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Kirsanova OV, Subach FV, Loiko AG, Eritja RI, Gromova ES. EcoRII Restriction Endonuclease Forms Specific Contacts to the Bases of Its Target Sequence Flipped from DNA in a Transition Complex with Photoactivatable Substrates. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2021. [DOI: 10.1134/s106816202102014x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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2
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Tamulaitiene G, Manakova E, Jovaisaite V, Tamulaitis G, Grazulis S, Bochtler M, Siksnys V. Unique mechanism of target recognition by PfoI restriction endonuclease of the CCGG-family. Nucleic Acids Res 2019; 47:997-1010. [PMID: 30445642 PMCID: PMC6344858 DOI: 10.1093/nar/gky1137] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2018] [Accepted: 10/26/2018] [Indexed: 01/23/2023] Open
Abstract
Restriction endonucleases (REs) of the CCGG-family recognize a set of 4–8 bp target sequences that share a common CCGG or CCNGG core and possess PD…D/ExK nuclease fold. REs that interact with 5 bp sequence 5′-CCNGG flip the central N nucleotides and ‘compress’ the bound DNA to stack the inner base pairs to mimic the CCGG sequence. PfoI belongs to the CCGG-family and cleaves the 7 bp sequence 5′-T|CCNGGA ("|" designates cleavage position). We present here crystal structures of PfoI in free and DNA-bound forms that show unique active site arrangement and mechanism of sequence recognition. Structures and mutagenesis indicate that PfoI features a permuted E…ExD…K active site that differs from the consensus motif characteristic to other family members. Although PfoI also flips the central N nucleotides of the target sequence it does not ‘compress’ the bound DNA. Instead, PfoI induces a drastic change in DNA backbone conformation that shortens the distance between scissile phosphates to match that in the unperturbed CCGG sequence. Our data demonstrate the diversity and versatility of structural mechanisms employed by restriction enzymes for recognition of related DNA sequences.
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Affiliation(s)
- Giedre Tamulaitiene
- Institute of Biotechnology, Vilnius University, Sauletekio al. 7, LT-10257 Vilnius, Lithuania
| | - Elena Manakova
- Institute of Biotechnology, Vilnius University, Sauletekio al. 7, LT-10257 Vilnius, Lithuania
| | - Virginija Jovaisaite
- Institute of Biotechnology, Vilnius University, Sauletekio al. 7, LT-10257 Vilnius, Lithuania
| | - Gintautas Tamulaitis
- Institute of Biotechnology, Vilnius University, Sauletekio al. 7, LT-10257 Vilnius, Lithuania
| | - Saulius Grazulis
- Institute of Biotechnology, Vilnius University, Sauletekio al. 7, LT-10257 Vilnius, Lithuania
| | - Matthias Bochtler
- Laboratory of Structural Biology, International Institute of Molecular and Cell Biology, Trojdena 4, 02-109 Warsaw, Poland.,Dept. of Bioinformatics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Virginijus Siksnys
- Institute of Biotechnology, Vilnius University, Sauletekio al. 7, LT-10257 Vilnius, Lithuania
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3
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Chakraborty S, Steinbach PJ, Paul D, Mu H, Broyde S, Min JH, Ansari A. Enhanced spontaneous DNA twisting/bending fluctuations unveiled by fluorescence lifetime distributions promote mismatch recognition by the Rad4 nucleotide excision repair complex. Nucleic Acids Res 2019; 46:1240-1255. [PMID: 29267981 PMCID: PMC5815138 DOI: 10.1093/nar/gkx1216] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 12/12/2017] [Indexed: 12/15/2022] Open
Abstract
Rad4/XPC recognizes diverse DNA lesions including ultraviolet-photolesions and carcinogen-DNA adducts, initiating nucleotide excision repair. Studies have suggested that Rad4/XPC senses lesion-induced helix-destabilization to flip out nucleotides from damaged DNA sites. However, characterizing how DNA deformability and/or distortions impact recognition has been challenging. Here, using fluorescence lifetime measurements empowered by a maximum entropy algorithm, we mapped the conformational heterogeneities of artificially destabilized mismatched DNA substrates of varying Rad4-binding specificities. The conformational distributions, as probed by FRET between a cytosine-analog pair exquisitely sensitive to DNA twisting/bending, reveal a direct connection between intrinsic DNA deformability and Rad4 recognition. High-specificity CCC/CCC mismatch, free in solution, sampled a strikingly broad range of conformations from B-DNA-like to highly distorted conformations that resembled those observed with Rad4 bound; the extent of these distortions increased with bound Rad4 and with temperature. Conversely, the non-specific TAT/TAT mismatch had a homogeneous, B-DNA-like conformation. Molecular dynamics simulations also revealed a wide distribution of conformations for CCC/CCC, complementing experimental findings. We propose that intrinsic deformability promotes Rad4 damage recognition, perhaps by stalling a diffusing protein and/or facilitating ‘conformational capture’ of pre-distorted damaged sites. Surprisingly, even mismatched DNA specifically bound to Rad4 remains highly dynamic, a feature that may reflect the versatility of Rad4/XPC to recognize many structurally dissimilar lesions.
