Journal article
A Chaperone for the Stator Units of a Bacterial Flagellum
mBio, Vol.10(4), e01732-19
08/06/2019
DOI: 10.1128/mBio.01732-19
PMCID: PMC6686046
PMID: 31387912
Abstract
The stator units of the flagellum supply power to the flagellar motor via ion transport across the cytoplasmic membrane and generate torque on the rotor for rotation. Flagellar motors across bacterial species have evolved adaptations that impact and enhance stator function to meet the demands of each species, including producing stator units using different fuel types or various stator units for different motility modalities.
produces one of the most complex and powerful flagellar motors by positioning 17 stator units at a greater radial distance than in most other bacteria to increase power and torque for high velocity of motility. We report another evolutionary adaptation impacting flagellar stators by identifying FlgX as a chaperone for
stator units to ensure sufficient power and torque for flagellar rotation and motility. We discovered that FlgX maintains MotA and MotB stator protein integrity likely through a direct interaction with MotA that prevents their degradation. Suppressor analysis suggested that the physiology of
drives the requirement for FlgX to protect stator units from proteolysis by the FtsH protease complex.
Δ
was strongly attenuated for colonization of the natural avian host, but colonization capacity was greatly restored by a single mutation in MotA. These findings suggest that the likely sole function of FlgX is to preserve stator unit integrity for the motility required for host interactions. Our findings demonstrate another evolved adaptation in motile bacteria to ensure the equipment of the flagellar motor with sufficient power to generate torque for motility.
The bacterial flagellum is a reversible rotating motor powered by ion transport through stator units, which also exert torque on the rotor component to turn the flagellum for motility. Species-specific adaptations to flagellar motors impact stator function to meet the demands of each species to sufficiently power flagellar rotation. We identified another evolutionary adaptation by discovering that FlgX of
preserves the integrity of stator units by functioning as a chaperone to protect stator proteins from degradation by the FtsH protease complex due to the physiology of the bacterium. FlgX is required to maintain a level of stator units sufficient to power the naturally high-torque flagellar motor of
for motility in intestinal mucosal layers to colonize hosts. Our work continues to identify an increasing number of adaptations to flagellar motors across bacterial species that provide the mechanics necessary for producing an effective rotating nanomachine for motility.
Details
- Title: Subtitle
- A Chaperone for the Stator Units of a Bacterial Flagellum
- Creators
- Deborah A Ribardo - The University of Texas Southwestern Medical CenterBrittni R Kelley - University of Tennessee at KnoxvilleJeremiah G Johnson - University of Tennessee at KnoxvilleDavid R Hendrixson - The University of Texas Southwestern Medical Center
- Resource Type
- Journal article
- Publication Details
- mBio, Vol.10(4), e01732-19
- DOI
- 10.1128/mBio.01732-19
- PMID
- 31387912
- PMCID
- PMC6686046
- ISSN
- 2161-2129
- eISSN
- 2150-7511
- Grant note
- R01 AI065539 / NIAID NIH HHS
- Language
- English
- Date published
- 08/06/2019
- Academic Unit
- Microbiology and Immunology
- Record Identifier
- 9984696722002771
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