Detection of peptide-phospholipid interaction sites in bilayer membranes by 13C NMR spectroscopy: observation of 2H/31P-selective 1H-depolarization under magic-angle spinning.
We have developed a solid-state NMR method for observing the signals due to 13C spins of a peptide in the close vicinity of 31P and 2H spins in deuterated phospholipid bilayers. The signal intensities in 13C high-resolution NMR spectra directly indicate the depolarization of 1H by 1H-31P and 1H-2H dipolar couplings under multiple-contact cross-polarization. This method was applied to a fully 13C-, 15N-labeled 14-residue peptide, mastoparan-X (MP-X), bound to phospholipid bilayers whose fatty acyl chains are deuterated. The 13C NMR spectra for the depolarization were simulated from the chemical shifts and structure of membrane-bound MP-X previously determined and the distribution of 2H and 31P spins in lipid bilayers. The minimization of RMSD between the simulated and the experimental spectra showed that the amphiphilic alpha-helix of MP-X was located in the interface between the water layer and the hydrophobic domain of the bilayer, with nonpolar residues facing the phosphorus atoms and alkyl chains of the lipids.
Harada
Erisa
E
Institute for Protein Research, Osaka University, Suita, 565-0871, Japan, and Japan Biological Informatics Consortium, Chuo-ku, Tokyo 104-0032, Japan.
Todokoro
Yasuto
Y
Akutsu
Hideo
H
Fujiwara
Toshimichi
T
D002247:Carbon Isotopes; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008567:Membranes, Artificial; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D010743:Phospholipids / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation
D002247:Carbon Isotopes; D008567:Membranes, Artificial; D010455:Peptides; D010743:Phospholipids