1
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Yi X, Fritzsching KJ, Rogawski R, Xu Y, McDermott AE. Contribution of protein conformational heterogeneity to NMR lineshapes at cryogenic temperatures. Proc Natl Acad Sci U S A 2024; 121:e2301053120. [PMID: 38346186 PMCID: PMC10895356 DOI: 10.1073/pnas.2301053120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 10/17/2023] [Indexed: 02/15/2024] Open
Abstract
While low-temperature Nuclear Magnetic Resonance (NMR) holds great promise for the analysis of unstable samples and for sensitizing NMR detection, spectral broadening in frozen protein samples is a common experimental challenge. One hypothesis explaining the additional linewidth is that a variety of conformations are in rapid equilibrium at room temperature and become frozen, creating an inhomogeneous distribution at cryogenic temperatures. Here, we investigate conformational heterogeneity by measuring the backbone torsion angle (Ψ) in Escherichia coli Dihydrofolate Reductase (DHFR) at 105 K. Motivated by the particularly broad N chemical shift distribution in this and other examples, we modified an established NCCN Ψ experiment to correlate the chemical shift of Ni+1 to Ψi. With selective 15N and 13C enrichment of Ile, only the unique I60-I61 pair was expected to be detected in 13C'-15N correlation spectrum. For this unique amide, we detected three different conformation basins based on dispersed chemical shifts. Backbone torsion angles Ψ were determined for each basin: 114 ± 7° for the major peak and 150 ± 8° and 164 ± 16° for the minor peaks as contrasted with 118° for the X-ray crystal structure (and 118° to 130° for various previously reported structures). These studies support the hypothesis that inhomogeneous distributions of protein backbone torsion angles contribute to the lineshape broadening in low-temperature NMR spectra.
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Affiliation(s)
- Xu Yi
- Department of Chemistry, Columbia University, New York, NY 1002
| | | | - Rivkah Rogawski
- Department of Chemistry, Columbia University, New York, NY 1002
| | - Yunyao Xu
- Department of Chemistry, Columbia University, New York, NY 1002
| | - Ann E McDermott
- Department of Chemistry, Columbia University, New York, NY 1002
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2
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Nouri S, Boudet J, Dreher-Teo H, Allain FHT, Glockshuber R, Salmon L, Giese C. Elongated Bacterial Pili as a Versatile Alignment Medium for NMR Spectroscopy. Angew Chem Int Ed Engl 2023; 62:e202305120. [PMID: 37248171 DOI: 10.1002/anie.202305120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 05/25/2023] [Accepted: 05/26/2023] [Indexed: 05/31/2023]
Abstract
In NMR spectroscopy, residual dipolar couplings (RDCs) have emerged as one of the most exquisite probes of biological structure and dynamics. The measurement of RDCs relies on the partial alignment of the molecule of interest, for example by using a liquid crystal as a solvent. Here, we establish bacterial type 1 pili as an alternative liquid-crystalline alignment medium for the measurement of RDCs. To achieve alignment at pilus concentrations that allow for efficient NMR sample preparation, we elongated wild-type pili by recombinant overproduction of the main structural pilus subunit. Building on the extraordinary stability of type 1 pili against spontaneous dissociation and unfolding, we show that the medium is compatible with challenging experimental conditions such as high temperature, the presence of detergents, organic solvents or very acidic pH, setting it apart from most established alignment media. Using human ubiquitin, HIV-1 TAR RNA and camphor as spectroscopic probes, we demonstrate the applicability of the medium for the determination of RDCs of proteins, nucleic acids and small molecules. Our results show that type 1 pili represent a very useful alternative to existing alignment media and may readily assist the characterization of molecular structure and dynamics by NMR.
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Affiliation(s)
- Sirine Nouri
- Centre de RMN à Très Hauts Champs, CNRS, ENSL, UCBL, Université de Lyon, 5 rue de la Doua, 69100, Villeurbanne, France
| | - Julien Boudet
- Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, 8093, Zürich, Switzerland
| | - Hiang Dreher-Teo
- Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, 8093, Zürich, Switzerland
| | - Frédéric H-T Allain
- Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, 8093, Zürich, Switzerland
- Institute of Biochemistry, ETH Zurich, Otto-Stern-Weg 3, 8093, Zürich, Switzerland
| | - Rudi Glockshuber
- Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, 8093, Zürich, Switzerland
| | - Loïc Salmon
- Centre de RMN à Très Hauts Champs, CNRS, ENSL, UCBL, Université de Lyon, 5 rue de la Doua, 69100, Villeurbanne, France
- Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, 8093, Zürich, Switzerland
| | - Christoph Giese
- Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, 8093, Zürich, Switzerland
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3
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Yi X, Fritzsching KJ, Rogawski R, Xu Y, McDermott AE. Contribution of protein conformational heterogeneity to NMR lineshapes at cryogenic temperatures. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.24.525358. [PMID: 36747795 PMCID: PMC9900807 DOI: 10.1101/2023.01.24.525358] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
While low temperature NMR holds great promise for the analysis of unstable samples and for sensitizing NMR detection, spectral broadening in frozen protein samples is a common experimental challenge. One hypothesis explaining the additional linewidth is that a variety of conformations are in rapid equilibrium at room temperature and become frozen, creating an inhomogeneous distribution at cryogenic temperatures. Here we investigate conformational heterogeneity by measuring the backbone torsion angle (Ψ) in E. coli DHFR at 105K. Motivated by the particularly broad N chemical shift distribution in this and other examples, we modified an established NCCN Ψ experiment to correlate the chemical shift of N i+1 to Ψ i . With selective 15 N and 13 C enrichment of Ile, only the unique I60-I61 pair was expected to be detected in 13 C'- 15 N correlation spectrum. For this unique amide we detected three different conformation basins based on dispersed chemical shifts. Backbone torsion angles Ψ were determined for each basin 114 ± 7 for the major peak, and 150 ± 8 and 164 ± 16° for the minor peak as contrasted with 118 for the X-ray crystal structure (and 118-130 for various previously reported structures). These studies support the hypothesis that inhomogeneous distributions of protein backbone torsion angles contribute to the lineshape broadening in low temperature NMR spectra. Significance Statement Understanding protein conformational flexibility is essential for insights into the molecular basis of protein function and the thermodynamics of proteins. Here we investigate the ensemble of protein backbone conformations in a frozen protein freezing, which is likely a close representation for the ensemble in rapid equilibrium at room temperature. Various conformers are spectrally resolved due to the exquisite sensitivity of NMR shifts to local conformations, and NMR methods allow us to directly probe the torsion angles corresponding to each band of chemical shifts.
