Bacterial flagella grow through an injection-diffusion mechanism
- Helmholtz Centre for Infection Research, Germany
- Osaka University, Japan
- Institute of Science and Technology Austria, Austria
- Laval University, Canada
- Max Planck Institute for Infection Biology, Germany
- IBM Thomas J. Watson Research Center, United States
- University of Utah, United States
Abstract
The bacterial flagellum is a self-assembling nanomachine. The external flagellar filament, several times longer than a bacterial cell body, is made of a few tens of thousands subunits of a single protein: flagellin. A fundamental problem concerns the molecular mechanism of how the flagellum grows outside the cell, where no discernible energy source is available. Here, we monitored the dynamic assembly of individual flagella using in situ labelling and real-time immunostaining of elongating flagellar filaments. We report that the rate of flagellum growth, initially ∼1,700 amino acids per second, decreases with length and that the previously proposed chain mechanism does not contribute to the filament elongation dynamics. Inhibition of the proton motive force-dependent export apparatus revealed a major contribution of substrate injection in driving filament elongation. The combination of experimental and mathematical evidence demonstrates that a simple, injection-diffusion mechanism controls bacterial flagella growth outside the cell.
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Author details
Funding
Helmholtz-Gemeinschaft (VH-NG-932)
- Marc Erhardt
Japan Society for the Promotion of Science (15H01640)
- Tohru Minamino
Max-Planck-Gesellschaft
- Emmanuelle Charpentier
National Institutes of Health (R01GM081747)
- Yuhai Tu
European Commission (334030)
- Marc Erhardt
Japan Society for the Promotion of Science (25000013)
- Keiichi Namba
Natural Sciences and Engineering Research Council of Canada
- Simon Rainville
Alexander von Humboldt-Stiftung
- Thibaud T Renault
Japan Society for the Promotion of Science (26293097)
- Tohru Minamino
Japan Society for the Promotion of Science (24117004)
- Tohru Minamino
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2017, Renault et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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