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Zhang Q, Lv H, Wang L, Chen M, Li F, Liang C, Yu Y, Jiang F, Lu A, Zhang G. Recent Methods for Purification and Structure Determination of Oligonucleotides. Int J Mol Sci 2016; 17:E2134. [PMID: 27999357 PMCID: PMC5187934 DOI: 10.3390/ijms17122134] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 12/13/2016] [Accepted: 12/14/2016] [Indexed: 12/14/2022] Open
Abstract
Aptamers are single-stranded DNA or RNA oligonucleotides that can interact with target molecules through specific three-dimensional structures. The excellent features, such as high specificity and affinity for target proteins, small size, chemical stability, low immunogenicity, facile chemical synthesis, versatility in structural design and engineering, and accessible for site-specific modifications with functional moieties, make aptamers attractive molecules in the fields of clinical diagnostics and biopharmaceutical therapeutics. However, difficulties in purification and structural identification of aptamers remain a major impediment to their broad clinical application. In this mini-review, we present the recently attractive developments regarding the purification and identification of aptamers. We also discuss the advantages, limitations, and prospects for the major methods applied in purifying and identifying aptamers, which could facilitate the application of aptamers.
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MESH Headings
- Aptamers, Nucleotide/chemistry
- Chromatography, High Pressure Liquid/methods
- Chromatography, Ion Exchange/methods
- Chromatography, Reverse-Phase/methods
- Crystallography, X-Ray/methods
- DNA, Single-Stranded/chemistry
- DNA, Single-Stranded/ultrastructure
- Electrophoresis, Gel, Two-Dimensional/methods
- Nuclear Magnetic Resonance, Biomolecular/methods
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Affiliation(s)
- Qiulong Zhang
- Institute of Integrated Bioinformedicine and Translational Science, School of Chinese Medicine, Hong Kong Baptist University (HKBU), Hong Kong, China.
- Institute of Precision Medicine and Innovative Drug Discovery, HKBU (Haimen) Institute of Science and Technology, Haimen 226100, China.
- Shenzhen Lab of Combinatorial Compounds and Targeted Drug Delivery, HKBU Institute of Research and Continuing Education, Shenzhen 518000, China.
| | - Huanhuan Lv
- Institute of Integrated Bioinformedicine and Translational Science, School of Chinese Medicine, Hong Kong Baptist University (HKBU), Hong Kong, China.
- Institute of Precision Medicine and Innovative Drug Discovery, HKBU (Haimen) Institute of Science and Technology, Haimen 226100, China.
- Shenzhen Lab of Combinatorial Compounds and Targeted Drug Delivery, HKBU Institute of Research and Continuing Education, Shenzhen 518000, China.
| | - Lili Wang
- Institute of Integrated Bioinformedicine and Translational Science, School of Chinese Medicine, Hong Kong Baptist University (HKBU), Hong Kong, China.
- Institute of Precision Medicine and Innovative Drug Discovery, HKBU (Haimen) Institute of Science and Technology, Haimen 226100, China.
- Shenzhen Lab of Combinatorial Compounds and Targeted Drug Delivery, HKBU Institute of Research and Continuing Education, Shenzhen 518000, China.
| | - Man Chen
- Institute of Integrated Bioinformedicine and Translational Science, School of Chinese Medicine, Hong Kong Baptist University (HKBU), Hong Kong, China.
- Institute of Precision Medicine and Innovative Drug Discovery, HKBU (Haimen) Institute of Science and Technology, Haimen 226100, China.
- Shenzhen Lab of Combinatorial Compounds and Targeted Drug Delivery, HKBU Institute of Research and Continuing Education, Shenzhen 518000, China.
| | - Fangfei Li
- Institute of Integrated Bioinformedicine and Translational Science, School of Chinese Medicine, Hong Kong Baptist University (HKBU), Hong Kong, China.
- Institute of Precision Medicine and Innovative Drug Discovery, HKBU (Haimen) Institute of Science and Technology, Haimen 226100, China.
- Shenzhen Lab of Combinatorial Compounds and Targeted Drug Delivery, HKBU Institute of Research and Continuing Education, Shenzhen 518000, China.
| | - Chao Liang
- Institute of Integrated Bioinformedicine and Translational Science, School of Chinese Medicine, Hong Kong Baptist University (HKBU), Hong Kong, China.
- Institute of Precision Medicine and Innovative Drug Discovery, HKBU (Haimen) Institute of Science and Technology, Haimen 226100, China.
