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Membrane Binding and Structure of De Novo Designed α‐Helical Cationic Coiled‐Coil‐Forming Peptides
Author(s) -
Vagt Toni,
Zschörnig Olaf,
Huster Daniel,
Koksch Beate
Publication year - 2006
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200600010
Subject(s) - coiled coil , peptide , circular dichroism , chemistry , vesicle , membrane , random coil , biophysics , crystallography , lipid bilayer , biochemistry , biology
We introduce a de novo designed peptide model system that enables the systematic study of 1) the role of a membrane environment in coiled‐coil peptide folding, 2) the impact of different domains of an α‐helical coiled‐coil heptad repeat on the interaction with membranes, and 3) the dynamics of coiled‐coil peptide–membrane interactions depending on environmental conditions. Starting from an ideal α‐helical coiled‐coil peptide sequence, several positively charged analogues were designed that exhibit a high propensity toward negatively charged lipid membranes. Furthermore, these peptides differ in their ability to form a stable α‐helical coiled‐coil structure. The influence of a membrane environment on peptide folding is studied. All positively charged peptides show strong interactions with negatively charged membranes. This interaction induces an α‐helical structure of the former random‐coil peptides, as revealed by circular dichroism measurements. Furthermore, vesicle aggregation is induced by a coiled‐coil interaction of vesicle‐bound peptides. Dynamic light scattering experiments show that the strength of vesicle aggregation increases with the peptide’s intrinsic ability to form a stable α ‐helical coiled coil. Thus, the peptide variant equipped with the strongest inter‐ and intra‐helical coiled‐coil interactions shows the strongest effect on vesicle aggregation. The secondary structure of this peptide in the membrane‐bound state was studied as well as its effect on the phospholipids. Peptide conformation within the peptide–lipid aggregates was analyzed by 13 C cross‐polarization magic‐angle spinning NMR experiments. A uniformly 13 C‐ and 15 N‐labeled Leu residue was introduced at position 12 of the peptide chain. The 13 C chemical shift and torsion angle measurements support the finding of an α‐helical structure of the peptide in its membrane‐bound state. Neither membrane leakage nor fusion was observed upon peptide binding, which is unusual for amphiphatic peptide structures. Our results lay the foundation for a systematic study of the influence of the α ‐helical coiled‐coil folding motif in membrane‐active events on a molecular level.