Molecular cloning and characterization of equine NK-lysin

NK-lysin is an antimicrobial peptide of cytotoxic and NK lymphocytes that has powerful antibacterial properties as well as antitumoral activity. Here we report the full-length cDNA and deduced amino acid sequence for equine NK-lysin. Equine NK-lysin is 67% identical to porcine NK-lysin, 53% identical to bovine NK-lysin and 41% identical to granulysin in amino acid sequence. Complete conservation of cysteine residues between equine, bovine and porcine NK-lysin suggests similar disulfide bonding patterns among these peptides. Equine NK-lysin has the most positive surface charge when compared with other homologues. Similar to expression profiles in other species, equine NK-lysin is constitutively transcribed in various lymphocytes that include CD4+ and CD8+ staining cells. These findings suggest that equine NK-lysin, similar in cDNA sequence to the porcine, bovine and human homologues may play a role in antimicrobial defense.