- Shenzhen Lab of Combinatorial Compounds and Targeted Drug Delivery, HKBU Institute of Research and Continuing Education, Shenzhen 518000, China.
| | - Yuanyuan Yu
- Institute of Integrated Bioinformedicine and Translational Science, School of Chinese Medicine, Hong Kong Baptist University (HKBU), Hong Kong, China.
- Institute of Precision Medicine and Innovative Drug Discovery, HKBU (Haimen) Institute of Science and Technology, Haimen 226100, China.
- Shenzhen Lab of Combinatorial Compounds and Targeted Drug Delivery, HKBU Institute of Research and Continuing Education, Shenzhen 518000, China.
| | - Feng Jiang
- Institute of Integrated Bioinformedicine and Translational Science, School of Chinese Medicine, Hong Kong Baptist University (HKBU), Hong Kong, China.
- The State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211, China.
- Institute of Precision Medicine and Innovative Drug Discovery, HKBU (Haimen) Institute of Science and Technology, Haimen 226100, China.
- Shenzhen Lab of Combinatorial Compounds and Targeted Drug Delivery, HKBU Institute of Research and Continuing Education, Shenzhen 518000, China.
| | - Aiping Lu
- Institute of Integrated Bioinformedicine and Translational Science, School of Chinese Medicine, Hong Kong Baptist University (HKBU), Hong Kong, China.
- Institute of Precision Medicine and Innovative Drug Discovery, HKBU (Haimen) Institute of Science and Technology, Haimen 226100, China.
- Shenzhen Lab of Combinatorial Compounds and Targeted Drug Delivery, HKBU Institute of Research and Continuing Education, Shenzhen 518000, China.
| | - Ge Zhang
- Institute of Integrated Bioinformedicine and Translational Science, School of Chinese Medicine, Hong Kong Baptist University (HKBU), Hong Kong, China.
- Institute of Precision Medicine and Innovative Drug Discovery, HKBU (Haimen) Institute of Science and Technology, Haimen 226100, China.
- Shenzhen Lab of Combinatorial Compounds and Targeted Drug Delivery, HKBU Institute of Research and Continuing Education, Shenzhen 518000, China.
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2
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Taranova M, Hirsh AD, Perkins NC, Andricioaei I. Role of microscopic flexibility in tightly curved DNA. J Phys Chem B 2014; 118:11028-36. [PMID: 25155114 PMCID: PMC4174995 DOI: 10.1021/jp502233u] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
The
genetic material in living cells is organized into complex
structures in which DNA is subjected to substantial contortions. Here
we investigate the difference in structure, dynamics, and flexibility
between two topological states of a short (107 base pair) DNA sequence
in a linear form and a covalently closed, tightly curved circular
DNA form. By employing a combination of all-atom molecular dynamics
(MD) simulations and elastic rod modeling of DNA, which allows capturing
microscopic details while monitoring the global dynamics, we demonstrate
that in the highly curved regime the microscopic flexibility of the
DNA drastically increases due to the local mobility of the duplex.
By analyzing vibrational entropy and Lipari–Szabo NMR order
parameters from the simulation data, we propose a novel model for
the thermodynamic stability of high-curvature DNA states based on
vibrational untightening of the duplex. This novel view of DNA bending
provides a fundamental explanation that bridges the gap between classical
models of DNA and experimental studies on DNA cyclization, which so
far have been in substantial disagreement.
