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Updated: Aug 30, 2026

Biophysical Characterization of Flagellar Motor Functions
Published on: January 18, 2017
Toll-like receptor 5 recognizes a conserved site on flagellin required for protofilament formation and bacterial
Kelly D Smith1, Erica Andersen-Nissen, Fumitaka Hayashi
1Institute for Systems Biology, 1441 North 34th Street, Seattle, Washington 98103, USA. kelsmith@u.washington.edu
Abstract:
Toll-like receptor 5 (TLR5) recognizes bacterial flagellin and activates host inflammatory responses. In this study, we examine the nature of the TLR5-flagellin interaction. With deletional, insertional and alanine-scanning mutagenesis, we precisely mapped the TLR5 recognition site on flagellin to a cluster of 13 amino acid residues that participate in intermolecular interactions within flagellar protofilaments and that are required for bacterial motility. The recognition site is buried in the flagellar filament, and monomeric flagellin, but not the filamentous molecule, stimulated TLR5. Finally, flagellin coprecipitated with TLR5, indicating close physical interaction between the molecules. These studies demonstrate the exquisite ability of the innate immune system to precisely target a conserved site on flagellin that is essential for bacterial motility.
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