Related Experiment Video
Updated: Jun 17, 2025
07:59
Investigating Flagella-Driven Motility in Escherichia coli by Applying Three Established Techniques in a Series
Published on: May 10, 2020
7.6K
Structural Basis of Directional Switching by the Bacterial Flagellum
Steven Johnson1, Justin C Deme1, Emily J Furlong2
1Center for Structural Biology, CCR, NCI, Frederick, MD 21702-1201 USA.
Research Square
|August 7, 2024
Summary
Salmonella bacteria use a unidirectional ion flow to achieve bidirectional flagellar rotation. This is accomplished through 180-degree domain rotations in the FliG protein, enabling bacterial swimming.
Area of Science:
- Microbiology
- Structural Biology
- Biophysics
Background:
- The bacterial flagellum powers swimming via ion flow across the inner membrane.
- Salmonella bacteria exhibit bidirectional flagellar rotation despite unidirectional ion flow, a mechanism not fully understood.
Purpose of the Study:
- To elucidate the structural basis of bidirectional flagellar rotation in Salmonella.
- To understand how unidirectional ion flow drives bidirectional rotation.
Main Methods:
- Cryo-electron microscopy (cryo-EM) was used to determine structures of Salmonella flagellar basal bodies.
- High-resolution cryo-EM was employed to visualize the MotA5B2 stator complex interacting with FliG.
Main Results:
- Cryo-EM structures revealed distinct conformations of the flagellar basal body for both rotation directions.
- Conformational changes involve 180-degree rotations of the N- and C-terminal domains of the FliG protein.
- The MotA5B2 stator complex interacts with the FliG C-terminal domain, explaining ion flow utilization.
Conclusions:
- Unidirectional ion flow is converted to bidirectional flagellar rotation through specific conformational changes in FliG.
- The study provides a structural mechanism for how Salmonella achieves directional swimming control.
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