Modification and characterization of a new recombinant marine antimicrobial peptide N2

A novel antimicrobial peptide N2 was designed based on parent peptide NZ17074 to reduce toxicity and expressed in P. pastoris in this study. The recombinant N2 peptide exhibited a lower hemolytic activity and higher antimicrobial activities than its parent. N2 may be used as a new therapeutic drug against gram-negative bacteria. [Display omitted] •Design of N2 based on increase in hydrophobicity by substitution Gly with Ala.•Substitution in the polar face with nonpolar residues decreased toxicity of AMPs.•Higher antibacterial activity and lower hemolysis of N2 than NZ17074.•Successful expression of N2 fused with SUMO in P. pastoris. NZ17074, a member of the arenicin family from Arenicola marina, exhibited potent antimicrobial activity against bacteria and fungi, but had some toxicity to human erythrocytes and porcine intestinal epithelial cells. To resolve this problem, one novel peptide N2 was designed based on NZ17074 by replacing Gly in position 1, 12 with Ala. N2 exhibited a typical β-sheet conformation in aqueous and almost had no hemolysis. N2 was expressed in Pichia pastoris using the small ubiquitin-like modifier fusion technology. The yield of N2 was approximately 6.5mg/l, and its molecular weight was 2665.0Da. The minimum inhibitory concentrations of N2 against Gram-negative bacteria ranged from 0.125 to 4μg/ml. The antibacterial activity of N2 against Escherichia coli CVCC 195 and Salmonella enteritidis CVCC 3377 was enhanced up to 1–3-fold over parent NZ17074. This result provides some information that assists in the rational design of toxic antimicrobial peptides.