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Affiliation(s)
- Sagnik Chakraborty
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Peter J Steinbach
- Center for Molecular Modeling, Center for Information Technology, National Institutes of Health, Bethesda, MD 20892, USA
| | - Debamita Paul
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Hong Mu
- Department of Biology, New York University, New York, NY 10003, USA
| | - Suse Broyde
- Department of Biology, New York University, New York, NY 10003, USA
| | - Jung-Hyun Min
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Anjum Ansari
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA.,Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
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4
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Brovarets’ OO, Hovorun DM. Key microstructural mechanisms of the 2-aminopurine mutagenicity: Results of extensive quantum-chemical research. J Biomol Struct Dyn 2019; 37:2716-2732. [DOI: 10.1080/07391102.2018.1495577] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Ol’ha O. Brovarets’
- Department of Molecular and Quantum Biophysics, Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kyiv, Ukraine
- Department of Molecular Biotechnology and Bioinformatics, Institute of High Technologies, Taras Shevchenko National University of Kyiv, 2-h Akademika Hlushkova Ave, Kyiv, Ukraine
| | - Dmytro M. Hovorun
- Department of Molecular and Quantum Biophysics, Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kyiv, Ukraine
- Department of Molecular Biotechnology and Bioinformatics, Institute of High Technologies, Taras Shevchenko National University of Kyiv, 2-h Akademika Hlushkova Ave, Kyiv, Ukraine
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5
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Brovarets' OO, Voiteshenko IS, Pérez-Sánchez H, Hovorun DM. A QM/QTAIM detailed look at the Watson-Crick↔wobble tautomeric transformations of the 2-aminopurine·pyrimidine mispairs. J Biomol Struct Dyn 2017; 36:1649-1665. [PMID: 28514900 DOI: 10.1080/07391102.2017.1331864] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
This work is devoted to the careful QM/QTAIM analysis of the evolution of the basic physico-chemical parameters along the intrinsic reaction coordinate (IRC) of the biologically important 2AP·T(WC)↔2AP·T*(w) and 2AP·C*(WC)↔2AP·C(w) Watson-Crick(WC)↔wobble(w) tautomeric transformations obtained at each point of the IRC using original authors' methodology. Established profiles reflect the high similarity between the courses of these processes. Basing on the scrupulous analysis of the profiles of their geometric and electron-topological parameters, it was established that the dipole-active WC↔w tautomerizations of the Watson-Crick-like 2AP·T(WC)/2AP·C*(WC) mispairs, stabilized by the two classical N3H⋯N1, N2H⋯O2 and one weak C6H⋯O4/N4 H-bonds, into the wobble 2AP·T*(w)/2AP·C(w) base pairs, respectively, joined by the two classical N2H⋯N3 and O4/N4H⋯N1 H-bonds, proceed via the concerted stepwise mechanism through the sequential intrapair proton transfer and subsequent large-scale shifting of the bases relative each other, through the planar, highly stable, zwitterionic transition states stabilized by the participation of the four H-bonds - N1+H⋯O4-/N4-, N1+H⋯N3-, N2+H⋯N3-, and N2+H⋯O2-. Moreover, it was found out that the 2AP·T(WC)↔2AP·T*(w)/2AP·C*(WC)↔2AP·C(w) tautomerization reactions occur non-dissociatively and are accompanied by the consequent replacement of the 10 unique patterns of the specific intermolecular interactions along the IRC. Obtained data are of paramount importance in view of their possible application for the control and management of the proton transfer, e.g. by external electric or laser fields.
