Bacterial flagellar capping proteins adopt diverse oligomeric states
- University of Maryland School of Medicine, United States
- University of Maryland School of Pharmacy, United States
- University of Virginia, United States
- University of Konstanz, Germany
- Technische Universitaet Braunschweig, Germany
- The Hebrew University of Jerusalem, Israel
- Technische Universität Braunschweig, Germany
- University of Maryland College Park, United States
Abstract
Flagella are critical for bacterial motility and pathogenesis. The flagellar capping protein (FliD) regulates filament assembly by chaperoning and sorting flagellin (FliC) proteins after they traverse the hollow filament and exit the growing flagellum tip. In the absence of FliD, flagella are not formed resulting in impaired motility and infectivity. Here, we report the 2.2 Å resolution X-ray crystal structure of FliD from Pseudomonas aeruginosa, the first high-resolution structure of any FliD protein from any bacterium. In combination with a multitude of biophysical and functional analyses, we find that Pseudomonas FliD exhibits unexpected structural similarity to other flagellar proteins at the domain level, adopts a unique hexameric oligomeric state, and depends on flexible determinants for oligomerization. Considering that the flagellin filaments on which FliD oligomers are affixed vary between bacteria in protofilament number, our results suggest that FliD oligomer stoichiometries vary across bacteria to complement their filament assemblies.
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Funding
National Center for Research Resources (NIH S10 RR15899)
- Dorothy Beckett
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2016, Postel 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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Bacterial flagellar capping proteins adopt diverse oligomeric states
eLife 5:e18857.
https://doi.org/10.7554/eLife.18857
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