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Samanta S, Raghunathan D, Mukherjee S. Effect of temperature on the structure and hydration layer of TATA-box DNA: A molecular dynamics simulation study. J Mol Graph Model 2016; 66:9-19. [PMID: 27017424 DOI: 10.1016/j.jmgm.2016.03.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 03/17/2016] [Accepted: 03/21/2016] [Indexed: 01/25/2023]
Abstract
DNA within the living cells experiences a diverse range of temperature, ranging from freezing condition to hot spring water. How the structure, the mechanical properties of DNA, and the solvation dynamics around DNA changes with the temperature is important to understand the functionality of DNA under those acute temperature conditions. In that notion, we have carried out molecular dynamics simulations of a DNA oligomer, containing TATA-box sequence for three different temperatures (250K, 300K and 350K). We observed that the structure of the DNA, in terms of backbone torsion angles, sugar pucker, base pair parameters, and base pair step parameters, did not show any unusual properties within the studied range of temperatures, but significant structural alteration was noticed between BI and BII forms at higher temperature. As expected, the flexibility of the DNA, in terms of the torsional rigidity and the bending rigidity is highly temperature dependent, confirming that flexibility increases with increase in temperature. Additionally, the groove widths of the studied DNA showed temperature sensitivity, specifically, the major groove width decreases and the minor groove width increases, respectively, with the increase in temperature. We observed that at higher temperature, water around both the major and the minor groove of the DNA is less structured. However, the water dynamics around the minor groove of the DNA is more restricted as compared to the water around the major groove throughout the studied range of temperatures, without any anomalous behavior.
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Affiliation(s)
- Sudipta Samanta
- BioSystems and Micromechanics IRG (BioSyM), Singapore-MIT Alliance for Research and Technology (SMART), 1 Create Way, 117543, Republic of Singapore; Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Devanathan Raghunathan
- Prochem Solutions Pte. Ltd., 89C Science Park Drive, The Rutherford, # 04-13, Singapore Science Park 1, 118261, Singapore
| | - Sanchita Mukherjee
- Indian Institute of Science Education and Research, Kolkata, Mohanpur, West Bengal, 741246, India
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2
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Applying Thymine Isostere 2,4-Difluoro-5-Methylbenzene as a NMR Assignment Tool and Probe of Homopyrimidine/Homopurine Tract Structural Dynamics. Methods Enzymol 2015; 566:89-110. [PMID: 26791977 DOI: 10.1016/bs.mie.2015.05.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Proton assignment of nuclear magnetic resonance (NMR) spectra of homopyrimidine/homopurine tract oligonucleotides becomes extremely challenging with increasing helical length due to severe cross-peak overlap. As an alternative to the more standard practice of (15)N and (13)C labeling of oligonucleotides, here, we describe a method for assignment of highly redundant DNA sequences that uses single-site substitution of the thymine isostere 2,4-difluoro-5-methylbenzene (dF). The impact of this approach in facilitating the assignment of intractable spectra and analyzing oligonucleotide structure and dynamics is demonstrated using A-tract and TATA box DNA and two polypurine tract-containing RNA:DNA hybrids derived from HIV-1 and the Saccharomyces cerevisiae long-terminal repeat-containing retrotransposon Ty3. Only resonances proximal to the site of dF substitution exhibit sizable chemical shift changes, providing spectral dispersion while still allowing chemical shift mapping of resonances from unaffected residues distal to the site of modification directly back to the unmodified sequence. It is further illustrated that dF incorporation can subtly alter the conformation and dynamics of homopyrimidine/homopurine tract oligonucleotides, and how these NMR observations can be correlated, in the cases of the TATA box DNA, with modulation in the TATA box-binding protein interaction using an orthogonal gel assay.
