Fatty Acid Conjugation Leads to Length-Dependent Antimicrobial Activity of a Synthetic Antibacterial Peptide (Pep19-4LF)

Abstract

The increasing number of infections caused by multidrug-resistant bacteria requires an intensified search for new antibiotics. Pep19-4LF is a synthetic antimicrobial peptide (GKKYRRFRWKFKGKLFLFG) that was previously designed with the main focus on high antimicrobial activity. The hydrophobic motif, LFLFG, was found to be essential for antimicrobial activity. However, this motif shows several limitations such as aggregation in biological media, low solubility, and small yields in peptide synthesis. In order to obtain more appropriate peptide characteristics, the hydrophobic motif was replaced with fatty acids. For this purpose, a shortened variant of Pep19-4LF (Pep19-short; GKKYRRFRWKFKGK) was synthesized and covalently linked to saturated fatty acids of different chain lengths. The peptide conjugates were tested with respect to their antibacterial activity by microdilution experiments on different bacterial strains. The length of the fatty acid was found to be directly correlated to the antimicrobial activity up to an ideal chain length (undecanoic acid, C11:0). This conjugate showed high antimicrobial activity in absence of toxicity. Time–kill studies revealed a fast and bactericidal mode of action. Furthermore, the first in vivo experiments of the conjugate in rodents demonstrated pharmacokinetics appropriate for application as a drug. These results clearly indicate that the hydrophobic motif of the peptide can be replaced by a single fatty acid of medium length, simplifying the design of this antimicrobial peptide while retaining high antimicrobial activity in the absence of toxicity.

C-Locked Analogs of the Antimicrobial Peptide BP214

“…As the lipidation of AMPs may have a significant effect on activity [ 17 ], we first investigated the effect of conjugating butanoic, hexanoic, octanoic, decanoic, lauric and myristic acids to BP214. The resulting C 4 , C 6 , and C 8 lipidated BP214 analogs (i.e., 1 – 3 ) showed a good activity (2–16 μg/mL) against the Gram-negative bacteria E. coli , K. pneumoniae , and A. baumanii , and a moderate activity against P. aeruginosa (32 μg/mL).…”

New N-terminal Fatty Acid Modified-Melittin Analogues With Potent Biological Activity

“…Recently, multiple studies have found that coupling a fatty acid to antimicrobial peptides could modify both the activity and selectivity of the peptide and the length of the fatty acid was found to be directly correlated to the antimicrobial activity of fatty acid-conjugated antibacterial peptide [20][21][22]. Alexander et al detected the antimicrobial activity, structure, and solution assembly properties of peptide AKK conjugated with fatty acids of different carbon chain lengths, and the result showed that the antimicrobial activity of conjugated peptide increased with the fatty acids carbon chain lengths up to 16 carbons [23].…”

Antimicrobial peptide-based materials: opportunities and challenges

“…132 The shortening of fatty acid led to improved antimicrobial activity against Gram-positive bacteria and a lower hemolytic activity. 133 The improved antimicrobial activity was due to pore formation, micellization of the phospholipid bilayer and peptide aggregation. 132 Similarly, Stachuski et al showed the role of shortening of the fatty acid chain in improving the antimicrobial activity of lipopeptides.…”