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Marton Menendez A, Nesbitt DJ. Thermodynamic compensation to temperature extremes in B. subtilis vs T. maritima lysine riboswitches. Biophys J 2024; 123:3331-3345. [PMID: 39091026 DOI: 10.1016/j.bpj.2024.07.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 06/17/2024] [Accepted: 07/29/2024] [Indexed: 08/04/2024] Open
Abstract
T. maritima and B. subtilis are bacteria that inhabit significantly different thermal environments, ∼80 vs. ∼40°C, yet employ similar lysine riboswitches to aid in the transcriptional regulation of the genes involved in the synthesis and transport of amino acids. Despite notable differences in G-C basepair frequency and primary sequence, the aptamer moieties of each riboswitch have striking similarities in tertiary structure, with several conserved motifs and long-range interactions. To explore genetic adaptation in extreme thermal environments, we compare the kinetic and thermodynamic behaviors in T. maritima and B. subtilis lysine riboswitches via single-molecule fluorescence resonance energy transfer analysis. Kinetic studies reveal that riboswitch folding rates increase with lysine concentration while the unfolding rates are independent of lysine. This indicates that both riboswitches bind lysine through an induced-fit ("bind-then-fold") mechanism, with lysine binding necessarily preceding conformational changes. Temperature-dependent van't Hoff studies reveal qualitative similarities in the thermodynamic landscapes for both riboswitches in which progression from the open, lysine-unbound state to both transition states (‡) and closed, lysine-bound conformations is enthalpically favored yet entropically penalized, with comparisons of enthalpic and entropic contributions extrapolated to a common [K+] = 100 mM in quantitative agreement. Finally, temperature-dependent Eyring analysis reveals the TMA and BSU riboswitches to have remarkably similar folding/unfolding rate constants when extrapolated to their respective (40 and 80°C) environmental temperatures. Such behavior suggests a shared strategy for ligand binding and aptamer conformational change in the two riboswitches, based on thermodynamic adaptations in number of G-C basepairs and/or modifications in tertiary structure that stabilize the ligand-unbound conformation to achieve biocompetence under both hyperthermophilic and mesothermophilic conditions.
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Affiliation(s)
- Andrea Marton Menendez
- JILA, University of Colorado Boulder and National Institute of Standards and Technology, Boulder, Colorado; Department of Chemistry, University of Colorado Boulder, Boulder, Colorado.
| | - David J Nesbitt
- JILA, University of Colorado Boulder and National Institute of Standards and Technology, Boulder, Colorado; Department of Chemistry, University of Colorado Boulder, Boulder, Colorado; Department of Physics, University of Colorado Boulder, Boulder, Colorado.
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2
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Rissone P, Severino A, Pastor I, Ritort F. Universal cold RNA phase transitions. Proc Natl Acad Sci U S A 2024; 121:e2408313121. [PMID: 39150781 PMCID: PMC11348302 DOI: 10.1073/pnas.2408313121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Accepted: 07/12/2024] [Indexed: 08/18/2024] Open
Abstract
RNA's diversity of structures and functions impacts all life forms since primordia. We use calorimetric force spectroscopy to investigate RNA folding landscapes in previously unexplored low-temperature conditions. We find that Watson-Crick RNA hairpins, the most basic secondary structure elements, undergo a glass-like transition below [Formula: see text]C where the heat capacity abruptly changes and the RNA folds into a diversity of misfolded structures. We hypothesize that an altered RNA biochemistry, determined by sequence-independent ribose-water interactions, outweighs sequence-dependent base pairing. The ubiquitous ribose-water interactions lead to universal RNA phase transitions below TG, such as maximum stability at [Formula: see text]C where water density is maximum, and cold denaturation at [Formula: see text]C. RNA cold biochemistry may have a profound impact on RNA function and evolution.
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Affiliation(s)
- Paolo Rissone
- Small Biosystems Lab, Condensed Matter Physics Department, Universitat de Barcelona, Barcelona 08028, Spain
| | - Aurélien Severino
- Small Biosystems Lab, Condensed Matter Physics Department, Universitat de Barcelona, Barcelona 08028, Spain
| | - Isabel Pastor
- Small Biosystems Lab, Condensed Matter Physics Department, Universitat de Barcelona, Barcelona 08028, Spain
| | - Felix Ritort
- Small Biosystems Lab, Condensed Matter Physics Department, Universitat de Barcelona, Barcelona 08028, Spain
- Institut de Nanociència i Nanotecnologia, Universitat de Barcelona, Barcelona 08028, Spain
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3
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Marcus AH, Matsika S, Heussman D, Sorour MI, Maurer J, Albrecht CS, Enkhbaatar L, Herbert P, Kistler KA, von Hippel PH. Spectroscopic approaches for studies of site-specific DNA base and backbone 'breathing' using exciton-coupled dimer-labeled DNA. ARXIV 2024:arXiv:2403.16251v2. [PMID: 38584614 PMCID: PMC10996769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
DNA regulation and repair processes require direct interactions between proteins and DNA at specific sites. Local fluctuations of the sugar-phosphate backbones and bases of DNA (a form of DNA 'breathing') play a central role in such processes. Here we review the development and application of novel spectroscopic methods and analyses - both at the ensemble and single-molecule levels - to study structural and dynamic properties of exciton-coupled cyanine and fluorescent nucleobase analogue dimer-labeled DNA constructs at key positions involved in protein-DNA complex assembly and function. The exciton-coupled dimer probes act as 'sensors' of the local conformations adopted by the sugar-phosphate backbones and bases immediately surrounding the dimer probes. These methods can be used to study the mechanisms of protein binding and function at these sites.
