title: Bioinformatics analysis of the structural and evolutionary characteristics for toll-like receptor 15.
abstract: Toll-like receptors (TLRs) play important role in the innate immune system. TLR15 is reported to have a unique role in defense against pathogens, but its structural and evolution characterizations are still poorly understood. In this study, we identified 57 completed TLR15 genes from avian and reptilian genomes. TLR15 clustered into an individual clade and was closely related to family 1 on the phylogenetic tree. Unlike the TLRs in family 1 with the broken asparagine ladders in the middle, TLR15 ectodomain had an intact asparagine ladder that is critical to maintain the overall shape of ectodomain. The conservation analysis found that TLR15 ectodomain had a highly evolutionarily conserved region on the convex surface of LRR11 module, which is probably involved in TLR15 activation process. Furthermore, the protein-protein docking analysis indicated that TLR15 TIR domains have the potential to form homodimers, the predicted interaction interface of TIR dimer was formed mainly by residues from the BB-loops and αC-helixes. Although TLR15 mainly underwent purifying selection, we detected 27 sites under positive selection for TLR15, 24 of which are located on its ectodomain. Our observations suggest the structural features of TLR15 which may be relevant to its function, but which requires further experimental validation.
authors.affiliation: Institute of Developmental Biology, School of Life Science, Shandong University , Jinan , 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 , China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Institute of Developmental Biology, School of Life Science, Shandong University , Jinan , China.
authors.forename: Fen
authors.initials: F
authors.lastname: Chang
authors.affiliation: School of Pharmacy, Central South University, Changsha, China; Department of Internal Medicine, College of Medicine, East Tennessee State University, Johnson, TN, USA.
authors.forename: Deling
authors.initials: D
authors.lastname: Yin
keywords: Innate immunity; Molecular evolution; Protein–protein interactions; Structural characteristics; Toll-like receptor 15