In:
Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 108, No. 41 ( 2011-10-11), p. 16974-16979
Kurzfassung:
NMR chemical shift tensors (CSTs) in proteins, as well as their orientations, represent an important new restraint class for protein structure refinement and determination. Here, we present the first determination of both CST magnitudes and orientations for 13 C α and 15 N (peptide backbone) groups in a protein, the β1 IgG binding domain of protein G from Streptococcus spp., GB1. Site-specific 13 C α and 15 N CSTs were measured using synchronously evolved recoupling experiments in which 13 C and 15 N tensors were projected onto the 1 H- 13 C and 1 H- 15 N vectors, respectively, and onto the 15 N- 13 C vector in the case of 13 C α . The orientations of the 13 C α CSTs to the 1 H- 13 C and 13 C- 15 N vectors agreed well with the results of ab initio calculations, with an rmsd of approximately 8°. In addition, the measured 15 N tensors exhibited larger reduced anisotropies in α-helical versus β-sheet regions, with very limited variation (18 ± 4°) in the orientation of the z -axis of the 15 N CST with respect to the 1 H- 15 N vector. Incorporation of the 13 C α CST restraints into structure calculations, in combination with isotropic chemical shifts, transferred echo double resonance 13 C- 15 N distances and vector angle restraints, improved the backbone rmsd to 0.16 Å (PDB ID code 2LGI) and is consistent with existing X-ray structures (0.51 Å agreement with PDB ID code 2QMT). These results demonstrate that chemical shift tensors have considerable utility in protein structure refinement, with the best structures comparable to 1.0-Å crystal structures, based upon empirical metrics such as Ramachandran geometries and χ 1 / χ 2 distributions, providing solid-state NMR with a powerful tool for de novo structure determination.
Materialart:
Online-Ressource
ISSN:
0027-8424
,
1091-6490
DOI:
10.1073/pnas.1103728108
Sprache:
Englisch
Verlag:
Proceedings of the National Academy of Sciences
Publikationsdatum:
2011
ZDB Id:
209104-5
ZDB Id:
1461794-8
SSG:
11
SSG:
12
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