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Affiliation(s)
- Andrew H. Marcus
- Center for Optical, Molecular and Quantum Science, Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403
- Institute of Molecular Biology, Department of Chemistry and Biochemistry, and University of Oregon, Eugene, Oregon 97403
| | - Spiridoula Matsika
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122
| | - Dylan Heussman
- Center for Optical, Molecular and Quantum Science, Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403
- Institute of Molecular Biology, Department of Chemistry and Biochemistry, and University of Oregon, Eugene, Oregon 97403
| | - Mohammed I. Sorour
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122
| | - Jack Maurer
- Center for Optical, Molecular and Quantum Science, Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403
- Institute of Molecular Biology, Department of Chemistry and Biochemistry, and University of Oregon, Eugene, Oregon 97403
| | - Claire S. Albrecht
- Center for Optical, Molecular and Quantum Science, Department of Physics, University of Oregon, Eugene, Oregon 97403
- Institute of Molecular Biology, Department of Physics, and University of Oregon, Eugene, Oregon 97403
| | - Lulu Enkhbaatar
- Center for Optical, Molecular and Quantum Science, Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403
- Institute of Molecular Biology, Department of Chemistry and Biochemistry, and University of Oregon, Eugene, Oregon 97403
| | - Patrick Herbert
- Center for Optical, Molecular and Quantum Science, Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403
- Institute of Molecular Biology, Department of Chemistry and Biochemistry, and University of Oregon, Eugene, Oregon 97403
| | - Kurt A. Kistler
- Department of Chemistry, Brandywine Campus, The Pennsylvania State University, Media, Pennsylvania 19063
| | - Peter H. von Hippel
- Institute of Molecular Biology, Department of Chemistry and Biochemistry, and University of Oregon, Eugene, Oregon 97403
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4
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Nicholson DA, Nesbitt DJ. Kinetic and Thermodynamic Control of G-Quadruplex Polymorphism by Na + and K + Cations. J Phys Chem B 2023; 127:6842-6855. [PMID: 37504511 DOI: 10.1021/acs.jpcb.3c01001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
G-Quadruplexes (G4s) are ubiquitous nucleic acid folding motifs that exhibit structural diversity that is dependent on cationic conditions. In this work, we exploit temperature-controlled single-molecule fluorescence resonance energy transfer (smFRET) to elucidate the kinetic and thermodynamic mechanisms by which monovalent cations (K+ and Na+) impact folding topologies for a simple G-quadruplex sequence (5'-GGG-(TAAGGG)3-3') with a three-state folding equilibrium. Kinetic measurements indicate that Na+ and K+ influence G4 formation in two distinctly different ways: the presence of Na+ modestly enhances an antiparallel G4 topology through an induced fit (IF) mechanism with a low affinity (Kd = 228 ± 26 mM), while K+ drives G4 into a parallel/hybrid topology via a conformational selection (CS) mechanism with much higher affinity (Kd = 1.9 ± 0.2 mM). Additionally, temperature-dependent studies of folding rate constants and equilibrium ratios reveal distinctly different thermodynamic driving forces behind G4 binding to K+ (ΔH°bind > 0, ΔS°bind > 0) versus Na+ (ΔH°bind < 0, ΔS°bind < 0), which further illuminates the diversity of the possible pathways for monovalent facilitation of G-quadruplex folding.
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Affiliation(s)
- David A Nicholson
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, United States
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - David J Nesbitt
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, United States
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States
- Department of Physics, University of Colorado, Boulder, Colorado 80309, United States
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5
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Marcus AH, Heussman D, Maurer J, Albrecht CS, Herbert P, von Hippel PH. Studies of Local DNA Backbone Conformation and Conformational Disorder Using Site-Specific Exciton-Coupled Dimer Probe Spectroscopy. Annu Rev Phys Chem 2023; 74:245-265. [PMID: 36696590 PMCID: PMC10590263 DOI: 10.1146/annurev-physchem-090419-041204] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The processes of genome expression, regulation, and repair require direct interactions between proteins and DNA at specific sites located at and near single-stranded-double-stranded DNA (ssDNA-dsDNA) junctions. Here, we review the application of recently developed spectroscopic methods and analyses that combine linear absorbance and circular dichroism spectroscopy with nonlinear 2D fluorescence spectroscopy to study the local conformations and conformational disorder of the sugar-phosphate backbones of ssDNA-dsDNA fork constructs that have been internally labeled with exciton-coupled cyanine (iCy3)2 dimer probes. With the application of these methods, the (iCy3)2 dimer can serve as a reliable probe of the mean local conformations and conformational distributions of the sugar-phosphate backbones of dsDNA at various critical positions. The results of our studies suggest a possible structural framework for understanding the roles of DNA breathing in driving the processes of protein-DNA complex assembly and function.
