Chemosensory systems interact to shape relevant traits for bacterial plant pathogenesis

Area of Science:

• Microbiology
• Bacterial Physiology
• Plant Pathology

Background:

• Chemosensory systems are crucial for bacterial adaptation to environmental cues.
• Understanding the distinct roles of multiple chemosensory systems in bacteria is limited.
• Pseudomonas syringae pv. tomato DC3000, a model plant pathogen, possesses several chemosensory systems.

Purpose of the Study:

• To deeply characterize the F6, F8, and alternative cellular functions (ACF) chemosensory systems in Pseudomonas syringae pv. tomato DC3000.
• To elucidate the specific functions of these systems in regulating bacterial traits, including motility, biofilm formation, and virulence.
• To investigate potential crosstalk among these chemosensory systems.

Main Methods:

• Cryo-electron tomography was used to visualize the F6 and F8 chemosensory systems.
• Functional analysis was performed to determine the roles of F6, F8, and ACF systems in bacterial behavior.
• Biochemical assays were employed to study interactions between system components.

Main Results:

• The F6 system controls chemotaxis and swimming motility.
• F8 and ACF systems also modulate swimming motility, with distinct regulatory mechanisms for biofilm formation.
• Crosstalk was observed between F6, F8, and ACF systems, particularly involving the WspR response regulator.
• All three chemosensory systems were found to play a role in regulating bacterial virulence.

Conclusions:

• The F6, F8, and ACF chemosensory systems in Pseudomonas syringae pv. tomato DC3000 have distinct and overlapping roles in regulating motility and biofilm formation.
• Interactions between kinases and response regulators highlight significant crosstalk among these systems.
• These chemosensory systems collectively contribute to the virulence of this important plant pathogen.