FREE SHIPPING over $40
OVER 9000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Home / Equine Research Bank / Vet Res / The molecular basis for recognition of bacterial ligands at ...
Veterinary research2013; 44(1); 50; doi: 10.1186/1297-9716-44-50

The molecular basis for recognition of bacterial ligands at equine TLR2, TLR1 and TLR6.

Abstract: TLR2 recognises bacterial lipopeptides and lipoteichoic acid, and forms heterodimers with TLR1 or TLR6. TLR2 is relatively well characterised in mice and humans, with published crystal structures of human TLR2/1/Pam3CSK4 and murine TLR2/6/Pam2CSK4. Equine TLR4 is activated by a different panel of ligands to human and murine TLR4, but less is known about species differences at TLR2. We therefore cloned equine TLR2, TLR1 and TLR6, which showed over 80% sequence identity with these receptors from other mammals, and performed a structure-function analysis. TLR2/1 and TLR2/6 from both horses and humans dose-dependently responded to lipoteichoic acid from Staphylococcus aureus, with no significant species difference in EC50 at either receptor pair. The EC50 of Pam2CSK4 was the same for equine and human TLR2/6, indicating amino acid differences between the two species' TLRs do not significantly affect ligand recognition. Species differences were seen between the responses to Pam2CSK4 and Pam3CSK4 at TLR2/1. Human TLR2/1, as expected, responded to Pam3CSK4 with greater potency and efficacy than Pam2CSK4. At equine TLR2/1, however, Pam3CSK4 was less potent than Pam2CSK4, with both ligands having similar efficacies. Molecular modelling indicates that the majority of non-conserved ligand-interacting residues are at the periphery of the TLR2 binding pocket and in the ligand peptide-interacting regions, which may cause subtle effects on ligand positioning. These results suggest that there are potentially important species differences in recognition of lipopeptides by TLR2/1, which may affect how the horse deals with bacterial infections.
Get Full Text
Publication Date: 2013-07-04 PubMed ID: 23826682PubMed Central: PMC3716717DOI: 10.1186/1297-9716-44-50Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
LinkedInCopy
  • Journal Article
  • Research Support
  • Non-U.S. Gov't

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research investigates the molecular basis of bacterial detection in horses, specifically through three types of Toll-like receptors (TLRs): TLR2, TLR1, and TLR6. It found that despite some species differences between horses and humans, these receptors in both species responded similarly to certain bacterial substances, suggesting they play a vital role in bacterial infection response.

Introduction and Purpose

  • The research aimed to understand how equine TLR2, TLR1, and TLR6 recognize bacterial ligands, substances that can cause an immune response.
  • The study was sparked by the knowledge that TLR4 activates differently in horses than in humans and mice, suggesting there might be species differences in the TLR2 receptor set as well.
  • Understanding these differences could have significance for how horses deal with bacterial infections.

Methodology

  • The researchers cloned the equine TLR2, TLR1, and TLR6 and conducted a structure-function analysis.
  • They gathered sequence identity information between the equine receptors and those of other mammals which appeared to show over 80% similarity.

Findings

  • TLR2/1 and TLR2/6 pairs from both horses and humans exhibited a dose-dependent response to lipoteichoic acid from Staphylococcus aureus and showed no significant species difference in EC50, the dosage concentration which triggers a half-max response.
  • The researchers found no significant differences in ligand recognition due to amino acid differences between human and horse TLRs when tested with Pam2CSK4, a synthetic bacterial lipopeptide.
  • There were differences observed between the response of human and horse TLR2/1 to two synthetic lipopeptides, Pam2CSK4 and Pam3CSK4. The human TLR2/1 responded to Pam3CSK4 more potently and efficiently than Pam2CSK4, while the horse TLR2/1 showed less potency for Pam3CSK4 than Pam2CSK4.
  • Molecular modelling suggested the occurrence of some non-conserved ligand-interacting residues, which might impact ligand positioning.

Conclusion

  • The study concluded that important species differences exist in lipopeptide recognition by TLR2/1, potentially influencing the equine response to bacterial infections.

