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Alnajjar KS, Wang K, Alvarado-Cruz I, Chavira C, Negahbani A, Nakhjiri M, Minard C, Garcia-Barboza B, Kashemirov BA, McKenna CE, Goodman MF, Sweasy JB. Modifying the Basicity of the dNTP Leaving Group Modulates Precatalytic Conformational Changes of DNA Polymerase β. Biochemistry 2024. [PMID: 38780930 DOI: 10.1021/acs.biochem.4c00065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
The catalytic function of DNA polymerase β (pol β) fulfills the gap-filling requirement of the base excision DNA repair pathway by incorporating a single nucleotide into a gapped DNA substrate resulting from the removal of damaged DNA bases. Most importantly, pol β can select the correct nucleotide from a pool of similarly structured nucleotides to incorporate into DNA in order to prevent the accumulation of mutations in the genome. Pol β is likely to employ various mechanisms for substrate selection. Here, we use dCTP analogues that have been modified at the β,γ-bridging group of the triphosphate moiety to monitor the effect of leaving group basicity of the incoming nucleotide on precatalytic conformational changes, which are important for catalysis and selectivity. It has been previously shown that there is a linear free energy relationship between leaving group pKa and the chemical transition state. Our results indicate that there is a similar relationship with the rate of a precatalytic conformational change, specifically, the closing of the fingers subdomain of pol β. In addition, by utilizing analogue β,γ-CHX stereoisomers, we identified that the orientation of the β,γ-bridging group relative to R183 is important for the rate of fingers closing, which directly influences chemistry.
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Affiliation(s)
- Khadijeh S Alnajjar
- Department of Cellular and Molecular Medicine, University of Arizona Cancer Center, University of Arizona, Tucson, Arizona 85724, United States
| | - Katarina Wang
- Therapeutic Radiology Department, Yale University, New Haven, Connecticut 06520, United States
| | - Isabel Alvarado-Cruz
- Department of Cellular and Molecular Medicine, University of Arizona Cancer Center, University of Arizona, Tucson, Arizona 85724, United States
| | - Cristian Chavira
- Fred and Pamela Buffett Cancer Center and Eppley Institute for Cancer Research, Omaha, Nebraska 68198, United States
- Department of Cellular and Molecular Medicine, University of Arizona Cancer Center, University of Arizona, Tucson, Arizona 85724, United States
| | - Amirsoheil Negahbani
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Maryam Nakhjiri
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Corinne Minard
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Beatriz Garcia-Barboza
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Boris A Kashemirov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Charles E McKenna
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Myron F Goodman
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
- Department of Biological Sciences, University of Southern California, Los Angeles, California 90089, United States
| | - Joann B Sweasy
- Fred and Pamela Buffett Cancer Center and Eppley Institute for Cancer Research, Omaha, Nebraska 68198, United States
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2
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Bakman AS, Boichenko SS, Kuznetsova AA, Ishchenko AA, Saparbaev M, Kuznetsov NA. The Impact of Human DNA Glycosylases on the Activity of DNA Polymerase β toward Various Base Excision Repair Intermediates. Int J Mol Sci 2023; 24:ijms24119594. [PMID: 37298543 DOI: 10.3390/ijms24119594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 05/25/2023] [Accepted: 05/30/2023] [Indexed: 06/12/2023] Open
Abstract
Base excision repair (BER) is one of the important systems for the maintenance of genome stability via repair of DNA lesions. BER is a multistep process involving a number of enzymes, including damage-specific DNA glycosylases, apurinic/apyrimidinic (AP) endonuclease 1, DNA polymerase β, and DNA ligase. Coordination of BER is implemented by multiple protein-protein interactions between BER participants. Nonetheless, mechanisms of these interactions and their roles in the BER coordination are poorly understood. Here, we report a study on Polβ's nucleotidyl transferase activity toward different DNA substrates (that mimic DNA intermediates arising during BER) in the presence of various DNA glycosylases (AAG, OGG1, NTHL1, MBD4, UNG, or SMUG1) using rapid-quench-flow and stopped-flow fluorescence approaches. It was shown that Polβ efficiently adds a single nucleotide into different types of single-strand breaks either with or without a 5'-dRP-mimicking group. The obtained data indicate that DNA glycosylases AAG, OGG1, NTHL1, MBD4, UNG, and SMUG1, but not NEIL1, enhance Polβ's activity toward the model DNA intermediates.
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Affiliation(s)
- Artemiy S Bakman
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences (SB RAS), 8 Prospekt Akad. Lavrentyeva, Novosibirsk 630090, Russia
| | - Stanislav S Boichenko
- Department of Natural Sciences, Novosibirsk State University, 2 Pirogova Str., Novosibirsk 630090, Russia
| | - Aleksandra A Kuznetsova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences (SB RAS), 8 Prospekt Akad. Lavrentyeva, Novosibirsk 630090, Russia
| | - Alexander A Ishchenko
- Group «Mechanisms of DNA Repair and Carcinogenesis», Gustave Roussy Cancer Campus, CNRS UMR9019, Université Paris-Saclay, 94805 Villejuif, France
| | - Murat Saparbaev
- Group «Mechanisms of DNA Repair and Carcinogenesis», Gustave Roussy Cancer Campus, CNRS UMR9019, Université Paris-Saclay, 94805 Villejuif, France
| | - Nikita A Kuznetsov
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences (SB RAS), 8 Prospekt Akad. Lavrentyeva, Novosibirsk 630090, Russia
- Department of Natural Sciences, Novosibirsk State University, 2 Pirogova Str., Novosibirsk 630090, Russia
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3
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Abstract
DNA polymerase beta (Pol β) is a 39 kD vertebrate polymerase that lacks proofreading ability, yet still maintains a moderate fidelity of DNA synthesis. Pol β is a key enzyme that functions in the base excision repair and non-homologous end joining pathways of DNA repair. Mechanisms of fidelity for Pol β are still being elucidated but are likely to involve dynamic conformational motions of the enzyme upon its binding to DNA and deoxynucleoside triphosphates. Recent studies have linked germline and somatic variants of Pol β with cancer and autoimmunity. These variants induce genomic instability by a number of mechanisms, including error-prone DNA synthesis and accumulation of single nucleotide gaps that lead to replication stress. Here, we review the structure and function of Pol β, and we provide insights into how structural changes in Pol β variants may contribute to genomic instability, mutagenesis, disease, cancer development, and impacts on treatment outcomes.
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Affiliation(s)
- Danielle L Sawyer
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - Joann B Sweasy
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
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4
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Primer terminal ribonucleotide alters the active site dynamics of DNA polymerase η and reduces DNA synthesis fidelity. J Biol Chem 2023; 299:102938. [PMID: 36702254 PMCID: PMC9976465 DOI: 10.1016/j.jbc.2023.102938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 01/19/2023] [Accepted: 01/20/2023] [Indexed: 01/25/2023] Open
Abstract
DNA polymerases catalyze DNA synthesis with high efficiency, which is essential for all life. Extensive kinetic and structural efforts have been executed in exploring mechanisms of DNA polymerases, surrounding their kinetic pathway, catalytic mechanisms, and factors that dictate polymerase fidelity. Recent time-resolved crystallography studies on DNA polymerase η (Pol η) and β have revealed essential transient events during the DNA synthesis reaction, such as mechanisms of primer deprotonation, separated roles of the three metal ions, and conformational changes that disfavor incorporation of the incorrect substrate. DNA-embedded ribonucleotides (rNs) are the most common lesion on DNA and a major threat to genome integrity. While kinetics of rN incorporation has been explored and structural studies have revealed that DNA polymerases have a steric gate that destabilizes ribonucleotide triphosphate binding, the mechanism of extension upon rN addition remains poorly characterized. Using steady-state kinetics, static and time-resolved X-ray crystallography with Pol η as a model system, we showed that the extra hydroxyl group on the primer terminus does alter the dynamics of the polymerase active site as well as the catalysis and fidelity of DNA synthesis. During rN extension, Pol η error incorporation efficiency increases significantly across different sequence contexts. Finally, our systematic structural studies suggest that the rN at the primer end improves primer alignment and reduces barriers in C2'-endo to C3'-endo sugar conformational change. Overall, our work provides further mechanistic insights into the effects of rN incorporation on DNA synthesis.
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5
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Zhu Y, Li Z, Zhong X, Wu X, Lu Y, Khan MA, Li H. Coordination Patterns of the Diphosphate in IDP Coordination Complexes: Crystal Structure and Chirality. Inorg Chem 2022; 61:19425-19439. [DOI: 10.1021/acs.inorgchem.2c03285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Yanhong Zhu
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, P. R. China
- School of Pharmacy, North China University of Science and Technology, Tangshan, Hebei 063210, China
| | - Zhongkui Li
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Xue Zhong
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Xuan Wu
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Yongqiu Lu
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Maroof Ahmad Khan
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Hui Li
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, P. R. China
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6
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The Role of Natural Polymorphic Variants of DNA Polymerase β in DNA Repair. Int J Mol Sci 2022; 23:ijms23042390. [PMID: 35216513 PMCID: PMC8877055 DOI: 10.3390/ijms23042390] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 02/18/2022] [Accepted: 02/18/2022] [Indexed: 11/17/2022] Open
Abstract
DNA polymerase β (Polβ) is considered the main repair DNA polymerase involved in the base excision repair (BER) pathway, which plays an important part in the repair of damaged DNA bases usually resulting from alkylation or oxidation. In general, BER involves consecutive actions of DNA glycosylases, AP endonucleases, DNA polymerases, and DNA ligases. It is known that protein-protein interactions of Polβ with enzymes from the BER pathway increase the efficiency of damaged base repair in DNA. However natural single-nucleotide polymorphisms can lead to a substitution of functionally significant amino acid residues and therefore affect the catalytic activity of the enzyme and the accuracy of Polβ action. Up-to-date databases contain information about more than 8000 SNPs in the gene of Polβ. This review summarizes data on the in silico prediction of the effects of Polβ SNPs on DNA repair efficacy; available data on cancers associated with SNPs of Polβ; and experimentally tested variants of Polβ. Analysis of the literature indicates that amino acid substitutions could be important for the maintenance of the native structure of Polβ and contacts with DNA; others affect the catalytic activity of the enzyme or play a part in the precise and correct attachment of the required nucleotide triphosphate. Moreover, the amino acid substitutions in Polβ can disturb interactions with enzymes involved in BER, while the enzymatic activity of the polymorphic variant may not differ significantly from that of the wild-type enzyme. Therefore, investigation regarding the effect of Polβ natural variants occurring in the human population on enzymatic activity and protein-protein interactions is an urgent scientific task.
