Structure and alignment of the membrane-associated antimicrobial peptide arenicin by oriented solid-state NMR spectroscopy.
Fiche publication
Date publication
mai 2011
Auteurs
Membres identifiés du Cancéropôle Est :
Pr BECHINGER Burkhard
Tous les auteurs :
Salnikov ES, Aisenbrey C, Balandin SV, Zhmak MN, Ovchinnikova TV, Bechinger B
Lien Pubmed
Résumé
The antimicrobial arenicin peptides are cationic amphipathic sequences that strongly interact with membranes. Through a cystine ring closure a cyclic beta-sheet structure is formed in aqueous solution, which persists when interacting with model membranes. In order to investigate the conformation, interactions, dynamics, and topology of their bilayer-associated states, arenicin 1 and 2 were prepared by chemical solid-phase peptide synthesis or by bacterial overexpression, labeled selectively or uniformly with (15)N, reconstituted into oriented membranes, and investigated by proton-decoupled (31)P and (15)N solid-state NMR spectroscopy. Whereas the (31)P NMR spectra indicate that the peptide induces orientational disorder at the level of the phospholipid head groups, the (15)N chemical shift spectra agree well with a regular beta-sheet conformation such as the one observed in micellar environments. In contrast, the data do not fit the twisted beta-sheet structure found in aqueous buffer. Furthermore, the chemical shift distribution is indicative of considerable conformational and/or topological heterogeneity when at the same time the (15)N NMR spectra exclude alignments of the peptide where the beta-sheet lies side ways on the membrane surface. The ensemble of experimental constraints, the amphipathic character of the peptide, and in particular the distribution of the six arginine residues are in agreement with a boatlike dimer structure, similar or related to the one observed in micellar solution, that floats on the membrane surface with the possibility to oligomerize into higher order structures and/or to insert in a transmembrane fashion.
Référence
Biochemistry. 2011 May 10;50(18):3784-95