Molecular cloning, relative expression, and structural analysis of pattern recognition molecule β-glucan binding...

A full-length cDNA of a β-glucan binding protein (β-GBP) gene was identified from the mangrove crab Episesarma tetragonum. The open reading frame of the E. tetragonum β-GBP (Epte β-GBP) is 1,167 bp long, encoding a polypeptide of 389 amino acids. The deduced amino acid sequence of Epte β-GBP gene has conserved a potential recognition motif for β-1,3 linkages of polysaccharides and putative RGD (Arg-Gly-Asp) cell adhesion sites. Phylogenetic analysis of the Epte β-GBP gene showed the similarity with β-GBPs of other crustaceans and arthropods. Quantitative RT-PCR results showed the upregulation of Epte β-GBP gene expression in E. tetragonum hemocytes following a 12-H challenge in response to β-glucan (β-G). Epte β-GBP was involved in the regulation and activation of the prophenoloxidase cascade. A three-dimensional structure of active Epte β-GBP was modeled by homology modeling and refined with molecular dynamics simulations. A structural aspect of the protein is discussed based on experimental and theoretical results obtained.