Effects of residue 5-point mutation and N-terminus hydrophobic residues on temporin-SHc physicochemical and biological properties.
Temporin-SHc (FLSHIAGFLSNLFamide) first isolated from skin extraction of the Tunisian frog Pelophylax saharica, which shows potent antimicrobial activity against Gram-positive bacteria and is highly active against yeasts and fungi without hemolytic activity at antimicrobial concentrations. The peptide adopts well-defined α-helical conformation when bound to SDS micelles. In this study, we explored the effects of residue at position 5 and the N-terminus hydrophobic character on the hydrophilic/polar face of temp-SHc, on its biological activities (antimicrobial and hemolytic) and biophysical properties (hydrophobicity, amphipathicity and helicity). Antibacterial and hemolytic properties of temporin-SHc derivatives depend strongly on physicochemical properties. Therefore, slight decreasing amphipathicity together with hydrophobicity and helicity by the substitution Ile(5) → Leu decreased antimicrobial potency approximately twofold without changing of hemolytic activity. It is noteworthy that a conservative amino acid substitution decreases the antimicrobial activity, underlining the differences between Leu/Ile side chains insertion into the lipid bilayer. While the modification of N-terminal hydrophobic character by four residue inversion decreased amphipathicity (twofold) of (4-1)L5temp-SHc and resulted in an increase in antibacterial activity against E. coli, E. faecalis and C. parapsilosis of at least fourfold, its therapeutic potential is limited by its drastic increase of hemolysis (LC₅₀ = 2 μM). We found that the percentage of helicity of temp-SHc analog is directly correlated to its hemolytic activity. Last, the hydrophobic N-terminal character is an important determinant of antimicrobial activity.
UPMC Univ Paris 06, ER3 Biogenèse des Signaux Peptidiques (BIOSIPE), Université Pierre et Marie Curie, 75005, Paris, France, abbassifeten@yahoo.fr.
Feten
F
Abbassi
Christophe
C
Piesse
Thierry
T
Foulon
Pierre
P
Nicolas
Ali
A
Ladram
D000595:Amino Acid Sequence; D029845:Amphibian Proteins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D000890:Anti-Infective Agents / Q000737:chemistry / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects / Q000254:growth & development; D002942:Circular Dichroism; D004305:Dose-Response Relationship, Drug; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship
D029845:Amphibian Proteins; D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; C000602143:temporin-SHc, Pelophylax saharica