Consequences of N-acylation on structure and membrane binding properties of dermaseptin derivative K₄-S4-(1-13)

Acyl conjugation to antimicrobial peptides is known to enhance antimicrobial properties. Here, we investigated the consequences of aminolauryl (NC₁₂) conjugation to the dermaseptin derivative K ₄-S4-(1-13) (P) on binding properties to bilayer models mimicking bacterial plasmamembrane, which is often cited as the ultimate site of action. Isothermal titration calorimetry revealed that acylation was responsible for enhancing the binding affinity of NC₁₂-P compared with P (K = 13 × 10⁵ and 1.5 × 10⁵ M^-1, respectively). Surface plasmon resonance measurements confirmed the isothermal titration calorimetry results (K_app = 12.6 × 10⁵ and 1.53 × 10₅ M^-1, respectively) and further indicated that enhanced adhesion affinity (K_adhesion = 3 × 10 ⁵ and 1 × 10⁵ M^-1, respectively) was coupled to enhanced tendency to insert within the bilayer (K_insertion = 4.5 and 1.5, respectively). To gain insight into the molecular basis for these observations, we investigated the three-dimensional structures in the presence of dodecylphosphocholine usingNMR.The ensemble of NMR-calculated structures (backbone root mean square deviation <0.6 Å) showed that the acyl moiety was responsible for a significant molecular reorganization, possibly affecting the electrostatic potential distribution in NC₁₂-P relative to that of P. The combined data present compelling evidence in support of the hypothesis that N-acylation affects antimicrobial properties by modifying the secondary structure of the peptide in a manner that facilitates contact with the membrane and consequently increases its disruption.