1
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Szekely O, Rangadurai AK, Gu S, Manghrani A, Guseva S, Al-Hashimi HM. NMR measurements of transient low-populated tautomeric and anionic Watson-Crick-like G·T/U in RNA:DNA hybrids: implications for the fidelity of transcription and CRISPR/Cas9 gene editing. Nucleic Acids Res 2024; 52:2672-2685. [PMID: 38281263 PMCID: PMC10954477 DOI: 10.1093/nar/gkae027] [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: 08/24/2023] [Revised: 01/02/2024] [Accepted: 01/17/2024] [Indexed: 01/30/2024] Open
Abstract
Many biochemical processes use the Watson-Crick geometry to distinguish correct from incorrect base pairing. However, on rare occasions, mismatches such as G·T/U can transiently adopt Watson-Crick-like conformations through tautomerization or ionization of the bases, giving rise to replicative and translational errors. The propensities to form Watson-Crick-like mismatches in RNA:DNA hybrids remain unknown, making it unclear whether they can also contribute to errors during processes such as transcription and CRISPR/Cas editing. Here, using NMR R1ρ experiments, we show that dG·rU and dT·rG mismatches in two RNA:DNA hybrids transiently form tautomeric (Genol·T/U $ \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\rightarrow\over {\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}}$ G·Tenol/Uenol) and anionic (G·T-/U-) Watson-Crick-like conformations. The tautomerization dynamics were like those measured in A-RNA and B-DNA duplexes. However, anionic dG·rU- formed with a ten-fold higher propensity relative to dT-·rG and dG·dT- and this could be attributed to the lower pKa (ΔpKa ∼0.4-0.9) of U versus T. Our findings suggest plausible roles for Watson-Crick-like G·T/U mismatches in transcriptional errors and CRISPR/Cas9 off-target gene editing, uncover a crucial difference between the chemical dynamics of G·U versus G·T, and indicate that anionic Watson-Crick-like G·U- could play a significant role evading Watson-Crick fidelity checkpoints in RNA:DNA hybrids and RNA duplexes.
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Affiliation(s)
- Or Szekely
- Department of Biology, Duke University, Durham, NC 27710, USA
- Howard Hughes Medical Institute, Duke University, Durham, NC 27710, USA
| | | | - Stephanie Gu
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Biochemistry and Molecular Biophysics, Columbia University, NY, NY 10032, USA
| | - Akanksha Manghrani
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Biochemistry and Molecular Biophysics, Columbia University, NY, NY 10032, USA
| | - Serafima Guseva
- Department of Biochemistry and Molecular Biophysics, Columbia University, NY, NY 10032, USA
| | - Hashim M Al-Hashimi
- Department of Biochemistry and Molecular Biophysics, Columbia University, NY, NY 10032, USA
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2
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Szekely O, Rangadurai AK, Gu S, Manghrani A, Guseva S, Al-Hashimi HM. NMR measurements of transient low-populated tautomeric and anionic Watson-Crick-like G·T/U in RNA:DNA hybrids: Implications for the fidelity of transcription and CRISPR/Cas9 gene editing. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.24.554670. [PMID: 37662220 PMCID: PMC10473728 DOI: 10.1101/2023.08.24.554670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Many biochemical processes use the Watson-Crick geometry to distinguish correct from incorrect base pairing. However, on rare occasions, mismatches such as G•T/U can transiently adopt Watson-Crick-like conformations through tautomerization or ionization of the bases, giving rise to replicative and translational errors. The propensities to form Watson-Crick-like mismatches in RNA:DNA hybrids remain unknown, making it unclear whether they can also contribute to errors during processes such as transcription and CRISPR/Cas editing. Here, using NMR R 1ρ experiments, we show that dG•rU and dT•rG mismatches in two RNA:DNA hybrids transiently form tautomeric (G enol •T/U ⇄G•T enol /U enol ) and anionic (G•T - /U - ) Watson-Crick-like conformations. The tautomerization dynamics were like those measured in A-RNA and B-DNA duplexes. However, anionic dG•rU - formed with a ten-fold higher propensity relative to dT - •rG and dG•dT - and this could be attributed to the lower pK a (Δ pK a ∼0.4-0.9) of U versus T. Our findings suggest plausible roles for Watson-Crick-like G•T/U mismatches in transcriptional errors and CRISPR/Cas9 off-target gene editing, uncover a crucial difference between the chemical dynamics of G•U versus G•T, and indicate that anionic Watson-Crick-like G•U - could play a significant role evading Watson-Crick fidelity checkpoints in RNA:DNA hybrids and RNA duplexes.