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Affiliation(s)
- Ol'ha O Brovarets'
- a Department of Molecular and Quantum Biophysics , Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine , 150 Akademika Zabolotnoho Str., Kyiv 03680 , Ukraine.,b Department of Molecular Biotechnology and Bioinformatics , Institute of High Technologies, Taras Shevchenko National University of Kyiv , 2-h Akademika Hlushkova Ave., Kyiv 03022 , Ukraine
| | - Ivan S Voiteshenko
- b Department of Molecular Biotechnology and Bioinformatics , Institute of High Technologies, Taras Shevchenko National University of Kyiv , 2-h Akademika Hlushkova Ave., Kyiv 03022 , Ukraine
| | - Horacio Pérez-Sánchez
- c Computer Science Department , Bioinformatics and High Performance Computing (BIO-HPC) Research Group, Universidad Católica San Antonio de Murcia (UCAM) , Guadalupe, Murcia 30107 , Spain
| | - Dmytro M Hovorun
- a Department of Molecular and Quantum Biophysics , Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine , 150 Akademika Zabolotnoho Str., Kyiv 03680 , Ukraine.,b Department of Molecular Biotechnology and Bioinformatics , Institute of High Technologies, Taras Shevchenko National University of Kyiv , 2-h Akademika Hlushkova Ave., Kyiv 03022 , Ukraine
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6
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Brovarets' OO, Pérez-Sánchez H. Whether 2-aminopurine induces incorporation errors at the DNA replication? A quantum-mechanical answer on the actual biological issue. J Biomol Struct Dyn 2016; 35:3398-3411. [PMID: 27794627 DOI: 10.1080/07391102.2016.1253504] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In this paper, we consider the mutagenic properties of the 2-aminopurine (2AP), which has intrigued molecular biologists, biophysicists and physical chemists for a long time and been widely studied by both experimentalists and theorists. We have shown for the first time using QM calculations, that 2AP very effectively produces incorporation errors binding with cytosine (C) into the wobble (w) C·2AP(w) mispair, which is supported by the N4H⋯N1 and N2H⋯N3 H-bonds and is tautomerized into the Watson-Crick (WC)-like base mispair C*·2AP(WC) (asterisk denotes the mutagenic tautomer of the base), that quite easily in the process of the thermal fluctuations acquires enzymatically competent conformation. 2AP less effectively produces transversions forming the wobble mispair with A base - A·2AP(w), stabilized by the participation of the N6H⋯N1 and N2H⋯N1 H-bonds, followed by further tautomerization A·2AP(w) → A*·2AP(WC) and subsequent conformational transition A*·2AP(WC) → A*·2APsyn thus acquiring enzymatically competent structure. In this case, incorporation errors occur only in those case, when 2AP belongs to the incoming nucleotide. Thus, answering the question posed in the title of the article, we affirm for certain that 2AP induces incorporation errors at the DNA replication. Obtained results are consistent well with numerous experimental data.
