Molecular identification of a novel antimicrobial peptide in giant Triton snail Charonia tritonis: mRNA profiles for tissues and its potential antibacterial activity

Two novel antimicrobial peptides P33-57 and mP168-187 from zebrafish showing potent antibacterial activities

It is known that overuse or abuse of antibiotics has undoubtedly accelerated the global antibiotic resistance crisis, and long-time use of antibiotics may have adverse effects on the health of animal, human, and ecosystem. Therefore, it is necessary to find antibiotic alternatives that can be used in aquaculture and are non-toxic to the human. Here we clearly demonstrated that both the PH and FYVE domain of Plekhf2 in zebrafish have antibacterial properties and can interact with PGN in this study. Therefore, we screened four candidate peptides from the two domains. It was demonstrated that P152-172 and P168-187 had no obvious antibacterial activities, while P33-57 and mP168-187 had strong antibacterial activities, which may be used as antimicrobial peptides. Additionally, transmission electron microscopy experiment revealed that P33-57 and mP168-187 can destroy the cell wall of bacteria, thereby directly killing bacteria. Importantly, it was found that P33-57 and mP168-187 had no hemolysis to red blood cells and lacked cytotoxicity. In summary, P33-57 and mP168-187could be seen as antibacterial activity centers of PLEKHF2 and may be promising antimicrobial peptides to combat bacterial infections facing an antibiotic-resistance crisis.

Optimizing Antimicrobial Peptide Design: Integration of Cell-Penetrating Peptides, Amyloidogenic Fragments, and Amino Acid Residue Modifications

The escalating threat of multidrug-resistant pathogens necessitates innovative approaches to combat infectious diseases. In this study, we examined peptides R23FS*, V31KS*, and R44KS*, which were engineered to include an amyloidogenic fragment sourced from the S1 protein of S. aureus, along with one or two cell-penetrating peptide (CPP) components. We assessed the antimicrobial efficacy of these peptides in a liquid medium against various strains of both Gram-positive bacteria, including S. aureus (209P and 129B strains), MRSA (SA 180 and ATCC 43300 strains), and B. cereus (strain IP 5832), and Gram-negative bacteria such as P. aeruginosa (ATCC 28753 and 2943 strains) and E. coli (MG1655 and K12 strains). Peptides R23FS*, V31KS*, and R44KS* exhibited antimicrobial activity comparable to gentamicin and meropenem against all tested bacteria at concentrations ranging from 24 to 48 μM. The peptides showed a stronger antimicrobial effect against B. cereus. Notably, peptide R44KS* displayed high efficacy compared to peptides R23FS* and V31KS*, particularly evident at lower concentrations, resulting in significant inhibition of bacterial growth. Furthermore, modified peptides V31KS* and R44KS* demonstrated enhanced inhibitory effects on bacterial growth across different strains compared to their unmodified counterparts V31KS and R44KS. These results highlight the potential of integrating cell-penetrating peptides, amyloidogenic fragments, and amino acid residue modifications to advance the innovation in the field of antimicrobial peptides, thereby increasing their effectiveness against a broad spectrum of pathogens.

New N-Terminal Fatty-Acid-Modified Melittin Analogs with Potent Biological Activity

Melittin, a natural antimicrobial peptide, has broad-spectrum antimicrobial activity. This has resulted in it gaining increasing attention as a potential antibiotic alternative; however, its practical use has been limited by its weak antimicrobial activity, high hemolytic activity, and low proteolytic stability. In this study, N-terminal fatty acid conjugation was used to develop new melittin-derived lipopeptides (MDLs) to improve the characteristics of melittin. Our results showed that compared with native melittin, the antimicrobial activity of MDLs was increased by 2 to 16 times, and the stability of these MDLs against trypsin and pepsin degradation was increased by 50 to 80%. However, the hemolytic activity of the MDLs decreased when the length of the carbon chain of fatty acids exceeded 10. Among the MDLs, the newly designed analog Mel-C8 showed optimal antimicrobial activity and protease stability. The antimicrobial mechanism studied revealed that the MDLs showed a rapid bactericidal effect by interacting with lipopolysaccharide (LPS) or lipoteichoic acid (LTA) and penetrating the bacterial cell membrane. In conclusion, we designed and synthesized a new class of MDLs with potent antimicrobial activity, high proteolytic stability, and low hemolytic activity through N-terminal fatty acid conjugation.