Structure of Chemokine-Derived Antimicrobial Peptide Interleukin-8α and Interaction with Detergent Micelles and Oriented Lipid Bilayers

Interleukin-8α (IL-8α) is an antimicrobial peptide derived from the chemokine IL-8. Solution NMR was used to determine the atomic-resolution structure of IL-8α in SDS micelles. Solid-state NMR and tryptophan fluorescence were used to probe the interaction of IL-8α with model membranes. The peptide interacted differently with anionic versus purely zwitterionic micelles or bilayers. Tryptophan fluorescence demonstrated a deeper position of Trp4 in SDS micelles and POPC/POPG bilayers compared to pure POPC bilayers, consistent with 2H order parameters, which also indicated a deeper position of the peptide in POPC/POPG bilayers compared to POPC bilayers. Paramagnetic probe data showed that IL-8α was situated roughly parallel to the SDS micelle surface, with a slight tilt that positioned the N-terminus more deeply in the micelle compared to the C-terminus. 15N solid-state NMR spectra indicated a similar, nearly parallel position for the peptide in POPC/POPG bilayers. 31P and 2H solid-state NMR demonstrated that...