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7
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Multiple deprotonation paths of the nucleophile 3'-OH in the DNA synthesis reaction. Proc Natl Acad Sci U S A 2021; 118:2103990118. [PMID: 34088846 DOI: 10.1073/pnas.2103990118] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
DNA synthesis by polymerases is essential for life. Deprotonation of the nucleophile 3'-OH is thought to be the obligatory first step in the DNA synthesis reaction. We have examined each entity surrounding the nucleophile 3'-OH in the reaction catalyzed by human DNA polymerase (Pol) η and delineated the deprotonation process by combining mutagenesis with steady-state kinetics, high-resolution structures of in crystallo reactions, and molecular dynamics simulations. The conserved S113 residue, which forms a hydrogen bond with the primer 3'-OH in the ground state, stabilizes the primer end in the active site. Mutation of S113 to alanine destabilizes primer binding and reduces the catalytic efficiency. Displacement of a water molecule that is hydrogen bonded to the 3'-OH using the 2'-OH of a ribonucleotide or 2'-F has little effect on catalysis. Moreover, combining the S113A mutation with 2'-F replacement, which removes two potential hydrogen acceptors of the 3'-OH, does not reduce the catalytic efficiency. We conclude that the proton can leave the O3' via alternative paths, supporting the hypothesis that binding of the third Mg2+ initiates the reaction by breaking the α-β phosphodiester bond of an incoming deoxyribonucleoside triphosphate (dNTP).
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8
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Haratipour P, Minard C, Nakhjiri M, Negahbani A, Chamberlain BT, Osuna J, Upton TG, Zhao M, Kashemirov BA, McKenna CE. Completing the β,γ-CXY-dNTP Stereochemical Probe Toolkit: Synthetic Access to the dCTP Diastereomers and 31P and 19F NMR Correlations with Absolute Configurations. J Org Chem 2020; 85:14592-14609. [PMID: 33125847 DOI: 10.1021/acs.joc.0c01204] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Nucleoside 5'-triphosphate (dNTP) analogues in which the β,γ-oxygen is mimicked by a CXY group (β,γ-CXY-dNTPs) have provided information about DNA polymerase catalysis and fidelity. Definition of CXY stereochemistry is important to elucidate precise binding modes. We previously reported the (R)- and (S)-β,γ-CHX-dGTP diastereomers (X = F, Cl), prepared via P,C-dimorpholinamide CHCl (6a, 6b) and CHF (7a, 7b) bisphosphonates (BPs) equipped with an (R)-mandelic acid as a chiral auxiliary, with final deprotection using H2/Pd. This method also affords the β,γ-CHCl-dTTP (11a, 11b), β,γ-CHF (12a, 12b), and β,γ-CHCl (13a, 13b) dATP diastereomers as documented here, but the reductive deprotection step is not compatible with dCTP or the bromo substituent in β,γ-CHBr-dNTP analogues. To complete assembly of the toolkit, we describe an alternative synthetic strategy featuring ethylbenzylamine or phenylglycine-derived chiral BP synthons incorporating a photolabile protecting group. After acid-catalyzed removal of the (R)-(+)-α-ethylbenzylamine auxiliary, coupling with activated dCMP and photochemical deprotection, the individual diastereomers of β,γ-CHBr- (33a, 33b), β,γ-CHCl- (34a, 34b), β,γ-CHF-dCTP (35a, 35b) were obtained. The β,γ-CH(CH3)-dATPs (44a, 44b) were obtained using a methyl (R)-(-)-phenylglycinate auxiliary. 31P and 19F NMR Δδ values are correlated with CXY stereochemistry and pKa2-4 values for 13 CXY-bisphosphonic acids and imidodiphosphonic acid are tabulated.
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Affiliation(s)
- Pouya Haratipour
- Department of Chemistry, Dana and David Dornsife College of Letters, Arts and Sciences, University of Southern California, University Park Campus, Los Angeles, California 90089, United States
| | - Corinne Minard
- Department of Chemistry, Dana and David Dornsife College of Letters, Arts and Sciences, University of Southern California, University Park Campus, Los Angeles, California 90089, United States
| | - Maryam Nakhjiri
- Department of Chemistry, Dana and David Dornsife College of Letters, Arts and Sciences, University of Southern California, University Park Campus, Los Angeles, California 90089, United States
| | - Amirsoheil Negahbani
- Department of Chemistry, Dana and David Dornsife College of Letters, Arts and Sciences, University of Southern California, University Park Campus, Los Angeles, California 90089, United States
| | - Brian T Chamberlain
- Department of Chemistry, Dana and David Dornsife College of Letters, Arts and Sciences, University of Southern California, University Park Campus, Los Angeles, California 90089, United States
| | - Jorge Osuna
- Department of Chemistry, Dana and David Dornsife College of Letters, Arts and Sciences, University of Southern California, University Park Campus, Los Angeles, California 90089, United States
| | - Thomas G Upton
- Department of Chemistry, Dana and David Dornsife College of Letters, Arts and Sciences, University of Southern California, University Park Campus, Los Angeles, California 90089, United States
| | - Michelle Zhao
- Department of Chemistry, Dana and David Dornsife College of Letters, Arts and Sciences, University of Southern California, University Park Campus, Los Angeles, California 90089, United States
| | - Boris A Kashemirov
- Department of Chemistry, Dana and David Dornsife College of Letters, Arts and Sciences, University of Southern California, University Park Campus, Los Angeles, California 90089, United States
| | - Charles E McKenna
- Department of Chemistry, Dana and David Dornsife College of Letters, Arts and Sciences, University of Southern California, University Park Campus, Los Angeles, California 90089, United States
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9
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Khan MI, Mishra A, Jha PK, Abhishek K, Chaba R, Das P, Sinha KK. DNA polymerase β of Leishmania donovani is important for infectivity and it protects the parasite against oxidative damage. Int J Biol Macromol 2019; 124:291-303. [DOI: 10.1016/j.ijbiomac.2018.11.159] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 11/15/2018] [Accepted: 11/16/2018] [Indexed: 01/22/2023]
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10
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Tsai M. Catalytic mechanism of DNA polymerases-Two metal ions or three? Protein Sci 2019; 28:288-291. [PMID: 30368961 PMCID: PMC6319748 DOI: 10.1002/pro.3542] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 10/24/2018] [Accepted: 10/24/2018] [Indexed: 12/21/2022]
Affiliation(s)
- Ming‐Daw Tsai
- Institute of Biological Chemistry, Academia SinicaTaipei115Taiwan
- Institute of Biochemical Sciences, National Taiwan UniversityTaipei106Taiwan
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11
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Huang J, Alnajjar KS, Mahmoud MM, Eckenroth B, Doublié S, Sweasy JB. The nature of the DNA substrate influences pre-catalytic conformational changes of DNA polymerase β. J Biol Chem 2018; 293:15084-15094. [PMID: 30068550 DOI: 10.1074/jbc.ra118.004564] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 07/29/2018] [Indexed: 11/06/2022] Open
Abstract
DNA polymerase β (Pol β) is essential for maintaining genomic integrity. During short-patch base excision repair (BER), Pol β incorporates a nucleotide into a single-gapped DNA substrate. Pol β may also function in long-patch BER, where the DNA substrate consists of larger gap sizes or 5'-modified downstream DNA. We have recently shown that Pol β fills small gaps in DNA during microhomology-mediated end-joining as part of a process that increases genomic diversity. Our previous results with single-nucleotide gapped DNA show that Pol β undergoes two pre-catalytic conformational changes upon binding to the correct nucleotide substrate. Here we use FRET to investigate nucleotide incorporation of Pol β with various DNA substrates. The results show that increasing the gap size influences the fingers closing step by increasing its reverse rate. However, the 5'-phosphate group has a more significant effect. The absence of the 5'-phosphate decreases the DNA binding affinity of Pol β and results in a conformationally more open binary complex. Moreover, upon addition of the correct nucleotide in the absence of 5'-phosphate, a slow fingers closing step is observed. Interestingly, either increasing the gap size or removing the 5'-phosphate group results in loss of the noncovalent step. Together, these results suggest that the character of the DNA substrate impacts the nature and rates of pre-catalytic conformational changes of Pol β. Our results also indicate that conformational changes are important for the fidelity of DNA synthesis by Pol β.