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Affiliation(s)
- Maryna Taranova
- Department of Chemistry, University of California , 1102 Natural Sciences 2, Irvine, California 92697, United States
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Nikolova EN, Bascom GD, Andricioaei I, Al-Hashimi HM. Probing sequence-specific DNA flexibility in a-tracts and pyrimidine-purine steps by nuclear magnetic resonance (13)C relaxation and molecular dynamics simulations. Biochemistry 2012; 51:8654-64. [PMID: 23035755 DOI: 10.1021/bi3009517] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Sequence-specific DNA flexibility plays a key role in a variety of cellular interactions that are critical for gene packaging, expression, and regulation, yet few studies have experimentally explored the sequence dependence of DNA dynamics that occur on biologically relevant time scales. Here, we use nuclear magnetic resonance (NMR) carbon spin relaxation combined with molecular dynamics (MD) simulations to examine the picosecond to nanosecond dynamics in a variety of dinucleotide steps as well as in varying length homopolymeric A(n)·T(n) repeats (A(n)-tracts, where n = 2, 4, or 6) that exhibit unusual structural and mechanical properties. We extend the NMR spin relaxation time scale sensitivity deeper into the nanosecond regime by using glycerol and a longer DNA duplex to slow overall tumbling. Our studies reveal a structurally unique A-tract core (for n > 3) that is uniformly rigid, flanked by junction steps that show increasing sugar flexibility with A-tract length. High sugar mobility is observed at pyrimidine residues at the A-tract junctions, which is encoded at the dinucleotide level (CA, TG, and CG steps) and increases with A-tract length. The MD simulations reproduce many of these trends, particularly the overall rigidity of A-tract base and sugar sites, and suggest that the sugar-backbone dynamics could involve transitions in sugar pucker and phosphate backbone BI ↔ BII equilibria. Our results reinforce an emerging view that sequence-specific DNA flexibility can be imprinted in dynamics occurring deep within the nanosecond time regime that is difficult to characterize experimentally at the atomic level. Such large-amplitude sequence-dependent backbone fluctuations might flag the genome for specific DNA recognition.
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Affiliation(s)
- Evgenia N Nikolova
- Department of Chemistry and Biophysics, University of Michigan, 930 North University Avenue, Ann Arbor, MI 48109, USA
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4
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Jaciuk M, Nowak E, Skowronek K, Tańska A, Nowotny M. Structure of UvrA nucleotide excision repair protein in complex with modified DNA. Nat Struct Mol Biol 2011; 18:191-7. [PMID: 21240268 PMCID: PMC3428727 DOI: 10.1038/nsmb.1973] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Accepted: 11/09/2010] [Indexed: 12/31/2022]
Abstract
One of the primary pathways for removal of DNA damage is nucleotide excision repair (NER). In bacteria, the UvrA protein is the component of NER that locates the lesion. A notable feature of NER is its ability to act on many DNA modifications that vary in chemical structure. So far, the mechanism underlying this broad specificity has been unclear. Here, we report the first crystal structure of a UvrA protein in complex with a chemically modified oligonucleotide. The structure shows that the UvrA dimer does not contact the site of lesion directly, but rather binds the DNA regions on both sides of the modification. The DNA region harboring the modification is deformed, with the double helix bent and unwound. UvrA uses damage-induced deformations of the DNA and a less rigid structure of the modified double helix for indirect readout of the lesion.
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Affiliation(s)
- Marcin Jaciuk
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Elżbieta Nowak
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Krzysztof Skowronek
- Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, Warsaw, Poland. Correspondence should be addressed to M.N. ()
| | - Anna Tańska
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Marcin Nowotny
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, Warsaw, Poland
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5
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Wilson DM, Seidman MM. A novel link to base excision repair? Trends Biochem Sci 2010; 35:247-52. [PMID: 20172733 DOI: 10.1016/j.tibs.2010.01.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2009] [Revised: 01/07/2010] [Accepted: 01/15/2010] [Indexed: 01/04/2023]
Abstract
DNA interstrand crosslinks (ICLs) can arise from reactions with endogenous chemicals, such as malondialdehyde - a lipid peroxidation product - or from exposure to various clinical anti-cancer drugs, most notably bifunctional alkylators and platinum compounds. Because they covalently link the two strands of DNA, ICLs completely block transcription and replication, and, as a result, are lethal to the cell. It is well established that proteins that function in nucleotide excision repair and homologous recombination are involved in ICL resolution. Recent work, coupled with a much earlier report, now suggest an emerging link between proteins of the base excision repair pathway and crosslink processing.
