Structure–activity relationship study of amphipathic antimicrobial peptides using helix‐destabilizing sarcosine

Abstract

Antimicrobial peptides (AMPs) are potential therapeutic agents against bacteria. We recently showed that a rationally designed AMP, termed Stripe, with an amphipathic distribution of native cationic and hydrophobic amino acids on its helical structure exhibited potent antimicrobial activity against Gram-positive and Gram-negative bacteria with negligible hemolytic activity and cytotoxicity. In this study, the structure-activity relationship of Stripe was elucidated by designing a series of antimicrobial peptides whereby amino acid residues of Stripe were exchanged with helix-destabilizing sarcosine residues. Stripe 1-5 peptides with hydrophobic amino acids substituted with sarcosine were predominantly unstructured and showed no antimicrobial activity, except against Escherichia coli (E. coli) (DH5α) cells. The activity against E. coli (DH5α) cells and the helicity of Stripe 1-5 peptides decreased concomitantly as the number of sarcosine residue substitutions increased. Stripe 1-5 peptides showed no hemolytic activity or cytotoxicity. The results indicate that sarcosine substitutions provide an approach to study the structure-activity relationship of helical AMPs, and the helicity of Stripe is an important feature defining its activity.

Is It Possible to Create Antimicrobial Peptides Based on the Amyloidogenic Sequence of Ribosomal S1 Protein of P. aeruginosa?

“…AMPs are usually characterized by a stable secondary structure, in particular, the presence of β-sheets and α-helices [68]. A decrease in the ordering of AMPs, in particular, caused by the replacement of amino acid residues with sarcosine, can lead to a decrease in the antimicrobial properties of modified peptides [64].…”

“…The antimicrobial properties of peptides can be seriously affected by a single point modification of a known sequence [62,63]. A similar approach based on the replacement of hydrophobic amino acid residues with sarcosine was used by other authors to show the importance of a stable conformation of the peptide for its antimicrobial action [64]. The domain organization of the S1 protein is shown schematically, each of the six protein domains (D1-D6) is color represented.…”

Antimicrobial Proteins: Structure, Molecular Action, and Therapeutic Potential

“…AMPs with reptile and avian sources belong to the members of the cathelicidin and defensin families [ 26 ]. Cathelicidins are small-sized AMPs secreted from macrophages and neutrophils upon their activation in response to infection.…”

“…The most common mammalian AMPs belong to the members of the cathelicidin and defensins families. Mammalian cathelicidins are cationic peptides with an amphipathic structure in the form of α-helical, β-hairpin, or elongated conformations [ 26 ]. LL-37, the most well-studied cathelicidin, has an amphipathic structure, which can be modified into an aqueous solution to form an α-helix upon membrane interaction [ 26 , 28 ].…”

“…Mammalian cathelicidins are cationic peptides with an amphipathic structure in the form of α-helical, β-hairpin, or elongated conformations [ 26 ]. LL-37, the most well-studied cathelicidin, has an amphipathic structure, which can be modified into an aqueous solution to form an α-helix upon membrane interaction [ 26 , 28 ]. Mammalian defensins are classified into three sub-families: α, β, and θ.…”