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4
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Camacho-Zarco AR, Schnapka V, Guseva S, Abyzov A, Adamski W, Milles S, Jensen MR, Zidek L, Salvi N, Blackledge M. NMR Provides Unique Insight into the Functional Dynamics and Interactions of Intrinsically Disordered Proteins. Chem Rev 2022; 122:9331-9356. [PMID: 35446534 PMCID: PMC9136928 DOI: 10.1021/acs.chemrev.1c01023] [Citation(s) in RCA: 45] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
![]()
Intrinsically disordered
proteins are ubiquitous throughout all
known proteomes, playing essential roles in all aspects of cellular
and extracellular biochemistry. To understand their function, it is
necessary to determine their structural and dynamic behavior and to
describe the physical chemistry of their interaction trajectories.
Nuclear magnetic resonance is perfectly adapted to this task, providing
ensemble averaged structural and dynamic parameters that report on
each assigned resonance in the molecule, unveiling otherwise inaccessible
insight into the reaction kinetics and thermodynamics that are essential
for function. In this review, we describe recent applications of NMR-based
approaches to understanding the conformational energy landscape, the
nature and time scales of local and long-range dynamics and how they
depend on the environment, even in the cell. Finally, we illustrate
the ability of NMR to uncover the mechanistic basis of functional
disordered molecular assemblies that are important for human health.
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Affiliation(s)
| | - Vincent Schnapka
- Université Grenoble Alpes, CEA, CNRS, IBS, 38000 Grenoble, France
| | - Serafima Guseva
- Université Grenoble Alpes, CEA, CNRS, IBS, 38000 Grenoble, France
| | - Anton Abyzov
- Université Grenoble Alpes, CEA, CNRS, IBS, 38000 Grenoble, France
| | - Wiktor Adamski
- Université Grenoble Alpes, CEA, CNRS, IBS, 38000 Grenoble, France
| | - Sigrid Milles
- Université Grenoble Alpes, CEA, CNRS, IBS, 38000 Grenoble, France
| | | | - Lukas Zidek
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 82500 Brno, Czech Republic.,Central European Institute of Technology, Masaryk University, Kamenice 5, 82500 Brno, Czech Republic
| | - Nicola Salvi
- Université Grenoble Alpes, CEA, CNRS, IBS, 38000 Grenoble, France
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5
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Karamanos TK, Kalverda AP, Radford SE. Generating Ensembles of Dynamic Misfolding Proteins. Front Neurosci 2022; 16:881534. [PMID: 35431773 PMCID: PMC9008329 DOI: 10.3389/fnins.2022.881534] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 03/08/2022] [Indexed: 01/09/2023] Open
Abstract
The early stages of protein misfolding and aggregation involve disordered and partially folded protein conformers that contain a high degree of dynamic disorder. These dynamic species may undergo large-scale intra-molecular motions of intrinsically disordered protein (IDP) precursors, or flexible, low affinity inter-molecular binding in oligomeric assemblies. In both cases, generating atomic level visualization of the interconverting species that captures the conformations explored and their physico-chemical properties remains hugely challenging. How specific sub-ensembles of conformers that are on-pathway to aggregation into amyloid can be identified from their aggregation-resilient counterparts within these large heterogenous pools of rapidly moving molecules represents an additional level of complexity. Here, we describe current experimental and computational approaches designed to capture the dynamic nature of the early stages of protein misfolding and aggregation, and discuss potential challenges in describing these species because of the ensemble averaging of experimental restraints that arise from motions on the millisecond timescale. We give a perspective of how machine learning methods can be used to extract aggregation-relevant sub-ensembles and provide two examples of such an approach in which specific interactions of defined species within the dynamic ensembles of α-synuclein (αSyn) and β2-microgloblulin (β2m) can be captured and investigated.
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Affiliation(s)
- Theodoros K. Karamanos
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | | | - Sheena E. Radford
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
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6
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East KW, Newton JC, Morzan UN, Narkhede Y, Acharya A, Skeens E, Jogl G, Batista VS, Palermo G, Lisi GP. Allosteric Motions of the CRISPR-Cas9 HNH Nuclease Probed by NMR and Molecular Dynamics. J Am Chem Soc 2020; 142:1348-1358. [PMID: 31885264 PMCID: PMC7497131 DOI: 10.1021/jacs.9b10521] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
CRISPR-Cas9 is a widely employed genome-editing tool with functionality reliant on the ability of the Cas9 endonuclease to introduce site-specific breaks in double-stranded DNA. In this system, an intriguing allosteric communication has been suggested to control its DNA cleavage activity through flexibility of the catalytic HNH domain. Here, solution NMR experiments and a novel Gaussian-accelerated molecular dynamics (GaMD) simulation method are used to capture the structural and dynamic determinants of allosteric signaling within the HNH domain. We reveal the existence of a millisecond time scale dynamic pathway that spans HNH from the region interfacing the adjacent RuvC nuclease and propagates up to the DNA recognition lobe in full-length CRISPR-Cas9. These findings reveal a potential route of signal transduction within the CRISPR-Cas9 HNH nuclease, advancing our understanding of the allosteric pathway of activation. Further, considering the role of allosteric signaling in the specificity of CRISPR-Cas9, this work poses the mechanistic basis for novel engineering efforts aimed at improving its genome-editing capability.