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3
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Tang Q, Gulkis M, McKenna R, Çağlayan M. Structures of LIG1 that engage with mutagenic mismatches inserted by polβ in base excision repair. Nat Commun 2022; 13:3860. [PMID: 35790757 PMCID: PMC9256674 DOI: 10.1038/s41467-022-31585-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 06/23/2022] [Indexed: 11/09/2022] Open
Abstract
DNA ligase I (LIG1) catalyzes the ligation of the nick repair intermediate after gap filling by DNA polymerase (pol) β during downstream steps of the base excision repair (BER) pathway. However, how LIG1 discriminates against the mutagenic 3'-mismatches incorporated by polβ at atomic resolution remains undefined. Here, we determine the X-ray structures of LIG1/nick DNA complexes with G:T and A:C mismatches and uncover the ligase strategies that favor or deter the ligation of base substitution errors. Our structures reveal that the LIG1 active site can accommodate a G:T mismatch in the wobble conformation, where an adenylate (AMP) is transferred to the 5'-phosphate of a nick (DNA-AMP), while it stays in the LIG1-AMP intermediate during the initial step of the ligation reaction in the presence of an A:C mismatch at the 3'-strand. Moreover, we show mutagenic ligation and aberrant nick sealing of dG:T and dA:C mismatches, respectively. Finally, we demonstrate that AP-endonuclease 1 (APE1), as a compensatory proofreading enzyme, removes the mismatched bases and interacts with LIG1 at the final BER steps. Our overall findings provide the features of accurate versus mutagenic outcomes coordinated by a multiprotein complex including polβ, LIG1, and APE1 to maintain efficient repair.
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Affiliation(s)
- Qun Tang
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, 32610, USA
| | - Mitchell Gulkis
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, 32610, USA
| | - Robert McKenna
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, 32610, USA
| | - Melike Çağlayan
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, 32610, USA.
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4
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Baranovskiy AG, Babayeva ND, Lisova AE, Morstadt LM, Tahirov TH. Structural and functional insight into mismatch extension by human DNA polymerase α. Proc Natl Acad Sci U S A 2022; 119:e2111744119. [PMID: 35467978 PMCID: PMC9169922 DOI: 10.1073/pnas.2111744119] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 03/08/2022] [Indexed: 12/11/2022] Open
Abstract
Human DNA polymerase α (Polα) does not possess proofreading ability and plays an important role in genome replication and mutagenesis. Polα extends the RNA primers generated by primase and provides a springboard for loading other replication factors. Here we provide the structural and functional analysis of the human Polα interaction with a mismatched template:primer. The structure of the human Polα catalytic domain in the complex with an incoming deoxycytidine triphosphate (dCTP) and the template:primer containing a T-C mismatch at the growing primer terminus was solved at a 2.9 Å resolution. It revealed the absence of significant distortions in the active site and in the conformation of the substrates, except the primer 3′-end. The T-C mismatch acquired a planar geometry where both nucleotides moved toward each other by 0.4 Å and 0.7 Å, respectively, and made one hydrogen bond. The binding studies conducted at a physiological salt concentration revealed that Polα has a low affinity to DNA and is not able to discriminate against a mispaired template:primer in the absence of deoxynucleotide triphosphate (dNTP). Strikingly, in the presence of cognate dNTP, Polα showed a more than 10-fold higher selectivity for a correct duplex versus a mismatched one. According to pre-steady-state kinetic studies, human Polα extends the T-C mismatch with a 249-fold lower efficiency due to reduction of the polymerization rate constant by 38-fold and reduced affinity to the incoming nucleotide by 6.6-fold. Thus, a mismatch at the postinsertion site affects all factors important for primer extension: affinity to both substrates and the rate of DNA polymerization.
