[Cloning, expression and antibacterial activity of histone H1 and its N-terminal peptide from Carassius auratus]

In order to determine whether H1 histone proteins are associated with innate immune antimicrobial response in goldfish, we extracted the total RNA from the hemocytes of goldfish (Carassius auratus), designed 3 pairs of primers based on the previous antimicrobial peptide sequences from fish and performed RT-PCR. Among 3 obtained-PCR products, we identified a novel histone H1 coding sequence of 576 bp which belongs to the histone H1 family and is 78% homologous with the amino acid sequence of histone H1 from Salmon salar that had been found with an important role in salmon defenses against infectious pathogens. The H1 histone of goldfish contained 3 predicting cleavage sites that divided the protein into 4 parts. We successfully cloned and expressed the whole CDs (No ATG) of H1 histone and its N-terminal part (2-38aa) in Pichia pPIC9K expression system. The products of H1 histone and its N-terminal deriving peptide (AEVAPAASAPPAKAPKKKSAAKAKKAGPAVGDLIVKA) show antimicrobial activity. The results suggested that the H1 histone fragment reported in this paper is a novel antimicrobial peptide found in goldfish. H1 histone plays an important role in innate immune responses of goldfish.