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Affiliation(s)
- Ji Huang
- From the Departments of Therapeutic Radiology and
| | | | | | - Brian Eckenroth
- the Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont 05405
| | - Sylvie Doublié
- the Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont 05405
| | - Joann B Sweasy
- From the Departments of Therapeutic Radiology and .,Genetics, Yale University School of Medicine, New Haven, Connecticut 06520 and
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12
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Oertell K, Kashemirov BA, Negahbani A, Minard C, Haratipour P, Alnajjar KS, Sweasy JB, Batra VK, Beard WA, Wilson SH, McKenna CE, Goodman MF. Probing DNA Base-Dependent Leaving Group Kinetic Effects on the DNA Polymerase Transition State. Biochemistry 2018; 57:3925-3933. [PMID: 29889506 DOI: 10.1021/acs.biochem.8b00417] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We examine the DNA polymerase β (pol β) transition state (TS) from a leaving group pre-steady-state kinetics perspective by measuring the rate of incorporation of dNTPs and corresponding novel β,γ-CXY-dNTP analogues, including individual β,γ-CHF and -CHCl diastereomers with defined stereochemistry at the bridging carbon, during the formation of right (R) and wrong (W) base pairs. Brønsted plots of log kpol versus p Ka4 of the leaving group bisphosphonic acids are used to interrogate the effects of the base identity, the dNTP analogue leaving group basicity, and the precise configuration of the C-X atom in R and S stereoisomers on the rate-determining step ( kpol). The dNTP analogues provide a range of leaving group basicity and steric properties by virtue of monohalogen, dihalogen, or methyl substitution at the carbon atom bridging the β,γ-bisphosphonate that mimics the natural pyrophosphate leaving group in dNTPs. Brønsted plot relationships with negative slopes are revealed by the data, as was found for the dGTP and dTTP analogues, consistent with a bond-breaking component to the TS energy. However, greater multiplicity was shown in the linear free energy relationship, revealing an unexpected dependence on the nucleotide base for both A and C. Strong base-dependent perturbations that modulate TS relative to ground-state energies are likely to arise from electrostatic effects on catalysis in the pol active site. Deviations from a uniform linear Brønsted plot relationship are discussed in terms of insights gained from structural features of the prechemistry DNA polymerase active site.
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Affiliation(s)
| | | | | | | | | | - Khadijeh S Alnajjar
- Department of Therapeutic Radiology and Department of Genetics , Yale University School of Medicine , New Haven , Connecticut 06520 , United States
| | - Joann B Sweasy
- Department of Therapeutic Radiology and Department of Genetics , Yale University School of Medicine , New Haven , Connecticut 06520 , United States
| | - Vinod K Batra
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences , National Institutes of Health , Research Triangle , North Carolina 27709 , United States
| | - William A Beard
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences , National Institutes of Health , Research Triangle , North Carolina 27709 , United States
| | - Samuel H Wilson
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences , National Institutes of Health , Research Triangle , North Carolina 27709 , United States
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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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Mahmoud MM, Schechter A, Alnajjar KS, Huang J, Towle-Weicksel J, Eckenroth BE, Doublié S, Sweasy JB. Defective Nucleotide Release by DNA Polymerase β Mutator Variant E288K Is the Basis of Its Low Fidelity. Biochemistry 2017; 56:5550-5559. [PMID: 28945359 DOI: 10.1021/acs.biochem.7b00869] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
DNA polymerases synthesize new DNA during DNA replication and repair, and their ability to do so faithfully is essential to maintaining genomic integrity. DNA polymerase β (Pol β) functions in base excision repair to fill in single-nucleotide gaps, and variants of Pol β have been associated with cancer. Specifically, the E288K Pol β variant has been found in colon tumors and has been shown to display sequence-specific mutator activity. To probe the mechanism that may underlie E288K's loss of fidelity, a fluorescence resonance energy transfer system that utilizes a fluorophore on the fingers domain of Pol β and a quencher on the DNA substrate was employed. Our results show that E288K utilizes an overall mechanism similar to that of wild type (WT) Pol β when incorporating correct dNTP. However, when inserting the correct dNTP, E288K exhibits a faster rate of closing of the fingers domain combined with a slower rate of nucleotide release compared to those of WT Pol β. We also detect enzyme closure upon mixing with the incorrect dNTP for E288K but not WT Pol β. Taken together, our results suggest that E288K Pol β incorporates all dNTPs more readily than WT because of an inherent defect that results in rapid isomerization of dNTPs within its active site. Structural modeling implies that this inherent defect is due to interaction of E288K with DNA, resulting in a stable closed enzyme structure.
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Affiliation(s)
- Mariam M Mahmoud
- Department of Therapeutic Radiology, Yale University School of Medicine , New Haven, Connecticut 06520, United States
| | - Allison Schechter
- Department of Therapeutic Radiology, Yale University School of Medicine , New Haven, Connecticut 06520, United States
| | - Khadijeh S Alnajjar
- Department of Therapeutic Radiology, Yale University School of Medicine , New Haven, Connecticut 06520, United States
| | - Ji Huang
- Department of Therapeutic Radiology, Yale University School of Medicine , New Haven, Connecticut 06520, United States
| | - Jamie Towle-Weicksel
- Department of Therapeutic Radiology, Yale University School of Medicine , New Haven, Connecticut 06520, United States
| | - Brian E Eckenroth
- Department of Microbiology and Molecular Genetics, University of Vermont , Burlington, Vermont 05405, United States
| | - Sylvie Doublié
- Department of Microbiology and Molecular Genetics, University of Vermont , Burlington, Vermont 05405, United States
| | - Joann B Sweasy
- Department of Therapeutic Radiology, Yale University School of Medicine , New Haven, Connecticut 06520, United States.,Department of Genetics, Yale University School of Medicine , New Haven, Connecticut 06520, United States
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15
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Wu WJ, Yang W, Tsai MD. How DNA polymerases catalyse replication and repair with contrasting fidelity. Nat Rev Chem 2017. [DOI: 10.1038/s41570-017-0068] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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16
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Moscato B, Swain M, Loria JP. Induced Fit in the Selection of Correct versus Incorrect Nucleotides by DNA Polymerase β. Biochemistry 2015; 55:382-95. [PMID: 26678253 DOI: 10.1021/acs.biochem.5b01213] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
DNA polymerase β (Pol β) repairs single-nucleotide gapped DNA (sngDNA) by enzymatic incorporation of the Watson-Crick partner nucleotide at the gapped position opposite the templating nucleotide. The process by which the matching nucleotide is incorporated into a sngDNA sequence has been relatively well-characterized, but the process of discrimination from nucleotide misincorporation remains unclear. We report here NMR spectroscopic characterization of full-length, uniformly labeled Pol β in apo, sngDNA-bound binary, and ternary complexes containing matching and mismatching nucleotide. Our data indicate that, while binding of the correct nucleotide to the binary complex induces chemical shift changes consistent with the process of enzyme closure, the ternary Pol β complex containing a mismatching nucleotide exhibits no such changes and appears to remain in an open, unstable, binary-like conformation. Our findings support an induced-fit mechanism for polymerases in which a closed ternary complex can only be achieved in the presence of matching nucleotide.
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Affiliation(s)
- Beth Moscato
- Department of Chemistry, Yale University , 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Monalisa Swain
- Department of Chemistry, Yale University , 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - J Patrick Loria
- Department of Chemistry, Yale University , 225 Prospect Street, New Haven, Connecticut 06520, United States.,Department of Molecular Biophysics and Biochemistry, Yale University , 260 Whitney Avenue, New Haven, Connecticut 06520, United States
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17
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SURESH GORLE, PRIYAKUMAR UDEVA. Atomistic details of the molecular recognition of DNA-RNA hybrid duplex by ribonuclease H enzyme. J CHEM SCI 2015. [DOI: 10.1007/s12039-015-0942-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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18
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Reprint of "Oxidant and environmental toxicant-induced effects compromise DNA ligation during base excision DNA repair". DNA Repair (Amst) 2015; 36:86-90. [PMID: 26596511 DOI: 10.1016/j.dnarep.2015.11.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
DNA lesions arise from many endogenous and environmental agents, and such lesions can promote deleterious events leading to genomic instability and cell death. Base excision repair (BER) is the main DNA repair pathway responsible for repairing single strand breaks, base lesions and abasic sites in mammalian cells. During BER, DNA substrates and repair intermediates are channeled from one step to the next in a sequential fashion so that release of toxic repair intermediates is minimized. This includes handoff of the product of gap-filling DNA synthesis to the DNA ligation step. The conformational differences in DNA polymerase β (pol β) associated with incorrect or oxidized nucleotide (8-oxodGMP) insertion could impact channeling of the repair intermediate to the final step of BER, i.e., DNA ligation by DNA ligase I or the DNA Ligase III/XRCC1 complex. Thus, modified DNA ligase substrates produced by faulty pol β gap-filling could impair coordination between pol β and DNA ligase. Ligation failure is associated with 5'-AMP addition to the repair intermediate and accumulation of strand breaks that could be more toxic than the initial DNA lesions. Here, we provide an overview of the consequences of ligation failure in the last step of BER. We also discuss DNA-end processing mechanisms that could play roles in reversal of impaired BER.
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19
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Çağlayan M, Wilson SH. Oxidant and environmental toxicant-induced effects compromise DNA ligation during base excision DNA repair. DNA Repair (Amst) 2015; 35:85-9. [PMID: 26466358 DOI: 10.1016/j.dnarep.2015.09.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
DNA lesions arise from many endogenous and environmental agents, and such lesions can promote deleterious events leading to genomic instability and cell death. Base excision repair (BER) is the main DNA repair pathway responsible for repairing single strand breaks, base lesions and abasic sites in mammalian cells. During BER, DNA substrates and repair intermediates are channeled from one step to the next in a sequential fashion so that release of toxic repair intermediates is minimized. This includes handoff of the product of gap-filling DNA synthesis to the DNA ligation step. The conformational differences in DNA polymerase β (pol β) associated with incorrect or oxidized nucleotide (8-oxodGMP) insertion could impact channeling of the repair intermediate to the final step of BER, i.e., DNA ligation by DNA ligase I or the DNA Ligase III/XRCC1 complex. Thus, modified DNA ligase substrates produced by faulty pol β gap-filling could impair coordination between pol β and DNA ligase. Ligation failure is associated with 5'-AMP addition to the repair intermediate and accumulation of strand breaks that could be more toxic than the initial DNA lesions. Here, we provide an overview of the consequences of ligation failure in the last step of BER. We also discuss DNA-end processing mechanisms that could play roles in reversal of impaired BER.