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Affiliation(s)
- Andrey G. Baranovskiy
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198
| | - Nigar D. Babayeva
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198
| | - Alisa E. Lisova
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198
| | - Lucia M. Morstadt
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198
| | - Tahir H. Tahirov
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198
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5
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Brovarets’ OO, Muradova A, Hovorun DM. Novel horizons of the conformationally-tautomeric transformations of the G·T base pairs: quantum-mechanical investigation. Mol Phys 2022. [DOI: 10.1080/00268976.2022.2026510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Ol’ha O. Brovarets’
- Department of Molecular and Quantum Biophysics, Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Alona Muradova
- Department of Molecular Biotechnology and Bioinformatics, Institute of High Technologies, Taras Shevchenko National University of Kyiv, Kyiv, Ukraine
| | - Dmytro M. Hovorun
- Department of Molecular and Quantum Biophysics, Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kyiv, Ukraine
- Department of Molecular Biotechnology and Bioinformatics, Institute of High Technologies, Taras Shevchenko National University of Kyiv, Kyiv, Ukraine
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6
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Geronimo I, Vidossich P, De Vivo M. Local Structural Dynamics at the Metal-Centered Catalytic Site of Polymerases is Critical for Fidelity. ACS Catal 2021. [DOI: 10.1021/acscatal.1c03840] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Inacrist Geronimo
- Laboratory of Molecular Modelling & Drug Discovery, Istituto Italiano di Tecnologia, Via Morego 30, Genoa 16163, Italy
| | - Pietro Vidossich
- Laboratory of Molecular Modelling & Drug Discovery, Istituto Italiano di Tecnologia, Via Morego 30, Genoa 16163, Italy
| | - Marco De Vivo
- Laboratory of Molecular Modelling & Drug Discovery, Istituto Italiano di Tecnologia, Via Morego 30, Genoa 16163, Italy
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7
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Multiscale Modeling of Wobble to Watson-Crick-Like Guanine-Uracil Tautomerization Pathways in RNA. Int J Mol Sci 2021; 22:ijms22115411. [PMID: 34063755 PMCID: PMC8196565 DOI: 10.3390/ijms22115411] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/05/2021] [Accepted: 05/09/2021] [Indexed: 01/02/2023] Open
Abstract
Energetically unfavorable Watson–Crick (WC)-like tautomeric forms of nucleobases are known to introduce spontaneous mutations, and contribute to replication, transcription, and translation errors. Recent NMR relaxation dispersion techniques were able to show that wobble (w) G•U mispair exists in equilibrium with the short-lived, low-population WC-like enolic tautomers. Presently, we have investigated the wG•U → WC-like enolic reaction pathway using various theoretical methods: quantum mechanics (QM), molecular dynamics (MD), and combined quantum mechanics/molecular mechanics (QM/MM). The previous studies on QM gas phase calculations were inconsistent with experimental data. We have also explored the environmental effects on the reaction energies by adding explicit water. While the QM-profile clearly becomes endoergic in the presence of water, the QM/MM-profile remains consistently endoergic in the presence and absence of water. Hence, by including microsolvation and QM/MM calculations, the experimental data can be explained. For the G•Uenol→ Genol•U pathway, the latter appears to be energetically more favorable throughout all computational models. This study can be considered as a benchmark of various computational models of wG•U to WC-like tautomerization pathways with and without the environmental effects, and may contribute on further studies of other mispairs as well.
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8
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Rangadurai A, Szymanski ES, Kimsey I, Shi H, Al-Hashimi HM. Probing conformational transitions towards mutagenic Watson-Crick-like G·T mismatches using off-resonance sugar carbon R 1ρ relaxation dispersion. JOURNAL OF BIOMOLECULAR NMR 2020; 74:457-471. [PMID: 32789613 PMCID: PMC7508749 DOI: 10.1007/s10858-020-00337-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Accepted: 07/13/2020] [Indexed: 05/30/2023]
Abstract
NMR off-resonance R1ρ relaxation dispersion measurements on base carbon and nitrogen nuclei have revealed that wobble G·T/U mismatches in DNA and RNA duplexes exist in dynamic equilibrium with short-lived, low-abundance, and mutagenic Watson-Crick-like conformations. As Watson-Crick-like G·T mismatches have base pairing geometries similar to Watson-Crick base pairs, we hypothesized that they would mimic Watson-Crick base pairs with respect to the sugar-backbone conformation as well. Using off-resonance R1ρ measurements targeting the sugar C3' and C4' nuclei, a structure survey, and molecular dynamics simulations, we show that wobble G·T mismatches adopt sugar-backbone conformations that deviate from the canonical Watson-Crick conformation and that transitions toward tautomeric and anionic Watson-Crick-like G·T mismatches restore the canonical Watson-Crick sugar-backbone. These measurements also reveal kinetic isotope effects for tautomerization in D2O versus H2O, which provide experimental evidence in support of a transition state involving proton transfer. The results provide additional evidence in support of mutagenic Watson-Crick-like G·T mismatches, help rule out alternative inverted wobble conformations in the case of anionic G·T-, and also establish sugar carbons as new non-exchangeable probes of this exchange process.