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Affiliation(s)
- David M Wilson
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
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6
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Rinnenthal J, Richter C, Nozinovic S, Fürtig B, Lopez JJ, Glaubitz C, Schwalbe H. RNA phosphodiester backbone dynamics of a perdeuterated cUUCGg tetraloop RNA from phosphorus-31 NMR relaxation analysis. JOURNAL OF BIOMOLECULAR NMR 2009; 45:143-55. [PMID: 19636800 DOI: 10.1007/s10858-009-9343-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Accepted: 06/19/2009] [Indexed: 05/13/2023]
Abstract
We have analyzed the relaxation properties of all (31)P nuclei in an RNA cUUCGg tetraloop model hairpin at proton magnetic field strengths of 300, 600 and 900 MHz in solution. Significant H, P dipolar contributions to R (1) and R (2) relaxation are observed in a protonated RNA sample at 600 MHz. These contributions can be suppressed using a perdeuterated RNA sample. In order to interpret the (31)P relaxation data (R (1), R (2)), we measured the (31)P chemical shift anisotropy (CSA) by solid-state NMR spectroscopy under various salt and hydration conditions. A value of 178.5 ppm for the (31)P CSA in the static state (S (2) = 1) could be determined. In order to obtain information about fast time scale dynamics we performed a modelfree analysis on the basis of our relaxation data. The results show that subnanosecond dynamics detected around the phosphodiester backbone are more pronounced than the dynamics detected for the ribofuranosyl and nucleobase moieties of the individual nucleotides (Duchardt and Schwalbe, J Biomol NMR 32:295-308, 2005; Ferner et al., Nucleic Acids Res 36:1928-1940, 2008). Furthermore, the dynamics of the individual phosphate groups seem to be correlated to the 5' neighbouring nucleobases.
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Affiliation(s)
- Jörg Rinnenthal
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max-von-Laue-Strasse 7, Frankfurt/Main, Germany
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7
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Nikolova EN, Al-Hashimi HM. Preparation, resonance assignment, and preliminary dynamics characterization of residue specific 13C/15N-labeled elongated DNA for the study of sequence-directed dynamics by NMR. JOURNAL OF BIOMOLECULAR NMR 2009; 45:9-16. [PMID: 19636798 DOI: 10.1007/s10858-009-9350-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2009] [Accepted: 06/19/2009] [Indexed: 05/28/2023]
Abstract
DNA is a highly flexible molecule that undergoes functionally important structural transitions in response to external cellular stimuli. Atomic level spin relaxation NMR studies of DNA dynamics have been limited to short duplexes in which sensitivity to biologically relevant fluctuations occurring at nanosecond timescales is often inadequate. Here, we introduce a method for preparing residue-specific (13)C/(15)N-labeled elongated DNA along with a strategy for establishing resonance assignments and apply the approach to probe fast inter-helical bending motions induced by an adenine tract. Preliminary results suggest the presence of elevated A-tract independent end-fraying internal motions occurring at nanosecond timescales, which evade detection in short DNA constructs and that penetrate deep (7 bp) within the DNA helix and gradually fade away towards the helix interior.
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Affiliation(s)
- Evgenia N Nikolova
- Department of Chemistry, Biophysics and Chemical Biology Program, University of Michigan, 930 North University Avenue, Ann Arbor, MI 48109-1055, USA
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8
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Duchardt E, Nilsson L, Schleucher J. Cytosine ribose flexibility in DNA: a combined NMR 13C spin relaxation and molecular dynamics simulation study. Nucleic Acids Res 2008; 36:4211-9. [PMID: 18579564 PMCID: PMC2475628 DOI: 10.1093/nar/gkn375] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Using (13)C spin relaxation NMR in combination with molecular dynamic (MD) simulations, we characterized internal motions within double-stranded DNA on the pico- to nano-second time scale. We found that the C-H vectors in all cytosine ribose moieties within the Dickerson-Drew dodecamer (5'-CGCGAATTCGCG-3') are subject to high amplitude motions, while the other nucleotides are essentially rigid. MD simulations showed that repuckering is a likely motional model for the cytosine ribose moiety. Repuckering occurs with a time constant of around 100 ps. Knowledge of DNA dynamics will contribute to our understanding of the recognition specificity of DNA-binding proteins such as cytosine methyltransferase.
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Affiliation(s)
- Elke Duchardt
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87 Umeå, Sweden.
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9
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Slupsky CM, Spyracopoulos L, Booth VK, Sykes BD, Crump MP. Probing nascent structures in peptides using natural abundance 13C NMR relaxation and reduced spectral density mapping. Proteins 2007; 67:18-30. [PMID: 17256768 DOI: 10.1002/prot.21294] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The main chain motional properties for a series of peptides that appear to have preferred conformations in solution have been systematically studied using solution-state nuclear magnetic resonance spectroscopy. The series of peptides were derived from the N-termini of pro-inflammatory chemokine proteins and HoxB1, a transcriptional regulator. As an unstructured control, a ten residue peptide was designed, synthesized, and found to be minimally structured from solution NMR data. The dynamic properties of the main chain for the peptides were assessed through longitudinal and transverse main chain (13)Calpha relaxation rates and the heteronuclear nuclear Overhauser effect. Motional parameters were interpreted using reduced spectral density mapping and compared with those derived from an extended Lipari-Szabo model in which the rotational correlation time was calculated for each main chain site of the peptide. Comparison of spectral density and Lipari-Szabo analyses for the peptides to those of the unstructured control peptide reveals significant differences in the dynamic behavior of the peptides. The amplitude of picosecond to nanosecond timescale motions for the main chain is observed to decrease for all of the chemokine peptides and HoxB1 over the regions that show partial structure at low temperatures. Comparatively, changes in picosecond to nanosecond timescale motions for the unstructured control peptide show no correlation with sequence position. These results indicate that there are distinguishable low temperature motional differences between an intrinsically unstructured peptide and peptides that have an inherent propensity to structure.
