IN SILICO Analysis of Toll-Like receptor 3 from an Indian coldwater fish, Schizothorax Richardsonii (GRAY)

The innate immune system recognises pathogens through pattern recognition receptors (PRRs) and Toll-like receptors (TLRs) represent one of the most important PRRs. Within the TLR family, 10 TLRs in human and 17 in fish have been reported. In fish, TLR3 recognises double stranded RNA (dsRNA), a viral replication intermediate. We have cloned TLR3 from Indian snow trout, Schizothorax richardsonii and characterised it in silico. Snow trout TLR3 has an open reading frame of 2, 712 bases that encodes a polypeptide of 904 amino acids. It has a signal peptide, an ectodomain (ECD), a transmembrane region and a cytoplasmic Toll/IL-1 receptor (TIR) domain. The ECD has 25 leucine rich repeats, 12 glycosylation sites in the ECD and one tyrosine phosphorylation site (Tyr⁷⁶¹) in TIR domain. The homology model of TLR3-ECD revealed 27-sheets arranged in parallel forming a concave hydrophobic core and the-helices are spread on the convex face.