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Affiliation(s)
- Melike Çağlayan
- Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Samuel H Wilson
- Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA.
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20
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Ligare MR, Rijs AM, Berden G, Kabeláč M, Nachtigallova D, Oomens J, de Vries MS. Resonant Infrared Multiple Photon Dissociation Spectroscopy of Anionic Nucleotide Monophosphate Clusters. J Phys Chem B 2015; 119:7894-901. [PMID: 26004928 DOI: 10.1021/acs.jpcb.5b02222] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report mid-infrared spectra and potential energy surfaces of four anionic, 2'-deoxynucleotide-5'-monophosphates (dNMPs) and the ionic DNA pairs [dGMP-dCMP-H](1-), [dAMP-dTMP-H](1-) with a total charge of the complex equal to -1. We recorded IR action spectra by resonant IR multiple-photon dissociation (IRMPD) using the FELIX free electron laser. The potential energy surface study employed an on-the-fly molecular dynamics quenching method (MD/Q), using a semiempirical AM1 method, followed by an optimization of the most stable structures using density functional theory. By employing infrared multiple-photon dissociation (IRMPD) spectroscopy in combination with high-level computational methods, we aim at a better understanding of the hydrogen bonding competition between the phosphate moieties and the nucleobases. We find that, unlike in multimer double stranded DNA structures, the hydrogen bonds in these isolated nucleotide pairs are predominantly formed between the phosphate groups. This intermolecular interaction appears to exceed the stabilization energy resulting from base pairing and directs the overall cluster structure and alignment.
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Affiliation(s)
- Marshall R Ligare
- †Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Anouk M Rijs
- ‡FELIX Facility, Institute for Molecules and Materials, Radboud University Nijmegen, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands
| | - Giel Berden
- ‡FELIX Facility, Institute for Molecules and Materials, Radboud University Nijmegen, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands
| | - Martin Kabeláč
- §Faculty of Science, University of South Bohemia, Branišovská 31, 370 05 České Budějovice, Czech Republic
| | - Dana Nachtigallova
- ∥Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 166 10 Prague 6, Czech Republic
| | - Jos Oomens
- ‡FELIX Facility, Institute for Molecules and Materials, Radboud University Nijmegen, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands.,∥Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 166 10 Prague 6, Czech Republic.,⊥van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098XH Amsterdam, The Netherlands
| | - Mattanjah S de Vries
- †Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
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21
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High-resolution crystal structure of Z-DNA in complex with Cr(3+) cations. J Biol Inorg Chem 2015; 20:595-602. [PMID: 25687556 PMCID: PMC4381091 DOI: 10.1007/s00775-015-1247-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 01/23/2015] [Indexed: 11/25/2022]
Abstract
This work is part of our project aimed at characterizing metal-binding properties of left-handed Z-DNA helices. The three Cr3+ cations found in the asymmetric unit of the d(CGCGCG)2–Cr3+ crystal structure do not form direct coordination bonds with atoms of the Z-DNA molecule. Instead, the hydrated Cr3+ ions are engaged in outer-sphere interactions with phosphate groups and O6 and N7 guanine atoms of the DNA. The Cr3+(1) and Cr3+(2) ions have disordered coordination spheres occupied by six water molecules each. These partial-occupancy chromium cations are 2.354(15) Å apart and are bridged by three water molecules from their hydration spheres. The Cr3+(3) cation has distorted square pyramidal geometry. In addition to the high degree of disorder of the DNA backbone, alternate conformations are also observed for the deoxyribose and base moieties of the G2 nucleotide. Our work illuminates the question of conformational flexibility of Z-DNA and its interaction mode with transition-metal cations.
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22
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Raising the shields: PCR in the presence of metallic surfaces protected by tailor-made coatings. Colloids Surf B Biointerfaces 2014; 122:576-582. [DOI: 10.1016/j.colsurfb.2014.07.035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 07/22/2014] [Accepted: 07/22/2014] [Indexed: 11/21/2022]
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Abstract
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DNA
polymerase (pol) β is a small eukaryotic DNA polymerase
composed of two domains. Each domain contributes an enzymatic activity
(DNA synthesis and deoxyribose phosphate lyase) during the repair
of simple base lesions. These domains are termed the polymerase and
lyase domains, respectively. Pol β has been an excellent model
enzyme for studying the nucleotidyl transferase reaction and substrate
discrimination at a molecular level. In this review, recent crystallographic
studies of pol β in various liganded and conformational states
during the insertion of right and wrong nucleotides as well as during
the bypass of damaged DNA (apurinic sites and 8-oxoguanine) are described.
Structures of these catalytic intermediates provide unexpected insights
into mechanisms by which DNA polymerases enhance genome stability.
These structures also provide an improved framework that permits computational
studies to facilitate the interpretation of detailed kinetic analyses
of this model enzyme.
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Affiliation(s)
- William A Beard
- Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health , 111 T. W. Alexander Drive, P.O. Box 12233, MD F3-01, Research Triangle Park, North Carolina 27709, United States
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24
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Tsai MD. How DNA polymerases catalyze DNA replication, repair, and mutation. Biochemistry 2014; 53:2749-51. [PMID: 24716436 DOI: 10.1021/bi500417m] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Ming-Daw Tsai
- Institute of Biological Chemistry, Academia Sinica , Nankang, Taipei 115, Taiwan , and Institute of Biochemical Sciences, National Taiwan University , Taipei 106, Taiwan
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25
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Maxwell BA, Suo Z. Recent insight into the kinetic mechanisms and conformational dynamics of Y-Family DNA polymerases. Biochemistry 2014; 53:2804-14. [PMID: 24716482 PMCID: PMC4018064 DOI: 10.1021/bi5000405] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
![]()
The
kinetic mechanisms by which DNA polymerases catalyze DNA replication
and repair have long been areas of active research. Recently discovered
Y-family DNA polymerases catalyze the bypass of damaged DNA bases
that would otherwise block replicative DNA polymerases and stall replication
forks. Unlike DNA polymerases from the five other families, the Y-family
DNA polymerases have flexible, solvent-accessible active sites that
are able to tolerate various types of damaged template bases and allow
for efficient lesion bypass. Their promiscuous active sites, however,
also lead to fidelities that are much lower than those observed for
other DNA polymerases and give rise to interesting mechanistic properties.
Additionally, the Y-family DNA polymerases have several other unique
structural features and undergo a set of conformational changes during
substrate binding and catalysis different from those observed for
replicative DNA polymerases. In recent years, pre-steady-state kinetic
methods have been extensively employed to reveal a wealth of information
about the catalytic properties of these fascinating noncanonical DNA
polymerases. Here, we review many of the recent findings on the kinetic
mechanisms of DNA polymerization with undamaged and damaged DNA substrates
by the Y-family DNA polymerases, and the conformational dynamics employed
by these error-prone enzymes during catalysis.
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Affiliation(s)
- Brian A Maxwell
- Ohio State Biophysics Program and ‡Department of Chemistry and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States
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26
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Abstract
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This review will summarize our structural
and kinetic studies of
RB69 DNA polymerase (RB69pol) as well as selected variants of the
wild-type enzyme that were undertaken to obtain a deeper understanding
of the exquisitely high fidelity of B family replicative DNA polymerases.
We discuss how the structures of the various RB69pol ternary complexes
can be used to rationalize the results obtained from pre-steady-state
kinetic assays. Our main findings can be summarized as follows. (i)
Interbase hydrogen bond interactions can increase catalytic efficiency
by 5000-fold; meanwhile, base selectivity is not solely determined
by the number of hydrogen bonds between the incoming dNTP and the
templating base. (ii) Minor-groove hydrogen bond interactions at positions n – 1 and n – 2 of the primer
strand and position n – 1 of the template
strand in RB69pol ternary complexes are essential for efficient primer
extension and base selectivity. (iii) Partial charge interactions
among the incoming dNTP, the penultimate base pair, and the hydration
shell surrounding the incoming dNTP modulate nucleotide insertion
efficiency and base selectivity. (iv) Steric clashes between mismatched
incoming dNTPs and templating bases with amino acid side chains in
the nascent base pair binding pocket (NBP) as well as weak interactions
and large gaps between the incoming dNTPs and the templating base
are some of the reasons that incorrect dNTPs are incorporated so inefficiently
by wild-type RB69pol. In addition, we developed a tC°–tCnitro Förster resonance energy transfer assay to monitor
partitioning of the primer terminus between the polymerase and exonuclease
subdomains.
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Affiliation(s)
- Shuangluo Xia
- Department of Molecular Biophysics and Biochemistry, Yale University , New Haven, Connecticut 06520-8024, United States
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27
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Wu WJ, Su MI, Wu JL, Kumar S, Lim LH, Wang CWE, Nelissen FHT, Chen MCC, Doreleijers JF, Wijmenga SS, Tsai MD. How a low-fidelity DNA polymerase chooses non-Watson-Crick from Watson-Crick incorporation. J Am Chem Soc 2014; 136:4927-37. [PMID: 24617852 DOI: 10.1021/ja4102375] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A dogma for DNA polymerase catalysis is that the enzyme binds DNA first, followed by MgdNTP. This mechanism contributes to the selection of correct dNTP by Watson-Crick base pairing, but it cannot explain how low-fidelity DNA polymerases overcome Watson-Crick base pairing to catalyze non-Watson-Crick dNTP incorporation. DNA polymerase X from the deadly African swine fever virus (Pol X) is a half-sized repair polymerase that catalyzes efficient dG:dGTP incorporation in addition to correct repair. Here we report the use of solution structures of Pol X in the free, binary (Pol X:MgdGTP), and ternary (Pol X:DNA:MgdGTP with dG:dGTP non-Watson-Crick pairing) forms, along with functional analyses, to show that Pol X uses multiple unprecedented strategies to achieve the mutagenic dG:dGTP incorporation. Unlike high fidelity polymerases, Pol X can prebind purine MgdNTP tightly and undergo a specific conformational change in the absence of DNA. The prebound MgdGTP assumes an unusual syn conformation stabilized by partial ring stacking with His115. Upon binding of a gapped DNA, also with a unique mechanism involving primarily helix αE, the prebound syn-dGTP forms a Hoogsteen base pair with the template anti-dG. Interestingly, while Pol X prebinds MgdCTP weakly, the correct dG:dCTP ternary complex is readily formed in the presence of DNA. H115A mutation disrupted MgdGTP binding and dG:dGTP ternary complex formation but not dG:dCTP ternary complex formation. The results demonstrate the first solution structural view of DNA polymerase catalysis, a unique DNA binding mode, and a novel mechanism for non-Watson-Crick incorporation by a low-fidelity DNA polymerase.
