Cloning and characterization of the homolog of mammalian lipopolysaccharide-binding protein and bactericidal permeability-increasing protein in rainbow trout oncorhynchus mykiss

摘要

We cloned two cDNAs denoted as RT-LBP/BPI-1 and RT-LBP/BPI-2,respectively,which were derived from the mRNA of head kidney from arinbow trout.Thsy showed strucral homology with LPS-binding protein (LBP) and bactericidal/perimeability-increasing protein (BPI) is mammals.The full-length cDNA or RT-LBP/BPI-1 and RT-LBP/BPI-3 is 1666 and 1741 bp,respetively.Both cDNAs encoded 473 aa residues,including the amino acids conserved in mammalian LPB and BPI proteins that were asssumed to be involved in LPS binding.The overall coding sequence of RT-LBP/BPI-1 has 33% amino acid homology ot human LBP and 34% to human BPI,and RT-LBP/BPI-2 has 325 amino acid homology to huamn LBP and 33% to human BPI.Three-dimensional structure analysis by three-dimensional/one-dimensional (3D-1D) methods also demonstrate that RT-LBP/BPI-1 and RT-/BLP-BPI-2 proteins showed significant similarity to human BPI,having a boormerang shape with N-terminal and C-terminal barrels.Phylogenetic analysis showed that the LBP and BPI genes seemed to be establised after the divergence of mammals from teleosts,These results suggested that TR-LBP/BPI-1 and RT/BLP-BPI-2 may be a putative ortholog for mammalian LBP and/or BPI genes.This is the first study to identify the LBP family genes from nonmammalian vertebrates.