Effect of Amino Acid Substitutions on Biological Activity of Antimicrobial Peptide: Design, Recombinant Production, and Biological Activity

Document Type: Research article

Authors

1 Department of Medicinal Biotechnology, School of Paramedicine, Guilan University of Medical Sciences, Rasht, Iran.

2 Medical Biotechnology Research Center, School of Paramedicine, Guilan University of Medical Sciences, Rasht, Iran.

3 Protein Technology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.

4 Department of Pharmaceutics, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran.

Abstract

Recently, antimicrobial peptides have been introduced as potent antibiotics with a wide range
of antimicrobial activities. They have also exhibited other biological activities, including antiinflammatory,
growth stimulating, and anti-cancer activities. In this study, an analog of Magainin
II was designed and produced as a recombinant fusion protein. The designed sequence contained
24 amino acid residues (P24), in which Lys, His, Ser residues were substituted with Arg and also,
hydrophobic Phe was replaced with Trp. Recombinant production of P24 in Escherichia coli (E.
coli) BL21 using pTYB21, containing chitin binding domain and intein sequence at the N-terminus
of the peptide gene, resulted in 1 μg mL-1 product from culture. Chitin column chromatography,
followed by online peptide cleavage with thiol reducing agent was applied to purify the peptide.
Antimicrobial activity was evaluated using five bacteria strains including Staphylococcus aureus,
Enterococcus faecalis, Klebsiella pneumonia, E. coli, and Pseudomonas aeruginosa. Designed
AMP exhibited promising antimicrobial activities with low minimum inhibitory concentration, in
the range of 64-256 μg/mL. P24 showed potent antimicrobial activity preferably against Grampositive
bacteria, and more potent than pexiganan as a successful Magainin II analog for topical
infections. In general, further modification can be applied to improve its therapeutic index.

Keywords

Main Subjects