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Affiliation(s)
- Kyle W. East
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI 02903, United States
| | - Jocelyn C. Newton
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI 02903, United States
| | - Uriel N. Morzan
- Department of Chemistry, Yale University, New Haven, CT 06520 , United States
| | - Yogesh Narkhede
- Department of Bioengineering, University of California Riverside, 900 University Avenue, Riverside, CA 52512, United States
| | - Atanu Acharya
- Department of Chemistry, Yale University, New Haven, CT 06520 , United States
| | - Erin Skeens
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI 02903, United States
| | - Gerwald Jogl
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI 02903, United States
| | - Victor S. Batista
- Department of Chemistry, Yale University, New Haven, CT 06520 , United States
| | - Giulia Palermo
- Department of Bioengineering, University of California Riverside, 900 University Avenue, Riverside, CA 52512, United States
| | - George P. Lisi
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI 02903, United States
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7
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Emani PS, Yimer YY, Davidowski SK, Gebhart RN, Ferreira HE, Kuprov I, Pfaendtner J, Drobny GP. Combining Molecular and Spin Dynamics Simulations with Solid-State NMR: A Case Study of Amphiphilic Lysine-Leucine Repeat Peptide Aggregates. J Phys Chem B 2019; 123:10915-10929. [PMID: 31769684 DOI: 10.1021/acs.jpcb.9b09245] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Interpreting dynamics in solid-state molecular systems requires characterization of the potentially heterogeneous environmental contexts of molecules. In particular, the analysis of solid-state nuclear magnetic resonance (ssNMR) data to elucidate molecular dynamics (MD) involves modeling the restriction to overall tumbling by neighbors, as well as the concentrations of water and buffer. In this exploration of the factors that influence motion, we utilize atomistic MD trajectories of peptide aggregates with varying hydration to mimic an amorphous solid-state environment and predict ssNMR relaxation rates. We also account for spin diffusion in multiply spin-labeled (up to 19 nuclei) residues, with several models of dipolar-coupling networks. The framework serves as a general approach to determine essential spin couplings affecting relaxation, benchmark MD force fields, and reveal the hydration dependence of dynamics in a crowded environment. We demonstrate the methodology on a previously characterized amphiphilic 14-residue lysine-leucine repeat peptide, LKα14 (Ac-LKKLLKLLKKLLKL-c), which has an α-helical secondary structure and putatively forms leucine-burying tetramers in the solid state. We measure the R1 relaxation rates of uniformly 13C-labeled and site-specific 2H-labeled leucines in the hydrophobic core of LKα14 at multiple hydration levels. Studies of 9 and 18 tetramer bundles reveal the following: (a) for the incoherent component of 13C relaxation, the nearest-neighbor spin interactions dominate, while the 1H-1H interactions have minimal impact; (b) the AMBER ff14SB dihedral barriers for the leucine Cγ-Cδ bond ("methyl rotation barriers") must be lowered by a factor of 0.7 to better match the 2H data; (c) proton-driven spin diffusion explains some of the discrepancy between experimental and simulated rates for the Cβ and Cα nuclei; and (d) 13C relaxation rates are mostly underestimated in the MD simulations at all hydrations, and the discrepancies identify likely motions missing in the 50 ns MD trajectories.
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Affiliation(s)
- Prashant S Emani
- Department of Chemistry , University of Washington , Box 351700 , Seattle , Washington 98195-1700 , United States
| | - Yeneneh Y Yimer
- Department of Chemical Engineering , University of Washington , 105 Benson Hall, Box 351750 , Seattle , Washington 98195-1750 , United States
| | - Stephen K Davidowski
- Department of Chemistry , University of Washington , Box 351700 , Seattle , Washington 98195-1700 , United States
| | - Rachel N Gebhart
- Department of Chemistry , University of Washington , Box 351700 , Seattle , Washington 98195-1700 , United States
| | - Helen E Ferreira
- Department of Chemistry , University of Washington , Box 351700 , Seattle , Washington 98195-1700 , United States
| | - Ilya Kuprov
- Department of Chemistry , University of Southampton , Highfield, Southampton SO17 1BJ , U.K
| | - Jim Pfaendtner
- Department of Chemical Engineering , University of Washington , 105 Benson Hall, Box 351750 , Seattle , Washington 98195-1750 , United States
| | - Gary P Drobny
- Department of Chemistry , University of Washington , Box 351700 , Seattle , Washington 98195-1700 , United States
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8
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Mapping the Dynamic Functions and Structural Features of AcrB Efflux Pump Transporter Using Accelerated Molecular Dynamics Simulations. Sci Rep 2018; 8:10470. [PMID: 29992991 PMCID: PMC6041327 DOI: 10.1038/s41598-018-28531-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 06/25/2018] [Indexed: 11/08/2022] Open
Abstract
Multidrug efflux pumps confer resistance to their bacterial hosts by pumping out a diverse range of compounds, including most antibiotics. Being more familiar with the details of functional dynamics and conformations of these types of pumps could help in discovering approaches to stop them functioning properly. Computational approaches, particularly conventional molecular dynamics simulations followed by diverse post simulation analysis, are powerful methods that help researchers by opening a new window to study phenomena that are not detectable in as much detail in vitro or in vivo as they are in silico. In this study, accelerated molecular dynamics simulations were applied to study the dynamics of AcrB efflux pump transporters in interaction with PAβN and tetracycline as an inhibitor and a substrate, respectively, to compare the differences in the dynamics and consequently the mechanism of action of the pump. The different dynamics for PAβN -bound form of AcrB compared to the TET-bound form is likely to affect the rotating mechanism typically observed for AcrB transporter. This shows the dynamics of the active AcrB transporter is different in a substrate-bound state compared to an inhibitor-bound state. This advances our knowledge and helps to unravel the mechanism of tripartite efflux pumps.