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Affiliation(s)
- Ol'ha O Brovarets'
- a Department of Molecular and Quantum Biophysics , Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine , 150 Akademika Zabolotnoho Str., Kyiv 03680 , Ukraine.,b Department of Molecular Biotechnology and Bioinformatics , Institute of High Technologies, Taras Shevchenko National University of Kyiv , 2-h Akademika Hlushkova Ave., Kyiv 03022 , Ukraine
| | - Horacio Pérez-Sánchez
- c Computer Science Department, Bioinformatics and High Performance Computing (BIO-HPC) Research Group , Universidad Católica San Antonio de Murcia (UCAM) , Murcia 30107 , Spain
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7
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Morris ER, Grey H, McKenzie G, Jones AC, Richardson JM. A bend, flip and trap mechanism for transposon integration. eLife 2016; 5. [PMID: 27223327 PMCID: PMC5481204 DOI: 10.7554/elife.15537] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 05/24/2016] [Indexed: 12/31/2022] Open
Abstract
Cut-and-paste DNA transposons of the mariner/Tc1 family are useful tools for genome engineering and are inserted specifically at TA target sites. A crystal structure of the mariner transposase Mos1 (derived from Drosophila mauritiana), in complex with transposon ends covalently joined to target DNA, portrays the transposition machinery after DNA integration. It reveals severe distortion of target DNA and flipping of the target adenines into extra-helical positions. Fluorescence experiments confirm dynamic base flipping in solution. Transposase residues W159, R186, F187 and K190 stabilise the target DNA distortions and are required for efficient transposon integration and transposition in vitro. Transposase recognises the flipped target adenines via base-specific interactions with backbone atoms, offering a molecular basis for TA target sequence selection. Our results will provide a template for re-designing mariner/Tc1 transposases with modified target specificities. DOI:http://dx.doi.org/10.7554/eLife.15537.001 The complete set of DNA in a cell is referred to as its genome. Most genomes contain short fragments of DNA called transposons that can jump from one place to another. Transposons carry sections of DNA with them when they move, which creates diversity and can influence the evolution of a species. Transposons are also being exploited to develop tools for biotechnology and medical applications. One family of transposons – the Mariner/Tc1 family – has proved particularly useful in these endeavours because it is widespread in nature and can jump around the genomes of a broad range of species, including mammals. DNA transposons are cut out of their position and then pasted at a new site by an enzyme called transposase, which is encoded by some of the DNA within the transposon. DNA is made up of strings of molecules called bases and Mariner/Tc1-family transposons can only insert into a new position in the genome at sites that have a specific sequence of two bases. However, it was not known how this target sequence is chosen and how the transposon inserts into it. Morris et al. have now used a technique called X-ray crystallography to build a three-dimensional model of a Mariner/Tc1-family transposon as it inserts into a new position. The model shows that, as the transposon is pasted into its new site, the surrounding DNA bends. This causes two DNA bases in the surrounding DNA to flip out from their normal position in the DNA molecule, which enables them to be recognised by the transposase. Further experiments showed that this base-flipping is dynamic, that is, the two bases continuously flip in and out of position. Furthermore, Morris et al. identified which parts of the transposase enzyme are required for the transposon to be efficiently pasted into the genome. Together these findings may help researchers to alter the transposase so that it can insert the transposon into different locations in a genome. This will hopefully lead to new tools for biotechnology and medical applications. DOI:http://dx.doi.org/10.7554/eLife.15537.002
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Affiliation(s)
- Elizabeth R Morris
- Institute of Quantitative Biology, Biochemistry and Biotechnology, University of Edinburgh, Edinburgh, United Kingdom
| | - Heather Grey
- Institute of Quantitative Biology, Biochemistry and Biotechnology, University of Edinburgh, Edinburgh, United Kingdom
| | | | - Anita C Jones
- EaStCHEM School of Chemistry, Edinburgh, United Kingdom
| | - Julia M Richardson
- Institute of Quantitative Biology, Biochemistry and Biotechnology, University of Edinburgh, Edinburgh, United Kingdom
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8
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Greiner VJ, Kovalenko L, Humbert N, Richert L, Birck C, Ruff M, Zaporozhets OA, Dhe-Paganon S, Bronner C, Mély Y. Site-Selective Monitoring of the Interaction of the SRA Domain of UHRF1 with Target DNA Sequences Labeled with 2-Aminopurine. Biochemistry 2015; 54:6012-20. [PMID: 26368281 DOI: 10.1021/acs.biochem.5b00419] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
UHRF1 plays a central role in the maintenance and transmission of epigenetic modifications by recruiting DNMT1 to hemimethylated CpG sites via its SET and RING-associated (SRA) domain, ensuring error-free duplication of methylation profiles. To characterize SRA-induced changes in the conformation and dynamics of a target 12 bp DNA duplex as a function of the methylation status, we labeled duplexes by the environment-sensitive probe 2-aminopurine (2-Ap) at various positions near or far from the central CpG recognition site containing either a nonmodified cytosine (NM duplex), a methylated cytosine (HM duplex), or methylated cytosines on both strands (BM duplex). Steady-state and time-resolved fluorescence indicated that binding of SRA induced modest conformational and dynamical changes in NM, HM, and BM duplexes, with only slight destabilization of base pairs, restriction of global duplex flexibility, and diminution of local nucleobase mobility. Moreover, significant restriction of the local motion of residues flanking the methylcytosine in the HM duplex suggested that these residues are more rigidly bound to SRA, in line with a slightly higher affinity of the HM duplex as compared to that of the NM or BM duplex. Our results are consistent with a "reader" role, in which the SRA domain scans DNA sequences for hemimethylated CpG sites without perturbation of the structure of contacted nucleotides.
