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Boelens R, Ivanov K, Matysik J. Introduction to a special issue of Magnetic Resonance in honour of Robert Kaptein at the occasion of his 80th birthday. MAGNETIC RESONANCE (GOTTINGEN, GERMANY) 2021; 2:465-474. [PMID: 37904778 PMCID: PMC10539797 DOI: 10.5194/mr-2-465-2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Indexed: 11/01/2023]
Abstract
This publication, in honour of Robert Kaptein's 80th birthday, contains contributions from colleagues, many of whom have worked with him, and others who admire his work and have been stimulated by his research. The contributions show current research in biomolecular NMR, spin hyperpolarisation and spin chemistry, including CIDNP (chemically induced dynamic nuclear polarisation), topics to which he has contributed enormously. His proposal of the radical pair mechanism was the birth of the field of spin chemistry, and the laser CIDNP NMR experiment on a protein was a major breakthrough in hyperpolarisation research. He set milestones for biomolecular NMR by developing computational methods for protein structure determination, including restrained molecular dynamics and 3D NMR methodology. With a lac repressor headpiece, he determined one of the first protein structures determined by NMR. His studies of the lac repressor provided the first examples of detailed studies of protein nucleic acid complexes by NMR. This deepened our understanding of protein DNA recognition and led to a molecular model for protein sliding along the DNA. Furthermore, he played a leading role in establishing the cluster of NMR large-scale facilities in Europe. This editorial gives an introduction to the publication and is followed by a biography describing his contributions to magnetic resonance.
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Affiliation(s)
- Rolf Boelens
- Bijvoet Centre for Biomolecular Research, Utrecht University, 3584 CH Utrecht, the Netherlands
| | - Konstantin Ivanov
- International Tomography Center, Siberian Branch of the Russian
Academy of Sciences, Novosibirsk 630090, Russia
- Department of Natural Sciences, Novosibirsk State University,
Novosibirsk 630090, Russia
| | - Jörg Matysik
- Institut für Analytische Chemie, Universität Leipzig, Linnéstraße 3, 04189 Leipzig, Germany
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Sahu D, Iwahara J. Discrete-State Kinetics Model for NMR-Based Analysis of Protein Translocation on DNA at Equilibrium. J Phys Chem B 2017; 121:9548-9556. [PMID: 28922916 DOI: 10.1021/acs.jpcb.7b07779] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
In the target DNA search process, sequence-specific DNA-binding proteins first nonspecifically bind to DNA and stochastically move from one site to another before reaching their targets. To rigorously assess how the translocation process influences NMR signals from proteins interacting with nonspecific DNA, we incorporated a discrete-state kinetic model for protein translocation on DNA into the McConnell equation. Using this equation, we simulated line shapes of NMR signals from proteins undergoing translocations on DNA through sliding, dissociation/reassociation, and intersegment transfer. Through this analysis, we validated an existing NMR approach for kinetic investigations of protein translocation on DNA, which utilizes NMR line shapes of two nonspecific DNA-protein complexes and their mixture. We found that, despite its use of simplistic two-state approximation neglecting the presence of many microscopic states, the previously proposed NMR approach provides accurate kinetic information on the intermolecular translocations of proteins between two DNA molecules. Interestingly, our results suggest that the same NMR approach can also provide qualitative information about the one-dimensional diffusion coefficient for proteins sliding on DNA.
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Affiliation(s)
- Debashish Sahu
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch , Galveston, Texas 77555-1068, United States
| | - Junji Iwahara
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch , Galveston, Texas 77555-1068, United States
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In-depth study of DNA binding of Cys2His2 finger domains in testis zinc-finger protein. PLoS One 2017; 12:e0175051. [PMID: 28384299 PMCID: PMC5383199 DOI: 10.1371/journal.pone.0175051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 03/20/2017] [Indexed: 11/26/2022] Open
Abstract
Previously, we identified that both fingers 1 and 2 in the three Cys2His2 zinc-finger domains (TZD) of testis zinc-finger protein specifically bind to its cognate DNA; however, finger 3 is non-sequence–specific. To gain insights into the interaction mechanism, here we further investigated the DNA-binding characteristics of TZD bound to non-specific DNAs and its finger segments bound to cognate DNA. TZD in non-specific DNA binding showed smaller chemical shift perturbations, as expected. However, the direction of shift perturbation, change of DNA imino-proton NMR signal, and dynamics on the 15N backbone atom significantly differed between specific and non-specific binding. Using these unique characteristics, we confirmed that the three single-finger segments (TZD1, TZD2 and TZD3) and the two-finger segment (TZD23) non-specifically bind to the cognate DNA. In comparison, the other two-finger segment (TZD12) binding to the cognate DNA features simultaneous non-specific and semi-specific binding, both slowly exchanged in terms of NMR timescale. The process of TZD binding to the cognate DNA is likely stepwise: initially TZD non-specifically binds to DNA, then fingers 1 and 2 insert cooperatively into the major groove of DNA by semi-specific binding, and finally finger 3 non-specifically binds to DNA, which promotes the specific binding on fingers 1 and 2 and stabilizes the formation of a specific TZD–DNA complex.