Cite This Article

APA
Irvine KL, Hopkins LJ, Gangloff M, Bryant CE. (2013). The molecular basis for recognition of bacterial ligands at equine TLR2, TLR1 and TLR6. Vet Res, 44(1), 50. https://doi.org/10.1186/1297-9716-44-50

Publication

Veterinary research
ISSN: 1297-9716
NlmUniqueID: 9309551
Country: England
Language: English
Volume: 44
Issue: 1
Pages: 50

Researcher Affiliations

Irvine, Katherine Lucy
  • Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB30ES, UK. ceb27@cam.ac.uk.
Hopkins, Lee Jason
    Gangloff, Monique
      Bryant, Clare Elizabeth

        MeSH Terms

        • Animals
        • HEK293 Cells
        • Horses / genetics
        • Horses / metabolism
        • Humans
        • Ligands
        • Lipopeptides / metabolism
        • Lipopolysaccharides / metabolism
        • Mice
        • Molecular Conformation
        • Reverse Transcriptase Polymerase Chain Reaction / veterinary
        • Staphylococcus aureus / physiology
        • Teichoic Acids / metabolism
        • Toll-Like Receptor 1 / chemistry
        • Toll-Like Receptor 1 / genetics
        • Toll-Like Receptor 1 / metabolism
        • Toll-Like Receptor 2 / chemistry
        • Toll-Like Receptor 2 / genetics
        • Toll-Like Receptor 2 / metabolism
        • Toll-Like Receptor 6 / chemistry
        • Toll-Like Receptor 6 / genetics
        • Toll-Like Receptor 6 / metabolism

        Grant Funding

        • Biotechnology and Biological Sciences Research Council
        • Wellcome Trust