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Affiliation(s)
- Atul Rangadurai
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Eric S Szymanski
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, 27710, USA
- Nymirum, 4324 S. Alston Avenue, Durham, NC, 27713, USA
| | - Isaac Kimsey
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, 27710, USA
- Nymirum, 4324 S. Alston Avenue, Durham, NC, 27713, USA
| | - Honglue Shi
- Department of Chemistry, Duke University, Durham, NC, 27710, USA
| | - Hashim M Al-Hashimi
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, 27710, USA.
- Department of Chemistry, Duke University, Durham, NC, 27710, USA.
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9
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Crystallographic evidence of Watson-Crick connectivity in the base pair of anionic adenine with thymine. Proc Natl Acad Sci U S A 2020; 117:18224-18230. [PMID: 32680959 PMCID: PMC7414232 DOI: 10.1073/pnas.2008379117] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Utilizing an ionic liquid strategy, we report crystal structures of salts of free anionic nucleobases and base pairs previously studied only computationally and in the gas phase. Reaction of tetrabutylammonium ([N4444]+) or tetrabutylphosphonium ([P4444]+) hydroxide with adenine (HAd) and thymine (HThy) led to hydrated salts of deprotonated adenine, [N4444][Ad]·2H2O, and thymine, [P4444][Thy]·2H2O, as well as the double salt cocrystal, [P4444]2[Ad][Thy]·3H2O·2HThy. The cocrystal includes the anionic [Ad-(HThy)] base pair which is a stable formation in the solid state that has previously not even been suggested. It exhibits Watson-Crick connectivity as found in DNA but which is unusual for the free neutral base pairs. The stability of the observed anionic bases and their supramolecular formations and hydrates has also been examined by electronic structure calculations, contributing to more insight into how base pairs can bind when a proton is removed and highlighting mechanisms of stabilization or chemical transformation in the DNA chains.
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10
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Li P, Rangadurai A, Al-Hashimi HM, Hammes-Schiffer S. Environmental Effects on Guanine-Thymine Mispair Tautomerization Explored with Quantum Mechanical/Molecular Mechanical Free Energy Simulations. J Am Chem Soc 2020; 142:11183-11191. [PMID: 32459476 DOI: 10.1021/jacs.0c03774] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
DNA bases can adopt energetically unfavorable tautomeric forms that enable the formation of Watson-Crick-like (WC-like) mispairs, which have been proposed to give rise to spontaneous mutations in DNA and misincorporation errors in DNA replication and translation. Previous NMR and computational studies have indicated that the population of WC-like guanine-thymine (G-T) mispairs depends on the environment, such as the local nucleic acid sequence and solvation. To investigate these environmental effects, herein G-T mispair tautomerization processes are studied computationally in aqueous solution, in A-form and B-form DNA duplexes, and within the active site of a DNA polymerase λ variant. The wobble G-T (wG-T), WC-like G-T*, and WC-like G*-T forms are considered, where * indicates the enol tautomer of the base. The minimum free energy paths for the tautomerization from the wG-T to the WC-like G-T* and from the WC-like G-T* to the WC-like G*-T are computed with mixed quantum mechanical/molecular mechanical (QM/MM) free energy simulations. The reaction free energies and free energy barriers are found to be significantly influenced by the environment. The wG-T→G-T* tautomerization is predicted to be endoergic in aqueous solution and the DNA duplexes but slightly exoergic in the polymerase, with Arg517 and Asn513 providing electrostatic stabilization of G-T*. The G-T*→G*-T tautomerization is also predicted to be slightly more thermodynamically favorable in the polymerase relative to these DNA duplexes. These simulations are consistent with an experimentally driven kinetic misincorporation model suggesting that G-T mispair tautomerization occurs in the ajar polymerase conformation or concertedly with the transition from the ajar to the closed polymerase conformation. Furthermore, the order of the associated two proton transfer reactions is predicted to be different in the polymerase than in aqueous solution and the DNA duplexes. These studies highlight the impact of the environment on the thermodynamics, kinetics, and fundamental mechanisms of G-T mispair tautomerization, which plays a role in a wide range of biochemically important processes.
