Temporin L: antimicrobial, haemolytic and cytotoxic activities, and effects on membrane permeabilization in lipid vesicles

Abstract

The temporins are a family of small, linear antibiotic peptides with intriguing biological properties. We investigated the antibacterial, haemolytic and cytotoxic activities of temporin L (FVQWFSKFLGRIL-NH2), isolated from the skin of the European red frog Rana temporaria. The peptide displayed the highest activity of temporins studied to date, against both human erythrocytes and bacterial and fungal strains. At variance with other known temporins, which are mainly active against Gram-positive bacteria, temporin L was also active against Gram-negative strains such as Pseudomonas aeruginosa A.T.C.C. 15692 and Escherichia coli D21 at concentrations comparable with those that are microbiocidal to Gram-positive bacteria. In addition, temporin L was cytotoxic to three different human tumour cell lines (Hut-78, K-562 and U-937), causing a necrosis-like cell death, although sensitivity to the peptide varied markedly with the specific cell line tested. A study of the interaction of temporin L with liposomes of different lipid compositions revealed that the peptide causes perturbation of bilayer integrity of both neutral and negatively charged membranes, as revealed by the release of a vesicle-encapsulated fluorescent marker, and that the action of the peptide is modulated to some extent by membrane lipid composition. In particular, the presence of negatively charged lipids in the model bilayer inhibits the lytic power of temporin L. We also show that the release of fluorescent markers caused by temporin L is size-dependent and that the peptide does not have a detergent-like effect on the membrane, suggesting that perturbation of bilayer organization takes place on a local scale, i.e. through the formation of pore-like openings.

A Synergism between Temporins toward Gram-negative Bacteria Overcomes Resistance Imposed by the Lipopolysaccharide Protective Layer

“…Therefore, before reaching the cytoplasmic membrane, the peptides need to interact and traverse both the LPS and the peptidoglycan layers (66,67). The outer cell envelope was previously considered to be a barrier against temporins, because E. coli strains with the progressively decreased LPS-polysaccharide chain were found to be concomitantly more sensitive to these peptides (30,68). Here, we provide an explanation for the inactivity of temporins A and B toward Gram-negative bacteria.…”

Ceragenins as Mimics of Endogenous Antimicrobial Peptides

“…As the impacts of ceragenins are better understood, their full potential and their limitations in clinical applications will become more apparent. As amphiphilic compounds, concerns about the hemolytic and general cytotoxic properties of ceragenins arise, and these concerns are common to AMPs [108]. For potential systemic applications of ceragenins, hemolytic activity may present an initial concern, and while hemolytic activity with CSA-13 has been observed, it comes at a concentration 10 times higher than bactericidal concentrations [47].…”

Formation of magnetite by bacteria and its application

“…Furthermore, an antimicrobial peptide, temporin L, and its derivative were also employed as anchor peptides and immobilized streptavidin on BacMPs ( Tanaka et al 2004a). Temporin L is a cationic linear peptide with varied structure, length and orientation (Rinaldi et al 2002). It forms an amphiphilic structure with the hydrophobic part that is organized in a helix when associated with a membrane.…”