Impact of 15N R2/R1 Relaxation Restraints on Molecular Size, Shape, and Bond Vector Orientation for NMR Protein Structure Determination with Sparse Dista
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- 作者：Yaroslav Ryabov ; Charles D. Schwieters ; G. Marius Clore
- 刊名：Journal of the American Chemical Society
- 出版年：2011
- 出版时间：April 27, 2011
- 年：2011
- 卷：133
- 期：16
- 页码：6154-6157
- 全文大小：746K
- 年卷期：v.133,no.16(April 27, 2011)
- ISSN：1520-5126
文摘
15N R2/R1 relaxation data contain information on molecular shape and size as well as on bond vector orientations relative to the diffusion tensor. Since the diffusion tensor can be directly calculated from the molecular coordinates, direct inclusion of 15N R2/R1 restraints in NMR structure calculations without any a priori assumptions is possible. Here we show that 15N R2/R1 restraints are particularly valuable when only sparse distance restraints are available. Using three examples of proteins of varying size, namely, GB3 (56 residues), ubiquitin (76 residues), and the N-terminal domain of enzyme I (EIN, 249 residues), we show that incorporation of 15N R2/R1 restraints results in large and significant increases in coordinate accuracy that can make the difference between being able or unable to determine an approximate global fold. For GB3 and ubiquitin, good coordinate accuracy was obtained using only backbone hydrogen-bond restraints supplemented by 15N R2/R1 relaxation restraints. For EIN, the global fold could be determined using sparse nuclear Overhauser enhancement (NOE) distance restraints involving only NH and methyl groups in conjunction with 15N R2/R1 restraints. These results are of practical significance in the study of larger and more complex systems, where the increasing spectral complexity and number of chemical shift degeneracies reduce the number of unambiguous NOE asssignments that can be readily obtained, resulting in progressively reduced NOE coverage as the size of the protein increases.