Antimicrobial Activity and Action Mechanisms of Arg-Rich Short Analog Peptides Designed from the C-Terminal Loop Region of American Oyster Defensin (AOD)

• Published in: Marine drugs 2021-08, Vol.19 (8), p.451
• Main Authors: Seo, Jung-Kil, Kim, Dong-Gyun, Lee, Ji-Eun, Park, Kwon-Sam, Lee, In-Ah, Lee, Ki-Young, Kim, Young-Ok, Nam, Bo-Hye
• Format: Article
• Language: English
• Subjects: Acidification; American oyster defensin (AOD); Amino acids; Analogs; Animals; Anti-Bacterial Agents - pharmacology; Antibiotics; Antiinfectives and antibacterials; Antimicrobial activity; Antimicrobial agents; antimicrobial mechanism; antimicrobial peptide; Aquatic Organisms; Arg-rich analogs; Arginine; Arthropods; Bacteria; Bonding strength; C-Terminus; Cytotoxicity; Defensins - pharmacology; Deoxyribonucleic acid; Design; Disease resistance; Disulfide bonds; DNA; E coli; Erythrocytes - drug effects; Gram-negative bacteria; Gram-Negative Bacteria - drug effects; Gram-positive bacteria; Gram-Positive Bacteria - drug effects; Hemolysis - drug effects; Humans; Investigations; Marine molluscs; Membranes; Microbial Sensitivity Tests; Microorganisms; Nucleotide sequence; Ostreidae; Oysters; Peptides; Permeability; Phytotherapy; Polymerization; Test organisms; Toxicity
• ISSN: 1660-3397; 1660-3397
• DOI: 10.3390/md19080451

American oyster defensin (AOD) was previously purified from acidified gill extract of the American oyster, . AOD is composed of 38 amino acids with three disulfide bonds and exhibits strong antimicrobial activity against Gram-positive bacteria as well as significant activity against Gram-negative bacteria. Here, to develop promising peptides into antibiotic candidates, we designed five arginine-rich analogs (A0, A1, A2, A3, and A4), predicted their loop and extended strand/random structures-including nine amino acids and a disulfide bond derived from the C-terminus of AOD-and described their antimicrobial and cytotoxic effects, as well as their modes of action. In our experimental results, the A3 and A4 analogs exhibited potent antimicrobial activity against all test organisms-including four Gram-positive bacteria, six Gram-negative bacteria, and -without cell toxicity. A sequence of experiments, including a membrane permeabilization assay, DNA binding study, and DNA polymerization inhibition test, indicated that the two analogs (A3 and A4) possibly did not act directly on the bacterial membrane but instead interacted with intracellular components such as DNA or DNA amplification reactions. AOD analogs also showed strong bacterial inhibition activity in the plasma environment. In addition, analog-treated microbial cells clearly exhibited membrane disruption, damage, and leakage of cytoplasmic contents. Collectively, our results suggest that two analogs, A3 and A4, have potent antimicrobial activity via DNA interaction and have the potential for development into novel antimicrobial agents.