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Affiliation(s)
- Pengfei Li
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Atul Rangadurai
- Department of Biochemistry, Duke University, Durham, North Carolina 27710, United States
| | - Hashim M Al-Hashimi
- Department of Biochemistry, Duke University, Durham, North Carolina 27710, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
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11
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Arangundy-Franklin S, Taylor AI, Porebski BT, Genna V, Peak-Chew S, Vaisman A, Woodgate R, Orozco M, Holliger P. A synthetic genetic polymer with an uncharged backbone chemistry based on alkyl phosphonate nucleic acids. Nat Chem 2019; 11:533-542. [PMID: 31011171 DOI: 10.1038/s41557-019-0255-4] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 03/15/2019] [Indexed: 12/24/2022]
Abstract
The physicochemical properties of nucleic acids are dominated by their highly charged phosphodiester backbone chemistry. This polyelectrolyte structure decouples information content (base sequence) from bulk properties, such as solubility, and has been proposed as a defining trait of all informational polymers. However, this conjecture has not been tested experimentally. Here, we describe the encoded synthesis of a genetic polymer with an uncharged backbone chemistry: alkyl phosphonate nucleic acids (phNAs) in which the canonical, negatively charged phosphodiester is replaced by an uncharged P-alkyl phosphonodiester backbone. Using synthetic chemistry and polymerase engineering, we describe the enzymatic, DNA-templated synthesis of P-methyl and P-ethyl phNAs, and the directed evolution of specific streptavidin-binding phNA aptamer ligands directly from random-sequence mixed P-methyl/P-ethyl phNA repertoires. Our results establish an example of the DNA-templated enzymatic synthesis and evolution of an uncharged genetic polymer and provide a foundational methodology for their exploration as a source of novel functional molecules.
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Affiliation(s)
| | - Alexander I Taylor
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, UK
| | - Benjamin T Porebski
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, UK
| | - Vito Genna
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Sew Peak-Chew
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, UK
| | - Alexandra Vaisman
- Section on DNA Replication, Repair and Mutagenesis, Bethesda, MD, USA
| | - Roger Woodgate
- Section on DNA Replication, Repair and Mutagenesis, Bethesda, MD, USA
| | - Modesto Orozco
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain.,Department of Biochemistry and Biomedicine, University of Barcelona, Barcelona, Spain
| | - Philipp Holliger
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, UK.
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12
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Engineering-driven biological insights into DNA polymerase mechanism. Curr Opin Biotechnol 2018; 60:9-16. [PMID: 30502514 DOI: 10.1016/j.copbio.2018.11.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 11/13/2018] [Indexed: 12/11/2022]
Abstract
DNA-dependent DNA polymerases have been extensively studied for over 60 years and lie at the core of multiple biotechnological and diagnostic applications. Nevertheless, these complex molecular machines remain only partially understood. Here we present some evidence on how polymerase engineering for the synthesis and replication of xenobiotic nucleic acids (XNAs) have improved our understanding of these enzymes and how that can be used to gain further insight into their mechanism. Better understanding of the mechanisms of DNA polymerases can accelerate their engineering and we highlight how it is now feasible to use structure-based and function-based approaches to systematically and iteratively develop XNA polymerases for increasingly divergent chemistries.
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13
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Raper AT, Reed AJ, Suo Z. Kinetic Mechanism of DNA Polymerases: Contributions of Conformational Dynamics and a Third Divalent Metal Ion. Chem Rev 2018; 118:6000-6025. [DOI: 10.1021/acs.chemrev.7b00685] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Austin T. Raper
- Department of Chemistry and Biochemistry, Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, United States
| | - Andrew J. Reed
- Department of Chemistry and Biochemistry, Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, United States
| | - Zucai Suo
- Department of Chemistry and Biochemistry, Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, United States
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14
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Kimsey IJ, Szymanski ES, Zahurancik WJ, Shakya A, Xue Y, Chu CC, Sathyamoorthy B, Suo Z, Al-Hashimi HM. Dynamic basis for dG•dT misincorporation via tautomerization and ionization. Nature 2018; 554:195-201. [PMID: 29420478 PMCID: PMC5808992 DOI: 10.1038/nature25487] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 12/21/2017] [Indexed: 12/22/2022]
Abstract
Tautomeric and anionic Watson-Crick-like mismatches have important roles in replication and translation errors through mechanisms that are not fully understood. Here, using NMR relaxation dispersion, we resolve a sequence-dependent kinetic network connecting G•T/U wobbles with three distinct Watson-Crick mismatches: two rapidly exchanging tautomeric species (Genol•T/UG•Tenol/Uenol; population less than 0.4%) and one anionic species (G•T-/U-; population around 0.001% at neutral pH). The sequence-dependent tautomerization or ionization step was inserted into a minimal kinetic mechanism for correct incorporation during replication after the initial binding of the nucleotide, leading to accurate predictions of the probability of dG•dT misincorporation across different polymerases and pH conditions and for a chemically modified nucleotide, and providing mechanisms for sequence-dependent misincorporation. Our results indicate that the energetic penalty for tautomerization and/or ionization accounts for an approximately 10-2 to 10-3-fold discrimination against misincorporation, which proceeds primarily via tautomeric dGenol•dT and dG•dTenol, with contributions from anionic dG•dT- dominant at pH 8.4 and above or for some mutagenic nucleotides.