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9
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Salvi N, Abyzov A, Blackledge M. Atomic resolution conformational dynamics of intrinsically disordered proteins from NMR spin relaxation. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2017; 102-103:43-60. [PMID: 29157493 DOI: 10.1016/j.pnmrs.2017.06.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 06/27/2017] [Accepted: 06/27/2017] [Indexed: 05/08/2023]
Abstract
Nuclear magnetic resonance (NMR) spectroscopy is one of the most powerful experimental approaches for investigating the conformational behaviour of intrinsically disordered proteins (IDPs). IDPs represent a significant fraction of all proteomes, and, despite their importance for understanding fundamental biological processes, the molecular basis of their activity still remains largely unknown. The functional mechanisms exploited by IDPs in their interactions with other biomolecules are defined by their intrinsic dynamic modes and associated timescales, justifying the considerable interest over recent years in the development of technologies adapted to measure and describe this behaviour. NMR spin relaxation delivers information-rich, site-specific data reporting on conformational fluctuations occurring throughout the molecule. Here we review recent progress in the use of 15N relaxation to identify local backbone dynamics and long-range chain-like motions in unfolded proteins.
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Affiliation(s)
- Nicola Salvi
- Institut de Biologie Structurale (IBS), CEA, CNRS, University Grenoble Alpes, Grenoble 38044, France
| | - Anton Abyzov
- Institut de Biologie Structurale (IBS), CEA, CNRS, University Grenoble Alpes, Grenoble 38044, France
| | - Martin Blackledge
- Institut de Biologie Structurale (IBS), CEA, CNRS, University Grenoble Alpes, Grenoble 38044, France.
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10
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Allison JR. Using simulation to interpret experimental data in terms of protein conformational ensembles. Curr Opin Struct Biol 2017; 43:79-87. [DOI: 10.1016/j.sbi.2016.11.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 11/15/2016] [Accepted: 11/21/2016] [Indexed: 01/03/2023]
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11
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Salvi N, Salmon L, Blackledge M. Dynamic Descriptions of Highly Flexible Molecules from NMR Dipolar Couplings: Physical Basis and Limitations. J Am Chem Soc 2017; 139:5011-5014. [PMID: 28290683 DOI: 10.1021/jacs.7b01566] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Biomolecules that control physiological function by changing their conformation play key roles in biology and remain poorly characterized. NMR dipolar couplings (DCs) depend intrinsically on both molecular shape and structural fluctuations, thereby providing the enticing prospect of tracking these conformational changes at atomic detail. Although this dual dependence has until now severely complicated analysis of DCs from highly dynamic systems, general approaches have recently been proposed that simplify interpretation of experimental DCs, by entirely eliminating molecular alignment from the analysis. Using simple and intuitive simulation of target ensembles, we investigate the impact of such approaches on the resulting descriptions of the conformational energy landscape. We find that ensemble descriptions of highly flexible systems derived from DCs without explicit consideration of the alignment properties of the constituent conformations can be compromised and inaccurate, despite exhibiting high correlation with experimental measurement.
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Affiliation(s)
- Nicola Salvi
- Institut de Biologie Structurale (IBS), CEA, CNRS, University Grenoble Alpes , Grenoble 38044, France
| | - Loïc Salmon
- Institut de Biologie Structurale (IBS), CEA, CNRS, University Grenoble Alpes , Grenoble 38044, France
| | - Martin Blackledge
- Institut de Biologie Structurale (IBS), CEA, CNRS, University Grenoble Alpes , Grenoble 38044, France
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12
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Kamenik AS, Kahler U, Fuchs JE, Liedl KR. Localization of Millisecond Dynamics: Dihedral Entropy from Accelerated MD. J Chem Theory Comput 2016; 12:3449-55. [PMID: 27322931 PMCID: PMC4980685 DOI: 10.1021/acs.jctc.6b00231] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Indexed: 11/28/2022]
Abstract
Here, we demonstrate a method to capture local dynamics on a time scale 3 orders of magnitude beyond state-of-the-art simulation approaches. We apply accelerated molecular dynamics simulations for conformational sampling and extract reweighted backbone dihedral distributions. Local dynamics are characterized by torsional probabilities, resulting in residue-wise dihedral entropies. Our approach is successfully validated for three different protein systems of increasing size: alanine dipeptide, bovine pancreatic trypsin inhibitor (BPTI), and the major birch pollen allergen Bet v 1a. We demonstrate excellent agreement of flexibility profiles with both large-scale computer simulations and NMR experiments. Thus, our method provides efficient access to local protein dynamics on extended time scales of high biological relevance.
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Affiliation(s)
- Anna S. Kamenik
- Institute of General, Inorganic
and Theoretical Chemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Ursula Kahler
- Institute of General, Inorganic
and Theoretical Chemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Julian E. Fuchs
- Institute of General, Inorganic
and Theoretical Chemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Klaus R. Liedl
- Institute of General, Inorganic
and Theoretical Chemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
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13
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Salmon L, Ahlstrom LS, Horowitz S, Dickson A, Brooks CL, Bardwell JCA. Capturing a Dynamic Chaperone-Substrate Interaction Using NMR-Informed Molecular Modeling. J Am Chem Soc 2016; 138:9826-39. [PMID: 27415450 DOI: 10.1021/jacs.6b02382] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Chaperones maintain a healthy proteome by preventing aggregation and by aiding in protein folding. Precisely how chaperones influence the conformational properties of their substrates, however, remains unclear. To achieve a detailed description of dynamic chaperone-substrate interactions, we fused site-specific NMR information with coarse-grained simulations. Our model system is the binding and folding of a chaperone substrate, immunity protein 7 (Im7), with the chaperone Spy. We first used an automated procedure in which NMR chemical shifts inform the construction of system-specific force fields that describe each partner individually. The models of the two binding partners are then combined to perform simulations on the chaperone-substrate complex. The binding simulations show excellent agreement with experimental data from multiple biophysical measurements. Upon binding, Im7 interacts with a mixture of hydrophobic and hydrophilic residues on Spy's surface, causing conformational exchange within Im7 to slow down as Im7 folds. Meanwhile, the motion of Spy's flexible loop region increases, allowing for better interaction with different substrate conformations, and helping offset losses in Im7 conformational dynamics that occur upon binding and folding. Spy then preferentially releases Im7 into a well-folded state. Our strategy has enabled a residue-level description of a dynamic chaperone-substrate interaction, improving our understanding of how chaperones facilitate substrate folding. More broadly, we validate our approach using two other binding partners, showing that this approach provides a general platform from which to investigate other flexible biomolecular complexes through the integration of NMR data with efficient computational models.
