Temporin-SHf, a New Type of Phe-rich and Hydrophobic Ultrashort Antimicrobial Peptide

Abstract

Because issues of cost and bioavailability have hampered the development of gene-encoded antimicrobial peptides to combat infectious diseases, short linear peptides with high microbial cell selectivity have been recently considered as antibiotic substitutes. A new type of short antimicrobial peptide, designated temporin-SHf, was isolated and cloned from the skin of the frog Pelophylax saharica. Temporin-SHf has a highly hydrophobic sequence (FFFLSRIFa) and possesses the highest percentage of Phe residues of any known peptide or protein. Moreover, it is the smallest natural linear antimicrobial peptide found to date, with only eight residues. Despite its small size and hydrophobicity, temporin-SHf has broad-spectrum microbicidal activity against Gram-positive and Gram-negative bacteria and yeasts, with no hemolytic activity. CD and NMR spectroscopy combined with restrained molecular dynamics calculations showed that the peptide adopts a well defined non-amphipathic ␣-helical structure from residue 3 to 8, when bound to zwitterionic dodecyl phosphocholine or anionic SDS micelles. Relaxation enhancement caused by paramagnetic probes showed that the peptide adopts nearly parallel orientations to the micelle surface and that the helical structure is stabilized by a compact hydrophobic core on one face that penetrates into the micelle interior. Differential scanning calorimetry on multilamellar vesicles combined with membrane permeabilization assays on bacterial cells indicated that temporin-SHf disrupts the acyl chain packing of anionic lipid bilayers, thereby triggering local cracks and microbial membrane disintegration through a detergent-like effect probably via the carpet mechanism. The short length, compositional simplicity, and broad-spectrum activity of temporin-SHf make it an attractive candidate to develop new antibiotic agents.

Membrane Perturbation Action Mode and Structure-Activity Relationships of Protonectin, a Novel Antimicrobial Peptide from the Venom of the Neotropical Social Wasp Agelaia pallipes pallipes

“…Our results showed that protonectin displayed a characteristic unordered structure in phos- phate-buffered saline (PBS), while in the membrane-mimicking environment it presented a strong positive band around 195 nm and two strong negative bands near 206 nm and 222 nm, which are indicative of the presence of ordered conformations. Such signatures are reminiscent of the spectra of well-defined ␣-helical peptides (30). As shown in Fig.…”

Short native antimicrobial peptides and engineered ultrashort lipopeptides: similarities and differences in cell specificities and modes of action

“…It represents the smallest naturally occurring linear AMP identified so far. It has a highly hydrophobic sequence, with the highest percentage of Phe residues (50%) of any known peptide or protein, and folds into a nonamphipathic a-helix when bound to the microbial membrane surface [55].…”

“…This has been established based on the following data: (1) a rapid induction of the collapse of membrane potential; (2) a rapid killing kinetics (within 15-20 min) concomitant with that of membrane permeation; (3) a correlation between the extent of membrane damage and the microbial killing; (4) an injured pattern of microbes (bacteria and parasites) as visualized by both transmission and scanning electron microscopy; and (5) leakage of large intracellular components (e.g., the enzyme b galactosidase) in a dose-dependent manner and with a kinetic superimposable to that of bacterial death [51,87]. Note that the ability to strongly alter the acyl chain packing of anionic phospholipid bilayers, thereby triggering local cracks and microbial membrane damage, is maintained in the 8-mer ultrashort temporin [55].…”

Insights into the membrane interaction mechanism and antibacterial properties of chensinin-1b

“…The interaction is dependent on a complex and sensitive balance between various interrelated peptide parameters, including net charge, hydrophobicity, amphipathicity, and a-helical or b-sheet structures [47]. Chensinin-1, a natural AMP previously extracted from Rana chensinensis, exhibits low cell selectivity and low antimicrobial activity because of its low hydrophobicity and a random coil structure in a membrane-mimetic environment.…”

“…Although we attempted to design a series of chensinin-1 analogues to increase the peptide hydrophobicity and ordered secondary structure, the antimicrobial activities against Gram-positive and Gram-negative bacteria had not been significantly improved. Several studies have shown that some membrane activities of AMPs, such as permeabilisation, are not entirely dependent on hydrophobicity or secondary structures, but on the interfacial activity of the peptide, i.e., its ability to partition into the membraneewater interface and to alter the packing and organisation of lipids [47]. Trp residues reportedly exhibit the unique property of being able to interact with the interfacial region of a membrane, thereby anchoring the peptide to the bilayer surface.…”