title: Dynamic structure of bombolitin II bound to lipid bilayers as revealed by solid-state NMR and molecular-dynamics simulation.
abstract: Bombolitin II (BLT2) is one of the hemolytic heptadecapeptides originally isolated from the venom of a bumblebee. Structure and orientation of BLT2 bound to 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) membranes were determined by solid-state (31)P and (13)C NMR spectroscopy. (31)P NMR spectra showed that BLT2-DPPC membranes were disrupted into small particles below the gel-to-liquid crystalline phase transition temperature (T(c)) and fused to form a magnetically oriented vesicle system where the membrane surface is parallel to the magnetic fields above the T(c). (13)C NMR spectra of site-specifically (13)C-labeled BLT2 at the carbonyl carbons were observed and the chemical shift anisotropies were analyzed to determine the dynamic structure of BLT2 bound to the magnetically oriented vesicle system. It was revealed that the membrane-bound BLT2 adopted an α-helical structure, rotating around the membrane normal with the tilt angle of the helical axis at 33°. Interatomic distances obtained from rotational-echo double-resonance experiments further showed that BLT2 adopted a straight α-helical structure. Molecular dynamics simulation performed in the BLT2-DPPC membrane system showed that the BLT2 formed a straight α-helix and that the C-terminus was inserted into the membrane. The α-helical axis is tilted 30° to the membrane normal, which is almost the same as the value obtained from solid-state NMR. These results suggest that the membrane disruption induced by BLT2 is attributed to insertion of BLT2 into the lipid bilayers.
authors.affiliation: Faculty of Engineering, Yokohama National University, Yokohama, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Toraya
authors.forename: Namsrai
authors.initials: N
authors.lastname: Javkhlantugs
authors.forename: Daisuke
authors.initials: D
authors.lastname: Mishima
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Nishimura
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Ueda
authors.forename: Akira
authors.initials: A
authors.lastname: Naito
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D001516:Bees; D002244:Carbon; D005612:Freeze Drying; D008051:Lipid Bilayers / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008280:Magnetics; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D013997:Time Factors
chemical_list: D008051:Lipid Bilayers; D010455:Peptides; C044299:bombolitins; D015060:1,2-Dipalmitoylphosphatidylcholine; D002244:Carbon