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Affiliation(s)
- Wen-Jin Wu
- Institute of Biological Chemistry, and ‡Genomics Research Center, Academia Sinica , 128 Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
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28
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Gridley CL, Rangarajan S, Firbank S, Dalal S, Sweasy JB, Jaeger J. Structural changes in the hydrophobic hinge region adversely affect the activity and fidelity of the I260Q mutator DNA polymerase β. Biochemistry 2013; 52:4422-32. [PMID: 23651085 DOI: 10.1021/bi301368f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The I260Q variant of DNA polymerase β is an efficient mutator polymerase with fairly indiscriminate misincorporation activities opposite all template bases. Previous modeling studies have suggested that I260Q harbors structural variations in its hinge region. Here, we present the crystal structures of wild type and I260Q rat polymerase β in the presence and absence of substrates. Both the I260Q apoenzyme structure and the closed ternary complex with double-stranded DNA and ddTTP show ordered water molecules in the hydrophobic hinge near Gln260, whereas this is not the case in the wild type polymerase. Compared to wild type polymerase β ternary complexes, there are subtle movements around residues 260, 272, 295, and 296 in the mutant. The rearrangements in this region, coupled with side chain movements in the immediate neighborhood of the dNTP-binding pocket, namely, residues 258 and 272, provide an explanation for the altered activity and fidelity profiles observed in the I260Q mutator polymerase.
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Affiliation(s)
- Chelsea L Gridley
- Division of Genetics, Wadsworth Center, New York State Department of Health, New Scotland Avenue, Albany, New York 12208, United States
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29
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Abstract
Phosphoryl transfer plays key roles in signaling, energy transduction, protein synthesis, and maintaining the integrity of the genetic material. On the surface, it would appear to be a simple nucleophile displacement reaction. However, this simplicity is deceptive, as, even in aqueous solution, the low-lying d-orbitals on the phosphorus atom allow for eight distinct mechanistic possibilities, before even introducing the complexities of the enzyme catalyzed reactions. To further complicate matters, while powerful, traditional experimental techniques such as the use of linear free-energy relationships (LFER) or measuring isotope effects cannot make unique distinctions between different potential mechanisms. A quarter of a century has passed since Westheimer wrote his seminal review, 'Why Nature Chose Phosphate' (Science 235 (1987), 1173), and a lot has changed in the field since then. The present review revisits this biologically crucial issue, exploring both relevant enzymatic systems as well as the corresponding chemistry in aqueous solution, and demonstrating that the only way key questions in this field are likely to be resolved is through careful theoretical studies (which of course should be able to reproduce all relevant experimental data). Finally, we demonstrate that the reason that nature really chose phosphate is due to interplay between two counteracting effects: on the one hand, phosphates are negatively charged and the resulting charge-charge repulsion with the attacking nucleophile contributes to the very high barrier for hydrolysis, making phosphate esters among the most inert compounds known. However, biology is not only about reducing the barrier to unfavorable chemical reactions. That is, the same charge-charge repulsion that makes phosphate ester hydrolysis so unfavorable also makes it possible to regulate, by exploiting the electrostatics. This means that phosphate ester hydrolysis can not only be turned on, but also be turned off, by fine tuning the electrostatic environment and the present review demonstrates numerous examples where this is the case. Without this capacity for regulation, it would be impossible to have for instance a signaling or metabolic cascade, where the action of each participant is determined by the fine-tuned activity of the previous piece in the production line. This makes phosphate esters the ideal compounds to facilitate life as we know it.
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30
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Structures of dNTP intermediate states during DNA polymerase active site assembly. Structure 2012; 20:1829-37. [PMID: 22959623 DOI: 10.1016/j.str.2012.08.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Revised: 08/08/2012] [Accepted: 08/10/2012] [Indexed: 11/23/2022]
Abstract
DNA polymerase and substrate conformational changes are essential for high-fidelity DNA synthesis. Structures of DNA polymerase (pol) β in complex with DNA show the enzyme in an "open" conformation. Subsequent to binding the nucleotide, the polymerase "closes" around the nascent base pair with two metals positioned for chemistry. However, structures of substrate/active site intermediates prior to closure are lacking. By destabilizing the closed complex, we determined unique ternary complex structures of pol β with correct and incorrect incoming nucleotides bound to the open conformation. These structures reveal that Watson-Crick hydrogen bonding is assessed upon initial complex formation. Importantly, nucleotide-bound states representing intermediate metal coordination states occur with active site assembly. The correct, but not incorrect, nucleotide maintains Watson-Crick hydrogen bonds during interconversion of these states. These structures indicate that the triphosphate of the incoming nucleotide undergoes rearrangement prior to closure, providing an opportunity to deter misinsertion and increase fidelity.
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31
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Wu Y, Zakharova VM, Kashemirov BA, Goodman MF, Batra VK, Wilson SH, McKenna CE. β,γ-CHF- and β,γ-CHCl-dGTP diastereomers: synthesis, discrete 31P NMR signatures, and absolute configurations of new stereochemical probes for DNA polymerases. J Am Chem Soc 2012; 134:8734-7. [PMID: 22397499 PMCID: PMC3595068 DOI: 10.1021/ja300218x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Deoxynucleoside 5'-triphosphate analogues in which the β,γ-bridging oxygen has been replaced with a CXY group are useful chemical probes to investigate DNA polymerase catalytic and base-selection mechanisms. A limitation of such probes has been that conventional synthetic methods generate a mixture of diastereomers when the bridging carbon substitution is nonequivalent (X ≠ Y). We report here a general solution to this long-standing problem with four examples of β,γ-CXY dNTP diastereomers: (S)- and (R)-β,γ-CHCl-dGTP (12a-1/12a-2) and (S)- and (R)-β,γ-CHF-dGTP (12b-1/12b-2). Central to their preparation was conversion of the prochiral parent bisphosphonic acids to the P,C-dimorpholinamide derivatives 7 of their (R)-mandelic acid monoesters, which provided access to the individual diastereomers 7a-1, 7a-2, 7b-1, and 7b-2 by preparative HPLC. Selective acidic hydrolysis of the P-N bond then afforded "portal" diastereomers, which were readily coupled to morpholine-activated dGMP. Removal of the chiral auxiliary by H(2) (Pd/C) gave the four individual diastereomeric nucleotides 12, which were characterized by (31)P, (1)H, and (19)F NMR spectroscopy and by mass spectrometry. After treatment with Chelex-100 to remove traces of paramagnetic ions, at pH ~10 the diastereomer pairs 12a,b exhibit discrete P(α) and P(β)(31)P resonances. The more upfield P(α) and more downfield P(β) resonances (and also the more upfield (19)F NMR resonance in 12b) are assigned to the R configuration at the P(β)-CHX-P(γ) carbons on the basis of the absolute configurations of the individual diastereomers as determined from the X-ray crystallographic structures of their ternary complexes with DNA and polymerase β.
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Affiliation(s)
- Yue Wu
- Department of Chemistry, University of Southern California, Los Angeles, California 90089
| | - Valeria M. Zakharova
- Department of Chemistry, University of Southern California, Los Angeles, California 90089
| | - Boris A. Kashemirov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089
| | - Myron F. Goodman
- Department of Chemistry, University of Southern California, Los Angeles, California 90089
- Department of Biological Sciences, University of Southern California, Los Angeles, California 90089
| | - Vinod K. Batra
- Laboratory of Structural Biology, NIEHS, National Institutes of Health DHHS, Research Triangle Park, North Carolina 27709
| | - Samuel H. Wilson
- Laboratory of Structural Biology, NIEHS, National Institutes of Health DHHS, Research Triangle Park, North Carolina 27709
| | - Charles E. McKenna
- Department of Chemistry, University of Southern California, Los Angeles, California 90089
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32
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Kirby TW, DeRose EF, Cavanaugh NA, Beard WA, Shock DD, Mueller GA, Wilson SH, London RE. Metal-induced DNA translocation leads to DNA polymerase conformational activation. Nucleic Acids Res 2011; 40:2974-83. [PMID: 22169953 PMCID: PMC3326329 DOI: 10.1093/nar/gkr1218] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Binding of the catalytic divalent ion to the ternary DNA polymerase β/gapped DNA/dNTP complex is thought to represent the final step in the assembly of the catalytic complex and is consequently a critical determinant of replicative fidelity. We have analyzed the effects of Mg2+ and Zn2+ on the conformational activation process based on NMR measurements of [methyl-13C]methionine DNA polymerase β. Unexpectedly, both divalent metals were able to produce a template base-dependent conformational activation of the polymerase/1-nt gapped DNA complex in the absence of a complementary incoming nucleotide, albeit with different temperature thresholds. This conformational activation is abolished by substituting Glu295 with lysine, thereby interrupting key hydrogen bonds necessary to stabilize the closed conformation. These and other results indicate that metal-binding can promote: translocation of the primer terminus base pair into the active site; expulsion of an unpaired pyrimidine, but not purine, base from the template-binding pocket; and motions of polymerase subdomains that close the active site. We also have performed pyrophosphorolysis studies that are consistent with predictions based on these results. These findings provide new insight into the relationships between conformational activation, enzyme activity and polymerase fidelity.
