Structural and orientational information of the membrane embedded M13 coatprotein by C-13-MAS NMR spectroscopy

Oriented and unoriented M13 coat protein, incorporated into dimyristoyl pho sphatidylcholine bilayers, has been studied by C-13-magic angle spinning nu clear magnetic resonance (MAS NMR) spectroscopy. Rotational resonance exper iments provided two distance constraints between C alpha and C=O positions of the labelled residues Val-29/Val-30 (0.4 +/- 0.5 nm) and Val-29Nal-31 (0 .45 +/- 0.5 nm) in its hydrophobic domain. The derived dihedral angles (Phi , Psi) for Val-3D revealed a local alpha-helical conformation. C-13-CP-MAS experiments on uniformly aligned samples (MAOSS experiments) using the C-13 = O labelled site of Val-30 allowed the determination of the helix tilt (2 0 degrees +/- 10 degrees) in the membrane. It is shown that one uniform MAS high-resolution solid state NMR approach can be used to obtain structural and orientational data. (C) 2000 Elsevier Science B.V. All rights reserved.