title: Adaptive evolution of Toll-like receptor 5 in domesticated mammals.
abstract: BACKGROUND
  Previous studies have proposed that mammalian toll like receptors (TLRs) have evolved under diversifying selection due to their role in pathogen detection. To determine if this is the case, we examined the extent of adaptive evolution in the TLR5 gene in both individual species and defined clades of the mammalia.
  
  
  RESULTS
  In support of previous studies, we find evidence of adaptive evolution of mammalian TLR5. However, we also show that TLR5 genes of domestic livestock have a concentration of single nucleotide polymorphisms suggesting a specific signature of adaptation. Using codon models of evolution we have identified a concentration of rapidly evolving codons within the TLR5 extracellular domain a site of interaction between host and the bacterial surface protein flagellin.
  
  
  CONCLUSIONS
  The results suggest that interactions between pathogen and host may be driving adaptive change in TLR5 by competition between species. In support of this, we have identified single nucleotide polymorphisms (SNP) in sheep and cattle TLR5 genes that are co-localised and co-incident with the predicted adaptive codons suggesting that adaptation in this region of the TLR5 gene is on-going in domestic species.
authors: School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington LE12 5RD, UK.
authors: Sarah A
authors: SA
authors: Smith
authors: Oliver C
authors: OC
authors: Jann
authors: David
authors: D
authors: Haig
authors: George C
authors: GC
authors: Russell
authors: Dirk
authors: D
authors: Werling
authors: Elizabeth J
authors: EJ
authors: Glass
authors: Richard D
authors: RD
authors: Emes
mesh_terms: D000220:Adaptation, Biological / Q000235:genetics; D000818:Animals; D001419:Bacteria / Q000235:genetics; D002417:Cattle / Q000235:genetics*; D003062:Codon; D019143:Evolution, Molecular; D005408:Flagellin / Q000235:genetics; D054884:Host-Pathogen Interactions / Q000235:genetics; D058751:Livestock / Q000235:genetics; D020641:Polymorphism, Single Nucleotide; D054730:Protein Interaction Domains and Motifs; D017434:Protein Structure, Tertiary; D012641:Selection, Genetic; D012756:Sheep / Q000235:genetics*; D051198:Toll-Like Receptor 5 / Q000235:genetics*
chemical_list: D003062:Codon; D051198:Toll-Like Receptor 5; D005408:Flagellin