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Affiliation(s)
- Thomas W Kirby
- Laboratory of Structural Biology, NIEHS, Research Triangle Park, NC 27709, USA
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33
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Abstract
Fluorescent sensors that make use of DNA structures have become widely useful in monitoring enzymatic activities. Early studies focused primarily on enzymes that naturally use DNA or RNA as the substrate. However, recent advances in molecular design have enabled the development of nucleic acid sensors for a wider range of functions, including enzymes that do not normally bind DNA or RNA. Nucleic acid sensors present some potential advantages over classical small-molecule sensors, including water solubility and ease of synthesis. An overview of the multiple strategies under recent development is presented in this critical review, and expected future developments in microarrays, single molecule analysis, and in vivo sensing are discussed (160 references).
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Affiliation(s)
- Nan Dai
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
| | - Eric T. Kool
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
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34
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Human DNA polymerase η is pre-aligned for dNTP binding and catalysis. J Mol Biol 2011; 415:627-34. [PMID: 22154937 DOI: 10.1016/j.jmb.2011.11.038] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 11/17/2011] [Accepted: 11/18/2011] [Indexed: 11/23/2022]
Abstract
Pre-steady-state kinetic studies on Y-family DNA polymerase η (Polη) have suggested that the polymerase undergoes a rate-limiting conformational change step before the phosphoryl transfer of the incoming nucleotide to the primer terminus. However, the nature of this rate-limiting conformational change step has been unclear, due in part to the lack of structural information on the Polη binary complex. We present here for the first time a crystal structure of human Polη (hPolη) in binary complex with its DNA substrate. We show that the hPolη domains move only slightly on dNTP binding and that the polymerase by and large is pre-aligned for dNTP binding and catalysis. We also show that there is no major reorientation of the DNA from a nonproductive to a productive configuration and that the active site is devoid of metals in the absence of dNTP. Together, these observations lead us to suggest that the rate-limiting conformational change step in the Polη replication cycle likely corresponds to a rate-limiting entry of catalytic metals in the active site.
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Ishido T, Yamazaki N, Ishikawa M, Hirano K. Characterization of DNA polymerase β from Danio rerio by overexpression in E. coli using the in vivo/in vitro compatible pIVEX plasmid. Microb Cell Fact 2011; 10:84. [PMID: 22018137 PMCID: PMC3214136 DOI: 10.1186/1475-2859-10-84] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 10/21/2011] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Eukaryotic DNA polymerase β (pol β), the polymerase thought to be responsible for DNA repair synthesis, has been extensively characterized in rats and humans. However, pol β has not been purified or enzymatically characterized from the model fish species Danio rerio (zebrafish). We used the in vitro/in vivo dual expression system plasmid, pIVEX, to express Danio rerio pol β (Danio pol β) for biochemical characterization. RESULTS Danio pol β encoded by the in vitro/in vivo-compatible pIVEX plasmid was expressed in E. coli BL21(DE3), BL21(DE3)pLysS, and KRX, and in vitro as a C-terminal His-tagged protein. Danio pol β expressed in vitro was subject to proteolysis; therefore, bacterial overexpression was used to produce the protein for kinetic analyses. KRX cells were preferred because of their reduced propensity for leaky expression of pol β. The cDNA of Danio rerio pol β encodes a protein of 337 amino acids, which is 2-3 amino acids longer than other pol β proteins, and contains a P63D amino acid substitution, unlike mammalian pol βs. This substitution lies in a hairpin sequence within an 8-kDa domain, likely to be important in DNA binding. We performed extensive biochemical characterization of Danio pol β in comparison with rat pol β, which revealed its sensitivity to metal ion activators (Mn2+ and Mg2+), its optimum salt concentration (10 mM KCl and 50 mM NaCl), alkaline pH optimum (pH 9.0), and low temperature optimum (30°C). Substituting Mn2+ for Mg2+ resulted in 8.6-fold higher catalytic efficiency (kcat/Km). CONCLUSIONS Our characterization of pol β from a model fish organism contributes to the study of the function and evolution of DNA polymerases, which are emerging as important cellular targets for chemical intervention in the development of anticancer agents.
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Affiliation(s)
- Tomomi Ishido
- Health Research Institute, National Institute of Advanced Industrial Science and Technology, Takamatsu, Kagawa, Japan
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Balbo PB, Wang ECW, Tsai MD. Kinetic mechanism of active site assembly and chemical catalysis of DNA polymerase β. Biochemistry 2011; 50:9865-75. [PMID: 22010960 DOI: 10.1021/bi200954r] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It has been inferred from structural and computational studies that the mechanism of DNA polymerases involves subtle but important discrete steps that occur between binding and recognition of the correct dNTP and chemical catalysis. These steps potentially include local conformational changes involving active site residues, reorganization of Mg(2+)-coordinating ligands, and proton transfer. Here we address this broad issue by conducting extensive transient state kinetic analyses of DNA polymerase β (Pol β). We also performed kinetic simulations to evaluate alternative kinetic models. These studies provide some support for two-step subdomain closing and define constraints under which a kinetically significant prechemistry step can occur. To experimentally identify additional microscopic steps, we developed a stopped flow absorbance assay to measure proton formation that occurs during catalysis. These studies provide direct evidence that formation of the enzyme-bound 3'-O(-) nucleophile is rate determining for chemistry. We additionally show that at low pH the chemical step is rate limiting for catalysis, but at high pH, a postchemistry conformational step is rate limiting due to a pH-dependent increase in the rate of nucleotidyl transfer. Finally, we performed exhaustive analyses of [Mg(2+)] and pH effects. In contrast to published studies, the results suggest an irregular pH dependence of k(pol), which is consistent with general base catalysis involving cooperativity between two or more protonic residues. Overall, the results represent significant advancement in the kinetic mechanism of Pol β and also reconcile some computational and experimental findings.
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Affiliation(s)
- Paul B Balbo
- Institute of Biological Chemistry, Academia Sinica, Nangang, Taipei 115, Taiwan
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37
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Ram Prasad B, Warshel A. Prechemistry versus preorganization in DNA replication fidelity. Proteins 2011; 79:2900-19. [PMID: 21905114 DOI: 10.1002/prot.23128] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2011] [Revised: 06/30/2011] [Accepted: 07/05/2011] [Indexed: 01/30/2023]
Abstract
The molecular origin of nucleotide insertion catalysis and fidelity of DNA polymerases is explored by means of computational simulations. Special attention is paid to the examination of the validity of proposals that invoke prechemistry effects, checkpoints concepts, and dynamical effects. The simulations reproduce the observed fidelity in Pol β, starting with the relevant observed X-ray structures of the complex with the right (R) and wrong (W) nucleotides. The generation of free energy surfaces for the R and W systems also allowed us to analyze different proposals about the origin of the fidelity and to reach several important conclusions. It is found that the potential of mean force (PMF) obtained by proper sampling does not support QM/MM-based proposals of a large barrier before the prechemistry state. Furthermore, examination of dynamical proposals by the renormalization approach indicates that the motions from open to close configurations do not contribute to catalysis or fidelity. Finally we discuss and analyze the induced fit concept and show that, despite its importance, it does not explain fidelity. That is, the fidelity is apparently due to the change in the preorganization of the chemical site, as a result of the relaxation of the binding site upon binding of the incorrect nucleotide. Finally and importantly, since the issue is the barrier associated with the enzyme-substrate (ES)/DNA complex at the chemical transition state and not the path to this complex formation (unless this path involves rate determining steps), it is also not useful to invoke checkpoints while discussing fidelity.
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Affiliation(s)
- B Ram Prasad
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
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38
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Martínez L, Malliavin TE, Blondel A. Mechanism of reactant and product dissociation from the anthrax edema factor: a locally enhanced sampling and steered molecular dynamics study. Proteins 2011; 79:1649-61. [PMID: 21425348 DOI: 10.1002/prot.22991] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Revised: 12/14/2010] [Accepted: 12/30/2010] [Indexed: 11/07/2022]
Abstract
The anthrax edema factor is a toxin overproducing damaging levels of cyclic adenosine monophosphate (cAMP) and pyrophosphate (PPi) from ATP. Here, mechanisms of dissociation of ATP and products (cAMP, PPi) from the active site are studied using locally enhanced sampling (LES) and steered molecular dynamics simulations. Various substrate conformations and ionic binding modes found in crystallographic structures are considered. LES simulations show that PPi and cAMP dissociate through different solvent accessible channels, while ATP dissociation requires significant active site exposure to solvent. The ionic content of the active site directly affects the dissociation of ATP and products. Only one ion dissociates along with ATP in the two-Mg(2+) binding site, suggesting that the other ion binds EF prior to ATP association. Dissociation of reaction products cAMP and PPi is impaired by direct electrostatic interactions between products and Mg(2+) ions. This provides an explanation for the inhibitory effect of high Mg(2+) concentrations on EF enzymatic activity. Breaking of electrostatic interactions is dependent on a competitive binding of water molecules to the ions, and thus on the solvent accessibility of the active site. Consequently, product dissociation seems to be a two-step process. First, ligands are progressively solvated while preserving the most important electrostatic interactions, in a process that is dependent on the flexibility of the active site. Second, breakage of the electrostatic bonds follows, and ligands diffuse into solvent. In agreement with this mechanism, product protonation facilitates dissociation.
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Affiliation(s)
- Leandro Martínez
- Unité de Bioinformatique Structurale, URA CNRS 2185, Institut Pasteur, 25, rue du Dr Roux, F-75015 Paris, France.