        References

        This article includes 38 references
        1. Kang J, Nan X, Jin M, Youn S, Ryu Y, Mah S, Han S, Lee H, Paik S, Lee J. Recognition of lipopeptide patterns by Toll-like receptor 2-Toll-like receptor 6 heterodimer. Immunity 2009;31:873–884.
          doi: 10.1016/j.immuni.2009.09.018pubmed: 19931471google scholar: lookup
        2. Jin M, Kim S, Heo J, Lee M, Kim H, Paik S, Lee H, Lee J. Crystal structure of the TLR1-TLR2 heterodimer induced by binding of a tri-acylated lipopeptide. Cell 2007;130:1071–1082.
          doi: 10.1016/j.cell.2007.09.008pubmed: 17889651google scholar: lookup
        3. Zahringer U, Lindner B, Inamura S, Heine H, Alexander C. TLR2 - promiscuous or specific? A critical re-evaluation of a receptor expressing apparent broad specificity. Immunobiology 2008;213:205–224.
          doi: 10.1016/j.imbio.2008.02.005pubmed: 18406368google scholar: lookup
        4. Omueti K, Beyer J, Johnson C, Lyle E, Tapping R. Domain exchange between human toll-like receptors 1 and 6 reveals a region required for lipopeptide discrimination. J Biol Chem 2005;280:36616–36625.
          doi: 10.1074/jbc.M504320200pubmed: 16129684google scholar: lookup
        5. Takeuchi O, Hoshino K, Akira S. Cutting edge: TLR2-deficient and MyD88-deficient mice are highly susceptible to Staphylococcus aureus infection. J Immunol 2000;165:5392–5396.
          pubmed: 11067888
        6. Texereau J, Chiche J, Taylor W, Choukroun G, Comba B, Mira J. The importance of Toll-like receptor 2 polymorphisms in severe infections. Clin Infect Dis 2005;41(Suppl 7):S408–S415.
          pubmed: 16237639
        7. Bochud P, Hawn T, Siddiqui M, Saunderson P, Britton S, Abraham I, Argaw A, Janer M, Zhao L, Kaplan G, Aderem A. Toll-like receptor 2 (TLR2) polymorphisms are associated with reversal reaction in leprosy. J Infect Dis 2008;197:253–261.
          doi: 10.1086/524688pmc: PMC3077295pubmed: 18177245google scholar: lookup
        8. Wood J, Newton J, Chanter N, Mumford J. Association between respiratory disease and bacterial and viral infections in British racehorses. J Clin Microbiol 2005;43:120–126.
          doi: 10.1128/JCM.43.1.120-126.2005pmc: PMC540098pubmed: 15634959google scholar: lookup
        9. Corley K, Pearce G, Magdesian K, Wilson W. Bacteraemia in neonatal foals: clinicopathological differences between Gram-positive and Gram-negative infections, and single organism and mixed infections. Equine Vet J 2007;39:84–89.
          doi: 10.2746/042516407X157585pubmed: 17228602google scholar: lookup
        10. Figueiredo M, Vandenplas M, Hurley D, Moore J. Differential induction of MyD88- and TRIF-dependent pathways in equine monocytes by Toll-like receptor agonists. Vet Immunol Immunopathol 2009;127:125–134.
          doi: 10.1016/j.vetimm.2008.09.028pubmed: 19019456google scholar: lookup
        11. Declue A, Johnson P, Day J, Amorim J, Honaker A. Pathogen associated molecular pattern motifs from Gram-positive and Gram-negative bacteria induce different inflammatory mediator profiles in equine blood. Vet J 2011;192:455–460.
          pubmed: 21974971
        12. Bryant C, Spring D, Gangloff M, Gay N. The molecular basis of the host response to lipopolysaccharide. Nat Rev Microbiol 2010;8:8–14.
          pubmed: 19946286
        13. Walsh C, Gangloff M, Monie T, Smyth T, Wei B, McKinley T, Maskell D, Gay N, Bryant C. Elucidation of the MD-2/TLR4 interface required for signaling by lipid IVa. J Immunol 2008;181:1245–1254.
          pubmed: 18606678
        14. Golenbock D, Hampton R, Qureshi N, Takayama K, Raetz C. Lipid A-like molecules that antagonize the effects of endotoxins on human monocytes. J Biol Chem 1991;266:19490–19498.
          pubmed: 1918061
        15. Fidalgo-Carvalho I, Craigo J, Barnes S, Costa-Ramos C, Montelaro R. Characterization of an equine macrophage cell line: application to studies of EIAV infection. Vet Microbiol 2009;136:8–19.
          doi: 10.1016/j.vetmic.2008.10.010pmc: PMC2689946pubmed: 19038510google scholar: lookup
        16. Schwede T, Kopp J, Guex N, Peitsch M. SWISS-MODEL: an automated protein homology-modeling server. Nucleic Acids Res 2003;31:3381–3385.
          doi: 10.1093/nar/gkg520pmc: PMC168927pubmed: 12824332google scholar: lookup
        17. Kopp J, Schwede T. The SWISS-MODEL Repository: new features and functionalities. Nucleic Acids Res 2006;34(Database issue):D315–D318.
          pmc: PMC1347419pubmed: 16381875
        18. Arnold K, Bordoli L, Kopp J, Schwede T. The SWISS-MODEL workspace: a web-based environment for protein structure homology modelling. Bioinformatics 2006;22:195–201.
          doi: 10.1093/bioinformatics/bti770pubmed: 16301204google scholar: lookup
        19. Kiefer F, Arnold K, Kunzli M, Bordoli L, Schwede T. The SWISS-MODEL repository and associated resources. Nucleic Acids Res 2009;37(Database issue):D387–D392.
          pmc: PMC2686475pubmed: 18931379
        20. Wang J, Manning B, Wu Q, Blankson S, Bouchier-Hayes D, Redmond H. Endotoxin/lipopolysaccharide activates NF-kappa B and enhances tumor cell adhesion and invasion through a beta 1 integrin-dependent mechanism. J Immunol 2003;170:795–804.
          pubmed: 12517943