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Integrated structural biology to unravel molecular mechanisms of protein-RNA recognition. Methods 2017; 118-119:119-136. [PMID: 28315749 DOI: 10.1016/j.ymeth.2017.03.015] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 02/19/2017] [Accepted: 03/13/2017] [Indexed: 12/20/2022] Open
Abstract
Recent advances in RNA sequencing technologies have greatly expanded our knowledge of the RNA landscape in cells, often with spatiotemporal resolution. These techniques identified many new (often non-coding) RNA molecules. Large-scale studies have also discovered novel RNA binding proteins (RBPs), which exhibit single or multiple RNA binding domains (RBDs) for recognition of specific sequence or structured motifs in RNA. Starting from these large-scale approaches it is crucial to unravel the molecular principles of protein-RNA recognition in ribonucleoprotein complexes (RNPs) to understand the underlying mechanisms of gene regulation. Structural biology and biophysical studies at highest possible resolution are key to elucidate molecular mechanisms of RNA recognition by RBPs and how conformational dynamics, weak interactions and cooperative binding contribute to the formation of specific, context-dependent RNPs. While large compact RNPs can be well studied by X-ray crystallography and cryo-EM, analysis of dynamics and weak interaction necessitates the use of solution methods to capture these properties. Here, we illustrate methods to study the structure and conformational dynamics of protein-RNA complexes in solution starting from the identification of interaction partners in a given RNP. Biophysical and biochemical techniques support the characterization of a protein-RNA complex and identify regions relevant in structural analysis. Nuclear magnetic resonance (NMR) is a powerful tool to gain information on folding, stability and dynamics of RNAs and characterize RNPs in solution. It provides crucial information that is complementary to the static pictures derived from other techniques. NMR can be readily combined with other solution techniques, such as small angle X-ray and/or neutron scattering (SAXS/SANS), electron paramagnetic resonance (EPR), and Förster resonance energy transfer (FRET), which provide information about overall shapes, internal domain arrangements and dynamics. Principles of protein-RNA recognition and current approaches are reviewed and illustrated with recent studies.
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Desjardins G, Okon M, Graves BJ, McIntosh LP. Conformational Dynamics and the Binding of Specific and Nonspecific DNA by the Autoinhibited Transcription Factor Ets-1. Biochemistry 2016; 55:4105-18. [PMID: 27362745 PMCID: PMC5568661 DOI: 10.1021/acs.biochem.6b00460] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The affinity of the Ets-1 transcription factor for DNA is autoinhibited by an intrinsically disordered serine-rich region (SRR) and a helical inhibitory module (IM) appended to its winged helix-turn-helix ETS domain. Using NMR spectroscopy, we investigated how Ets-1 recognizes specific versus nonspecific DNA, with a focus on the roles of protein dynamics and autoinhibition in these processes. Upon binding either DNA, the two marginally stable N-terminal helices of the IM predominantly unfold, but still sample partially ordered conformations. Also, on the basis of amide chemical shift perturbation mapping, Ets-1 associates with both specific and nonspecific DNA through the same canonical ETS domain interface. These interactions are structurally independent of the SRR, and thus autoinhibition does not impart DNA-binding specificity. However, relative to the pronounced NMR spectroscopic changes in Ets-1 resulting from specific DNA binding, the spectra of the nonspecific DNA complexes showed conformational exchange broadening and lacked several diagnostic amide and indole signals attributable to hydrogen bonding interactions seen in reported X-ray crystallographic structures of this transcription factor with its cognate DNA sequences. Such differences are highlighted by the chemical shift and relaxation properties of several interfacial lysine and arginine side chains. Collectively, these data support a general model in which Ets-1 interacts with nonspecific DNA via dynamic electrostatic interactions, whereas hydrogen bonding drives the formation of well-ordered complexes with specific DNA.