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Affiliation(s)
- Vanille J Greiner
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de pharmacie , 74 route du Rhin, 67401 Illkirch, France
| | - Lesia Kovalenko
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de pharmacie , 74 route du Rhin, 67401 Illkirch, France.,Analytical Chemistry Department, Taras Shevchenko National University of Kyiv , 64 Volodymyrska Street, 01033 Kyiv, Ukraine
| | - Nicolas Humbert
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de pharmacie , 74 route du Rhin, 67401 Illkirch, France
| | - Ludovic Richert
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de pharmacie , 74 route du Rhin, 67401 Illkirch, France
| | - Catherine Birck
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964 CNRS UMR 7104, Université de Strasbourg , 1 rue Laurent Fries, Illkirch, France
| | - Marc Ruff
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964 CNRS UMR 7104, Université de Strasbourg , 1 rue Laurent Fries, Illkirch, France
| | - Olga A Zaporozhets
- Analytical Chemistry Department, Taras Shevchenko National University of Kyiv , 64 Volodymyrska Street, 01033 Kyiv, Ukraine
| | - Sirano Dhe-Paganon
- Department of Cancer Biology, Dana-Farber Cancer Institute, Harvard Medical School , 360 Brookline Avenue, Boston, Massachusetts 02215, United States
| | - Christian Bronner
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de pharmacie , 74 route du Rhin, 67401 Illkirch, France.,Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964 CNRS UMR 7104, Université de Strasbourg , 1 rue Laurent Fries, Illkirch, France
| | - Yves Mély
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de pharmacie , 74 route du Rhin, 67401 Illkirch, France
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9
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2-aminopurine as a fluorescent probe of DNA conformation and the DNA–enzyme interface. Q Rev Biophys 2015; 48:244-79. [DOI: 10.1017/s0033583514000158] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractNearly 50 years since its potential as a fluorescent base analogue was first recognized, 2-aminopurine (2AP) continues to be the most widely used fluorescent probe of DNA structure and the perturbation of that structure by interaction with enzymes and other molecules. In this review, we begin by considering the origin of the dramatic and intriguing difference in photophysical properties between 2AP and its structural isomer, adenine; although 2AP differs from the natural base only in the position of the exocyclic amine group, its fluorescence intensity is one thousand times greater. We then discuss the mechanism of interbase quenching of 2AP fluorescence in DNA, which is the basis of its use as a conformational probe but remains imperfectly understood. There are hundreds of examples in the literature of the use of changes in the fluorescence intensity of 2AP as the basis of assays of conformational change; however, in this review we will consider in detail only a few intensity-based studies. Our primary aim is to highlight the use of time-resolved fluorescence measurements, and the interpretation of fluorescence decay parameters, to explore the structure and dynamics of DNA. We discuss the salient features of the fluorescence decay of 2AP when incorporated in DNA and review the use of decay measurements in studying duplexes, single strands and other structures. We survey the use of 2AP as a probe of DNA-enzyme interaction and enzyme-induced distortion, focusing particularly on its use to study base flipping and the enhanced mechanistic insights that can be gained by a detailed analysis of the decay parameters, rather than merely monitoring changes in fluorescence intensity. Finally we reflect on the merits and shortcomings of 2AP and the prospects for its wider adoption as a fluorescence-decay-based probe.
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10
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Time-resolved fluorescence of 2-aminopurine in DNA duplexes in the presence of the EcoP15I Type III restriction–modification enzyme. Biochem Biophys Res Commun 2014; 449:120-5. [DOI: 10.1016/j.bbrc.2014.04.162] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 04/30/2014] [Indexed: 11/23/2022]
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11
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Ma L, Wu X. WITHDRAWN: Type III restriction-modification enzyme EcoP15I's base flipping mechanism and its mismatch cleavage on two head-to-head oriented recognition sites. Biochem Biophys Res Commun 2014:S0006-291X(14)00373-8. [PMID: 24589737 DOI: 10.1016/j.bbrc.2014.02.102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 02/21/2014] [Indexed: 10/25/2022]
Abstract
This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.