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Affiliation(s)
- Andrew H Marcus
- Center for Optical, Molecular and Quantum Science, University of Oregon, Eugene, Oregon, USA;
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon, USA
- Department of Physics, University of Oregon, Eugene, Oregon, USA
| | - Dylan Heussman
- Center for Optical, Molecular and Quantum Science, University of Oregon, Eugene, Oregon, USA;
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon, USA
| | - Jack Maurer
- Center for Optical, Molecular and Quantum Science, University of Oregon, Eugene, Oregon, USA;
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon, USA
| | - Claire S Albrecht
- Center for Optical, Molecular and Quantum Science, University of Oregon, Eugene, Oregon, USA;
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
- Department of Physics, University of Oregon, Eugene, Oregon, USA
| | - Patrick Herbert
- Center for Optical, Molecular and Quantum Science, University of Oregon, Eugene, Oregon, USA;
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon, USA
| | - Peter H von Hippel
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon, USA
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6
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Yoo H, Davis CM. An in vitro cytomimetic of in-cell RNA folding. Chembiochem 2022; 23:e202200406. [PMID: 35999178 DOI: 10.1002/cbic.202200406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/21/2022] [Indexed: 11/07/2022]
Abstract
To discover the cytomimetic that accounts for cytoplasmic crowding and sticking on RNA stability, we conducted a two-dimensional scan of mixtures of artificial crowding and sticking agents, PEG10k and M-PERTM. As our model RNA, we investigate the fourU RNA thermometer motif of Salmonella, a hairpin-structured RNA that regulates translation by unfolding and exposing its RBS in response to temperature perturbations. We found that the addition of artificial crowding and sticking agents leads to a stabilization and destabilization of RNA folding, respectively, through the excluded volume effect and surface interactions. FRET-labels were added to the fourU RNA and Fast Relaxation Imaging (FReI), fluorescence microscopy coupled to temperature-jump spectroscopy, probed differences between folding stability of RNA inside single living cells and in vitro. Our results suggest that the cytoplasmic environment affecting RNA folding is comparable to a combination of 20% v/v M-PERTM and 150 g/L PEG10k.
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Affiliation(s)
- Hyejin Yoo
- Yale University, Chemistry, 225 Prospect St, 06511, New Haven, UNITED STATES
| | - Caitlin M Davis
- Yale University, Chemistry, 225 Prospect St., 06511, New Haven, UNITED STATES
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7
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Electro-conductive 3D printed polycaprolactone/gold nanoparticles nanocomposite scaffolds for myocardial tissue engineering. J Mech Behav Biomed Mater 2022; 132:105271. [DOI: 10.1016/j.jmbbm.2022.105271] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 05/07/2022] [Accepted: 05/11/2022] [Indexed: 12/13/2022]
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8
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Hennecker CD, Lachance-Brais C, Sleiman H, Mittermaier A. Using transient equilibria (TREQ) to measure the thermodynamics of slowly assembling supramolecular systems. SCIENCE ADVANCES 2022; 8:eabm8455. [PMID: 35385301 PMCID: PMC8985918 DOI: 10.1126/sciadv.abm8455] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 02/14/2022] [Indexed: 06/14/2023]
Abstract
Supramolecular chemistry involves the noncovalent assembly of monomers into materials with unique properties and wide-ranging applications. Thermal analysis is a key analytical tool in this field, as it provides quantitative thermodynamic information on both the structural stability and nature of the underlying molecular interactions. However, there exist many supramolecular systems whose kinetics are so slow that the thermodynamic methods currently applied are unreliable or fail completely. We have developed a simple and rapid spectroscopic method for extracting accurate thermodynamic parameters from these systems. It is based on repeatedly raising and lowering the temperature during assembly and identifying the points of transient equilibrium as they are passed on the up- and down-scans. In a proof-of-principle application to the coassembly of polydeoxyadenosine (polyA) containing 15 adenosines and cyanuric acid (CA), we found that roughly 30% of the CA binding sites on the polyA chains were unoccupied, with implications for high-valence systems.
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9
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Eskew MW, Benight AS. Equivalence of the transition heat capacities of proteins and DNA. Biochem Biophys Res Commun 2022; 597:98-101. [PMID: 35134611 DOI: 10.1016/j.bbrc.2022.01.129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Accepted: 01/31/2022] [Indexed: 01/18/2023]
Abstract
It has been reported for many globular proteins that the native heat capacity at 25 °C, per gram, is the same. This has been interpreted to indicate that heat capacity is a fundamental property of native proteins that provides important information on molecular structure and stability. Heat capacities for both proteins and DNA has been suggested to be related to universal effects of hydration/solvation on native structures. Here we report on results from thermal denaturation analysis of two well-known proteins, human serum albumin and lysozyme, and a short DNA hairpin. The transition heat capacities at the Tm for the three molecules were quantitatively evaluated by differential scanning calorimetry. When normalized per gram rather than per mol the transition heat capacities were found to be precisely equivalent. This observation for the transition heat capacities of the proteins is consistent with previous reports. However, an identical transition heat capacity for DNA has not been reported and was unexpected. Further analysis of the collected data suggested a mass dependence of hydration effects on thermal denaturation that is preserved at the individual protein amino acid and DNA base levels. Equivalence of transition heat capacities suggests the possibility of a universal role of hydration effects on the thermal stability of both proteins and DNA.
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Affiliation(s)
- Matthew W Eskew
- ThermoCap Laboratories Inc, Portland, OR, USA; Department of Chemistry, Portland State University, Portland, OR, USA.
