Article Information

• PDF (1345 kb)

PubMed

• Articles by L.R. Brown
• Articles by K. Wüthrich

Related Articles

• Solid-State NMR Structure Determination of Melittin in a Lip...

  Solid-State NMR Structure Determination of Melittin in a Lipid Environment Biophysical Journal, Volume 81, Issue 5, 1 November 2001, Pages 2752-2761 Y.H. Lam, S.R. Wassall, C.J. Morton, R. Smith and F. Separovic Abstract Solid-state C NMR spectroscopy was used to investigate the three-dimensional structure of melittin as lyophilized powder and in ditetradecylphosphatidylcholine (DTPC) membranes. The distance between specifically labeled carbons in analogs [1-C]Gly3-[2-C]Ala4, [1-C]Gly3-[2-C]Leu6, [1-C]Leu13-[2-C]Ala15, [2-C]Leu13-[1-C]Ala15, and [1-C]Leu13-[2-C]Leu16 was measured by rotational resonance. As expected, the internuclear distances measured in [1-C]Gly3-[2-C]Ala4 and [1-C]Gly3-[2-C]Leu6 were consistent with -helical structure in the N-terminus irrespective of environment. The internuclear distances measured in [1-C]Leu13-[2-C]Ala15, [2-C]Leu13-[1-C]Ala15, and [1-C]Leu13-[2-C]Leu16 revealed, via molecular modeling, some dependence upon environment for conformation in the region of the bend in helical structure induced by Pro14. A slightly larger interhelical angle between the N- and C-terminal helices was indicated for peptide in dry or hydrated gel state DTPC (139°–145°) than in lyophilized powder (121°–139°) or crystals (129°). The angle, however, is not as great as deduced for melittin in aligned bilayers of DTPC in the liquid-crystalline state (∼160°) (R. Smith, F. Separovic, T. J. Milne, A. Whittaker, F. M. Bennett, B. A. Cornell, and A. Makriyannis, 1994, 241:456–466). The study illustrates the utility of rotational resonance in determining local structure within peptide-lipid complexes. Abstract | Full Text | PDF (238 kb)

• The Alignment of a Voltage-Sensing Peptide in Dodecylphospho...

  The Alignment of a Voltage-Sensing Peptide in Dodecylphosphocholine Micelles and in Oriented Lipid Bilayers by Nuclear Magnetic Resonance and Molecular Modeling Biophysical Journal, Volume 77, Issue 4, 1 October 1999, Pages 2102-2113 Kimmo Mattila, Rudolf Kinder and Burkhard Bechinger Abstract The S4 segments of voltage-gated sodium channels are important parts of the voltage-sensing elements of these proteins. Furthermore, the addition of the isolated S4 polypeptide to planar lipid bilayers results in stepwise increases of ion conductivity. In order to gain insight into the mechanisms of pore formation by amphipathic peptides, the structure and orientation of the S4 segment of the first internal repeat of the rat brain II sodium channel was investigated in the presence of DPC micelles by multidimensional solution NMR spectroscopy and solid-state NMR spectroscopy on oriented phospholipid bilayers. Both the anisotropic chemical shift observed by proton-decoupled N solid-state NMR spectroscopy and the attenuating effects of DOXYL-stearates on TOCSY crosspeak intensities of micelle-associated S4 indicate that the central -helical portion of this peptide is oriented approximately parallel to the membrane surface. Simulated annealing and molecular dynamics calculations of the peptide in a biphasic tetrachloromethane-water environment indicate that the peptide -helix extends over ∼12 residues. A less regular structure further toward the C-terminus allows for the hydrophobic residues of this part of the peptide to be positioned in the tetrachloromethane environment. The implications for possible pore-forming mechanisms are discussed. Abstract | Full Text | PDF (569 kb)

• Morphological Behavior of Lipid Bilayers Induced by Melittin...

  Morphological Behavior of Lipid Bilayers Induced by Melittin near the Phase Transition Temperature Biophysical Journal, Volume 89, Issue 5, 1 November 2005, Pages 3214-3222 Shuichi Toraya, Takashi Nagao, Kazushi Norisada, Satoru Tuzi, Hazime Saitô, Shunsuke Izumi and Akira Naito Abstract Morphological changes of DMPC, DLPC, and DPPC bilayers containing melittin (lecithin/melittin molar ratio of 10:1) around the gel-to-liquid crystalline phase transition temperatures (c) were examined by a variety of biophysical methods. First, giant vesicles with the diameters of ∼20m were observed by optical microscopy for melittin-DMPC bilayers at 27.9°C. When the temperature was lowered to 24.9°C (c=23°C for the neat DMPC bilayers), the surface of vesicles became blurred and dynamic pore formation was visible in the microscopic picture taken at different exposure times. Phase separation and association of melittin molecules in the bilayers were further detected by fluorescent microscopy and mass spectrometry, respectively. These vesicles disappeared completely at 22.9°C. It was thus found that the melittin-lecithin bilayers reversibly undergo their fusion and disruption near the respective cs. The fluctuation of lipids is, therefore, responsible for the membrane fusion above the c, and the association of melittin molecules causes membrane fragmentation below the c. Subsequent magnetic alignments were observed by solid-state P NMR spectra for the melittin-lecithin vesicles at a temperature above the respective cs. On the other hand, additional large amplitude motion induced by melittin at a temperature near the c breaks down the magnetic alignment. Abstract | Full Text | PDF (528 kb)

• …more

Abstract

Previously, the size and stoichiometry of mixed micelles of perdeuterated dodecylphosphocholine and melittin were characterized and the 1H NMR spin systems of most amino acid residues of micelle-bound melittin identified. One- and two-dimensional 1H-1H Overhauser experiments have now been used to obtain qualitative information on intramolecular proton-proton distances. These data show that the N-terminal and the C-terminal segments of melittin form two spatially distinct, compact domains; using lipid spin labels these could be located near the micelle surface. For the C-terminal domain a detailed conformation was determined by using the distance contraints from the Overhauser studies as input for a distance geometry algorithm.