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Affiliation(s)
- Isaac J Kimsey
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Eric S Szymanski
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Walter J Zahurancik
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, USA
- The Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, USA
| | - Anisha Shakya
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Yi Xue
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Chia-Chieh Chu
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
| | | | - Zucai Suo
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, USA
- The Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, USA
| | - Hashim M Al-Hashimi
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
- Department of Chemistry, Duke University, Durham, North Carolina 27710, USA
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15
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Maximoff SN, Kamerlin SCL, Florián J. DNA Polymerase λ Active Site Favors a Mutagenic Mispair between the Enol Form of Deoxyguanosine Triphosphate Substrate and the Keto Form of Thymidine Template: A Free Energy Perturbation Study. J Phys Chem B 2017; 121:7813-7822. [PMID: 28732447 DOI: 10.1021/acs.jpcb.7b04874] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Human DNA polymerase λ is an intermediate fidelity member of the X family, which plays a role in DNA repair. Recent X-ray diffraction structures of a ternary complex of a loop-deletion mutant of polymerase λ, a deoxyguanosine triphosphate analogue, and a gapped DNA show that guanine and thymine form a mutagenic mispair with an unexpected Watson-Crick-like geometry rather than a wobble geometry. Hence, there is an intriguing possibility that either thymine in the DNA or guanine in the deoxyguanosine triphosphate analogue may spend a substantial fraction of time in a deprotonated or enol form (both are minor species in aqueous solution) in the active site of the polymerase λ mutant. The experiments do not determine particular forms of the nucleobases that contribute to this mutagenic mispair. Thus, we investigate the thermodynamics of formation of various mispairs between guanine and thymine in the ternary complex at a neutral pH using classical molecular dynamics simulations and the free energy perturbation method. Our free energy calculations, as well as a comparison of the experimental and computed structures of mispairs, indicate that the Watson-Crick-like mispair between the enol tautomer of guanine and the keto tautomer of thymine is dominant. The wobble mispair between the keto forms of guanine and thymine and the Watson-Crick-like mispair between the keto tautomer of guanine and the enol tautomer of thymine are less prevalent, and mispairs that involve deprotonated guanine or thymine are thermodynamically unlikely. These findings are consistent with the experiment and relevant for understanding mechanisms of spontaneous mutagenesis.
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Affiliation(s)
- Sergey N Maximoff
- Department of Chemistry and Biochemistry, Loyola University Chicago , 1032 W. Sheridan Road, Chicago, Illinois 60660, United States
| | | | - Jan Florián
- Department of Chemistry and Biochemistry, Loyola University Chicago , 1032 W. Sheridan Road, Chicago, Illinois 60660, United States
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Structures of DNA Polymerase Mispaired DNA Termini Transitioning to Pre-catalytic Complexes Support an Induced-Fit Fidelity Mechanism. Structure 2016; 24:1863-1875. [PMID: 27642161 DOI: 10.1016/j.str.2016.08.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 08/09/2016] [Accepted: 08/10/2016] [Indexed: 11/24/2022]
Abstract
High-fidelity DNA synthesis requires that polymerases display a strong preference for right nucleotide insertion. When the wrong nucleotide is inserted, the polymerase deters extension from the mismatched DNA terminus. Twenty-three crystallographic structures of DNA polymerase β with terminal template-primer mismatches were determined as binary DNA and ternary pre-catalytic substrate complexes. These structures indicate that the mismatched termini adopt various distorted conformations that attempt to satisfy stacking and hydrogen-bonding interactions. The binary complex structures indicate an induced strain in the mismatched template nucleotide. Addition of a non-hydrolyzable incoming nucleotide stabilizes the templating nucleotide with concomitant strain in the primer terminus. Several dead-end ternary complex structures suggest that DNA synthesis might occur as the enzyme transitions from an open to a closed complex. The structures are consistent with an induced-fit mechanism where a mismatched terminus is misaligned relative to the correct incoming nucleotide to deter or delay further DNA synthesis.
