Investigation of N- and C- termini in Lytic Properties of chimeric Antimicrobial Peptides
Antibiotic resistance continues to be a major threat to humanity. A potential solution to the dire issue is antimicrobial peptides (AMPs), which are relatively short amino acid sequences that are naturally produced by all living organisms. Work in this lab has been focusing on AMPs with α-helical secondary structure, specifically chimeras of melittin, naturally found in bee venom, and a peptide sequence within neuronal Nitric Oxide Synthase (nNOS). For this study, chimeras with 8 amino acids from the N and C termini of melittin were substituted with the 8 amino acids from the N and C termini of the nNOS peptide, generating chimeras named Mel-nnNOS and Mel-cnNOS, respectively. This change was done in an effort to assess which part of the melittin peptide sequence gives it its antibiotic properties. These chimeras were tested for their ability to inhibit the growth of S. aureus and E. coli, and were also tested for their ability to lyse red blood cells and liposomes. The results show that the chimera with the N terminus of melittin (Mel-cnNOS) was able to inhibit bacterial cell growth, as well as lyse red blood cells and liposomes at a concentration of 10 μM. The melittin C terminus chimera (Mel-nnNOS) was on the other hand, only able to inhibit bacterial growth. These results suggest that both termini of melittin are related to its antibacterial properties, however the N terminus of melittin is what gives it its ability to lyse liposomes.