        21. Schroder N, Morath S, Alexander C, Hamann L, Hartung T, Zahringer U, Gobel U, Weber J, Schumann R. Lipoteichoic acid (LTA) of streptococcus pneumoniae and staphylococcus aureus activates immune cells via Toll-like receptor (TLR)-2, lipopolysaccharide-binding protein (LBP), and CD14, whereas TLR-4 and MD-2 are not involved. J Biol Chem 2003;278:15587–15594.
          doi: 10.1074/jbc.M212829200pubmed: 12594207google scholar: lookup
        22. Figueroa L, Xiong Y, Song C, Piao W, Vogel S, Medvedev A. The Asp299Gly polymorphism alters TLR4 signaling by interfering with recruitment of MyD88 and TRIF. J Immunol 2012;188:4506–4515.
          doi: 10.4049/jimmunol.1200202pmc: PMC3531971pubmed: 22474023google scholar: lookup
        23. Schwandner R, Dziarski R, Wesche H, Rothe M, Kirschning C. Peptidoglycan- and lipoteichoic acid-induced cell activation is mediated by toll-like receptor 2. J Biol Chem 1999;274:17406–17409.
          doi: 10.1074/jbc.274.25.17406pubmed: 10364168google scholar: lookup
        24. Bunk S, Sigel S, Metzdorf D, Sharif O, Triantafilou K, Triantafilou M, Hartung T, Knapp S, von Aulock S. Internalization and coreceptor expression are critical for TLR2-mediated recognition of lipoteichoic acid in human peripheral blood. J Immunol 2010;185:3708–3717.
          doi: 10.4049/jimmunol.0901660pubmed: 20713893google scholar: lookup
        25. Guan Y, Ranoa D, Jiang S, Mutha S, Li X, Baudry J, Tapping R. Human TLRs 10 and 1 share common mechanisms of innate immune sensing but not signaling. J Immunol 2010;184:5094–5103.
          doi: 10.4049/jimmunol.0901888pubmed: 20348427google scholar: lookup
        26. O’Neill L, Bowie A. The family of five: TIR-domain-containing adaptors in Toll-like receptor signalling. Nat Rev Immunol 2007;7:353–364.
          doi: 10.1038/nri2079pubmed: 17457343google scholar: lookup
        27. Kruithof E, Satta N, Liu J, Dunoyer-Geindre S, Fish R. Gene conversion limits divergence of mammalian TLR1 and TLR6. BMC Evol Biol 2007;7:148.
          doi: 10.1186/1471-2148-7-148pmc: PMC2077338pubmed: 17727694google scholar: lookup
        28. Grabiec A, Meng G, Fichte S, Bessler W, Wagner H, Kirschning C. Human but not murine toll-like receptor 2 discriminates between tri-palmitoylated and tri-lauroylated peptides. J Biol Chem 2004;279:48004–48012.
          doi: 10.1074/jbc.M405311200pubmed: 15342637google scholar: lookup
        29. Yamamoto M, Sato S, Hemmi H, Sanjo H, Uematsu S, Kaisho T, Hoshino K, Takeuchi O, Kobayashi M, Fujita T, Takeda K, Akira S. Essential role for TIRAP in activation of the signalling cascade shared by TLR2 and TLR4. Nature 2002;420:324–329.
          doi: 10.1038/nature01182pubmed: 12447441google scholar: lookup
        30. Horng T, Barton G, Flavell R, Medzhitov R. The adaptor molecule TIRAP provides signalling specificity for Toll-like receptors. Nature 2002;420:329–333.
          doi: 10.1038/nature01180pubmed: 12447442google scholar: lookup
        31. Kenny E, Talbot S, Gong M, Golenbock D, Bryant C, O’Neill L. MyD88 adaptor-like is not essential for TLR2 signaling and inhibits signaling by TLR3. J Immunol 2009;183:3642–3651.
          doi: 10.4049/jimmunol.0901140pubmed: 19717524google scholar: lookup
        32. Santos-Sierra S, Deshmukh S, Kalnitski J, Kuenzi P, Wymann M, Golenbock D, Henneke P. Mal connects TLR2 to PI3Kinase activation and phagocyte polarization. EMBO J 2009;28:2018–2027.
          doi: 10.1038/emboj.2009.158pmc: PMC2718282pubmed: 19574958google scholar: lookup
        33. Verstak B, Nagpal K, Bottomley S, Golenbock D, Hertzog P, Mansell A. MyD88 adapter-like (Mal)/TIRAP interaction with TRAF6 is critical for TLR2- and TLR4-mediated NF-kappaB proinflammatory responses. J Biol Chem 2009;284:24192–24203.
          doi: 10.1074/jbc.M109.023044pmc: PMC2782013pubmed: 19592497google scholar: lookup
        34. Mansell A, Smith R, Doyle S, Gray P, Fenner J, Crack P, Nicholson S, Hilton D, O’Neill L, Hertzog P. Suppressor of cytokine signaling 1 negatively regulates Toll-like receptor signaling by mediating Mal degradation. Nat Immunol 2006;7:148–155.
          pubmed: 16415872
        35. Gray P, Dunne A, Brikos C, Jefferies C, Doyle S, O’Neill L. MyD88 adapter-like (Mal) is phosphorylated by Bruton’s tyrosine kinase during TLR2 and TLR4 signal transduction. J Biol Chem 2006;281:10489–10495.
          doi: 10.1074/jbc.M508892200pubmed: 16439361google scholar: lookup
        36. Gupta S, Wu H. Identification and subcellular localization of apolipoprotein N-acyltransferase in escherichia coli. FEMS Microbiol Lett 1991;62:37–41.
          pubmed: 2032623
        37. Kurokawa K, Kim M, Ichikawa R, Ryu K, Dohmae N, Nakayama H, Lee B, Marche P. Environment-mediated accumulation of diacyl lipoproteins over their triacyl counterparts in staphylococcus aureus. J Bacteriol 2012;194:3299–3306.
          doi: 10.1128/JB.00314-12pmc: PMC3434734pubmed: 22467779google scholar: lookup
        38. Olson N, Hellyer P, Dodam J. Mediators and vascular effects in response to endotoxin. Br Vet J 1995;151:489–522.
          doi: 10.1016/S0007-1935(05)80023-5pubmed: 8556312google scholar: lookup
        Subscribe to our newsletter
        Join 99,344 horse owners like you who receive our email updates on horse health and nutrition.