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Affiliation(s)
- Loïc Salmon
- Department of Molecular, Cellular and Developmental Biology, and the Howard Hughes Medical Institute, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Logan S Ahlstrom
- Department of Molecular, Cellular and Developmental Biology, and the Howard Hughes Medical Institute, University of Michigan , Ann Arbor, Michigan 48109, United States.,Department of Chemistry, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Scott Horowitz
- Department of Molecular, Cellular and Developmental Biology, and the Howard Hughes Medical Institute, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Alex Dickson
- Department of Chemistry, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Charles L Brooks
- Department of Chemistry, University of Michigan , Ann Arbor, Michigan 48109, United States.,Biophysics Program, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - James C A Bardwell
- Department of Molecular, Cellular and Developmental Biology, and the Howard Hughes Medical Institute, University of Michigan , Ann Arbor, Michigan 48109, United States
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14
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Maximova T, Moffatt R, Ma B, Nussinov R, Shehu A. Principles and Overview of Sampling Methods for Modeling Macromolecular Structure and Dynamics. PLoS Comput Biol 2016; 12:e1004619. [PMID: 27124275 PMCID: PMC4849799 DOI: 10.1371/journal.pcbi.1004619] [Citation(s) in RCA: 132] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Investigation of macromolecular structure and dynamics is fundamental to understanding how macromolecules carry out their functions in the cell. Significant advances have been made toward this end in silico, with a growing number of computational methods proposed yearly to study and simulate various aspects of macromolecular structure and dynamics. This review aims to provide an overview of recent advances, focusing primarily on methods proposed for exploring the structure space of macromolecules in isolation and in assemblies for the purpose of characterizing equilibrium structure and dynamics. In addition to surveying recent applications that showcase current capabilities of computational methods, this review highlights state-of-the-art algorithmic techniques proposed to overcome challenges posed in silico by the disparate spatial and time scales accessed by dynamic macromolecules. This review is not meant to be exhaustive, as such an endeavor is impossible, but rather aims to balance breadth and depth of strategies for modeling macromolecular structure and dynamics for a broad audience of novices and experts.
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Affiliation(s)
- Tatiana Maximova
- Department of Computer Science, George Mason University, Fairfax, Virginia, United States of America
| | - Ryan Moffatt
- Department of Computer Science, George Mason University, Fairfax, Virginia, United States of America
| | - Buyong Ma
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland, United States of America
| | - Ruth Nussinov
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland, United States of America
- Sackler Institute of Molecular Medicine, Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Amarda Shehu
- Department of Computer Science, George Mason University, Fairfax, Virginia, United States of America
- Department of Biongineering, George Mason University, Fairfax, Virginia, United States of America
- School of Systems Biology, George Mason University, Manassas, Virginia, United States of America
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15
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Salmon L, Blackledge M. Investigating protein conformational energy landscapes and atomic resolution dynamics from NMR dipolar couplings: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2015; 78:126601. [PMID: 26517337 DOI: 10.1088/0034-4885/78/12/126601] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Nuclear magnetic resonance spectroscopy is exquisitely sensitive to protein dynamics. In particular inter-nuclear dipolar couplings, that become measurable in solution when the protein is dissolved in a dilute liquid crystalline solution, report on all conformations sampled up to millisecond timescales. As such they provide the opportunity to describe the Boltzmann distribution present in solution at atomic resolution, and thereby to map the conformational energy landscape in unprecedented detail. The development of analytical methods and approaches based on numerical simulation and their application to numerous biologically important systems is presented.
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Affiliation(s)
- Loïc Salmon
- Université Grenoble Alpes, Institut de Biologie Structurale (IBS), F-38027 Grenoble, France. CEA, DSV, IBS, F-38027 Grenoble, France. CNRS, IBS, F-38027 Grenoble, France
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16
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Salmon L, Giambaşu GM, Nikolova EN, Petzold K, Bhattacharya A, Case DA, Al-Hashimi HM. Modulating RNA Alignment Using Directional Dynamic Kinks: Application in Determining an Atomic-Resolution Ensemble for a Hairpin using NMR Residual Dipolar Couplings. J Am Chem Soc 2015; 137:12954-65. [PMID: 26306428 PMCID: PMC4748170 DOI: 10.1021/jacs.5b07229] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Approaches that combine experimental data and computational molecular dynamics (MD) to determine atomic resolution ensembles of biomolecules require the measurement of abundant experimental data. NMR residual dipolar couplings (RDCs) carry rich dynamics information, however, difficulties in modulating overall alignment of nucleic acids have limited the ability to fully extract this information. We present a strategy for modulating RNA alignment that is based on introducing variable dynamic kinks in terminal helices. With this strategy, we measured seven sets of RDCs in a cUUCGg apical loop and used this rich data set to test the accuracy of an 0.8 μs MD simulation computed using the Amber ff10 force field as well as to determine an atomic resolution ensemble. The MD-generated ensemble quantitatively reproduces the measured RDCs, but selection of a sub-ensemble was required to satisfy the RDCs within error. The largest discrepancies between the RDC-selected and MD-generated ensembles are observed for the most flexible loop residues and backbone angles connecting the loop to the helix, with the RDC-selected ensemble resulting in more uniform dynamics. Comparison of the RDC-selected ensemble with NMR spin relaxation data suggests that the dynamics occurs on the ps-ns time scales as verified by measurements of R(1ρ) relaxation-dispersion data. The RDC-satisfying ensemble samples many conformations adopted by the hairpin in crystal structures indicating that intrinsic plasticity may play important roles in conformational adaptation. The approach presented here can be applied to test nucleic acid force fields and to characterize dynamics in diverse RNA motifs at atomic resolution.