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Rozov A, Demeshkina N, Westhof E, Yusupov M, Yusupova G. New Structural Insights into Translational Miscoding. Trends Biochem Sci 2016; 41:798-814. [PMID: 27372401 DOI: 10.1016/j.tibs.2016.06.001] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 05/23/2016] [Accepted: 06/02/2016] [Indexed: 01/16/2023]
Abstract
The fidelity of translation depends strongly on the selection of the correct aminoacyl-tRNA that is complementary to the mRNA codon present in the ribosomal decoding center. The ribosome occasionally makes mistakes by selecting the wrong substrate from the pool of aminoacyl-tRNAs. Here, we summarize recent structural advances that may help to clarify the origin of missense errors that occur during decoding. These developments suggest that discrimination between tRNAs is based primarily on steric complementarity and shape acceptance rather than on the number of hydrogen bonds between the molding of the decoding center and the codon-anticodon duplex. They strengthen the hypothesis that spatial mimicry, due either to base tautomerism or ionization, drives infidelity in ribosomal translation.
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Affiliation(s)
- Alexey Rozov
- Department of Integrated Structural Biology, Institute of Genetics and Molecular and Cellular Biology, CNRS, UMR7104/INSERM, U964/University of Strasbourg, Strasbourg, France
| | - Natalia Demeshkina
- Department of Integrated Structural Biology, Institute of Genetics and Molecular and Cellular Biology, CNRS, UMR7104/INSERM, U964/University of Strasbourg, Strasbourg, France
| | - Eric Westhof
- Architecture and Reactivity of RNA, Institute of Molecular and Cellular Biology of the CNRS UPR9002/University of Strasbourg, Strasbourg, France
| | - Marat Yusupov
- Department of Integrated Structural Biology, Institute of Genetics and Molecular and Cellular Biology, CNRS, UMR7104/INSERM, U964/University of Strasbourg, Strasbourg, France
| | - Gulnara Yusupova
- Department of Integrated Structural Biology, Institute of Genetics and Molecular and Cellular Biology, CNRS, UMR7104/INSERM, U964/University of Strasbourg, Strasbourg, France.
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Rozov A, Westhof E, Yusupov M, Yusupova G. The ribosome prohibits the G•U wobble geometry at the first position of the codon-anticodon helix. Nucleic Acids Res 2016; 44:6434-41. [PMID: 27174928 PMCID: PMC5291260 DOI: 10.1093/nar/gkw431] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 05/06/2016] [Indexed: 01/05/2023] Open
Abstract
Precise conversion of genetic information into proteins is essential to cellular health. However, a margin of error exists and is at its highest on the stage of translation of mRNA by the ribosome. Here we present three crystal structures of 70S ribosome complexes with messenger RNA and transfer RNAs and show that when a G•U base pair is at the first position of the codon-anticodon helix a conventional wobble pair cannot form because of inescapable steric clash between the guanosine of the A codon and the key nucleotide of decoding center adenosine 1493 of 16S rRNA. In our structure the rigid ribosomal decoding center, which is identically shaped for cognate or near-cognate tRNAs, forces this pair to adopt a geometry close to that of a canonical G•C pair. We further strengthen our hypothesis that spatial mimicry due either to base tautomerism or ionization dominates the translation infidelity mechanism.
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Affiliation(s)
- Alexey Rozov
- Department of Integrated Structural Biology, Institute of Genetics and Molecular and Cellular Biology, INSERM, U964; CNRS, UMR7104/University of Strasbourg, 1 rue Laurent Fries, 67404 Illkirch, France
| | - Eric Westhof
- Architecture & Reactivity of RNA, University of Strasbourg, Institute of Molecular and Cellular Biology of the CNRS, UPR9002, 15 rue R. Descartes, 67084 Strasbourg, France
| | - Marat Yusupov
- Department of Integrated Structural Biology, Institute of Genetics and Molecular and Cellular Biology, INSERM, U964; CNRS, UMR7104/University of Strasbourg, 1 rue Laurent Fries, 67404 Illkirch, France
| | - Gulnara Yusupova
- Department of Integrated Structural Biology, Institute of Genetics and Molecular and Cellular Biology, INSERM, U964; CNRS, UMR7104/University of Strasbourg, 1 rue Laurent Fries, 67404 Illkirch, France
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19
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Kou Y, Koag MC, Lee S. N7 methylation alters hydrogen-bonding patterns of guanine in duplex DNA. J Am Chem Soc 2015; 137:14067-70. [PMID: 26517568 DOI: 10.1021/jacs.5b10172] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
N7-Alkyl-2'-deoxyguanosines are major adducts in DNA that are generated by various alkylating mutagens and drugs. However, the effect of the N7 alkylation on the hydrogen-bonding patterns of the guanine remains poorly understood. We prepared N7-methyl-2'-deoxyguanosine (N7mdG)-containing DNA using a transition-state destabilization strategy, developed a novel polβ-host-guest complex system, and determined eight crystal structures of N7mdG or dG paired with dC, dT, dG, and dA. The structures of N7mdG:dC and N7mdG:dG are very similar to those of dG:dC and dG:dG, respectively, indicating the involvement of the keto tautomeric form of N7mdG in the base pairings with dC and dG. On the other hand, the structure of N7mdG:dT shows that the mispair forms three hydrogen bonds and adopts a Watson-Crick-like geometry rather than a wobble geometry, suggesting that the enol tautomeric form of N7mdG involves in its base pairing with dT. In addition, N7mdG:dA adopts a novel shifted anti:syn base pair presumably via the enol tautomeric form of N7mdG. The polβ-host-guest complex structures reveal that guanine-N7 methylation changes the hydrogen-bonding patterns of the guanine when paired with dT or dA and suggest that N7 alkylation may alter the base pairing patterns of guanine by promoting the formation of the rare enol tautomeric form of guanine.