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Affiliation(s)
- Carolyn M Slupsky
- Protein Engineering Network Centres of Excellence, University of Alberta, Edmonton, Alberta, Canada
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10
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Duchardt E, Schwalbe H. Residue specific ribose and nucleobase dynamics of the cUUCGg RNA tetraloop motif by MNMR 13C relaxation. JOURNAL OF BIOMOLECULAR NMR 2005; 32:295-308. [PMID: 16211483 DOI: 10.1007/s10858-005-0659-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The dynamics of the nucleobase and the ribose moieties in a 14-nt RNA cUUCGg hairpin-loop uniformly labeled with 13C and 15N were studied by 13C spin relaxation experiments. R1, R1rho and the 13C-[1H] steady-state NOE of C6 and C1' in pyrimidine and C8 and C1' in purine residues were obtained at 298 K. The relaxation data were analyzed by the model-free formalism to yield dynamic information on timescales of pico-, nano- and milli-seconds. An axially symmetric diffusion tensor with an overall rotational correlation time tau(c) of 2.31 +/- 0.13 ns and an axial ratio of 1.35 +/- 0.02 were determined. Both findings are in agreement with hydrodynamic calculations. For the nucleobase carbons, the validity of different reported 13C chemical shift anisotropy values (Stueber, D. and Grant, D. M., 2002 J. Am. Chem. Soc. 124, 10539-10551; Fiala et al., 2000 J. Biomol. NMR 16, 291-302; Sitkoff, D. and Case, D. A., 1998 Prog. NMR Spectroscopy 32, 165-190) is discussed. The resulting dynamics are in agreement with the structural features of the cUUCGg motif in that all residues are mostly rigid (0.82 < S2 < 0.96) in both the nucleobase and the ribose moiety except for the nucleobase of U7, which is protruding into solution (S2 = 0.76). In general, ribose mobility follows nucleobase dynamics, but is less pronounced. Nucleobase dynamics resulting from the analysis of 13C relaxation rates were found to be in agreement with 15N relaxation data derived dynamic information (Akke et al., 1997 RNA 3, 702-709).
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Affiliation(s)
- Elke Duchardt
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University Frankfurt, Marie-Curie Str. 11, D-60439, Frankfurt/Main, Germany
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Isaacs RJ, Rayens WS, Spielmann HP. Structural differences in the NOE-derived structure of G-T mismatched DNA relative to normal DNA are correlated with differences in (13)C relaxation-based internal dynamics. J Mol Biol 2002; 319:191-207. [PMID: 12051946 DOI: 10.1016/s0022-2836(02)00265-6] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Detailed description of the characteristics of mismatched DNA that are distinct from normal DNA is vital to the understanding of how mismatch repair proteins are able to recognize and repair these DNA lesions. To this end, we have used nuclear Overhauser effect spectroscopy (NOESY)-based distance restraints and (13)C relaxation measurements to solve the solution structures and measure some of the internal dynamics of the G-T mismatched DNA oligomer d(CCATGCGTGG)(2) (GT) and its parent DNA sequence d(CCACGCGTGG)(2) (GC). In GT, the mismatched G7 is structurally perturbed much more than the mismatched T4 relative to their corresponding bases in GC. The degree of G7 displacement differs from previous high-resolution structures of G-T mismatch-containing B-DNA, suggesting a dependence of G-T mismatch-induced structural perturbation on sequence context. The internal dynamics of GC and GT differ on multiple timescales. The mismatched G7 of GT contains spins that decrease significantly in order in GT compared to GC, while spins in C6, T8, and A3 have significantly higher order in GT compared to GC. Linear correlations between helical parameters of GC and GT and the order of C-1' and aromatic methine carbon atoms relate differences in internal dynamics to the structures quantitatively. The dynamic differences between the normal and mismatched DNA signify changes in local flexibility that may be exploited by the mismatch repair system to bind mismatched DNA preferentially while ignoring normal DNA.
