Solid-state NMR spectroscopy of human immunodeficiency virus fusion peptides associated with host-cell-like membranes: 2D correlation spectra and distance measurements support a fully extended conformation and models for specific antiparallel strand registries.
The human immunodeficiency virus (HIV) is "enveloped" by a membrane, and infection of a host cell begins with fusion between viral and target cell membranes. Fusion is catalyzed by the HIV gp41 protein which contains a functionally critical approximately 20-residue apolar "fusion peptide" (HFP) that associates with target cell membranes. In this study, chemically synthesized HFPs were associated with host-cell-like membranes and had "scatter-uniform" labeling (SUL), that is, only one residue of each amino acid type was U-(13)C, (15)N labeled. For the first sixteen HFP residues, an unambiguous (13)C chemical shift assignment was derived from 2D (13)C/(13)C correlation spectra with short mixing times, and the shifts were consistent with continuous beta-strand conformation. (13)C-(13)C contacts between residues on adjacent strands were derived from correlation spectra with long mixing times and suggested close proximity of the following residues: Ala-6/Gly-10, Ala-6/Phe-11, and Ile-4/Gly-13. Specific antiparallel beta-strand registries were further tested using a set of HFPs that were (13)CO-labeled at Ala-14 and (15)N-labeled at either Val-2, Gly-3, Ile-4, or Gly-5. The solid-state NMR data were fit with 50-60% population of antiparallel HFP with either Ala-14/Gly-3 or Ala-14/Ile-4 registries and 40-50% population of structures not specified by the NMR experiments. The first two registries correlated with intermolecular hydrogen bonding of 15-16 apolar N-terminal residues and this hydrogen-bonding pattern would be consistent with a predominant location of these residues in the hydrophobic membrane interior. To our knowledge, these results provide the first residue-specific structural models for membrane-associated HFP in its beta-strand conformation.
Qiang
Wei
W
Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA.
Bodner
Michele L
ML
Weliky
David P
DP
D000595:Amino Acid Sequence; D002250:Carbon Radioisotopes / Q000737:chemistry; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D006678:HIV / Q000737:chemistry*; D015700:HIV Envelope Protein gp41 / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008561:Membrane Fusion / Q000502:physiology*; D008969:Molecular Sequence Data; D009587:Nitrogen Isotopes / Q000737:chemistry; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism; D017433:Protein Structure, Secondary
D002250:Carbon Radioisotopes; D015700:HIV Envelope Protein gp41; D009587:Nitrogen Isotopes; D010455:Peptides