker by killing Pseudomonas syringae pv. actinidiae (Psa). It disrupts bacterial membranes and targets the methionine synthase II (MetE) gene, offering a promising alternative to copper hydroxide treatments.
Area of Science:
- Plant Pathology
- Microbiology
- Biochemistry
Background:
- Bacterial canker, caused by Pseudomonas syringae pv. actinidiae (Psa), poses a significant threat to global kiwifruit production.
- Current control methods, such as copper hydroxide, have limitations and raise environmental concerns.
Purpose of the Study:
- To evaluate the bactericidal activity of 5-fluoroindole against Psa.
- To elucidate the mechanism of action of 5-fluoroindole in Psa.
- To explore the potential of 5-fluoroindole as a novel agent for controlling kiwifruit bacterial canker.
Main Methods:
- Determination of half-maximal effective concentration (EC50) for 5-fluoroindole and copper hydroxide.
- Assessment of membrane integrity, reactive oxygen species (ROS) accumulation, and apoptosis induction in Psa.
- Transcriptome analysis to identify gene expression changes.
- Microscale thermophoresis and isothermal titration calorimetry to study protein-ligand interactions.
- Molecular docking to identify binding sites.
Main Results:
- 5-Fluoroindole exhibited significant bactericidal activity against Psa (EC50 = 15.34 μg/mL), outperforming copper hydroxide (EC50 = 58.65 μg/mL).
- 5-Fluoroindole induced membrane disruption, ROS accumulation, and apoptosis in Psa.
- Treatment with 5-fluoroindole led to a 6.28-fold increase in methionine synthase II (MetE) gene expression.
- Binding studies confirmed the interaction between 5-fluoroindole and MetE protein, with dissociation constants of 0.33 μM and 8.55 μM.
- Molecular docking identified Asp693 as a key binding site, with no binding observed for the MetE D693A mutant.
Conclusions:
- 5-Fluoroindole is a potent bactericide against Psa, demonstrating superior efficacy compared to copper hydroxide.
- The mechanism of action involves membrane disruption, ROS generation, apoptosis induction, and specific binding to the MetE protein.
- 5-Fluoroindole represents a promising candidate for developing novel strategies to manage kiwifruit bacterial canker.
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