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Affiliation(s)
- Geneviève Desjardins
- Department of Biochemistry and Molecular Biology, Department of Chemistry, and Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Mark Okon
- Department of Biochemistry and Molecular Biology, Department of Chemistry, and Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Barbara J. Graves
- Department of Oncological Sciences, University of Utah School of Medicine, Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah 84112-5550, United States
- Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, United States
| | - Lawrence P. McIntosh
- Department of Biochemistry and Molecular Biology, Department of Chemistry, and Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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Ryu KS, Tugarinov V, Clore GM. Probing the rate-limiting step for intramolecular transfer of a transcription factor between specific sites on the same DNA molecule by (15)Nz-exchange NMR spectroscopy. J Am Chem Soc 2014; 136:14369-72. [PMID: 25253516 PMCID: PMC4210153 DOI: 10.1021/ja5081585] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Indexed: 11/30/2022]
Abstract
The kinetics of translocation of the homeodomain transcription factor HoxD9 between specific sites of the same or opposite polarities on the same DNA molecule have been studied by (15)Nz-exchange NMR spectroscopy. We show that exchange occurs by two facilitated diffusion mechanisms: a second-order intermolecular exchange reaction between specific sites located on different DNA molecules without the protein dissociating into free solution that predominates at high concentrations of free DNA, and a first-order intramolecular process involving direct transfer between specific sites located on the same DNA molecule. Control experiments using a mixture of two DNA molecules, each possessing only a single specific site, indicate that transfer between specific sites by full dissociation of HoxD9 into solution followed by reassociation is too slow to measure by z-exchange spectroscopy. Intramolecular transfer with comparable rate constants occurs between sites of the same and opposing polarity, indicating that both rotation-coupled sliding and hopping/flipping (analogous to geminate recombination) occur. The half-life for intramolecular transfer (0.5-1 s) is many orders of magnitude larger than the calculated transfer time (1-100 μs) by sliding, leading us to conclude that the intramolecular transfer rates measured by z-exchange spectroscopy represent the rate-limiting step for a one-base-pair shift from the specific site to the immediately adjacent nonspecific site. At zero concentration of added salt, the intramolecular transfer rate constants between sites of opposing polarity are smaller than those between sites of the same polarity, suggesting that hopping/flipping may become rate-limiting at very low salt concentrations.
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Affiliation(s)
- Kyoung-Seok Ryu
- Laboratory
of Chemical Physics, National Institute
of Diabetes and Digestive and Kidney Diseases, National Institutes
of Health, Bethesda, Maryland 20892-0520, United States
- Korean
Basic Science Institute, Ochang-Eup, Chunbuk-Do 363-883, South Korea
| | - Vitali Tugarinov
- Laboratory
of Chemical Physics, National Institute
of Diabetes and Digestive and Kidney Diseases, National Institutes
of Health, Bethesda, Maryland 20892-0520, United States
| | - G. Marius Clore
- Laboratory
of Chemical Physics, National Institute
of Diabetes and Digestive and Kidney Diseases, National Institutes
of Health, Bethesda, Maryland 20892-0520, United States
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De S, Chan ACK, Coyne HJ, Bhachech N, Hermsdorf U, Okon M, Murphy MEP, Graves BJ, McIntosh LP. Steric mechanism of auto-inhibitory regulation of specific and non-specific DNA binding by the ETS transcriptional repressor ETV6. J Mol Biol 2014; 426:1390-406. [PMID: 24333486 PMCID: PMC4278593 DOI: 10.1016/j.jmb.2013.11.031] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 11/05/2013] [Accepted: 11/09/2013] [Indexed: 11/29/2022]
Abstract
DNA binding by the ETS transcriptional repressor ETV6 (or TEL) is auto-inhibited ~50-fold due to an α-helix that sterically blocks its ETS domain binding interface. Using NMR spectroscopy, we demonstrate that this marginally stable helix is unfolded, and not displaced to a non-inhibitory position, when ETV6 is bound to DNA containing a consensus (5')GGAA(3') recognition site. Although significantly lower in affinity, binding to non-specific DNA is auto-inhibited ~5-fold and is also accompanied by helix unfolding. Based on NMR chemical shift perturbations, both specific and non-specific DNA are bound via the same canonical ETS domain interface. However, spectral perturbations are smaller for the non-specific complex, suggesting weaker and less well-defined interactions than in the specific complex. In parallel, the crystal structure of ETV6 bound to a specific DNA duplex was determined. The structure of this complex reveals that a non-conserved histidine residue in the ETS domain recognition helix helps establish the specificity of ETV6 for DNA-binding sites containing (5')GGAA(3')versus(5')GGAT(3'). These studies provide a unified steric mechanism for attenuating ETV6 binding to both specific and non-specific DNA and expand the repertoire of characterized auto-inhibitory strategies utilized to regulate ETS factors.
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Affiliation(s)
- Soumya De
- Department of Biochemistry and Molecular Biology, Department of Chemistry, and Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
| | - Anson C K Chan
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
| | - H Jerome Coyne
- Department of Biochemistry and Molecular Biology, Department of Chemistry, and Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
| | - Niraja Bhachech
- Department of Oncological Sciences, University of Utah School of Medicine, and Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112-5550, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815-6789, USA
| | - Ulrike Hermsdorf
- Department of Biochemistry and Molecular Biology, Department of Chemistry, and Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
| | - Mark Okon
- Department of Biochemistry and Molecular Biology, Department of Chemistry, and Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
| | - Michael E P Murphy
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
| | - Barbara J Graves
- Department of Oncological Sciences, University of Utah School of Medicine, and Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112-5550, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815-6789, USA
| | - Lawrence P McIntosh
- Department of Biochemistry and Molecular Biology, Department of Chemistry, and Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada V6T 1Z3.
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