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Affiliation(s)
- Long Ma
- Biomolecular Sciences Research Complex, EaStCHEM School of Chemistry, University of St Andrews, Fife KY16 9ST, UK.
| | - Xiaohua Wu
- EaStChem School of Chemistry, University of Edinburgh, The King's Buildings, Edinburgh, EH9 3JJ, UK
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12
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Finger LD, Patel N, Beddows A, Ma L, Exell JC, Jardine E, Jones AC, Grasby JA. Observation of unpaired substrate DNA in the flap endonuclease-1 active site. Nucleic Acids Res 2013; 41:9839-47. [PMID: 23975198 PMCID: PMC3834815 DOI: 10.1093/nar/gkt737] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The structure- and strand-specific phosphodiesterase flap endonuclease-1 (FEN1), the prototypical 5′-nuclease, catalyzes the essential removal of 5′-single-stranded flaps during replication and repair. FEN1 achieves this by selectively catalyzing hydrolysis one nucleotide into the duplex region of substrates, always targeting the 5′-strand. This specificity is proposed to arise by unpairing the 5′-end of duplex to permit the scissile phosphate diester to contact catalytic divalent metal ions. Providing the first direct evidence for this, we detected changes induced by human FEN1 (hFEN1) in the low-energy CD spectra and fluorescence lifetimes of 2-aminopurine in substrates and products that were indicative of unpairing. Divalent metal ions were essential for unpairing. However, although 5′-nuclease superfamily-conserved active-site residues K93 and R100 were required to produce unpaired product, they were not necessary to unpair substrates. Nevertheless, a unique arrangement of protein residues around the unpaired DNA was detected only with wild-type protein, suggesting a cooperative assembly of active-site residues that may be triggered by unpaired DNA. The general principles of FEN1 strand and reaction-site selection, which depend on the ability of juxtaposed divalent metal ions to unpair the end of duplex DNA, may also apply more widely to other structure- and strand-specific nucleases.
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Affiliation(s)
- L David Finger
- Department of Chemistry, Centre for Chemical Biology, Krebs Institute, University of Sheffield, Sheffield, S3 7HF, UK and EaStCHEM School of Chemistry and Collaborative Optical Spectroscopy, Micromanipulation and Imaging Centre, The University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, UK
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13
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Ma L, Chen K, Clarke DJ, Nortcliffe CP, Wilson GG, Edwardson JM, Morton AJ, Jones AC, Dryden DTF. Restriction endonuclease TseI cleaves A:A and T:T mismatches in CAG and CTG repeats. Nucleic Acids Res 2013; 41:4999-5009. [PMID: 23525471 PMCID: PMC3643589 DOI: 10.1093/nar/gkt176] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The type II restriction endonuclease TseI recognizes the DNA target sequence 5′-G^CWGC-3′ (where W = A or T) and cleaves after the first G to produce fragments with three-base 5′-overhangs. We have determined that it is a dimeric protein capable of cleaving not only its target sequence but also one containing A:A or T:T mismatches at the central base pair in the target sequence. The cleavage of targets containing these mismatches is as efficient as cleavage of the correct target sequence containing a central A:T base pair. The cleavage mechanism does not apparently use a base flipping mechanism as found for some other type II restriction endonuclease recognizing similarly degenerate target sequences. The ability of TseI to cleave targets with mismatches means that it can cleave the unusual DNA hairpin structures containing A:A or T:T mismatches formed by the repetitive DNA sequences associated with Huntington’s disease (CAG repeats) and myotonic dystrophy type 1 (CTG repeats).