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Bermek O, Grindley NDF, Joyce CM. Distinct roles of the active-site Mg2+ ligands, Asp882 and Asp705, of DNA polymerase I (Klenow fragment) during the prechemistry conformational transitions. J Biol Chem 2010; 286:3755-66. [PMID: 21084297 DOI: 10.1074/jbc.m110.167593] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA polymerases catalyze the incorporation of deoxynucleoside triphosphates into a growing DNA chain using a pair of Mg(2+) ions, coordinated at the active site by two invariant aspartates, whose removal by mutation typically reduces the polymerase activity to barely detectable levels. Using two stopped-flow fluorescence assays that we developed previously, we have investigated the role of the carboxylate ligands, Asp(705) and Asp(882), of DNA polymerase I (Klenow fragment) in the early prechemistry steps that prepare the active site for catalysis. We find that neither carboxylate is required for an early conformational transition, reported by a 2-aminopurine probe, that takes place in the open ternary complex after binding of the complementary dNTP. However, the subsequent fingers-closing step requires Asp(882); this step converts the open ternary complex into the closed conformation, creating the active-site geometry required for catalysis. Crystal structures indicate that the Asp(882) position changes very little during fingers-closing; this side chain may therefore serve as an anchor point to receive the dNTP-associated metal ion as the nucleotide is delivered into the active site. The Asp(705) carboxylate is not required until after the fingers-closing step, and we suggest that its role is to facilitate the entry of the second Mg(2+) into the active site. The two early prechemistry steps that we have studied take place normally at very low Mg(2+) concentrations, although higher concentrations are needed for covalent nucleotide addition, consistent with the second metal ion entering the ternary complex after fingers-closing.
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Affiliation(s)
- Oya Bermek
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
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40
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Wang M, Lee HR, Konigsberg W. Effect of A and B metal ion site occupancy on conformational changes in an RB69 DNA polymerase ternary complex. Biochemistry 2009; 48:2075-86. [PMID: 19228037 DOI: 10.1021/bi801627h] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Rapid chemical quench assays, as well as equilibrium and stopped-flow fluorescence experiments, were performed with an RB69 DNA polymerase (RB69 pol)-primer-template (P/T) complex containing 2-aminopurine (dAP) and a metal exchange-inert Rh(III) derivative of a deoxynucleoside triphosphate (Rh.dTTP). The objective was to determine the effect of catalytic metal ion (A site) occupancy on the affinity of an incoming Rh.dTTP for the RB69 pol-P/T binary complex and on the rate of the conformational change induced by Rh.dTTP binding. With Ca(2+) in the A site, the affinity of the incoming Rh.dTTP for the RB69 pol-P/T binary complex and the conformational change rate can be determined in the absence of chemistry. When Mg(2+) was added to a ternary complex containing Rh.dTTP opposite dAP, the templating base, nucleotidyl transfer occurred, but the rate of product formation was only one-tenth of that found with Mg.dTTP, as determined by rapid chemical quench assays. Rates of conformational change subsequent to formation of a ternary complex, in the absence of chemistry, were estimated from the rate of change in dAP fluorescence with an increase in the Rh.dTTP concentration. We have shown that there is an initial rapid quenching of dAP fluorescence followed by a second phase of dAP quenching, which has nearly the same rate as that of dTMP incorporation, as estimated from rapid chemical quench experiments. We have also demonstrated that the affinity of Rh.dTTP for occupancy of the B metal ion site is dependent on the presence of Ca(2+). However, a saturating Rh.dTTP concentration in the absence of Ca(2+) results in full quenching of dAP fluorescence, whereas a saturating Ca(2+) concentration in the absence of Rh.dTTP gives only partial quenching of dAP fluorescence. The implications of these results for the mechanism of Fingers closing, metal ion binding, and base selectivity are discussed.
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Affiliation(s)
- Mina Wang
- Molecular Biophysics and Biochemistry Department, Yale University, 333 Cedar Street, New Haven, Connecticut 06520, USA
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41
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Lee HR, Wang M, Konigsberg W. The reopening rate of the fingers domain is a determinant of base selectivity for RB69 DNA polymerase. Biochemistry 2009; 48:2087-98. [PMID: 19228036 DOI: 10.1021/bi8016284] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two divalent metal ions are required for nucleotide incorporation by DNA polymerases. Here we use the bacteriophage RB69 DNA polymerase (RB69 pol) and the metal ion exchange-inert nucleotide analogue rhodium(III) deoxythymidine triphosphate (Rh.dTTP) to investigate the requirements of metal binding to the "A" site and to the "B" site, independently. We show that while binding of a metal ion to the A site is required for the nucleotidyl transfer reaction to occur, this metal binding is insufficient to initiate the prechemistry enzyme isomerization that has been observed with this polymerase. Moreover, we show that binding of a deoxynucleoside triphosphate (dNTP), in the absence of a catalytic metal ion, is sufficient to induce this conformational change. In this report, we also present several lines of evidence (from pulse-chase, rapid chemical quench-flow, and stopped-flow fluorescence experiments) for the reverse rate of the enzyme isomerization, closed to open, of a DNA polymerase complex. The implications of these data for the fidelity of DNA polymerization by RB69 pol are discussed.
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Affiliation(s)
- Harold R Lee
- Molecular Biophysics and Biochemistry Department, Yale University, 333 Cedar Street, New Haven, Connecticut 06520, USA
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42
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Affiliation(s)
- Anthony J Berdis
- Department of Pharmacology, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, USA.
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43
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Joyce CM. Techniques used to study the DNA polymerase reaction pathway. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1804:1032-40. [PMID: 19665596 DOI: 10.1016/j.bbapap.2009.07.021] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2009] [Revised: 07/21/2009] [Accepted: 07/28/2009] [Indexed: 11/24/2022]
Abstract
A minimal reaction pathway for DNA polymerases was established over 20years ago using chemical-quench methods. Since that time there has been considerable interest in noncovalent steps in the reaction pathway, conformational changes involving the polymerase or its DNA substrate that may play a role in substrate specificity. Fluorescence-based assays have been devised in order to study these conformational transitions and the results obtained have added new detail to the reaction pathway.
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Affiliation(s)
- Catherine M Joyce
- Department of Molecular Biophysics and Biochemistry, Yale University, 266 Whitney Avenue, P.O. Box 208114, New Haven, CT 06520-8114, USA.
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44
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Yamtich J, Sweasy JB. DNA polymerase family X: function, structure, and cellular roles. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1804:1136-50. [PMID: 19631767 DOI: 10.1016/j.bbapap.2009.07.008] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2009] [Revised: 07/02/2009] [Accepted: 07/03/2009] [Indexed: 10/20/2022]
Abstract
The X family of DNA polymerases in eukaryotic cells consists of terminal transferase and DNA polymerases beta, lambda, and mu. These enzymes have similar structural portraits, yet different biochemical properties, especially in their interactions with DNA. None of these enzymes possesses a proofreading subdomain, and their intrinsic fidelity of DNA synthesis is much lower than that of a polymerase that functions in cellular DNA replication. In this review, we discuss the similarities and differences of three members of Family X: polymerases beta, lambda, and mu. We focus on biochemical mechanisms, structural variation, fidelity and lesion bypass mechanisms, and cellular roles. Remarkably, although these enzymes have similar three-dimensional structures, their biochemical properties and cellular functions differ in important ways that impact cellular function.
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Affiliation(s)
- Jennifer Yamtich
- Department of Therapeutic Radiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
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45
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Bakhtina M, Roettger MP, Tsai MD. Contribution of the reverse rate of the conformational step to polymerase beta fidelity. Biochemistry 2009; 48:3197-208. [PMID: 19231836 DOI: 10.1021/bi802119f] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A complete understanding of the kinetic mechanism of fidelity requires comparison of correct and incorrect dNTP incorporation pathways in both the forward and reverse directions. The studies presented here focus on the dNTP-induced conformational step, which has historically been proposed by many to be the major determinant of fidelity. As it was recently highlighted [Tsai, Y. C., and Johnson, K. A. (2006) Biochemistry 45, 9675-9687], chemistry can be the slowest step in the forward direction of the correct dNTP incorporation pathway, yet the corresponding microscopic rate constant would not contribute toward fidelity in the case when the reverse rate of the conformational step is slower than chemistry. Here we use a stopped-flow technique to directly measure the reverse rate of the conformational step in the DNA polymerase beta (Pol beta) kinetic pathway. Extensive pre-steady-state kinetic studies presented include the utilization of 2-aminopurine-labeled DNA substrates, 2-aminopurine nucleotide triphosphate, a nonhydrolyzable nucleotide analogue dAMPCPP, and a rapid sequential mixing reaction scheme. Additionally, the effect of mismatched dNTPs, various metal ions, and the presence of the 3'-terminal hydroxyl group of the primer on the rate of the reverse "opening" conformational step were analyzed. Our analyses indicate that reverse "opening" is drastically facilitated in the presence of mismatched ternary complexes, which is in agreement with the hypothesis that the ternary complex is destabilized by the presence of incorrect dNTP. By analysis of the relative magnitudes of chemistry and reverse "opening" in the presence of both matched and mismatched matched ternary complexes, this work further validates that, for Pol beta, fidelity is dictated by the differences in free energy required to reach the highest energy transition state of the chemical step.