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3
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Contribution of phenylalanine side chain intercalation to the TATA-box binding protein–DNA interaction: molecular dynamics and dispersion-corrected density functional theory studies. J Mol Model 2014; 20:2499. [DOI: 10.1007/s00894-014-2499-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 10/13/2014] [Indexed: 10/24/2022]
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MURATA KATSUMI, SUGITA YUJI, OKAMOTO YUKO. MOLECULAR DYNAMICS SIMULATIONS OF DNA DIMERS BASED ON REPLICA-EXCHANGE UMBRELLA SAMPLING I: TEST OF SAMPLING EFFICIENCY. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2011. [DOI: 10.1142/s0219633605001611] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In order to elucidate the stacking-unstacking process of DNA dimers, we have performed molecular dynamics simulations based on replica-exchange umbrella sampling (REUS), which is one of powerful conformational sampling techniques. We studied four DNA dimers composed of the adenine and thymine bases in both the 5′ and the 3′ positions (dApdA, dApdT, dTpdA, and dTpdT). We examined the time series of the distance between the glycosidic nitrogen atoms, root-mean-square deviations from A-DNA and B-DNA, various backbone and glycosidic torsion angles, and the pseudorotation phase angles as functions of the simulation time step. All these time series imply that the present simulation has indeed sampled a very wide conformational space. The results for the backbone and glycosidic torsion angles and pseudorotation phase angles imply that B-DNA structures are the dominant motif of the stacked dimers, while a small population of A-DNA also exists in the stacked states.
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Affiliation(s)
- KATSUMI MURATA
- Department of Functional Molecular Science, The Graduate University for Advanced Studies, Okazaki, Aichi 444-8585, Japan
| | - YUJI SUGITA
- Department of Structural Biology, Institute of Molecular and Cellular Biosciences, University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - YUKO OKAMOTO
- Department of Functional Molecular Science, The Graduate University for Advanced Studies, Okazaki, Aichi 444-8585, Japan
- Department of Theoretical Studies, Institute for Molecular Science, Okazaki, Aichi 444-8585, Japan
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Meyer S, Becker NB, Syed SH, Goutte-Gattat D, Shukla MS, Hayes JJ, Angelov D, Bednar J, Dimitrov S, Everaers R. From crystal and NMR structures, footprints and cryo-electron-micrographs to large and soft structures: nanoscale modeling of the nucleosomal stem. Nucleic Acids Res 2011; 39:9139-54. [PMID: 21835779 PMCID: PMC3241633 DOI: 10.1093/nar/gkr573] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 06/17/2011] [Accepted: 06/25/2011] [Indexed: 01/18/2023] Open
Abstract
The interaction of histone H1 with linker DNA results in the formation of the nucleosomal stem structure, with considerable influence on chromatin organization. In a recent paper [Syed,S.H., Goutte-Gattat,D., Becker,N., Meyer,S., Shukla,M.S., Hayes,J.J., Everaers,R., Angelov,D., Bednar,J. and Dimitrov,S. (2010) Single-base resolution mapping of H1-nucleosome interactions and 3D organization of the nucleosome. Proc. Natl Acad. Sci. USA, 107, 9620-9625], we published results of biochemical footprinting and cryo-electron-micrographs of reconstituted mono-, di- and tri-nucleosomes, for H1 variants with different lengths of the cationic C-terminus. Here, we present a detailed account of the analysis of the experimental data and we include thermal fluctuations into our nano-scale model of the stem structure. By combining (i) crystal and NMR structures of the nucleosome core particle and H1, (ii) the known nano-scale structure and elasticity of DNA, (iii) footprinting information on the location of protected sites on the DNA backbone and (iv) cryo-electron micrographs of reconstituted tri-nucleosomes, we arrive at a description of a polymorphic, hierarchically organized stem with a typical length of 20 ± 2 base pairs. A comparison to linker conformations inferred for poly-601 fibers with different linker lengths suggests, that intra-stem interactions stabilize and facilitate the formation of dense chromatin fibers.
