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Updated: Sep 7, 2025
06:08
Biophysical Characterization of Flagellar Motor Functions
Published on: January 18, 2017
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Swimming Using a Unidirectionally Rotating, Single Stopping Flagellum in the Alpha Proteobacterium Rhodobacter
1Department of Biochemistry, University of Oxford, Oxford, United Kingdom.
Frontiers in Microbiology
|June 20, 2022
Summary
Rhodobacter sphaeroides uses a unique counterclockwise-rotating flagellum for motility. Stops in swimming are caused by CheY homologs binding to the motor, altering flagellar structure and reorienting the cell.
Area of Science:
- Microbiology
- Bacterial Motility
- Cell Biology
Background:
- Rhodobacter sphaeroides possesses two flagellar operons, Fla1 and Fla2.
- Fla1 encodes a single, randomly positioned flagellum, while Fla2 encodes a polar tuft not expressed in lab conditions.
- Unlike other species, R. sphaeroides flagella exclusively rotate counterclockwise.
Purpose of the Study:
- To investigate the mechanism of flagellar rotation and motility in Rhodobacter sphaeroides.
- To understand the role of CheY homologs in regulating flagellar function and cell reorientation.
Main Methods:
- Analysis of flagellar operons and their expression.
- Observation of flagellar rotation patterns.
- Investigation of protein-protein interactions between CheY homologs and the flagellar motor.
Main Results:
- The single flagellum of R. sphaeroides rotates only counterclockwise.
- Motility is characterized by smooth swimming periods interrupted by brief stops.
- Stops are triggered by the binding of one of three competing CheY homologs to the motor.
- During stops, the flagellar filament changes conformation, and the cell reorients.
Conclusions:
- Rhodobacter sphaeroides exhibits a unique flagellar motility system.
- CheY homologs play a critical role in regulating flagellar stops and enabling directed cell movement.
- The conformational changes in the flagellar filament during stops are key to reorientation.
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