| | - Albert S Benight
- ThermoCap Laboratories Inc, Portland, OR, USA; Department of Chemistry, Portland State University, Portland, OR, USA; Department of Physics, Portland State University, Portland, OR, USA
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10
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Heussman D, Kittell J, von Hippel PH, Marcus AH. Temperature-dependent local conformations and conformational distributions of cyanine dimer labeled single-stranded-double-stranded DNA junctions by 2D fluorescence spectroscopy. J Chem Phys 2022; 156:045101. [PMID: 35105081 PMCID: PMC9448411 DOI: 10.1063/5.0076261] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
DNA replication and the related processes of genome expression require binding, assembly, and function of protein complexes at and near single-stranded (ss)-double-stranded (ds) DNA junctions. These central protein-DNA interactions are likely influenced by thermally induced conformational fluctuations of the DNA scaffold across an unknown distribution of functionally relevant states to provide regulatory proteins access to properly conformed DNA binding sites. Thus, characterizing the nature of conformational fluctuations and the associated structural disorder at ss-dsDNA junctions is critical for understanding the molecular mechanisms of these central biological processes. Here, we describe spectroscopic studies of model ss-dsDNA fork constructs that contain dimers of "internally labeled" cyanine (iCy3) chromophore probes that have been rigidly inserted within the sugar-phosphate backbones of the DNA strands. Our combined analyses of absorbance, circular dichroism, and two-dimensional fluorescence spectroscopy permit us to characterize the local conformational parameters and conformational distributions. We find that the DNA sugar-phosphate backbones undergo abrupt successive changes in their local conformations-initially from a right-handed and ordered DNA state to a disordered splayed-open structure and then to a disordered left-handed conformation-as the dimer probes are moved across the ss-dsDNA junction. Our results suggest that the sugar-phosphate backbones at and near ss-dsDNA junctions adopt specific position-dependent local conformations and exhibit varying extents of conformational disorder that deviate widely from the Watson-Crick structure. We suggest that some of these conformations can function as secondary-structure motifs for interaction with protein complexes that bind to and assemble at these sites.
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Affiliation(s)
| | - Justin Kittell
- Center for Optical, Molecular and Quantum Science, Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403, USA
| | - Peter H. von Hippel
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, USA
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11
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Nicholson DA, Jia B, Nesbitt DJ. Measuring Excess Heat Capacities of Deoxyribonucleic Acid (DNA) Folding at the Single-Molecule Level. J Phys Chem B 2021; 125:9719-9726. [PMID: 34415161 DOI: 10.1021/acs.jpcb.1c05555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Measurements of the thermodynamic properties of biomolecular folding (ΔG°, ΔH°, ΔS°, etc.) provide a wealth of information on the folding process and have long played a central role in biophysical investigation. In particular, the excess heat capacity of folding (ΔCP) is crucial, as typically measured in bulk ensemble studies by differential scanning calorimetry (DSC) and isothermal titration calorimetry (ITC). Here, we report the first measurements of ΔCP at the single-molecule level using the single-molecule fluorescence resonance energy transfer (smFRET) as well as the very first measurements of the heat capacity change associated with achieving the transition state (ΔC‡P) for nucleic acid folding. The deoxyribonucleic acid (DNA) hairpin used in these studies exhibits an excess heat capacity for hybridization (ΔCP = -340 ± 60 J/mol/K per base pair) consistent with the range of literature expectations (ΔCP = -100 to -420 J/mol/K per base pair). Furthermore, the measured activation heat capacities (ΔC‡P) for such hairpin unfolding are consistent with a folding transition state containing few fully formed base pairs, in agreement with prevailing models of DNA hybridization.
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Affiliation(s)
- David A Nicholson
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, United States.,Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Bin Jia
- Department of Physics, University of Colorado, Boulder, Colorado 80309, United States
| | - David J Nesbitt
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, United States.,Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States.,Department of Physics, University of Colorado, Boulder, Colorado 80309, United States
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12
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Majikes JM, Patrone PN, Kearsley AJ, Zwolak M, Liddle JA. Failure Mechanisms in DNA Self-Assembly: Barriers to Single-Fold Yield. ACS NANO 2021; 15:3284-3294. [PMID: 33565312 PMCID: PMC11005093 DOI: 10.1021/acsnano.0c10114] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Understanding the folding process of DNA origami is a critical stepping stone to the broader implementation of nucleic acid nanofabrication technology but is notably nontrivial. Origami are formed by several hundred cooperative hybridization events-folds-between spatially separate domains of a scaffold, derived from a viral genome, and oligomeric staples. Individual events are difficult to detect. Here, we present a real-time probe of the unit operation of origami assembly, a single fold, across the scaffold as a function of hybridization domain separation-fold distance-and staple/scaffold ratio. This approach to the folding problem elucidates a predicted but previously unobserved blocked state that acts as a limit on yield for single folds, which may manifest as a barrier in whole origami assembly.
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Affiliation(s)
- Jacob M. Majikes
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6203, United States
| | - Paul N. Patrone
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6203, United States
| | - Anthony J. Kearsley
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6203, United States
| | - Michael Zwolak
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6203, United States
| | - J. Alexander Liddle
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6203, United States
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13
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Banerjee D, Tateishi-Karimata H, Ohyama T, Ghosh S, Endoh T, Takahashi S, Sugimoto N. Improved nearest-neighbor parameters for the stability of RNA/DNA hybrids under a physiological condition. Nucleic Acids Res 2020; 48:12042-12054. [PMID: 32663294 PMCID: PMC7708073 DOI: 10.1093/nar/gkaa572] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 07/09/2020] [Indexed: 12/17/2022] Open
Abstract
The stability of Watson–Crick paired RNA/DNA hybrids is important for designing optimal oligonucleotides for ASO (Antisense Oligonucleotide) and CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)–Cas9 techniques. Previous nearest-neighbour (NN) parameters for predicting hybrid stability in a 1 M NaCl solution, however, may not be applicable for predicting stability at salt concentrations closer to physiological condition (e.g. ∼100 mM Na+ or K+ in the presence or absence of Mg2+). Herein, we report measured thermodynamic parameters of 38 RNA/DNA hybrids at 100 mM NaCl and derive new NN parameters to predict duplex stability. Predicted ΔG°37 and Tm values based on the established NN parameters agreed well with the measured values with 2.9% and 1.1°C deviations, respectively. The new results can also be used to make precise predictions for duplexes formed in 100 mM KCl or 100 mM NaCl in the presence of 1 mM Mg2+, which can mimic an intracellular and extracellular salt condition, respectively. Comparisons of the predicted thermodynamic parameters with published data using ASO and CRISPR–Cas9 may allow designing shorter oligonucleotides for these techniques that will diminish the probability of non-specific binding and also improve the efficiency of target gene regulation.