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Affiliation(s)
- Sam Meyer
- Laboratoire de Physique and Centre Blaise Pascal, École Normale Supérieure de Lyon, Université de Lyon, CNRS UMR 5672, 46 allée d'Italie 69364 Lyon cedex 07, France.
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6
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Yang B, Zhu Y, Wang Y, Chen G. Interaction identification of Zif268 and TATA(ZF) proteins with GC-/AT-rich DNA sequence: A theoretical study. J Comput Chem 2011; 32:416-28. [PMID: 20658568 DOI: 10.1002/jcc.21630] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Molecular dynamics (MD) simulations for Zif268 (a zinc-finger-protein binding specifically to the GC-rich DNA)-d(A(1) G(2) C(3) G(4) T(5) G(6) G(7) G(8) C(9) A(10) C(11) )(2) and TATA(ZF) (a zinc-finger-protein recognizing the AT-rich DNA)-d(A(1) C(2) G(3) C(4) T(5) A(6) T(7) A(8) A(9) A(10) A(11) G(12) G(13) )(2) complexes have been performed for investigating the DNA binding affinities and specific recognitions of zinc fingers to GC-rich and AT-rich DNA sequences. The binding free energies for the two systems have been further analyzed by using the molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) method. The calculations of the binding free energies reveal that the affinity energy of Zif268-DNA complex is larger than that of TATA(ZF) -DNA one. The affinity between the zinc-finger-protein and DNA is mainly driven by more favorable van-der-Waals and nonpolar/solvation interactions in both complexes. However, the affinity energy difference of the two binding systems is mainly caused by the difference of van-der-Waals interactions and entropy components. The decomposition analysis of MM-PBSA free energies on each residue of the proteins predicts that the interactions between the residues with the positive charges and DNA favor the binding process; while the interactions between the residues with the negative charges and DNA behave in the opposite way. The interhydrogen-bonds at the protein-DNA interface and the induced intrafinger hydrogen bonds between the residues of protein for the Zif268-DNA complex have been identified at some key contact sites. However, only the interhydrogen-bonds between the residues of protein and DNA for TATA(ZF) -DNA complex have been found. The interactions of hydrogen-bonds, electrostatistics and van-der-Waals type at some new contact sites have been identified. Moreover, the recognition characteristics of the two studied zinc-finger-proteins have also been discussed.
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Affiliation(s)
- Bo Yang
- College of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China
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Biomolecular Structure and Modeling: Historical Perspective. INTERDISCIPLINARY APPLIED MATHEMATICS 2010. [PMCID: PMC7124002 DOI: 10.1007/978-1-4419-6351-2_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
physics, chemistry, and biology have been connected by a web of causal explanation organized by induction-based theories that telescope into one another. … Thus, quantum theory underlies atomic physics, which is the foundation of reagent chemistry and its specialized offshoot biochemistry, which interlock with molecular biology — essentially, the chemistry of organic macromolecules — and hence, through successively higher levels of organization, cellular, organismic, and evolutionary biology. … Such is the unifying and highly productive understanding of the world that has evolved in the natural sciences.
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Millán-Pacheco C, Capistrán VM, Pastor N. On the consequences of placing amino groups at the TBP-DNA interface. Does TATA really matter? J Mol Recognit 2009; 22:453-64. [DOI: 10.1002/jmr.963] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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9
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Schlick T. Monte Carlo, harmonic approximation, and coarse-graining approaches for enhanced sampling of biomolecular structure. F1000 BIOLOGY REPORTS 2009; 1:48. [PMID: 20948637 PMCID: PMC2924683 DOI: 10.3410/b1-48] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The rugged energy landscape of biomolecules and associated large-scale conformational changes have triggered the development of many innovative enhanced sampling methods, either based or not based on molecular dynamics (MD) simulations. Surveyed here are methods in the latter class - including Monte Carlo methods, harmonic approximations, and coarse graining - many of which yield valuable conformational insights into biomolecular structure and flexibility, despite altered kinetics. MD-based methods are surveyed in an upcoming issue of F1000 Biology Reports.
