title: Structural and evolutionary characteristics of fish-specific TLR19.
abstract: Toll-like receptors (TLRs) are important pattern recognition receptors in the innate immune system of fish. Although ten years have passed since the first identification, the systematic knowledge about fish-specific TLR19 is still far insufficient. In present study, a phylogenetic analysis showed that TLR19 belonged to family 11, and clustered with TLR20 and TLR11/12 on the evolutionary tree. TLR20 is the closest paralogue of TLR19. The ectodomain of TLR19 contains 24 leucine-rich repeat (LRR) modules. The electrostatic surface potential analysis indicated that the modeled structure of TLR19 ectodomain showed much stronger polarity on the ascending lateral surface than on the descending lateral surface. The ascending lateral surface with strong electrostatic surface potential possibly mainly participates in the ligand binding of TLR19 ectodomain. The quite small dN/dS value at the TLR19 locus showed that TLR19 was very conserved. Approximately one third codons in the coding sequence of TLR19 were subjected to significantly negative selection, whereas only 5 codons underwent significantly positive selection. Overall, these findings possibly help in deepening the understanding to fish-specific TLR19.
authors.affiliation: Institute of Developmental Biology, School of Life Science, Shandong University, Jinan 250100, PR China.
authors.forename: Jinlan
authors.initials: J
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan 250100, PR China. Electronic address: zhzhang@mail.sdu.edu.cn.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Institute of Developmental Biology, School of Life Science, Shandong University, Jinan 250100, PR China.
authors.forename: Hui
authors.initials: H
authors.lastname: Fu
authors.affiliation: Institute of Developmental Biology, School of Life Science, Shandong University, Jinan 250100, PR China.
authors.forename: Shangli
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Institute of Developmental Biology, School of Life Science, Shandong University, Jinan 250100, PR China.
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.affiliation: Institute of Developmental Biology, School of Life Science, Shandong University, Jinan 250100, PR China.
authors.forename: Fen
authors.initials: F
authors.lastname: Chang
authors.affiliation: Institute of Developmental Biology, School of Life Science, Shandong University, Jinan 250100, PR China.
authors.forename: Fang
authors.initials: F
authors.lastname: Li
authors.affiliation: Institute of Developmental Biology, School of Life Science, Shandong University, Jinan 250100, PR China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Internal Medicine, College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA. Electronic address: yin@etsu.edu.
authors.forename: Deling
authors.initials: D
authors.lastname: Yin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019143:Evolution, Molecular; D029941:Fish Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005399:Fishes / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D008968:Molecular Conformation; D010802:Phylogeny; D051193:Toll-Like Receptors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D029941:Fish Proteins; D051193:Toll-Like Receptors
keywords: Electrostatic surface potential; Innate immunity; Molecular evolution; Structural characteristics; Toll-like receptor 19