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 alpha-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.
Highlights
The nucleotide sequence(s) reported in this paper has been submitted to the GenBankTM/EBI Data Bank with accession number(s) FN557009, FN557010, FN557011, FN557012, and FN557013
In vitro and in vivo studies have demonstrated that antimicrobial activities of antimicrobial peptides (AMPs) are mediated by a complex and sensitive balance between various interrelated peptide parameters and that the role of each parameter changes from one peptide to another [5,6,7,8,9,10,11,12]
Temporin-SHf, with sequence FFFLSRIFa, kills Gram-positive and Gram-negative bacteria and yeasts by permeating/disrupting the microbial membrane but does not resemble any antimicrobial peptide identified to date: (i) temporin-SHf is the smallest (8-mer) among the linear AMPs hitherto found in nature, (ii) it possesses the highest percentage of Phe residues (50%) of any known peptide or protein, and (iii) once bound parallel to the microbial membrane surface, it folds into a non-amphipathic hydrophobic ␣-helix
Summary
We have used the conservation of the preproregion sequences of the preprodermaseptin transcripts to identify eight new members of the dermaseptin superfamily in the North African ranid frog Pelophylax saharica (family: Ranidae) One of these peptides, temporin-SHf, with sequence FFFLSRIFa, kills Gram-positive and Gram-negative bacteria and yeasts by permeating/disrupting the microbial membrane but does not resemble any antimicrobial peptide identified to date: (i) temporin-SHf is the smallest (8-mer) among the linear AMPs hitherto found in nature, (ii) it possesses the highest percentage of Phe residues (50%) of any known peptide or protein, and (iii) once bound parallel to the microbial membrane surface, it folds into a non-amphipathic hydrophobic ␣-helix. Owing to its short length, simple composition, and broad spectrum of antimicrobial activity, temporin-SHf is a promising candidate for the development of a new class of antimicrobial drugs
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