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Affiliation(s)
- Tamar Schlick
- Department of Chemistry and Courant Institute of Mathematical Sciences, New York University 251 Mercer Street, New York, NY 10012 USA.
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Whittington JE, Delgadillo RF, Attebury TJ, Parkhurst LK, Daugherty MA, Parkhurst LJ. TATA-Binding Protein Recognition and Bending of a Consensus Promoter Are Protein Species Dependent. Biochemistry 2008; 47:7264-73. [DOI: 10.1021/bi800139w] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- JoDell E. Whittington
- Department of Chemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588-0304, and Department of Chemistry and Biochemistry, Middlebury College, Middlebury, Vermont 05753
| | - Roberto F. Delgadillo
- Department of Chemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588-0304, and Department of Chemistry and Biochemistry, Middlebury College, Middlebury, Vermont 05753
| | - Torrissa J. Attebury
- Department of Chemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588-0304, and Department of Chemistry and Biochemistry, Middlebury College, Middlebury, Vermont 05753
| | - Laura K. Parkhurst
- Department of Chemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588-0304, and Department of Chemistry and Biochemistry, Middlebury College, Middlebury, Vermont 05753
| | - Margaret A. Daugherty
- Department of Chemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588-0304, and Department of Chemistry and Biochemistry, Middlebury College, Middlebury, Vermont 05753
| | - Lawrence J. Parkhurst
- Department of Chemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588-0304, and Department of Chemistry and Biochemistry, Middlebury College, Middlebury, Vermont 05753
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Bjornsdottir G, Myers LC. Minimal components of the RNA polymerase II transcription apparatus determine the consensus TATA box. Nucleic Acids Res 2008; 36:2906-16. [PMID: 18385157 PMCID: PMC2396422 DOI: 10.1093/nar/gkn130] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
In Saccharomyces cerevisiae, multiple approaches have arrived at a consensus TATA box sequence of TATA(T/A)A(A/T)(A/G). TATA-binding protein (TBP) affinity alone does not determine TATA box function. To discover how a minimal set of factors required for basal and activated transcription contributed to the sequence requirements for a functional TATA box, we performed transcription reactions using highly purified proteins and CYC1 promoter TATA box mutants. The TATA box consensus sequence is a good predictor of promoter activity. However, several nonconsensus sequences are almost fully functional, indicating that mechanistic requirements are not the only selective pressure on the TATA box. We also found that the effect of a mutation at a certain position is often dependent on other bases within a particular TATA box. Although activators and coactivators strongly influence TBP recruitment and stability at promoters, neither Mediator, the activator Gal4-V16, nor TFIID specifically compensate for the low transcription levels of the weak TATA boxes. The addition of Mediator to purified transcription reactions did, however, increase the functional selectivity for certain consensus TATA sequences. Transcription in whole-cell extracts or in vivo with these TATA box mutants indicated that factors, other than those in our purified system, may help initiate transcription from weak TATA boxes.
