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Yu B, Bolik-Coulon N, Rangadurai AK, Kay LE, Iwahara J. Gadolinium-Based NMR Spin Relaxation Measurements of Near-Surface Electrostatic Potentials of Biomolecules. J Am Chem Soc 2024; 146:20788-20801. [PMID: 39028837 PMCID: PMC11295196 DOI: 10.1021/jacs.4c04433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Revised: 06/09/2024] [Accepted: 06/28/2024] [Indexed: 07/21/2024]
Abstract
NMR spectroscopy is an important tool for the measurement of the electrostatic properties of biomolecules. To this point, paramagnetic relaxation enhancements (PREs) of 1H nuclei arising from nitroxide cosolutes in biomolecular solutions have been used to measure effective near-surface electrostatic potentials (ϕENS) of proteins and nucleic acids. Here, we present a gadolinium (Gd)-based NMR method, exploiting Gd chelates with different net charges, for measuring ϕENS values and demonstrate its utility through applications to a number of biomolecular systems. The use of Gd-based cosolutes offers several advantages over nitroxides for ϕENS measurements. First, unlike nitroxide compounds, Gd chelates enable electrostatic potential measurements on oxidation-sensitive proteins that require reducing agents. Second, the large electron spin quantum number of Gd (7/2) results in notably larger PREs for Gd chelates when used at the same concentrations as nitroxide radicals. Thus, it is possible to measure ϕENS values exclusively from + and - charged compounds even for highly charged biomolecules, avoiding the use of neutral cosolutes that, as we further establish here, limits the accuracy of the measured electrostatic potentials. In addition, the smaller concentrations of cosolutes required minimize potential binding to sites on macromolecules. Fourth, the closer proximity of the paramagnetic center and charged groups within Gd chelates, in comparison to the corresponding nitroxide compounds, enables more accurate predictions of ϕENS potentials for cross-validation of the experimental results. The Gd-based method described here, thus, broadens the applicability of studies of biomolecular electrostatics using solution NMR spectroscopy.
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Affiliation(s)
- Binhan Yu
- Department
of Biochemistry & Molecular Biology, Sealy Center for Structural
Biology & Molecular Biophysics, University
of Texas Medical Branch, Galveston, Texas 77555-1068, United States
| | - Nicolas Bolik-Coulon
- Department
of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
- Department
of Biochemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Atul K. Rangadurai
- Department
of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
- Department
of Biochemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
- Program
in Molecular Medicine, Hospital for Sick
Children Research Institute, Toronto, Ontario M5G 0A4, Canada
| | - Lewis E. Kay
- Department
of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
- Department
of Biochemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
- Program
in Molecular Medicine, Hospital for Sick
Children Research Institute, Toronto, Ontario M5G 0A4, Canada
| | - Junji Iwahara
- Department
of Biochemistry & Molecular Biology, Sealy Center for Structural
Biology & Molecular Biophysics, University
of Texas Medical Branch, Galveston, Texas 77555-1068, United States
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Wang X, Yu B, Sakurabayashi S, Paz-Villatoro JM, Iwahara J. Robust Enzymatic Production of DNA G-Quadruplex, Aptamer, DNAzyme, and Other Oligonucleotides: Applications for NMR. J Am Chem Soc 2024; 146:1748-1752. [PMID: 38191993 PMCID: PMC10926321 DOI: 10.1021/jacs.3c11219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
Single-stranded DNA (ssDNA) oligonucleotides are widely used in biological research, therapeutics, biotechnology, and nanomachines. Large-scale enzymatic production of ssDNA oligonucleotides forming noncanonical structures has been difficult. Here, we present a simple and robust method named "palindrome-nicking-dependent amplification" (PaNDA) for enzymatic production of a large amount of ssDNA oligonucleotides. It utilizes a strand-displacing DNA polymerase and a nicking enzyme together with input DNA and deoxynucleotide triphosphates at 55 °C. Scaling up of PaNDA is straightforward due to its isothermal nature. The ssDNA products can easily be isolated through anion-exchange chromatography under nondenaturing conditions. We demonstrate applications of PaNDA to 13C/15N-labeling of various DNA strands, including a 22-nt telomere repeat G-quadruplex, a 26-nt therapeutic aptamer, and a 33-nt DNAzyme. The 13C/15N-labeling by PaNDA greatly facilitates the characterization of noncanonical DNA by nuclear magnetic resonance (NMR) spectroscopy. For example, the behavior of therapeutic DNA aptamers in human serum can be investigated.