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Affiliation(s)
- Dipanwita Banerjee
- FIBER (Frontier Institute for Biomolecular Engineering Research), Konan University, 7-1-20 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan
| | - Hisae Tateishi-Karimata
- FIBER (Frontier Institute for Biomolecular Engineering Research), Konan University, 7-1-20 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan
| | - Tatsuya Ohyama
- FIBER (Frontier Institute for Biomolecular Engineering Research), Konan University, 7-1-20 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan
| | - Saptarshi Ghosh
- FIBER (Frontier Institute for Biomolecular Engineering Research), Konan University, 7-1-20 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan
| | - Tamaki Endoh
- FIBER (Frontier Institute for Biomolecular Engineering Research), Konan University, 7-1-20 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan
| | - Shuntaro Takahashi
- FIBER (Frontier Institute for Biomolecular Engineering Research), Konan University, 7-1-20 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan
| | - Naoki Sugimoto
- FIBER (Frontier Institute for Biomolecular Engineering Research), Konan University, 7-1-20 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan.,FIRST (Graduate School of Frontiers of Innovative Research in Science and Technology), Konan University, 7-1-20 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan
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14
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Hadži S, Lah J. Origin of heat capacity increment in DNA folding: The hydration effect. Biochim Biophys Acta Gen Subj 2020; 1865:129774. [PMID: 33164852 DOI: 10.1016/j.bbagen.2020.129774] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 10/09/2020] [Accepted: 10/20/2020] [Indexed: 02/03/2023]
Abstract
BACKGROUND Understanding DNA folding thermodynamics is crucial for prediction of DNA thermal stability. It is now well established that DNA folding is accompanied by a decrease of the heat capacity ∆cp, F, however its molecular origin is not understood. In analogy to protein folding it has been assumed that this is due to dehydration of DNA constituents, however no evidence exists to support this conclusion. METHODS Here we analyze partial molar heat capacity of nucleic bases and nucleosides in aqueous solutions obtained from calorimetric experiments and calculate the hydration heat capacity contribution ∆cphyd. RESULTS We present hydration heat capacity contributions of DNA constituents and show that they correlate with the solvent accessible surface area. The average contribution for nucleic base dehydration is +0.56 J mol-1 K-1 Å-2 and can be used to estimate the ∆cp, F contribution for DNA folding. CONCLUSIONS We show that dehydration is one of the major sources contributing to the observed ∆cp, F increment in DNA folding. Other possible sources contributing to the overall ∆cp, F should be significant but appear to compensate each other to high degree. The calculated ∆cphyd for duplexes and noncanonical DNA structures agree excellently with the overall experimental ∆cp, F values. By contrast, empirical parametrizations developed for proteins result in poor ∆cphyd predictions and should not be applied to DNA folding. GENERAL SIGNIFICANCE Heat capacity is one of the main thermodynamic quantities that strongly affects thermal stability of macromolecules. At the molecular level the heat capacity in DNA folding stems from removal of water from nucleobases.
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Affiliation(s)
- S Hadži
- Department of Physical Chemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000 Ljubljana, Slovenia.
| | - J Lah
- Department of Physical Chemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000 Ljubljana, Slovenia.
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15
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Völker J, Plum GE, Breslauer KJ. Heat Capacity Changes (Δ Cp) for Interconversions between Differentially-Ordered DNA States within Physiological Temperature Domains: Implications for Biological Regulatory Switches. J Phys Chem B 2020; 124:5614-5625. [PMID: 32531155 DOI: 10.1021/acs.jpcb.0c04065] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Knowledge of differences in heat capacity changes (ΔCp) between biopolymer states provides essential information about the temperature dependence of the thermodynamic properties of these states, while also revealing insights into the nature of the forces that drive the formation of functional and dysfunctional biopolymer "order." In contrast to proteins, for nucleic acids there is a dearth of direct experimental determination of this information-rich parameter, a deficiency that compromises interpretations of the ever-increasing thermodynamic analyses of nucleic acid properties; particularly as they relate to differential nucleic acid (meta)stability states and their potential biological functions. Here we demonstrate that such heat capacity differences, in fact, exist not only between traditionally measured native to fully unfolded (assumed "random coil") DNA states, but also between competing order-to-order transformations. We illustrate the experimental approach by measuring the heat capacity change between "native"/ordered, sequence homologous, "isomeric" DNA states that differ in conformation but not sequence. Importantly, these heat capacity differences occur within biologically relevant temperature ranges. In short, we describe a new and general method to measure the value of such heat capacity differences anywhere in experimentally accessible conformational and temperature space; in this case, between two metastable bulge loop states, implicated in DNA expansion diseases, and their competing, fully paired, thermodynamically more stable duplex states. This measurement reveals a ΔCp of 61 ± 7 cal molbp -1 K -1. Such heat capacity differences between competing DNA "native" ensemble states must be considered when evaluating equilibria between different DNA "ordered" conformations, including the assessment of the differential stabilizing forces and potential biological functions of competing DNA "structured" motifs.