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Affiliation(s)
- Gudrun Bjornsdottir
- Department of Biochemistry, Dartmouth Medical School, Hanover, NH 03755, USA
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12
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Hieb AR, Halsey WA, Betterton MD, Perkins TT, Kugel JF, Goodrich JA. TFIIA changes the conformation of the DNA in TBP/TATA complexes and increases their kinetic stability. J Mol Biol 2007; 372:619-32. [PMID: 17681538 DOI: 10.1016/j.jmb.2007.06.061] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2007] [Revised: 06/11/2007] [Accepted: 06/25/2007] [Indexed: 10/23/2022]
Abstract
Eukaryotic mRNA transcription by RNA polymerase II is a highly regulated complex reaction involving numerous proteins. In order to control tissue and promoter specific gene expression, transcription factors must work in concert with each other and with the promoter DNA to form the proper architecture to activate the gene of interest. The TATA binding protein (TBP) binds to TATA boxes in core promoters and bends the TATA DNA. We have used quantitative solution fluorescence resonance energy transfer (FRET) and gel-based FRET (gelFRET) to determine the effect of TFIIA on the conformation of the DNA in TBP/TATA complexes and on the kinetic stability of these complexes. Our results indicate that human TFIIA decreases the angle to which human TBP bends consensus TATA DNA from 104 degrees to 80 degrees when calculated using a two-kink model. The kinetic stability of TBP/TATA complexes was greatly reduced by increasing the KCl concentration from 50 mM to 140 mM, which is more physiologically relevant. TFIIA significantly enhanced the kinetic stability of TBP/TATA complexes, thereby attenuating the effect of higher salt concentrations. We also found that TBP bent non-consensus TATA DNA to a lesser degree than consensus TATA DNA and complexes between TBP and a non-consensus TATA box were kinetically unstable even at 50 mM KCl. Interestingly, TFIIA increased the calculated bend angle and kinetic stability of complexes on a non-consensus TATA box, making them similar to those on a consensus TATA box. Our data show that TFIIA induces a conformational change within the TBP/TATA complex that enhances its stability under both in vitro and physiological salt conditions. Furthermore, we present a refined model for the effect that TFIIA has on DNA conformation that takes into account potential changes in bend angle as well as twist angle.
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Affiliation(s)
- Aaron R Hieb
- Department of Chemistry and Biochemistry, University of Colorado at Boulder, 215 UCB, Boulder, CO 80309-0215, USA
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Hsieh TY, Shiu TY, Huang SM, Lin HH, Lee TC, Chen PJ, Chu HC, Chang WK, Jeng KS, Lai MMC, Chao YC. Molecular pathogenesis of Gilbert's syndrome: decreased TATA-binding protein binding affinity of UGT1A1 gene promoter. Pharmacogenet Genomics 2007; 17:229-36. [PMID: 17496722 DOI: 10.1097/fpc.0b013e328012d0da] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES Gilbert's syndrome is a congenital, nonhemolytic, unconjugated hyperbilirubinemia. The most common genotype of Gilbert's syndrome is the homozygous polymorphism, A(TA)7TAA, in the promoter of the gene for UDP-glucuronosyltransferase 1A1 (UGT1A1), with a thymine adenine insertion in the TATA-box-like sequence, which results in a decrease in UGT1A1 activity. The mechanism responsible for this decrease in UGT1A1 activity, however, has not been elucidated. To clarify the mechanism underlying this deficiency in UGT1A1 activity in patients with Gilbert's syndrome. METHODS The promoter activity assay using the wild-type A(TA)6TAA or the mutant A(TA)7TAA promoter and a luciferase reporter was performed in two different hepatoma cell lines. The binding affinity for a nuclear protein complex or for TATA-binding protein was evaluated by a competitive electophoretic mobility shift assay using wild-type or mutant TATA-box-like oligonucleotide probes and nuclear extract or TATA-binding protein. The formation of complexes between TATA-binding protein and wild-type or mutant oligonucleotide probes was also studied by a quantitive electophoretic mobility shift assay. RESULTS A TA insertion in the TATA-box-like sequence of the promoter activity of UGT1A1 gene. A competitive electrophoretic mobility shift assay showed a decrease in nuclear protein complex binding affinity and TATA-binding protein binding affinity of the mutant TATA-box-like sequence A(TA)7TAA. When the mutants A(TA)5TAA and A(TA)8TAA were also compared, quantitative electrophoretic mobility shift assay demonstrated that the TATA-binding protein binding affinity progressively decreased as the number of TA repeats in the TATA-box-like sequence increased. CONCLUSION TA insertion in the TATA-box-like sequence of the UGT1A1 promoter affected its binding affinity for TATA-binding protein, causing a decrease in its activity. This explains the pathogenesis of Gilbert's syndrome.