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Affiliation(s)
- Long Ma
- EaStChem School of Chemistry, University of Edinburgh, The King's Buildings, Edinburgh EH9 3JJ, UK
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14
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Godet J, Kenfack C, Przybilla F, Richert L, Duportail G, Mély Y. Site-selective probing of cTAR destabilization highlights the necessary plasticity of the HIV-1 nucleocapsid protein to chaperone the first strand transfer. Nucleic Acids Res 2013; 41:5036-48. [PMID: 23511968 PMCID: PMC3643577 DOI: 10.1093/nar/gkt164] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The HIV-1 nucleocapsid protein (NCp7) is a nucleic acid chaperone required during reverse transcription. During the first strand transfer, NCp7 is thought to destabilize cTAR, the (−)DNA copy of the TAR RNA hairpin, and subsequently direct the TAR/cTAR annealing through the zipping of their destabilized stem ends. To further characterize the destabilizing activity of NCp7, we locally probe the structure and dynamics of cTAR by steady-state and time resolved fluorescence spectroscopy. NC(11–55), a truncated NCp7 version corresponding to its zinc-finger domain, was found to bind all over the sequence and to preferentially destabilize the penultimate double-stranded segment in the lower part of the cTAR stem. This destabilization is achieved through zinc-finger–dependent binding of NC to the G10 and G50 residues. Sequence comparison further revealed that C•A mismatches close to the two G residues were critical for fine tuning the stability of the lower part of the cTAR stem and conferring to G10 and G50 the appropriate mobility and accessibility for specific recognition by NC. Our data also highlight the necessary plasticity of NCp7 to adapt to the sequence and structure variability of cTAR to chaperone its annealing with TAR through a specific pathway.
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Affiliation(s)
- Julien Godet
- Laboratoire de Biophotonique et Pharmacologie, Faculté de Pharmacie, UMR 7213 CNRS, Université de Strasbourg, 67401 Illkirch, France
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Tessmer I, Melikishvili M, Fried MG. Cooperative cluster formation, DNA bending and base-flipping by O6-alkylguanine-DNA alkyltransferase. Nucleic Acids Res 2012; 40:8296-308. [PMID: 22730295 PMCID: PMC3458534 DOI: 10.1093/nar/gks574] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
O6-Alkylguanine-DNA alkyltransferase (AGT) repairs mutagenic O6-alkylguanine and O4-alkylthymine adducts in DNA, protecting the genome and also contributing to the resistance of tumors to chemotherapeutic alkylating agents. AGT binds DNA cooperatively, and cooperative interactions are likely to be important in lesion search and repair. We examined morphologies of complexes on long, unmodified DNAs, using analytical ultracentrifugation and atomic force microscopy. AGT formed clusters of ≤11 proteins. Longer clusters, predicted by the McGhee–von Hippel model, were not seen even at high [protein]. Interestingly, torsional stress due to DNA unwinding has the potential to limit cluster size to the observed range. DNA at cluster sites showed bend angles (∼0, ∼30 and ∼60°) that are consistent with models in which each protein induces a bend of ∼30°. Distributions of complexes along the DNA are incompatible with sequence specificity but suggest modest preference for DNA ends. These properties tell us about environments in which AGT may function. Small cooperative clusters and the ability to accommodate a range of DNA bends allow function where DNA topology is constrained, such as near DNA-replication complexes. The low sequence specificity allows efficient and unbiased lesion search across the entire genome.
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Affiliation(s)
- Ingrid Tessmer
- Rudolf Virchow Center for Experimental Biomedicine, Institute for Structural Biology, University of Würzburg, Josef-Schneider-Strasse 2, 97080 Würzburg, Germany.
