Structure and alignment of the membrane-associated peptaibols ampullosporin A and alamethicin by oriented 15N and 31P solid-state NMR spectroscopy.
Ampullosporin A and alamethicin are two members of the peptaibol family of antimicrobial peptides. These compounds are produced by fungi and are characterized by a high content of hydrophobic amino acids, and in particular the alpha-tetrasubstituted amino acid residue ?-aminoisobutyric acid. Here ampullosporin A and alamethicin were uniformly labeled with (15)N, purified and reconstituted into oriented phophatidylcholine lipid bilayers and investigated by proton-decoupled (15)N and (31)P solid-state NMR spectroscopy. Whereas alamethicin (20 amino acid residues) adopts transmembrane alignments in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) or 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) membranes the much shorter ampullosporin A (15 residues) exhibits comparable configurations only in thin membranes. In contrast the latter compound is oriented parallel to the membrane surface in 1,2-dimyristoleoyl-sn-glycero-3-phosphocholine and POPC bilayers indicating that hydrophobic mismatch has a decisive effect on the membrane topology of these peptides. Two-dimensional (15)N chemical shift -(1)H-(15)N dipolar coupling solid-state NMR correlation spectroscopy suggests that in their transmembrane configuration both peptides adopt mixed alpha-/3(10)-helical structures which can be explained by the restraints imposed by the membranes and the bulky alpha-aminoisobutyric acid residues. The (15)N solid-state NMR spectra also provide detailed information on the helical tilt angles. The results are discussed with regard to the antimicrobial activities of the peptides.
Université Louis Pasteur/Centre national de recherche scientifique, Unité mixte de recherche 7177, Institut de Chimie, Strasbourg, France.
Evgeniy S
ES
Salnikov
Herdis
H
Friedrich
Xing
X
Li
Philippe
P
Bertani
Siegmund
S
Reissmann
Christian
C
Hertweck
Joe D J
JD
O'Neil
Jan
J
Raap
Burkhard
B
Bechinger
D000408:Alamethicin / Q000737:chemistry*; D003198:Computer Simulation; D006999:Hypocreales; D008051:Lipid Bilayers / Q000737:chemistry*; D008956:Models, Chemical; D009587:Nitrogen Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular; D054848:Peptaibols / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D010759:Phosphorus Isotopes; D010767:Phosphorylcholine / Q000737:chemistry; D017433:Protein Structure, Secondary; D011522:Protons; D053719:Tandem Mass Spectrometry; D014961:X-Ray Diffraction
D008051:Lipid Bilayers; D009587:Nitrogen Isotopes; D054848:Peptaibols; D010455:Peptides; D010759:Phosphorus Isotopes; D011522:Protons; C109004:ampullosporin; D010767:Phosphorylcholine; D000408:Alamethicin