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Affiliation(s)
- Jens Völker
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 610 Taylor Road, Piscataway, New Jersey 08854, United States
| | - G Eric Plum
- UNICON International, Inc. 241 Outerbelt Street, Columbus, Ohio 43213, United States
| | - Kenneth J Breslauer
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 610 Taylor Road, Piscataway, New Jersey 08854, United States.,The Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08901, United States
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16
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Structural Insights into RNA Dimerization: Motifs, Interfaces and Functions. Molecules 2020; 25:molecules25122881. [PMID: 32585844 PMCID: PMC7357161 DOI: 10.3390/molecules25122881] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 06/18/2020] [Accepted: 06/19/2020] [Indexed: 12/26/2022] Open
Abstract
In comparison with the pervasive use of protein dimers and multimers in all domains of life, functional RNA oligomers have so far rarely been observed in nature. Their diminished occurrence contrasts starkly with the robust intrinsic potential of RNA to multimerize through long-range base-pairing ("kissing") interactions, self-annealing of palindromic or complementary sequences, and stable tertiary contact motifs, such as the GNRA tetraloop-receptors. To explore the general mechanics of RNA dimerization, we performed a meta-analysis of a collection of exemplary RNA homodimer structures consisting of viral genomic elements, ribozymes, riboswitches, etc., encompassing both functional and fortuitous dimers. Globally, we found that domain-swapped dimers and antiparallel, head-to-tail arrangements are predominant architectural themes. Locally, we observed that the same structural motifs, interfaces and forces that enable tertiary RNA folding also drive their higher-order assemblies. These feature prominently long-range kissing loops, pseudoknots, reciprocal base intercalations and A-minor interactions. We postulate that the scarcity of functional RNA multimers and limited diversity in multimerization motifs may reflect evolutionary constraints imposed by host antiviral immune surveillance and stress sensing. A deepening mechanistic understanding of RNA multimerization is expected to facilitate investigations into RNA and RNP assemblies, condensates, and granules and enable their potential therapeutical targeting.
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17
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Majikes JM, Patrone PN, Schiffels D, Zwolak M, Kearsley AJ, Forry SP, Liddle JA. Revealing thermodynamics of DNA origami folding via affine transformations. Nucleic Acids Res 2020; 48:5268-5280. [PMID: 32347943 PMCID: PMC7261180 DOI: 10.1093/nar/gkaa283] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 04/07/2020] [Accepted: 04/28/2020] [Indexed: 01/25/2023] Open
Abstract
Structural DNA nanotechnology, as exemplified by DNA origami, has enabled the design and construction of molecularly-precise objects for a myriad of applications. However, limitations in imaging, and other characterization approaches, make a quantitative understanding of the folding process challenging. Such an understanding is necessary to determine the origins of structural defects, which constrain the practical use of these nanostructures. Here, we combine careful fluorescent reporter design with a novel affine transformation technique that, together, permit the rigorous measurement of folding thermodynamics. This method removes sources of systematic uncertainty and resolves problems with typical background-correction schemes. This in turn allows us to examine entropic corrections associated with folding and potential secondary and tertiary structure of the scaffold. Our approach also highlights the importance of heat-capacity changes during DNA melting. In addition to yielding insight into DNA origami folding, it is well-suited to probing fundamental processes in related self-assembling systems.
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Affiliation(s)
- Jacob M Majikes
- National Institute of Standards and Technology, Gaithersburg, MD 20899-6203, USA
| | - Paul N Patrone
- National Institute of Standards and Technology, Gaithersburg, MD 20899-6203, USA
| | - Daniel Schiffels
- National Institute of Standards and Technology, Gaithersburg, MD 20899-6203, USA
| | - Michael Zwolak
- National Institute of Standards and Technology, Gaithersburg, MD 20899-6203, USA
| | - Anthony J Kearsley
- National Institute of Standards and Technology, Gaithersburg, MD 20899-6203, USA
| | - Samuel P Forry
- National Institute of Standards and Technology, Gaithersburg, MD 20899-6203, USA
| | - J Alexander Liddle
- National Institute of Standards and Technology, Gaithersburg, MD 20899-6203, USA
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18
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Wang S, Sha X, Yu S, Zhao Y. Nanocalorimeters for biomolecular analysis and cell metabolism monitoring. BIOMICROFLUIDICS 2020; 14:011503. [PMID: 32038739 PMCID: PMC6994269 DOI: 10.1063/1.5134870] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 01/10/2020] [Indexed: 05/28/2023]
Abstract
Nanocalorimeters, or microfabricated calorimeters, provide a promising way to characterize the thermal process of biological processes, such as biomolecule interactions and cellular metabolic activities. They enabled miniaturized heat measurement onto a chip device with potential benefits including low sample consumption, low cost, portability, and high throughput. Over the past few decades, researchers have tried to improve nanocalorimeters' performance, in terms of sensitivity, accuracy, and detection resolution, by exploring different sensing methods, thermal insulation techniques, and liquid handling methods. The enhanced devices resulted in new applications in recent years, and here we have summarized the performance parameters and applications based on categories. Finally, we have listed the current technical difficulties in nanocalorimeter research and hope for future solutions to overcome them.
