Solution structure and model membrane interactions of temporins-SH, antimicrobial peptides from amphibian skin. A NMR spectroscopy and differential scanning calorimetry study.
Temporin-SHa and temporin-SHc are 13 residue long antimicrobial peptides from frog skin that have similar sequences but differ markedly in their membrane-damaging properties. Temporin-SHa contains a single basic lysine residue and has a unique antimicrobial spectrum of action among temporins, being very potent against Gram-positive and Gram-negative bacteria, yeasts, fungi, and protozoa. Temporin-SHc, which contains a single basic histidine residue, is inactive against Gram-negative bacteria, has a reduced efficacy against Gram-positive bacteria, but is still active against yeasts and fungi. Temporin-SHb, with no basic residue, has no antimicrobial activity. The three-dimensional structures of the peptides bound to SDS micelles were analyzed by CD and NMR spectroscopy combined with restrained molecular dynamics calculations. The peptides adopt well-defined amphipathic alpha-helical structures extending from residue 3 to residue 12, when bound to SDS micelles. The structures are stabilized by extensive interactions between aliphatic and aromatic side chains on the nonpolar face. Relaxation enhancements caused by paramagnetic probes showed that the peptides adopt nearly parallel orientations to the micelle surface and do not deeply penetrate into the micelle. The interaction of the peptides with model membranes was investigated by differential scanning calorimetry on anionic and zwitterionic multilamellar vesicles and membrane-permeabilization assays on calcein-loaded large unilamellar vesicles. Calorimetric data indicated that both temporin-SHa and -SHc reside at the hydrocarbon core-water interface of the anionic lipid bilayer but interact with anionic bilayers in a very different manner. This suggests that the charge-induced activity of temporins-SH for bacterial cells is due to changes in the membrane-disturbing mechanism of the bound peptides.
Abbassi
Feten
F
UPMC Univ Paris 06, CNRS FRE 2852, Peptidome de la Peau des Amphibiens, F-75005 Paris, France.
Galanth
Cécile
C
Amiche
Mohamed
M
Saito
Kazuko
K
Piesse
Christophe
C
Zargarian
Loussiné
L
Hani
Khaled
K
Nicolas
Pierre
P
Lequin
Olivier
O
Ladram
Ali
A
D000595:Amino Acid Sequence; D029845:Amphibian Proteins / Q000737:chemistry*; D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry*; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry*; D001001:Anura / Q000378:metabolism*; D002152:Calorimetry, Differential Scanning / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008958:Models, Molecular; D017433:Protein Structure, Secondary; D011506:Proteins; D012867:Skin / Q000378:metabolism*; D012996:Solutions
D029845:Amphibian Proteins; D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D011506:Proteins; D012996:Solutions; C104501:temporin; C000595450:temporin-SHa peptide, Pelophylax saharica; C000602143:temporin-SHc, Pelophylax saharica