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SARS‐CoV heptad repeat 2 is a trimer of parallel helices
Author(s) -
Celigoy Jessica,
Ramirez Benjamin,
Caffrey Michael
Publication year - 2011
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.736
Subject(s) - trimer , heptad repeat , chemistry , tetramer , crystallography , nuclear magnetic resonance spectroscopy , peptide , protein structure , biophysics , stereochemistry , peptide sequence , dimer , biochemistry , biology , organic chemistry , gene , enzyme
In severe acute respiratory syndrome coronavirus, the envelope heptad repeat 2 (HR2) plays a critical role in viral entry. Moreover, HR2 is both the target for novel antiviral therapies and, as an isolated peptide, presents a potential antiviral therapeutic. The structure of HR2, as determined by NMR spectroscopy in the presence of the co‐solvent trifluoroethanol (TFE), is a trimer of parallel helices, whereas the structure of HR2, as determined by X‐ray crystallography, is a tetramer of anti‐parallel helices. In this work, we added a nitroxide spin label to the N‐terminal region of HR2 and used paramagnetic relaxation enhancement to assess the orientation of the HR2 helices under different solution conditions. We find that the relaxation effects are consistent with an orientation corresponding to a trimer of parallel helices in both the presence and absence of TFE. This work suggests that the different orientation and oligomerization states observed by NMR and X‐ray are due to the 11 additional residues present at the N‐terminus of the NMR construct.