title: Identification of a transcript encoding a soluble form of toll-like receptor 5 (TLR5) in Atlantic salmon during Aeromonas salmonicida infection.
abstract: Toll-like receptors (TLRs) are involved in the innate immune response against microbial pathogens in vertebrates and insects. The extracellular region of a TLR recognizes pathogen-associated molecules, while the intracellular region initiates the signaling pathway leading to immune response. Membrane-bound TLRs have been found in most vertebrates, but few soluble forms have been reported. A novel transcript corresponding to a portion of a soluble TLR was identified in liver of infected Atlantic salmon. The complete coding sequence of this TLR was obtained and BLASTN analysis showed the highest sequence identity to a recently described full-length cDNA sequence of a soluble TLR5 from rainbow trout (GenBank Accession No.: ). The deduced protein is 40% identical to the mammalian counterpart of the leucine-rich repeat (LRR)/LRR-like motifs of TLR5. Based on the structure of human TLRs, it contains 21 LRRs with conserved LxxLxLxxNx*xx*xxxxFxxL pattern. Since TLR5 is essential for the recognition of bacterial flagellins, we hypothesize that flagellin and perhaps some other pathogen-derived factors from Aeromonas salmonicida bind to this soluble TLR through an unknown binding domain within the LRR.
authors.affiliation: National Research Council, Institute for Marine Biosciences, 1411 Oxford Street, Halifax, NS, Canada. stsoi@uams.edu
authors.forename: Stephen
authors.initials: S
authors.lastname: Tsoi
authors.forename: Kyoung C
authors.initials: KC
authors.lastname: Park
authors.forename: Helen H
authors.initials: HH
authors.lastname: Kay
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: O'Brien
authors.forename: Eszter
authors.initials: E
authors.lastname: Podor
authors.forename: Genlou
authors.initials: G
authors.lastname: Sun
authors.forename: Susan E
authors.initials: SE
authors.lastname: Douglas
authors.forename: Laura L
authors.initials: LL
authors.lastname: Brown
authors.forename: Stewart C
authors.initials: SC
authors.lastname: Johnson
mesh_terms: D048409:Aeromonas salmonicida / Q000276:immunology*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005393:Fish Diseases / Q000235:genetics / Q000276:immunology / Q000382:microbiology*; D005667:Furunculosis / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D016905:Gram-Negative Bacterial Infections / Q000235:genetics / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D008969:Molecular Sequence Data; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics* / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D020317:Salmo salar / Q000235:genetics*; D016415:Sequence Alignment; D051198:Toll-Like Receptor 5 / Q000235:genetics* / Q000276:immunology
chemical_list: D012329:RNA, Bacterial; D012333:RNA, Messenger; D051198:Toll-Like Receptor 5