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Affiliation(s)
- Marina Bakhtina
- Department of Chemistry and The Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, USA
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46
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Arehart E, Gleim S, White B, Hwa J, Moore JH. Multifactor dimensionality reduction analysis identifies specific nucleotide patterns promoting genetic polymorphisms. BioData Min 2009; 2:2. [PMID: 19331672 PMCID: PMC2669078 DOI: 10.1186/1756-0381-2-2] [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: 05/21/2008] [Accepted: 03/30/2009] [Indexed: 11/30/2022] Open
Abstract
Background The fidelity of DNA replication serves as the nidus for both genetic evolution and genomic instability fostering disease. Single nucleotide polymorphisms (SNPs) constitute greater than 80% of the genetic variation between individuals. A new theory regarding DNA replication fidelity has emerged in which selectivity is governed by base-pair geometry through interactions between the selected nucleotide, the complementary strand, and the polymerase active site. We hypothesize that specific nucleotide combinations in the flanking regions of SNP fragments are associated with mutation. Results We modeled the relationship between DNA sequence and observed polymorphisms using the novel multifactor dimensionality reduction (MDR) approach. MDR was originally developed to detect synergistic interactions between multiple SNPs that are predictive of disease susceptibility. We initially assembled data from the Broad Institute as a pilot test for the hypothesis that flanking region patterns associate with mutagenesis (n = 2194). We then confirmed and expanded our inquiry with human SNPs within coding regions and their flanking sequences collected from the National Center for Biotechnology Information (NCBI) database (n = 29967) and a control set of sequences (coding region) not associated with SNP sites randomly selected from the NCBI database (n = 29967). We discovered seven flanking region pattern associations in the Broad dataset which reached a minimum significance level of p ≤ 0.05. Significant models (p << 0.001) were detected for each SNP type examined in the larger NCBI dataset. Importantly, the flanking region models were elongated or truncated depending on the nucleotide change. Additionally, nucleotide distributions differed significantly at motif sites relative to the type of variation observed. The MDR approach effectively discerned specific sites within the flanking regions of observed SNPs and their respective identities, supporting the collective contribution of these sites to SNP genesis. Conclusion The present study represents the first use of this computational methodology for modeling nonlinear patterns in molecular genetics. MDR was able to identify distinct nucleotide patterning around sites of mutations dependent upon the observed nucleotide change. We discovered one flanking region set that included five nucleotides clustered around a specific type of SNP site. Based on the strongly associated patterns identified in this study, it may become possible to scan genomic databases for such clustering of nucleotides in order to predict likely sites of future SNPs, and even the type of polymorphism most likely to occur.
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Affiliation(s)
- Eric Arehart
- Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, NH, USA
| | - Scott Gleim
- Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, NH, USA
| | - Bill White
- Computational Genetics Laboratory, Department of Genetics, Norris-Cotton Cancer Center, Dartmouth Medical School, Lebanon, NH, USA
| | - John Hwa
- Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, NH, USA.,Dartmouth-Hitchcock Medical Center, Department of Medicine (Cardiology), Lebanon, NH, USA
| | - Jason H Moore
- Computational Genetics Laboratory, Department of Genetics, Norris-Cotton Cancer Center, Dartmouth Medical School, Lebanon, NH, USA.,Department of Biological Sciences, Dartmouth College, Hanover, NH, USA.,Department of Computer Science, University of New Hampshire, Durham, NH, USA.,Department of Computer Science, University of Vermont, Burlington, VT, USA
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Kamerlin SCL, Williams NH, Warshel A. Dineopentyl phosphate hydrolysis: evidence for stepwise water attack. J Org Chem 2008; 73:6960-9. [PMID: 18729515 DOI: 10.1021/jo801207q] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Phosphate ester hydrolysis is ubiquitous in biology, playing a central role in energy production, signaling, biosynthesis, and the regulation of protein function among other things. Although the mechanism of action of the enzymes regulating this reaction has been the focus of intensive research in the past few decades, the correct description of this apparently simple reaction remains controversial. A clear understanding of the mechanism that takes place in solution is crucial to be able to evaluate whether proposals for the enzyme-catalyzed mechanisms are reasonable. For the pH-independent hydrolysis of phosphate diesters, several kinetically equivalent mechanisms are plausible, including hydroxide attack on the neutral phosphate. However, it is very difficult to measure the rate of this reaction directly by experimental methods, so it has been evaluated by examining the rate of hydrolysis of neutral phosphate triesters, where a methyl group has replaced a proton. This may not be an accurate model of the neutral phosphate diester and does not provide information about a reaction pathway that is concerted with nucleophilic attack to generate a similar phosphorane. We have carefully mapped out free energy surfaces for both hydroxide and water attack on the dineopentyl phosphate anion and for water attack on the neutral diester. In doing so, we have accurately reproduced existing experimental data and demonstrate that water attack proceeds through an associative mechanism with proton transfer to the phosphate to generate a phosphorane intermediate. Our data show that the substrate-as-base mechanism is viable for phosphate ester hydrolysis, which may have important implications for the studies of phosphate ester hydrolysis by enzymes.
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Affiliation(s)
- Shina C L Kamerlin
- Department of Chemistry, SGM 418, University of Southern California, 3620 McClintock Avenue, Los Angeles, California 90089, USA.
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48
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Roettger MP, Bakhtina M, Tsai MD. Mismatched and matched dNTP incorporation by DNA polymerase beta proceed via analogous kinetic pathways. Biochemistry 2008; 47:9718-27. [PMID: 18717589 PMCID: PMC2646765 DOI: 10.1021/bi800689d] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
While matched nucleotide incorporation by DNA polymerase beta (Pol beta) has been well-studied, a true understanding of polymerase fidelity requires comparison of both matched and mismatched dNTP incorporation pathways. Here we examine the mechanism of misincorporation for wild-type (WT) Pol beta and an error-prone I260Q variant using stopped-flow fluorescence assays and steady-state fluorescence spectroscopy. In stopped-flow, a biphasic fluorescence trace is observed for both enzymes during mismatched dNTP incorporation. The fluorescence transitions are in the same direction as that observed for matched dNTP, albeit with lower amplitude. Assignments of the fast and slow fluorescence phases are designated to the same mechanistic steps previously determined for matched dNTP incorporation. For both WT and I260Q mismatched dNTP incorporation, the rate of the fast phase, reflecting subdomain closing, is comparable to that induced by correct dNTP. Pre-steady-state kinetic evaluation reveals that both enzymes display similar correct dNTP insertion profiles, and the lower fidelity intrinsic to the I260Q mutant results from enhanced efficiency of mismatched incorporation. Notably, in comparison to WT, I260Q demonstrates enhanced intensity of fluorescence emission upon mismatched ternary complex formation. Both kinetic and steady-state fluorescence data suggest that relaxed discrimination against incorrect dNTP by I260Q is a consequence of a loss in ability to destabilize the mismatched ternary complex. Overall, our results provide first direct evidence that mismatched and matched dNTP incorporations proceed via analogous kinetic pathways, and support our standing hypothesis that the fidelity of Pol beta originates from destabilization of the mismatched closed ternary complex and chemical transition state.
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Affiliation(s)
- Michelle P Roettger
- The Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, USA
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49
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Murphy DL, Kosa J, Jaeger J, Sweasy JB. The Asp285 variant of DNA polymerase beta extends mispaired primer termini via increased nucleotide binding. Biochemistry 2008; 47:8048-57. [PMID: 18616290 DOI: 10.1021/bi702104y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Endogenous DNA damage occurs at a rate of at least 20,000 lesions per cell per day. Base excision repair (BER) is a key pathway for maintaining genome stability. Several pol beta variants were identified as conferring resistance to 3'-azido-3'-deoxythymidine (AZT) in Escherichia coli (Kosa et al. (1999) J. Biol. Chem. 274, 3851-3858). Detailed biochemical studies on one of these AZT-resistant variants, His285 to Asp, have shown that the H285D variant of pol beta possesses pre-steady-state kinetics that are similar to the wild-type polymerase. In gap filling assays with 5-bp gapped DNA, H285D showed a slight mutator phenotype. In depth single turnover kinetic analysis revealed that H285D is much more efficient than wild-type pol beta at extending mispaired primer termini. This mispair extension property of H285D is attributed to a greatly increased binding to the next correct nucleotide in the presence of a mispair. This change in K d(dNTP),app is not accompanied by a change in k pol; values for k pol are the same for both H285D and wild-type. Close examination of available structural data, as well as molecular modeling, has shown that residue 285 is able to make several stabilizing contacts in the fingers domain of the polymerase, and the introduction of a negatively charged side chain could have important effects on the enzyme. It is postulated that the loss of the contact between His285, Lys289, and Ile323 is responsible for the ability of H285D to extend mispairs through disruption of contacts near the C-terminal end of pol beta and propagation into the nucleotide binding pocket.
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Affiliation(s)
- Drew L Murphy
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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50
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Joyce CM, Potapova O, Delucia AM, Huang X, Basu VP, Grindley NDF. Fingers-closing and other rapid conformational changes in DNA polymerase I (Klenow fragment) and their role in nucleotide selectivity. Biochemistry 2008; 47:6103-16. [PMID: 18473481 DOI: 10.1021/bi7021848] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We have developed a FRET-based assay for the fingers-closing conformational transition that occurs when a binary complex of DNA polymerase I (Klenow fragment) with a primer-template binds a complementary dNTP and have used this and other fluorescence assays to place the fingers-closing step within the reaction pathway. Because the rate of fingers-closing was substantially faster than the rate of nucleotide incorporation measured in chemical quench experiments, fingers-closing cannot be the rate-limiting prechemistry step defined by earlier kinetic studies. Experiments using Ca (2+) instead of Mg (2+) as the metal cofactor suggest instead that the prechemistry step may involve a change in metal ion occupancy at the polymerase active site. The use of ribonucleotide substrates shows there is a base discriminating step that precedes fingers-closing. This earlier step, detected by 2-AP fluorescence, is promoted by complementary nucleotides (ribo- as well as deoxyribo-) but is blocked by mismatches. The complementary rNTP blocks the subsequent fingers-closing step. Thus, discrimination against rNTPs occurs during the transition from open to closed conformations, whereas selection against mismatched bases is initiated earlier in the pathway, in the open complex. Mismatched dNTPs accelerate DNA release from the polymerase, suggesting the existence of an early intermediate in which DNA binding is destabilized relative to the binary complex; this could correspond to a conformation that allows an incoming dNTP to preview the template base. The early kinetic checkpoints identified by this study provide an efficient mechanism for the rejection of mismatched bases and ribose sugars and thus enhance polymerase throughput.
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Affiliation(s)
- Catherine M Joyce
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA.
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