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Gaalswyk K, Liu Z, Vogel HJ, MacCallum JL. An Integrative Approach to Determine 3D Protein Structures Using Sparse Paramagnetic NMR Data and Physical Modeling. Front Mol Biosci 2021; 8:676268. [PMID: 34476238 PMCID: PMC8407082 DOI: 10.3389/fmolb.2021.676268] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 07/29/2021] [Indexed: 11/13/2022] Open
Abstract
Paramagnetic nuclear magnetic resonance (NMR) methods have emerged as powerful tools for structure determination of large, sparsely protonated proteins. However traditional applications face several challenges, including a need for large datasets to offset the sparsity of restraints, the difficulty in accounting for the conformational heterogeneity of the spin-label, and noisy experimental data. Here we propose an integrative approach to structure determination combining sparse paramagnetic NMR with physical modelling to infer approximate protein structural ensembles. We use calmodulin in complex with the smooth muscle myosin light chain kinase peptide as a model system. Despite acquiring data from samples labeled only at the backbone amide positions, we are able to produce an ensemble with an average RMSD of ∼2.8 Å from a reference X-ray crystal structure. Our approach requires only backbone chemical shifts and measurements of the paramagnetic relaxation enhancement and residual dipolar couplings that can be obtained from sparsely labeled samples.
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Affiliation(s)
- Kari Gaalswyk
- Department of Chemistry, University of Calgary, Calgary, AB, Canada
| | - Zhihong Liu
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Hans J. Vogel
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
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Parigi G, Ravera E, Fragai M, Luchinat C. Unveiling protein dynamics in solution with field-cycling NMR relaxometry. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2021; 124-125:85-98. [PMID: 34479712 DOI: 10.1016/j.pnmrs.2021.05.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 05/04/2021] [Accepted: 05/04/2021] [Indexed: 06/13/2023]
Abstract
Field-cycling NMR relaxometry is a well-established technique that can give information on molecular structure and dynamics of biological systems. It provides the nuclear relaxation rates as a function of the applied magnetic field, starting from fields as low as ~ 10-4 T up to about 1-3 T. The profiles so collected, called nuclear magnetic relaxation dispersion (NMRD) profiles, can be extended to include the relaxation rates at the largest fields achievable with high resolution NMR spectrometers. By exploiting this wide range of frequencies, the NMRD profiles can provide information on motions occurring on time scales from 10-6 to 10-9 s. 1H NMRD measurements have proved very useful also for the characterization of paramagnetic proteins, because they can help characterise a number of parameters including the number, distance and residence time of water molecules coordinated to the paramagnetic center, the reorientation correlation times and the electron spin relaxation time, and the electronic structure at the metal site.
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Affiliation(s)
- Giacomo Parigi
- Magnetic Resonance Center (CERM) University of Florence, via Sacconi 6, Sesto Fiorentino, Italy; Department of Chemistry, "Ugo Schiff", University of Florence, via della Lastruccia 3, Sesto Fiorentino, Italy; Consorzio Interuniversitario Risonanze Magnetiche di Metalloproteine (CIRMMP), via Sacconi 6, Sesto Fiorentino, Italy.
| | - Enrico Ravera
- Magnetic Resonance Center (CERM) University of Florence, via Sacconi 6, Sesto Fiorentino, Italy; Department of Chemistry, "Ugo Schiff", University of Florence, via della Lastruccia 3, Sesto Fiorentino, Italy; Consorzio Interuniversitario Risonanze Magnetiche di Metalloproteine (CIRMMP), via Sacconi 6, Sesto Fiorentino, Italy
| | - Marco Fragai
- Magnetic Resonance Center (CERM) University of Florence, via Sacconi 6, Sesto Fiorentino, Italy; Department of Chemistry, "Ugo Schiff", University of Florence, via della Lastruccia 3, Sesto Fiorentino, Italy; Consorzio Interuniversitario Risonanze Magnetiche di Metalloproteine (CIRMMP), via Sacconi 6, Sesto Fiorentino, Italy
| | - Claudio Luchinat
- Magnetic Resonance Center (CERM) University of Florence, via Sacconi 6, Sesto Fiorentino, Italy; Department of Chemistry, "Ugo Schiff", University of Florence, via della Lastruccia 3, Sesto Fiorentino, Italy; Consorzio Interuniversitario Risonanze Magnetiche di Metalloproteine (CIRMMP), via Sacconi 6, Sesto Fiorentino, Italy
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