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Affiliation(s)
- Yi Kou
- Division of Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin , Austin, Texas 78712, United States
| | - Myong-Chul Koag
- Division of Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin , Austin, Texas 78712, United States
| | - Seongmin Lee
- Division of Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin , Austin, Texas 78712, United States
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Gouge J, Rosario S, Romain F, Poitevin F, Béguin P, Delarue M. Structural basis for a novel mechanism of DNA bridging and alignment in eukaryotic DSB DNA repair. EMBO J 2015; 34:1126-42. [PMID: 25762590 PMCID: PMC4406656 DOI: 10.15252/embj.201489643] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 01/08/2015] [Accepted: 01/09/2015] [Indexed: 01/18/2023] Open
Abstract
Eukaryotic DNA polymerase mu of the PolX family can promote the association of the two 3'-protruding ends of a DNA double-strand break (DSB) being repaired (DNA synapsis) even in the absence of the core non-homologous end-joining (NHEJ) machinery. Here, we show that terminal deoxynucleotidyltransferase (TdT), a closely related PolX involved in V(D)J recombination, has the same property. We solved its crystal structure with an annealed DNA synapsis containing one micro-homology (MH) base pair and one nascent base pair. This structure reveals how the N-terminal domain and Loop 1 of Tdt cooperate for bridging the two DNA ends, providing a templating base in trans and limiting the MH search region to only two base pairs. A network of ordered water molecules is proposed to assist the incorporation of any nucleotide independently of the in trans templating base. These data are consistent with a recent model that explains the statistics of sequences synthesized in vivo by Tdt based solely on this dinucleotide step. Site-directed mutagenesis and functional tests suggest that this structural model is also valid for Pol mu during NHEJ.
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Affiliation(s)
- Jérôme Gouge
- Unité de Dynamique Structurale des Macromolécules, Institut Pasteur, UMR 3528 du C.N.R.S., Paris, France
| | - Sandrine Rosario
- Unité de Dynamique Structurale des Macromolécules, Institut Pasteur, UMR 3528 du C.N.R.S., Paris, France
| | - Félix Romain
- Unité de Dynamique Structurale des Macromolécules, Institut Pasteur, UMR 3528 du C.N.R.S., Paris, France
| | - Frédéric Poitevin
- Institut de Physique Théorique, CEA-Saclay, CNRS URA 2306, Gif-sur-Yvette, France
| | - Pierre Béguin
- Unité de Biologie Moléculaire du Gène chez les Extrêmophiles, Institut Pasteur, Paris, France
| | - Marc Delarue
- Unité de Dynamique Structurale des Macromolécules, Institut Pasteur, UMR 3528 du C.N.R.S., Paris, France
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21
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Visualizing transient Watson-Crick-like mispairs in DNA and RNA duplexes. Nature 2015; 519:315-20. [PMID: 25762137 DOI: 10.1038/nature14227] [Citation(s) in RCA: 176] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 01/09/2015] [Indexed: 11/08/2022]
Abstract
Rare tautomeric and anionic nucleobases are believed to have fundamental biological roles, but their prevalence and functional importance has remained elusive because they exist transiently, in low abundance, and involve subtle movements of protons that are difficult to visualize. Using NMR relaxation dispersion, we show here that wobble dG•dT and rG•rU mispairs in DNA and RNA duplexes exist in dynamic equilibrium with short-lived, low-populated Watson-Crick-like mispairs that are stabilized by rare enolic or anionic bases. These mispairs can evade Watson-Crick fidelity checkpoints and form with probabilities (10(-3) to 10(-5)) that strongly imply a universal role in replication and translation errors. Our results indicate that rare tautomeric and anionic bases are widespread in nucleic acids, expanding their structural and functional complexity beyond that attainable with canonical bases.
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