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Affiliation(s)
- Richard J Isaacs
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536-0084, USA
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Isaacs RJ, Spielmann HP. NMR evidence for mechanical coupling of phosphate B(I)-B(II) transitions with deoxyribose conformational exchange in DNA. J Mol Biol 2001; 311:149-60. [PMID: 11469864 DOI: 10.1006/jmbi.2001.4855] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The conformational exchange of the phosphate and deoxyribose groups of the DNA oligomers d(GCGTACGC)(2) and d(CGCTAGCG)(2) have been investigated using a combination of homonuclear and heteronuclear NMR techniques. Two-state exchange between phosphate B(I) and B(II) conformations and deoxyribose N and S conformations was expressed as percent population of the major conformer, %B(I) or %S. Sequence context-dependent variations in %B(I) and %S were observed. The positions of the phosphate and deoxyribose equilibria provide a quantitative measure of the ps to ns timescale dynamic exchange processes in the DNA backbone. Linear correlations between %B(I), %S, and previously calculated model free (13)C order parameters (S(2)) were observed. The %B(I) of the phosphates were found to be correlated to the S(2) of the flanking C3' and C4' atoms. The %B(I) was also found to be correlated with the %S and C1' S(2) of the deoxyribose ring 5' of the phosphates. The %B(I) of opposing phosphates is correlated, while the %B(I) of sequential phosphates is anti-correlated. These correlations suggest that conformational exchange processes in DNA are coupled to each other and are modulated by DNA base sequence, which may have important implications for DNA-protein interactions.
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Affiliation(s)
- R J Isaacs
- Department of Molecular and Cellular Biochemistry Department of Chemistry, & Kentucky Center for Structural Biology, University of Kentucky, Lexington, KY 40536-0084, USA
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13
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Isaacs RJ, Spielmann HP. Relationship of DNA structure to internal dynamics: correlation of helical parameters from NOE-based NMR solution structures of d(GCGTACGC)(2) and d(CGCTAGCG)(2) with (13)C order parameters implies conformational coupling in dinucleotide units. J Mol Biol 2001; 307:525-40. [PMID: 11254380 DOI: 10.1006/jmbi.2001.4498] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The coupling between the conformational properties of double-stranded DNA and its internal dynamics has been examined. The solution structures of the isomeric DNA oligomers d(GCGTACGC)(2) (UM) and d(CGCTAGCG)(2) (CTSYM) were determined with (1)H NMR spectroscopy by utilizing distance restraints from total relaxation matrix analysis of NOESY cross-peak intensities in restrained molecular dynamics calculations. The root-mean-square deviation of the coordinates for the ensemble of structures was 0.13 A for UM and 0.49 A for CTSYM, with crystallographic equivalent R(c)=0.41 and 0.39 and sixth-root residual R(x)=0.11 and 0.10 for UM and CTSYM, respectively. Both UM and CTSYM are B-form with straight helical axes and show sequence-dependent variations in conformation. The internal dynamics of UM and CTSYM were previously determined by analysis of (13)C relaxation parameters in the context of the Lipari & Szabo model-free formalism. Helical parameters for the two DNA oligomers were examined for linear correlations with the order parameters (S(2)) of groups of (13)C spins in base-pairs and dinucleotide units of UM and CTSYM. Correlations were found for six interstrand base-pair parameters tip, y-displacement, inclination, buckle and stretch with various combinations of S(2) for atoms in Watson-Crick base-pairs and for two inter-base-pair parameters, rise and roll with various combinations of S(2) for atoms in dinucleotides. The correlations for the interstrand base-pair helical parameters indicate that the conformations of the deoxyribose residues of each strand are dynamically coupled. Also, the inter-base-pair separation has a profound effect on the local internal motions available to the DNA, supporting the idea that rise is a principal degree of freedom for DNA conformational variability. The correlations indicate collective atomic motions of spins that may represent specific motional modes in DNA, and that base sequence has a predictable effect on the relative order of groups of spins both in the bases and in the deoxyribose ring of the DNA backbone. These observations suggest that an important functional outcome of DNA base sequence is the modulation of both the conformation and dynamic behavior of the DNA backbone.