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Affiliation(s)
- Loïc Salmon
- Department of Molecular, Cellular, and Developmental Biology and Howard Hughes Medical Institute, University of Michigan, Ann Arbor, Michigan, USA
| | - George M. Giambaşu
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey, USA
| | - Evgenia N. Nikolova
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Katja Petzold
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | | | - David A. Case
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey, USA
| | - Hashim M. Al-Hashimi
- Department of Biochemistry and Chemistry, Duke University School of Medicine, Durham, North Carolina, USA
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17
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Yang S, Al-Hashimi HM. Unveiling Inherent Degeneracies in Determining Population-Weighted Ensembles of Interdomain Orientational Distributions Using NMR Residual Dipolar Couplings: Application to RNA Helix Junction Helix Motifs. J Phys Chem B 2015; 119:9614-26. [PMID: 26131693 DOI: 10.1021/acs.jpcb.5b03859] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
A growing number of studies employ time-averaged experimental data to determine dynamic ensembles of biomolecules. While it is well-known that different ensembles can satisfy experimental data to within error, the extent and nature of these degeneracies, and their impact on the accuracy of the ensemble determination remains poorly understood. Here, we use simulations and a recently introduced metric for assessing ensemble similarity to explore degeneracies in determining ensembles using NMR residual dipolar couplings (RDCs) with specific application to A-form helices in RNA. Various target ensembles were constructed representing different domain-domain orientational distributions that are confined to a topologically restricted (<10%) conformational space. Five independent sets of ensemble averaged RDCs were then computed for each target ensemble and a "sample and select" scheme used to identify degenerate ensembles that satisfy RDCs to within experimental uncertainty. We find that ensembles with different ensemble sizes and that can differ significantly from the target ensemble (by as much as ∑Ω ∼ 0.4 where ∑Ω varies between 0 and 1 for maximum and minimum ensemble similarity, respectively) can satisfy the ensemble averaged RDCs. These deviations increase with the number of unique conformers and breadth of the target distribution, and result in significant uncertainty in determining conformational entropy (as large as 5 kcal/mol at T = 298 K). Nevertheless, the RDC-degenerate ensembles are biased toward populated regions of the target ensemble, and capture other essential features of the distribution, including the shape. Our results identify ensemble size as a major source of uncertainty in determining ensembles and suggest that NMR interactions such as RDCs and spin relaxation, on their own, do not carry the necessary information needed to determine conformational entropy at a useful level of precision. The framework introduced here provides a general approach for exploring degeneracies in ensemble determination for different types of experimental data.
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Affiliation(s)
- Shan Yang
- †Department of Biochemistry, Stanford University School of Medicine, 279 Campus Drive, Stanford, California 94305, United States
| | - Hashim M Al-Hashimi
- ‡Department of Biochemistry and Chemistry, Duke University Medical Center, Durham, North Carolina 27705, United States
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18
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Pastor N, Amero C. Information flow and protein dynamics: the interplay between nuclear magnetic resonance spectroscopy and molecular dynamics simulations. FRONTIERS IN PLANT SCIENCE 2015; 6:306. [PMID: 25999971 PMCID: PMC4419604 DOI: 10.3389/fpls.2015.00306] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 04/17/2015] [Indexed: 06/04/2023]
Abstract
Proteins participate in information pathways in cells, both as links in the chain of signals, and as the ultimate effectors. Upon ligand binding, proteins undergo conformation and motion changes, which can be sensed by the following link in the chain of information. Nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations represent powerful tools for examining the time-dependent function of biological molecules. The recent advances in NMR and the availability of faster computers have opened the door to more detailed analyses of structure, dynamics, and interactions. Here we briefly describe the recent applications that allow NMR spectroscopy and MD simulations to offer unique insight into the basic motions that underlie information transfer within and between cells.
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Affiliation(s)
- Nina Pastor
- Laboratorio de Dinámica de Proteínas y Ácidos Nucleicos, Centro de Investigación en Dinámica Celular, Universidad Autónoma del Estado de Morelos, Cuernavaca, Mexico
| | - Carlos Amero
- Laboratorio de Bioquímica y Resonancia Magnética Nuclear, Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos, Cuernavaca, Mexico
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19
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Kragelj J, Blackledge M, Jensen MR. Ensemble Calculation for Intrinsically Disordered Proteins Using NMR Parameters. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 870:123-47. [PMID: 26387101 DOI: 10.1007/978-3-319-20164-1_4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Intrinsically disordered proteins (IDPs) perform their function despite their lack of well-defined tertiary structure. Residual structure has been observed in IDPs, commonly described as transient/dynamic or expressed in terms of fractional populations. In order to understand how the protein primary sequence dictates the dynamic and structural properties of IDPs and in general to understand how IDPs function, atomic-level descriptions are needed. Nuclear magnetic resonance spectroscopy provides information about local and long-range structure in IDPs at amino acid specific resolution and can be used in combination with ensemble descriptions to represent the dynamic nature of IDPs. In this chapter we describe sample-and-select approaches for ensemble modelling of local structural propensities in IDPs with specific emphasis on validation of these ensembles.
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Affiliation(s)
- Jaka Kragelj
- IBS, University Grenoble Alpes, 38044, Grenoble, France.,IBS, CNRS, 38044, Grenoble, France.,IBS, CEA, 38044, Grenoble, France
| | - Martin Blackledge
- IBS, University Grenoble Alpes, 38044, Grenoble, France.,IBS, CNRS, 38044, Grenoble, France.,IBS, CEA, 38044, Grenoble, France
| | - Malene Ringkjøbing Jensen
- IBS, University Grenoble Alpes, 38044, Grenoble, France. .,IBS, CNRS, 38044, Grenoble, France. .,IBS, CEA, 38044, Grenoble, France.
