A conserved surface on Toll-like receptor 5 recognizes bacterial flagellin

Erica Andersen-Nissen, Kelly D. Smith, Richard Bonneau, Roland K. Strong, Alan Aderem

Research output: Contribution to journalArticlepeer-review


The molecular basis for Toll-like receptor (TLR) recognition of microbial ligands is unknown. We demonstrate that mouse and human TLR5 discriminate between different flagellins, and we use this difference to map the flagellin recognition site on TLR5 to 228 amino acids of the extracellular domain. Through molecular modeling of the TLR5 ectodomain, we identify two conserved surface-exposed regions. Mutagenesis studies demonstrate that naturally occurring amino acid variation in TLR5 residue 268 is responsible for human and mouse discrimination between flagellin molecules. Mutations within one conserved surface identify residues D295 and D367 as important for flagellin recognition. These studies localize flagellin recognition to a conserved surface on the modeled TLR5 structure, providing detailed analysis of the interaction of a TLR with its ligand. These findings suggest that ligand binding at the β sheets results in TLR activation and provide a new framework for understanding TLR-agonist interactions. JEM

Original languageEnglish (US)
Pages (from-to)393-403
Number of pages11
JournalJournal of Experimental Medicine
Issue number2
StatePublished - Feb 2007

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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