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Affiliation(s)
- Shuyu Wang
- Department of Control Engineering, Northeastern University, Qinhuangdao, Hebei 066001, People’s Republic of China
| | - Xiaopeng Sha
- Department of Control Engineering, Northeastern University, Qinhuangdao, Hebei 066001, People’s Republic of China
| | - Shifeng Yu
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA
| | - Yuliang Zhao
- Department of Control Engineering, Northeastern University, Qinhuangdao, Hebei 066001, People’s Republic of China
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19
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Ghosh S, Takahashi S, Endoh T, Tateishi-Karimata H, Hazra S, Sugimoto N. Validation of the nearest-neighbor model for Watson-Crick self-complementary DNA duplexes in molecular crowding condition. Nucleic Acids Res 2019; 47:3284-3294. [PMID: 30753582 PMCID: PMC6468326 DOI: 10.1093/nar/gkz071] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 01/21/2019] [Accepted: 01/29/2019] [Indexed: 01/03/2023] Open
Abstract
Recent advancement in nucleic acid techniques inside cells demands the knowledge of the stability of nucleic acid structures in molecular crowding. The nearest-neighbor model has been successfully used to predict thermodynamic parameters for the formation of nucleic acid duplexes, with significant accuracy in a dilute solution. However, knowledge about the applicability of the model in molecular crowding is still limited. To determine and predict the stabilities of DNA duplexes in a cell-like crowded environment, we systematically investigated the validity of the nearest-neighbor model for Watson–Crick self-complementary DNA duplexes in molecular crowding. The thermodynamic parameters for the duplex formation were measured in the presence of 40 wt% poly(ethylene glycol)200 for different self-complementary DNA oligonucleotides consisting of identical nearest-neighbors in a physiological buffer containing 0.1 M NaCl. The thermodynamic parameters as well as the melting temperatures (Tm) obtained from the UV melting studies revealed similar values for the oligonucleotides having identical nearest-neighbors, suggesting the validity of the nearest-neighbor model in the crowding condition. Linear relationships between the measured ΔG°37 and Tm in crowding condition and those predicted in dilute solutions allowed us to predict ΔG°37, Tm and nearest-neighbor parameters in molecular crowding using existing parameters in the dilute condition, which provides useful information about the thermostability of the self-complementary DNA duplexes in molecular crowding.
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Affiliation(s)
- Saptarshi Ghosh
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 7-1-20 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan
| | - Shuntaro Takahashi
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 7-1-20 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan
| | - Tamaki Endoh
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 7-1-20 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan
| | - Hisae Tateishi-Karimata
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 7-1-20 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan
| | - Soumitra Hazra
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 7-1-20 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan
| | - Naoki Sugimoto
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 7-1-20 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan.,Graduate School of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, 7-1-20 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan
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20
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Spasic A, Berger KD, Chen JL, Seetin MG, Turner DH, Mathews DH. Improving RNA nearest neighbor parameters for helices by going beyond the two-state model. Nucleic Acids Res 2019; 46:4883-4892. [PMID: 29718397 PMCID: PMC6007268 DOI: 10.1093/nar/gky270] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 04/22/2018] [Indexed: 12/31/2022] Open
Abstract
RNA folding free energy change nearest neighbor parameters are widely used to predict folding stabilities of secondary structures. They were determined by linear regression to datasets of optical melting experiments on small model systems. Traditionally, the optical melting experiments are analyzed assuming a two-state model, i.e. a structure is either complete or denatured. Experimental evidence, however, shows that structures exist in an ensemble of conformations. Partition functions calculated with existing nearest neighbor parameters predict that secondary structures can be partially denatured, which also directly conflicts with the two-state model. Here, a new approach for determining RNA nearest neighbor parameters is presented. Available optical melting data for 34 Watson–Crick helices were fit directly to a partition function model that allows an ensemble of conformations. Fitting parameters were the enthalpy and entropy changes for helix initiation, terminal AU pairs, stacks of Watson–Crick pairs and disordered internal loops. The resulting set of nearest neighbor parameters shows a 38.5% improvement in the sum of residuals in fitting the experimental melting curves compared to the current literature set.
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Affiliation(s)
- Aleksandar Spasic
- Department of Biochemistry & Biophysics, University of Rochester Medical Center, Rochester, NY 14642, USA.,Center for RNA Biology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Kyle D Berger
- Department of Biochemistry & Biophysics, University of Rochester Medical Center, Rochester, NY 14642, USA.,Center for RNA Biology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Jonathan L Chen
- Center for RNA Biology, University of Rochester Medical Center, Rochester, NY 14642, USA.,Department of Chemistry, University of Rochester, Rochester, NY 14627, USA
| | - Matthew G Seetin
- Department of Biochemistry & Biophysics, University of Rochester Medical Center, Rochester, NY 14642, USA.,Center for RNA Biology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Douglas H Turner
- Center for RNA Biology, University of Rochester Medical Center, Rochester, NY 14642, USA.,Department of Chemistry, University of Rochester, Rochester, NY 14627, USA
| | - David H Mathews
- Department of Biochemistry & Biophysics, University of Rochester Medical Center, Rochester, NY 14642, USA.,Center for RNA Biology, University of Rochester Medical Center, Rochester, NY 14642, USA.,Department of Biostatistics & Computational Biology, University of Rochester Medical Center, Rochester, NY 14642, USA
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21
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Sato T, Sakamoto N, Nishizawa S. Kinetic and thermodynamic analysis of triplex formation between peptide nucleic acid and double-stranded RNA. Org Biomol Chem 2019; 16:1178-1187. [PMID: 29376179 DOI: 10.1039/c7ob02912h] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Kinetics and thermodynamics of triplex formation between 9-mer homopyrimidine PNA (H2N-Lys-TCTCCTCCC-CONH2) and double-stranded RNA (dsRNA, 5'-AGAGGAGGG-3'/3'-UCUCCUCCC-5') at acidic pH were studied by means of a stopped-flow technique and isothermal titration calorimetry (ITC). These results revealed the following main findings: (i) the stable PNA-dsRNA triplex formation mostly originated from the large association rate constant (kon), which was dominated by both the charge neutral PNA backbone and the protonation level of the PNA cytosine. (ii) The temperature dependence of the enthalpy change (ΔH) and kon suggested that the association phase of the PNA-dsRNA triplex formation comprised a non-directional nucleation-zipping mechanism that was coupled with the conformational transition of the unbound PNA. (iii) The destabilization by a mismatch in the dsRNA sequence mainly resulted from the decreased magnitude of both kon and ΔH. (iv) There was sequence and position dependence of the mismatch on ΔH and the activation energy (Eon), which illustrated the importance of base pairing in the middle of the sequence. Our results for the first time revealed an association mechanism for the PNA-dsRNA triplex formation. A set of the kinetic and thermodynamic data we reported here will also expand the scope of understanding for nucleic acid recognition by PNA.