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20
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Accelerated molecular dynamics and protein conformational change: a theoretical and practical guide using a membrane embedded model neurotransmitter transporter. Methods Mol Biol 2015; 1215:253-87. [PMID: 25330967 DOI: 10.1007/978-1-4939-1465-4_12] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Molecular dynamics simulation provides a powerful and accurate method to model protein conformational change, yet timescale limitations often prevent direct assessment of the kinetic properties of interest. A large number of molecular dynamic steps are necessary for rare events to occur, which allow a system to overcome energy barriers and conformationally transition from one potential energy minimum to another. For many proteins, the energy landscape is further complicated by a multitude of potential energy wells, each separated by high free-energy barriers and each potentially representative of a functionally important protein conformation. To overcome these obstacles, accelerated molecular dynamics utilizes a robust bias potential function to simulate the transition between different potential energy minima. This straightforward approach more efficiently samples conformational space in comparison to classical molecular dynamics simulation, does not require advanced knowledge of the potential energy landscape and converges to the proper canonical distribution. Here, we review the theory behind accelerated molecular dynamics and discuss the approach in the context of modeling protein conformational change. As a practical example, we provide a detailed, step-by-step explanation of how to perform an accelerated molecular dynamics simulation using a model neurotransmitter transporter embedded in a lipid cell membrane. Changes in protein conformation of relevance to the substrate transport cycle are then examined using principle component analysis.
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21
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Jensen MR, Zweckstetter M, Huang JR, Blackledge M. Exploring free-energy landscapes of intrinsically disordered proteins at atomic resolution using NMR spectroscopy. Chem Rev 2014; 114:6632-60. [PMID: 24725176 DOI: 10.1021/cr400688u] [Citation(s) in RCA: 214] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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22
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Abstract
Conformational changes in nucleic acids play a key role in the way genetic information is stored, transferred, and processed in living cells. Here, we describe new approaches that employ a broad range of experimental data, including NMR-derived chemical shifts and residual dipolar couplings, small-angle X-ray scattering, and computational approaches such as molecular dynamics simulations to determine ensembles of DNA and RNA at atomic resolution. We review the complementary information that can be obtained from diverse sets of data and the various methods that have been developed to combine these data with computational methods to construct ensembles and assess their uncertainty. We conclude by surveying RNA and DNA ensembles determined using these methods, highlighting the unique physical and functional insights obtained so far.
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Affiliation(s)
- Loïc Salmon
- Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, Michigan 48109;
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23
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Measuring dynamic and kinetic information in the previously inaccessible supra-τ(c) window of nanoseconds to microseconds by solution NMR spectroscopy. Molecules 2013; 18:11904-37. [PMID: 24077173 PMCID: PMC6270068 DOI: 10.3390/molecules181011904] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 08/28/2013] [Accepted: 09/17/2013] [Indexed: 11/16/2022] Open
Abstract
Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful tool that has enabled experimentalists to characterize molecular dynamics and kinetics spanning a wide range of time-scales from picoseconds to days. This review focuses on addressing the previously inaccessible supra-tc window (defined as τ(c) < supra-τ(c) < 40 μs; in which tc is the overall tumbling time of a molecule) from the perspective of local inter-nuclear vector dynamics extracted from residual dipolar couplings (RDCs) and from the perspective of conformational exchange captured by relaxation dispersion measurements (RD). The goal of the first section is to present a detailed analysis of how to extract protein dynamics encoded in RDCs and how to relate this information to protein functionality within the previously inaccessible supra-τ(c) window. In the second section, the current state of the art for RD is analyzed, as well as the considerable progress toward pushing the sensitivity of RD further into the supra-τ(c) scale by up to a factor of two (motion up to 25 μs). From the data obtained with these techniques and methodology, the importance of the supra-τ(c) scale for protein function and molecular recognition is becoming increasingly clearer as the connection between motion on the supra-τ(c) scale and protein functionality from the experimental side is further strengthened with results from molecular dynamics simulations.
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24
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Cavalli A, Camilloni C, Vendruscolo M. Molecular dynamics simulations with replica-averaged structural restraints generate structural ensembles according to the maximum entropy principle. J Chem Phys 2013; 138:094112. [PMID: 23485282 DOI: 10.1063/1.4793625] [Citation(s) in RCA: 144] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In order to characterise the dynamics of proteins, a well-established method is to incorporate experimental parameters as replica-averaged structural restraints into molecular dynamics simulations. Here, we justify this approach in the case of interproton distance information provided by nuclear Overhauser effects by showing that it generates ensembles of conformations according to the maximum entropy principle. These results indicate that the use of replica-averaged structural restraints in molecular dynamics simulations, given a force field and a set of experimental data, can provide an accurate approximation of the unknown Boltzmann distribution of a system.
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Affiliation(s)
- Andrea Cavalli
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom
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25
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Guerry P, Mollica L, Blackledge M. Mapping Protein Conformational Energy Landscapes Using NMR and Molecular Simulation. Chemphyschem 2013; 14:3046-58. [DOI: 10.1002/cphc.201300377] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2013] [Indexed: 02/06/2023]
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26
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Salmon L, Bascom G, Andricioaei I, Al-Hashimi HM. A general method for constructing atomic-resolution RNA ensembles using NMR residual dipolar couplings: the basis for interhelical motions revealed. J Am Chem Soc 2013; 135:5457-66. [PMID: 23473378 DOI: 10.1021/ja400920w] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The ability to modulate alignment and measure multiple independent sets of NMR residual dipolar couplings (RDCs) has made it possible to characterize internal motions in proteins at atomic resolution and with time scale sensitivity ranging from picoseconds up to milliseconds. The application of such methods to the study of RNA dynamics, however, remains fundamentally limited by the inability to modulate alignment and by strong couplings between internal and overall motions that complicate the quantitative interpretation of RDCs. Here, we address this problem by showing that RNA alignment can be generally modulated, in a controlled manner, by variable elongation of A-form helices and that the information contained within the measured RDCs can be extracted even in the presence of strong couplings between motions and overall alignment via structure-based prediction of alignment. Using this approach, four RDC data sets, and a broad conformational pool obtained from a 8.2 μs molecular dynamics simulation, we successfully construct and validate an atomic resolution ensemble of human immunodeficiency virus type I transactivation response element RNA. This ensemble reveals local motions in and around the bulge involving changes in stacking and hydrogen-bonding interactions, which are undetectable by traditional spin relaxation and drive global changes in interhelical orientation. This new approach broadens the scope of using RDCs in characterizing the dynamics of nucleic acids.