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Affiliation(s)
- Xi Wang
- 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
| | - Binhan Yu
- 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
| | - Shuhei Sakurabayashi
- 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
| | - Jonathan M Paz-Villatoro
- 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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Yu B, Wang X, Wang T, Iwahara J. DNA base order parameter determination without influence of chemical exchange. Methods 2023; 210:1-9. [PMID: 36596431 PMCID: PMC9898221 DOI: 10.1016/j.ymeth.2022.12.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 12/23/2022] [Accepted: 12/30/2022] [Indexed: 01/01/2023] Open
Abstract
Nuclear magnetic resonance (NMR) spectroscopy is a versatile tool used to investigate the dynamic properties of biological macromolecules and their complexes. NMR relaxation data can provide order parameters S2, which represent the mobility of bond vectors reorienting within a molecular frame. Determination of S2 parameters typically involves the use of transverse NMR relaxation rates. However, the accuracy in S2 determination can be diminished by elevation of the transverse relaxation rates through conformational or chemical exchange involving protonation/deprotonation or non-Watson-Crick base-pair states of nucleic acids. Here, we propose an approach for determination of S2 parameters without the influence of exchange processes. This approach utilizes transverse and longitudinal 13C chemical shift anisotropy (CSA) - dipole-dipole (DD) cross-correlation rates instead of 13C transverse relaxation rates. Anisotropy in rotational diffusion is taken into consideration. An application of this approach to nucleotide base CH groups of a uniformly 13C/15N-labeled DNA duplex is demonstrated.
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Affiliation(s)
- Binhan Yu
- Department of Biochemistry & Molecular Biology, Sealy Center for Structural Biology & Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Xi Wang
- Department of Biochemistry & Molecular Biology, Sealy Center for Structural Biology & Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Tianzhi Wang
- Department of Biochemistry & Molecular Biology, Sealy Center for Structural Biology & Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Junji Iwahara
- Department of Biochemistry & Molecular Biology, Sealy Center for Structural Biology & Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA.
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Yu B, Wang X, Iwahara J. Measuring Local Electrostatic Potentials Around Nucleic Acids by Paramagnetic NMR Spectroscopy. J Phys Chem Lett 2022; 13:10025-10029. [PMID: 36264151 PMCID: PMC9700389 DOI: 10.1021/acs.jpclett.2c02623] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Electrostatic potentials around macromolecules in the presence of mobile charges are difficult to assess especially for highly charged systems. Here, we report measurements of local electrostatic potentials around DNA by paramagnetic NMR. Through quantitative analysis of NMR paramagnetic relaxation enhancement arising from positively charged or neutral paramagnetic cosolutes, we were able to determine local electrostatic potentials around 1H nuclei at >100 sites in major and minor grooves of 13C,15N-labeled 15-bp DNA at 100 mM NaCl. Our experimental electrostatic potential data directly confirmed the Coulombic end effects of DNA. The effective near-surface electrostatic potentials from the NMR data were in good agreement with the theoretical predictions with the Poisson-Boltzmann equation. This NMR method allows for unprecedented experimental investigations into the electrostatic properties of nucleic acids.
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Affiliation(s)
| | | | - Junji Iwahara
- Department of Biochemistry & Molecular Biology, Sealy Center for Structural Biology & Molecular Biophysics, University of Texas Medical Branch, 301 University Blvd, Galveston, Texas 77555-1068, USA
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