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16
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Bonnist EY, Liebert K, Dryden DT, Jeltsch A, Jones AC. Using the fluorescence decay of 2-aminopurine to investigate conformational change in the recognition sequence of the EcoRV DNA-(adenine-N6)-methyltransferase on enzyme binding. Biophys Chem 2012; 160:28-34. [DOI: 10.1016/j.bpc.2011.09.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 09/03/2011] [Accepted: 09/04/2011] [Indexed: 10/17/2022]
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17
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Lee IJ, Park M, Joo T, Kim BH. Using fluorescence changes of F1U units at terminal and mid-loop positions to probe i-motif structures. ACTA ACUST UNITED AC 2012; 8:486-90. [DOI: 10.1039/c1mb05343d] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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18
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Melikishvili M, Rodgers DW, Fried MG. 6-Carboxyfluorescein and structurally similar molecules inhibit DNA binding and repair by O⁶-alkylguanine DNA alkyltransferase. DNA Repair (Amst) 2011; 10:1193-202. [PMID: 21982443 DOI: 10.1016/j.dnarep.2011.09.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Revised: 09/06/2011] [Accepted: 09/09/2011] [Indexed: 11/18/2022]
Abstract
Human O⁶-alkylguanine-DNA alkyltransferase (AGT) repairs mutagenic O⁶-alkylguanine and O⁴-alkylthymine adducts in single-stranded and duplex DNAs. These activities protect normal cells and tumor cells against drugs that alkylate DNA; drugs that inactivate AGT are under test as chemotherapeutic enhancers. In studies using 6-carboxyfluorescein (FAM)-labeled DNAs, AGT reduced the fluorescence intensity by ∼40% at binding saturation, whether the FAM was located at the 5' or the 3' end of the DNA. AGT protected residual fluorescence from quenching, indicating a solute-inaccessible binding site for FAM. Sedimentation equilibrium analyses showed that saturating AGT-stoichiometries were higher with FAM-labeled DNAs than with unlabeled DNAs, suggesting that the FAM provides a protein binding site that is not present in unlabeled DNAs. Additional fluorescence and sedimentation measurements showed that AGT forms a 1:1 complex with free FAM. Active site benzylation experiments and docking calculations support models in which the primary binding site is located in or near the active site of the enzyme. Electrophoretic analyses show that FAM inhibits DNA binding (IC₅₀∼76μM) and repair of DNA containing an O⁶-methylguanine residue (IC₅₀∼63μM). Similar results were obtained with other polycyclic aromatic compounds. These observations demonstrate the existence of a new class of non-covalent AGT-inhibitors. After optimization for binding-affinity, members of this class might be useful in cancer chemotherapy.
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Affiliation(s)
- Manana Melikishvili
- Center for Structural Biology, Department of Molecular and Cellular Biochemistry, University of Kentucky, 741 South Limestone, Lexington, KY 40536-0509, United States
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19
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Preus S, Kilså K, Wilhelmsson LM, Albinsson B. Photophysical and structural properties of the fluorescent nucleobase analogues of the tricyclic cytosine (tC) family. Phys Chem Chem Phys 2010; 12:8881-92. [PMID: 20532361 DOI: 10.1039/c000625d] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Fundamental insight into the unique fluorescence and nucleobase-mimicking properties of the fluorescent nucleobase analogues of the tC family is not only vital in explaining the behaviour of these probes in nucleic acid environments, but will also be profitable in the development of new and improved fluorescent base analogues. Here, temperature-dependent fluorescence quantum yield measurements are used to successfully separate and quantify the temperature-dependent and temperature-independent non-radiative excited-state decay processes of the three nucleobase analogues tC, tC(O) and tC(nitro); all of which are derivatives of a phenothiazine or phenoxazine tricyclic framework. These results strongly suggest that the non-radiative decay process dominating the fast deactivation of tC(nitro) is an internal conversion of a different origin than the decay pathways of tC and tC(O). tC(nitro) is reported to be fluorescent only in less dipolar solvents at room temperature, which is explained by an increase in excited-state dipole moment along the main non-radiative decay pathway, a suggestion that applies in the photophysical discussion of large polycyclic nitroaromatics in general. New insight into the ground and excited-state potential energy surfaces of the isolated tC bases is obtained by means of high level DFT and TDDFT calculations. The S(0) potential energy surfaces of tC and tC(nitro) possess two global minima corresponding to geometries folded along the middle sulfur-nitrogen axis separated by an energy barrier of 0.05 eV as calculated at the B3LYP/6-311+G(2d,p) level. The ground-state potential energy surface of tC(O) is also predicted to be shallow along the bending coordinate but with an equilibrium geometry corresponding to the planar conformation of the tricyclic framework, which may explain some of the dissimilar properties of tC and tC(O) in various confined (biological) environments. The S(1) equilibrium geometries of all three base analogues are predicted to be planar. These results are discussed in the context of the tC bases positioned in double-stranded DNA scenarios.
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Affiliation(s)
- Søren Preus
- Department of Chemistry, University of Copenhagen, DK-2100 Copenhagen, Denmark.
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