TY - JOUR
T1 - Residue-specific vibrational echoes yield 3D structures of a transmembrane helix dimer
AU - Remorino, Amanda
AU - Korendovych, Ivan V.
AU - Wu, Yibing
AU - DeGrado, William F.
AU - Hochstrasser, Robin M.
PY - 2011/6/3
Y1 - 2011/6/3
N2 - Two-dimensional (2D) vibrational echo spectroscopy has previously been applied to structural determination of small peptides. Here we extend the technique to a more complex, biologically important system: the homodimeric transmembrane dimer from the a chain of the integrin α IIbβ 3. We prepared micelle suspensions of the pair of 30-residue chains that span the membrane in the native structure, with varying levels of heavy ( 13C= 18O) isotopes substituted in the backbone of the central 10th through 20th positions. The constraints derived from vibrational coupling of the precisely spaced heavy residues led to determination of an optimized structure from a range of model candidates: Glycine residues at the 12th, 15th, and 16th positions form a tertiary contact in parallel right-handed helix dimers with crossing angles of -58° ± 9° and interhelical distances of 7.7 ± 0.5 angstroms. The frequency correlation established the dynamical model used in the analysis, and it indicated the absence of mobile water associated with labeled residues. Delocalization of vibrational excitations between the helices was also quantitatively established.
AB - Two-dimensional (2D) vibrational echo spectroscopy has previously been applied to structural determination of small peptides. Here we extend the technique to a more complex, biologically important system: the homodimeric transmembrane dimer from the a chain of the integrin α IIbβ 3. We prepared micelle suspensions of the pair of 30-residue chains that span the membrane in the native structure, with varying levels of heavy ( 13C= 18O) isotopes substituted in the backbone of the central 10th through 20th positions. The constraints derived from vibrational coupling of the precisely spaced heavy residues led to determination of an optimized structure from a range of model candidates: Glycine residues at the 12th, 15th, and 16th positions form a tertiary contact in parallel right-handed helix dimers with crossing angles of -58° ± 9° and interhelical distances of 7.7 ± 0.5 angstroms. The frequency correlation established the dynamical model used in the analysis, and it indicated the absence of mobile water associated with labeled residues. Delocalization of vibrational excitations between the helices was also quantitatively established.
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U2 - 10.1126/science.1202997
DO - 10.1126/science.1202997
M3 - Article
C2 - 21636774
AN - SCOPUS:79957962090
SN - 0036-8075
VL - 332
SP - 1206
EP - 1209
JO - Science
JF - Science
IS - 6034
ER -