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Affiliation(s)
- R J Isaacs
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536-0084, USA
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14
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Khandelwal P, Panchal SC, Radha PK, Hosur RV. Solution structure and dynamics of GCN4 cognate DNA: NMR investigations. Nucleic Acids Res 2001; 29:499-505. [PMID: 11139620 PMCID: PMC29655 DOI: 10.1093/nar/29.2.499] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2000] [Revised: 10/23/2000] [Accepted: 11/01/2000] [Indexed: 11/13/2022] Open
Abstract
A 12 bp long GCN4-binding, self-complementary duplex DNA d(CATGACGTCATG)(2) has been investigated by NMR spectroscopy to study the structure and dynamics of the molecule in aqueous solution. The NMR structure of the DNA obtained using simulated annealing and iterative relaxation matrix calculations compares quite closely with the X-ray structure of ATF/CREB DNA in complex with GCN4 protein (DNA-binding domain). The DNA is also seen to be curved in the free state and this has a significant bearing on recognition by the protein. The dynamic characteristics of the molecule have been studied by (13)C relaxation measurements at natural abundance. A correlation has been observed between sequence-dependent dynamics and recognition by GCN4 protein.
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Affiliation(s)
- P Khandelwal
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India
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Naimushin AN, Fujimoto BS, Schurr JM. Dynamic bending rigidity of a 200-bp DNA in 4 mM ionic strength: a transient polarization grating study. Biophys J 2000; 78:1498-518. [PMID: 10692335 PMCID: PMC1300748 DOI: 10.1016/s0006-3495(00)76703-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
DNA may exhibit three different kinds of bends: 1) permanent bends; 2) slowly relaxing bends due to fluctuations in a prevailing equilibrium between differently curved secondary conformations; and 3) rapidly relaxing dynamic bends within a single potential-of-mean-force basin. The dynamic bending rigidity (kappa(d)), or equivalently the dynamic persistence length, P(d) = kappa(d)/k(B)T, governs the rapidly relaxing bends, which are responsible for the flexural dynamics of DNA on a short time scale, t < or = 10(-5) s. However, all three kinds of bends contribute to the total equilibrium persistence length, P(tot), according to 1/P(tot) congruent with 1/P(pb) + 1/P(sr) + 1/P(d), where P(pb) is the contribution of the permanent bends and P(sr) is the contribution of the slowly relaxing bends. Both P(d) and P(tot) are determined for the same 200-bp DNA in 4 mM ionic strength by measuring its optical anisotropy, r(t), from 0 to 10 micros. Time-resolved fluorescence polarization anisotropy (FPA) measurements yield r(t) for DNA/ethidium complexes (1 dye/200 bp) from 0 to 120 ns. A new transient polarization grating (TPG) experiment provides r(t) for DNA/methylene blue complexes (1 dye/100 bp) over a much longer time span, from 20 ns to 10 micros. Accurate data in the very tail of the decay enable a model-independent determination of the relaxation time (tau(R)) of the end-over-end tumbling motion, from which P(tot) = 500 A is estimated. The FPA data are used to obtain the best-fit pairs of P(d) and torsion elastic constant (alpha) values that fit those data equally well, and which are used to eliminate alpha as an independent variable. When the relevant theory is fitted to the entire TPG signal (S(t)), the end-over-end rotational diffusion coefficient is fixed at its measured value and alpha is eliminated in favor of P(d). Neither a true minimum in chi-squared nor a satisfactory fit could be obtained for P(d) anywhere in the range 500-5000 A, unless an adjustable amplitude of azimuthal wobble of the methylene blue was admitted. In that case, a well-defined global minimum and a reasonably good fit emerged at P(d) = 2000 A and <deltazeta(2)>(1/2) = 25 degrees. The discrimination against P(d) values <1600 A is very great. By combining the values, P(tot) = 500 A and P(d) = 2000 A with a literature estimate, P(pb) = 1370 A, a value P(sr) = 1300 A is estimated for the contribution of slowly relaxing bends. This value is analyzed in terms of a simple model in which the DNA is divided up into domains containing m bp, each of which experiences an all-or-none equilibrium between a straight and a uniformly curved conformation. With an appropriate estimate of the average bend angle per basepair of the curved conformation, a lower bound estimate, m = 55 bp, is obtained for the domain size of the coherently bent state. Previous measurements suggest that this coherent bend is not directional, or phase-locked, to the azimuthal orientation of the filament.
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Affiliation(s)
- A N Naimushin
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, USA
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