Structural and Functional Characterization of Hejiangin-A1, a Potent Antimicrobial Peptide against Resistant Pathogens

Abstract

Antimicrobial peptides (AMPs) are the potent components of host innate defense mechanism that protects organisms from biotic and abiotic environmental threats. By the course of evolution microbes acquired resistance to conventional antibiotics. In this context, AMPs provides an eminent source to develop new generation of antimicrobials to combat with antibiotic resistant microbes. In the present work, we selected a 16-residue peptide (RFIYMKGFGKPRFGKR), Hejiangin-A1 (APD ID: AP01891), a potent AMP from the skin secretions of Odoranna hejiangensis, a Chinese odorous frog which has not been characterized for its structure and mechanism (Yang X, et al., 2012). Different experiments like MIC of the peptide, hemolytic assay, circular dichroism and NMR spectroscopic studies in the presence of D8PG micelles were carried out to characterize the selected AMP, Hejiangin-A1. The AMP shown the activity against both gram^+ve and gram^-ve bacteria and human fungal strains and no hemolytic activity against the human red blood cells was found for the AMP. The CD spectrum of peptide, suggested an α-helical configuration in the LPS medium in 1:3 ratio at a pH of 7.4. Solution NMR studies of Hejiangin-A1 reveal that it does not adopt any structure in presence of D8PG micelles.

Keywords
Hejiangin –A1, Antimicrobial peptide, Circular dichroism, NMR spectroscopy