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Affiliation(s)
- Loïc Salmon
- Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, Michigan 48109, USA
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27
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Guerry P, Salmon L, Mollica L, Ortega Roldan JL, Markwick P, van Nuland NAJ, McCammon JA, Blackledge M. Mapping the Population of Protein Conformational Energy Sub-States from NMR Dipolar Couplings. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201209669] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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28
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Guerry P, Salmon L, Mollica L, Ortega Roldan J, Markwick P, van Nuland NAJ, McCammon JA, Blackledge M. Mapping the Population of Protein Conformational Energy Sub‐States from NMR Dipolar Couplings. Angew Chem Int Ed Engl 2013; 52:3181-5. [DOI: 10.1002/anie.201209669] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Indexed: 11/12/2022]
Affiliation(s)
- Paul Guerry
- Protein Dynamics and Flexibility, Institut de Biologie Structurale Jean‐Pierre Ebel, CNRS‐CEA‐UJF UMR 5075, 41 rue Jules Horowitz, 38027 Grenoble Cedex (France)
| | - Loïc Salmon
- Protein Dynamics and Flexibility, Institut de Biologie Structurale Jean‐Pierre Ebel, CNRS‐CEA‐UJF UMR 5075, 41 rue Jules Horowitz, 38027 Grenoble Cedex (France)
| | - Luca Mollica
- Protein Dynamics and Flexibility, Institut de Biologie Structurale Jean‐Pierre Ebel, CNRS‐CEA‐UJF UMR 5075, 41 rue Jules Horowitz, 38027 Grenoble Cedex (France)
| | | | - Phineus Markwick
- Department of Chemistry and Biochemistry UCSD San Diego CA, Howard Hughes Medical Institute, San Diego Supercomputer Center, La Jolla CA (USA)
| | | | - J. Andrew McCammon
- Department of Chemistry and Biochemistry UCSD San Diego CA, Howard Hughes Medical Institute, San Diego Supercomputer Center, La Jolla CA (USA)
| | - Martin Blackledge
- Protein Dynamics and Flexibility, Institut de Biologie Structurale Jean‐Pierre Ebel, CNRS‐CEA‐UJF UMR 5075, 41 rue Jules Horowitz, 38027 Grenoble Cedex (France)
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29
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Elber R, Kirmizialtin S. Molecular machines. Curr Opin Struct Biol 2013; 23:206-11. [PMID: 23305848 DOI: 10.1016/j.sbi.2012.12.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 12/03/2012] [Indexed: 12/12/2022]
Abstract
Molecular machines (MM) are essential components of living cells. They conduct mechanical work, transport materials into and out of cells, assist in processing enzymatic reactions, and more. Their operations are frequently combined with significant conformational transitions. Computational studies of these conformational transitions and their coupling to molecular functions are discussed. It is argued that coarse descriptions of these molecules which are based on mass density and shape provide useful information on directions of action. It is further argued that MM are likely to have well focused and narrow reaction pathways. The proposal for such pathways is supported by evolutionary analyses of homologous machines. Finally, these observations are used to build atomically detailed models of these systems that are making the link from structure to functions (kinetics and thermodynamics). For that purpose enhanced sampling techniques are required.
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Affiliation(s)
- Ron Elber
- Department of Chemistry and Biochemistry, University of Texas at Austin, 105 East 24th St., Stop A5300 Austin, TX 78712-0165, USA.
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30
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Mollica L, Baias M, Lewandowski JR, Wylie BJ, Sperling LJ, Rienstra CM, Emsley L, Blackledge M. Atomic-Resolution Structural Dynamics in Crystalline Proteins from NMR and Molecular Simulation. J Phys Chem Lett 2012; 3:3657-62. [PMID: 26291002 DOI: 10.1021/jz3016233] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Solid-state NMR can provide atomic-resolution information about protein motions occurring on a vast range of time scales under similar conditions to those of X-ray diffraction studies and therefore offers a highly complementary approach to characterizing the dynamic fluctuations occurring in the crystal. We compare experimentally determined dynamic parameters, spin relaxation, chemical shifts, and dipolar couplings, to values calculated from a 200 ns MD simulation of protein GB1 in its crystalline form, providing insight into the nature of structural dynamics occurring within the crystalline lattice. This simulation allows us to test the accuracy of commonly applied procedures for the interpretation of experimental solid-state relaxation data in terms of dynamic modes and time scales. We discover that the potential complexity of relaxation-active motion can lead to significant under- or overestimation of dynamic amplitudes if different components are not taken into consideration.
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Affiliation(s)
- Luca Mollica
- †Protein Dynamics and Flexibility, Institut de Biologie Structurale, CEA, CNRS, UJF-Grenoble 1, 41 Rue Jules Horowitz, Grenoble 38027, France
| | - Maria Baias
- ‡CNRS/ENS-Lyon/UCB-Lyon 1, Centre de RMN à Très Hauts Champs, Université de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France
| | - Józef R Lewandowski
- §Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom
| | - Benjamin J Wylie
- ⊥Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, United States
| | - Lindsay J Sperling
- #Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Chad M Rienstra
- ∥Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Lyndon Emsley
- ‡CNRS/ENS-Lyon/UCB-Lyon 1, Centre de RMN à Très Hauts Champs, Université de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France
| | - Martin Blackledge
- †Protein Dynamics and Flexibility, Institut de Biologie Structurale, CEA, CNRS, UJF-Grenoble 1, 41 Rue Jules Horowitz, Grenoble 38027, France
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