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    • Keywords


      Toll-like receptors; TIR domain; LRR domain; domain combination.

    • Abstract


      Domain shuffling, which is an important mechanism in the evolution of multi-domain proteins, has shaped the evolutionary development of the immune system in animals. Toll and Toll-like receptors (TLRs) are a class of proteins that play a key role in the innate and adaptive immune systems. Draft genome sequences provide the opportunity to compare the Toll/TLR gene repertoire among representative metazoans. In this study, we investigated the combination of Toll/interleukin-1 receptor (TIR) and leucine-rich repeat (LRR) domains of metazoan Toll/TLRs. Before Toll with both domains occurred in Cnidaria (sea anemone, Nematostella vectensis), through domain combinations, TIR-only and LRR-only proteins had already appeared in sponges (Amphimedon queenslandica). Although vertebrate-like TIR (V-TIR) domain already appeared in Cnidaria, the vertebrate-like TLR (V-TLR) with both domains appeared much later. The first combination between V-TIR domain and vertebrate-like LRR (V-LRR) domain for V-TLR may have occurred after the divergence of Cnidaria and bilateria. Then, another combination for V-TLR, a recombination of both domains, possibly occurred before or during the evolution of primitive vertebrates. Taken together, two rounds of domain combinations may thus have co-shaped the vertebrate TLRs.

    • Author Affiliations


      Baojun Wu1 Tianxiao Huan1 2 Jing Gong3 Pin Zhou4 Zengliang Bai1

      1. Laboratory of Developmental Immunology, School of Life Science, Shandong University, Jinan 250100, People’s Republic of China
      2. Framingham Heart Study, National Heart, Lung, and Blood Institute, Framingham 01702, USA
      3. Institute of Biomedical Engineering, School of Medicine, Shandong University, Jinan 250012, People’s Republic of China
      4. Center for Disease Control and Prevention of Shizhong District, Jining 272000, People’s Republic of China
    • Dates

    • Supplementary Material

  • Journal of Genetics | News

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      Posted on July 25, 2019

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