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NMR structural characterization of HIV‐1 virus protein U cytoplasmic domain in the presence of dodecylphosphatidylcholine micelles
Author(s) -
Wittlich Marc,
Koenig Bernd W.,
Stoldt Matthias,
Schmidt Holger,
Willbold Dieter
Publication year - 2009
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2009.07363.x
Subject(s) - micelle , chemistry , crystallography , paramagnetism , helix (gastropod) , heteronuclear molecule , relaxation (psychology) , biophysics , nuclear magnetic resonance spectroscopy , aqueous solution , stereochemistry , biology , physics , ecology , quantum mechanics , snail , neuroscience
The HIV‐1 encoded virus protein U (VpU) is required for efficient viral release from human host cells and for induction of CD4 degradation in the endoplasmic reticulum. The cytoplasmic domain of the membrane protein VpU (VpUcyt) is essential for the latter activity. The structure and dynamics of VpUcyt were characterized in the presence of membrane simulating dodecylphosphatidylcholine (DPC) micelles by high‐resolution liquid state NMR. VpUcyt is unstructured in aqueous buffer. The addition of DPC micelles induces a well‐defined membrane proximal α‐helix (residues I39–E48) and an additional helical segment (residues L64–R70). A tight loop (L73–V78) is observed close to the C‐terminus, whereas the interhelical linker (R49–E63) remains highly flexible. A 3D structure of VpUcyt in the presence of DPC micelles was calculated from a large set of proton–proton distance constraints. The topology of micelle‐associated VpUcyt was derived from paramagnetic relaxation enhancement of protein nuclear spins after the introduction of paramagnetic probes into the interior of the micelle or the aqueous buffer. Qualitative analysis of secondary chemical shift and paramagnetic relaxation enhancement data in conjunction with dynamic information from heteronuclear NOEs and structural insight from homonuclear NOE‐based distance constraints indicated that micelle‐associated VpUcyt retains a substantial degree of structural flexibility.