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Affiliation(s)
- Tsai-Yuan Hsieh
- Department of Internal Medicine, Tri-Service General Hospital, Taipei, Taiwan, ROC
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Tsihlis ND, Grove A. The Saccharomyces cerevisiae RNA polymerase III recruitment factor subunits Brf1 and Bdp1 impose a strict sequence preference for the downstream half of the TATA box. Nucleic Acids Res 2006; 34:5585-93. [PMID: 17028095 PMCID: PMC1636458 DOI: 10.1093/nar/gkl534] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Association of the TATA-binding protein (TBP) with its cognate site within eukaryotic promoters is key to accurate and efficient transcriptional initiation. To achieve recruitment of Saccharomyces cerevisiae RNA polymerase III, TBP is associated with two additional factors, Brf1 and Bdp1, to form the initiation factor TFIIIB. Previous data have suggested that the structure or dynamics of the TBP–DNA complex may be altered upon entry of Brf1 and Bdp1 into the complex. We show here, using the altered specificity TBP mutant TBPm3 and an iterative in vitro selection assay, that entry of Brf1 and Bdp1 into the complex imposes a strict sequence preference for the downstream half of the TATA box. Notably, the selected sequence (TGTAAATA) is a perfect match to the TATA box of the RNA polymerase III-transcribed U6 small nuclear RNA (SNR6) gene. We suggest that the selected T•A base pair step at the downstream end of the 8 bp TBP site may provide a DNA flexure that promotes TFIIIB-DNA complex formation.
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Affiliation(s)
| | - Anne Grove
- To whom correspondence should be addressed. Tel: +1 225 578 5148; Fax: +1 225 578 8790;
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Zhang Q, Broyde S, Schlick T. Deformations of promoter DNA bound to carcinogens help interpret effects on TATA-element structure and activity. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2004; 362:1479-1496. [PMID: 15306462 DOI: 10.1098/rsta.2004.1386] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The TATA-box binding protein (TBP) is required by eukaryotic RNA polymerases for correct transcription initiation. TBP binds to the minor groove of an 8 base pair (bp) DNA-promoter element known as the TATA box and severely bends the TATA box. The promoter-DNA substrate can be damaged by components present in the cell or the environment to produce covalent carcinogen-DNA adducts. These may lead to transcription blockage or unfaithful transcription. Benzo[a]pyrene (BP) is a widespread environmental chemical carcinogen which can be metabolically converted to DNA-reactive enantiomeric (+) and (-)-anti-benzo[a]pyrene diol epoxides (BPDEs). Recent experimental studies of a pair of stereoisomeric adenine adducts, derived from (+) and (-)-anti-BPDEs, have revealed how these lesions influence the complexation of TBP with the TATA box. Depending on the adduct's location in the TATA box and its stereochemistry, the stability of monomeric TATA-TBP complexes was found to increase or decrease relative to the unmodified DNA. We report here analyses of molecular-dynamics simulations to interpret these findings. Structural analyses of 12 DNA-protein systems representing different combinations of adduct stereoisomer type and placement within the promoter reveal that the location of the adduct within the TATA octamer determines whether the stability of TATA-TBP complexes is increased or decreased. The effect on binding stability can be interpreted in terms of conformational freedom and major-groove space available to BP due to the hydrogen bonds and inserted phenylalanines of the TATA-TBP complex; that is, depending on the position of the adenine to which BP is covalently bound, BP can be accommodated in an intercalated or major-groove orientation with ease or with difficulty (due to interference with TATA-TBP interactions). The unravelled structures and interactions thus reveal the effect of different adduct locations on TATA-TBP complex formation and suggest how transcription initiation may be affected by the presence of a bulky BP.
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Affiliation(s)
- Qing Zhang
- Department of Chemistry and Courant Institute of Mathematical Sciences, New York University and the Howard Hughes Medical Institute, 251 Mercer Street, New York, NY 10012, USA
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