Related Experiment Video
Updated: Jul 17, 2026
07:42
Fluorescence Assays for the Study of Mycobacterium tuberculosis Interaction with the Immune Receptor SLAMF1
Published on: February 28, 2025
A conserved surface on Toll-like receptor 5 recognizes bacterial flagellin
Erica Andersen-Nissen1, Kelly D Smith, Richard Bonneau
1Institute for Systems Biology, Seattle, WA 98103, USA.
The Journal of Experimental Medicine
|February 7, 2007
Summary
Toll-like receptor 5 (TLR5) recognizes bacterial flagellins. Researchers mapped the flagellin recognition site on TLR5, identifying key residues responsible for discriminating between different flagellins and enabling TLR activation.
Area of Science:
- Immunology
- Molecular Biology
- Structural Biology
Background:
- The molecular mechanisms underlying Toll-like receptor (TLR) ligand recognition remain largely unelucidated.
- Toll-like receptor 5 (TLR5) is crucial for detecting bacterial flagellins, a key component of microbial ligands.
Purpose of the Study:
- To determine the molecular basis of flagellin recognition by TLR5.
- To map the specific region on TLR5 responsible for discriminating between different flagellin molecules.
Main Methods:
- Utilized comparative analysis of mouse and human TLR5 function.
- Employed molecular modeling of the TLR5 ectodomain.
- Conducted site-directed mutagenesis studies on conserved residues.
Main Results:
- Identified a 228-amino acid region within the TLR5 extracellular domain critical for flagellin recognition.
- Discovered that variation at TLR5 residue 268 underlies species-specific flagellin discrimination.
- Pinpointed residues D295 and D367 within a conserved surface as essential for flagellin binding and subsequent TLR activation.
Conclusions:
- Flagellin recognition by TLR5 is localized to a specific conserved surface on its extracellular domain.
- Ligand binding to beta sheets within this region initiates TLR activation.
- These findings provide a structural framework for understanding TLR-ligand interactions and TLR activation pathways.
Related Concept Videos
01:18Flagella and Motility in Bacteria
Flagella are specialized, thread-like structures that extend from a bacteria's cell envelope. They play a crucial role in motility and chemotaxis. Their structural organization and functioning exemplify sophisticated biological engineering, enabling bacterial survival and adaptability in diverse environments.Structure of the FlagellumA bacterial flagellum consists of three key components: the filament, the hook, and basal body. The filament, a long, helical structure composed of repeating...
01:19Formation of Lipopolysaccharides
Lipopolysaccharides (LPS) are crucial components of the outer membrane of Gram-negative bacteria, serving both structural and functional roles. It contributes to membrane stability and protects bacteria from host immune responses. LPS is composed of three major regions—lipid A, a core oligosaccharide, and an O antigen. The biosynthesis and assembly of LPS involve a highly coordinated set of enzymatic reactions and transport mechanisms. Additionally, LPS is recognized as an endotoxin, triggering...
01:28Fimbriae, Pili, and Axial Filaments
Fimbriae and pili are specialized bacterial surface structures that play pivotal roles in adhesion, genetic exchange, and motility. Composed primarily of pilin protein, these hairlike appendages are crucial for bacterial survival and pathogenicity in various environments.Fimbriae: Adhesion and PathogenicityFimbriae are fine, filamentous structures measuring 2–10 nanometers in diameter and are densely distributed on the bacterial cell surface. They facilitate bacterial adhesion to abiotic...
01:27Chemotaxis in E. coli
Chemotaxis in Escherichia coli is a sensory-driven motility mechanism that enables bacteria to navigate chemical gradients, moving toward beneficial environments while avoiding harmful conditions. This process relies on a signal transduction system integrating external chemical cues with flagellar motor control.Chemoreceptors and Signal DetectionE. coli detects chemical gradients through methyl-accepting chemotaxis proteins (MCPs), which are membrane-bound chemoreceptors that sense attractants...
01:29Cytoskeletal Proteins in Bacteria
Bacterial cells were initially considered simple, randomly organized structures lacking a cytoskeleton. However, the discovery of cytoskeleton homologs in bacteria led to the change of this opinion. Bacterial cytoskeletal filaments regulate the cell shape, cell polarity, cell division, and partitioning of plasmids during cell division. It was later discovered that bacterial cytoskeletal proteins, mainly actin and tubulin homologs, are diverse compared to their eukaryotic counterparts. On the...
01:13Special Staining Techniques
Specialized staining techniques play a vital role in microbiology by enabling the visualization of specific bacterial structures that remain undetectable with standard microscopy methods. These techniques not only enhance the structural visualization of bacterial cells but also provide critical insights into their pathogenicity and classification. Additionally, they support diagnostic and research endeavors in microbiology by identifying key bacterial features.Capsule Staining for Virulence...