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Affiliation(s)
- Takaya Sato
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
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22
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Jasiński M, Kulik M, Wojciechowska M, Stolarski R, Trylska J. Interactions of 2'-O-methyl oligoribonucleotides with the RNA models of the 30S subunit A-site. PLoS One 2018; 13:e0191138. [PMID: 29351348 PMCID: PMC5774723 DOI: 10.1371/journal.pone.0191138] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Accepted: 12/28/2017] [Indexed: 12/15/2022] Open
Abstract
Synthetic oligonucleotides targeting functional regions of the prokaryotic rRNA could be promising antimicrobial agents. Indeed, such oligonucleotides were proven to inhibit bacterial growth. 2’-O-methylated (2’-O-Me) oligoribonucleotides with a sequence complementary to the decoding site in 16S rRNA were reported as inhibitors of bacterial translation. However, the binding mode and structures of the formed complexes, as well as the level of selectivity of the oligonucleotides between the prokaryotic and eukaryotic target, were not determined. We have analyzed three 2’-O-Me oligoribonucleotides designed to hybridize with the models of the prokaryotic rRNA containing two neighboring aminoglycoside binding pockets. One pocket is the paromomycin/kanamycin binding site corresponding to the decoding site in the small ribosomal subunit and the other one is the close-by hygromycin B binding site whose dynamics has not been previously reported. Molecular dynamics (MD) simulations, as well as isothermal titration calorimetry, gel electrophoresis and spectroscopic studies have shown that the eukaryotic rRNA model is less conformationally stable (in terms of hydrogen bonds and stacking interactions) than the corresponding prokaryotic one. In MD simulations of the eukaryotic construct, the nucleotide U1498, which plays an important role in correct positioning of mRNA during translation, is flexible and spontaneously flips out into the solvent. In solution studies, the 2’-O-Me oligoribonucleotides did not interact with the double stranded rRNA models but all formed stable complexes with the single-stranded prokaryotic target. 2’-O-Me oligoribonucleotides with one and two mismatches bound less tightly to the eukaryotic target. This shows that at least three mismatches between the 2’-O-Me oligoribonucleotide and eukaryotic rRNA are required to ensure target selectivity. The results also suggest that, in the ribosome environment, the strand invasion is the preferred binding mode of 2’-O-Me oligoribonucleotides targeting the aminoglycoside binding sites in 16S rRNA.
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Affiliation(s)
- Maciej Jasiński
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
- College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, University of Warsaw, Warsaw, Poland
| | - Marta Kulik
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
| | | | - Ryszard Stolarski
- Department of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland
| | - Joanna Trylska
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
- * E-mail:
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23
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White NA, Hoogstraten CG. Thermodynamics and kinetics of RNA tertiary structure formation in the junctionless hairpin ribozyme. Biophys Chem 2017; 228:62-68. [PMID: 28710920 PMCID: PMC5572644 DOI: 10.1016/j.bpc.2017.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 06/24/2017] [Accepted: 07/02/2017] [Indexed: 11/15/2022]
Abstract
The hairpin ribozyme consists of two RNA internal loops that interact to form the catalytically active structure. This docking transition is a rare example of intermolecular formation of RNA tertiary structure without coupling to helix annealing. We have used temperature-dependent surface plasmon resonance (SPR) to characterize the thermodynamics and kinetics of RNA tertiary structure formation for the junctionless form of the ribozyme, in which loops A and B reside on separate molecules. We find docking to be strongly enthalpy-driven and to be accompanied by substantial activation barriers for association and dissociation, consistent with the structural reorganization of both internal loops upon complex formation. Comparisons with the parallel analysis of a ribozyme variant carrying a 2'-O-methyl modification at the self-cleavage site and with published data in other systems reveal a surprising diversity of thermodynamic signatures, emphasizing the delicate balance of contributions to the free energy of formation of RNA tertiary structure.
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Affiliation(s)
- Neil A White
- Department of Biochemistry and Molecular Biology, 603 Wilson Road, Room 302D, Michigan State University, East Lansing, MI 48824, USA
| | - Charles G Hoogstraten
- Department of Biochemistry and Molecular Biology, 603 Wilson Road, Room 302D, Michigan State University, East Lansing, MI 48824, USA.
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24
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Aslanyan L, Ko J, Kim BG, Vardanyan I, Dalyan YB, Chalikian TV. Effect of Urea on G-Quadruplex Stability. J Phys Chem B 2017; 121:6511-6519. [DOI: 10.1021/acs.jpcb.7b03479] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lusine Aslanyan
- Department
of Molecular Physics, Faculty of Physics, Yerevan State University, 1 Alex Manoogian Street, Yerevan 375025, Armenia
| | - Jordan Ko
- Department
of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - Byul G. Kim
- Department
of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - Ishkhan Vardanyan
- Department
of Molecular Physics, Faculty of Physics, Yerevan State University, 1 Alex Manoogian Street, Yerevan 375025, Armenia
| | - Yeva B. Dalyan
- Department
of Molecular Physics, Faculty of Physics, Yerevan State University, 1 Alex Manoogian Street, Yerevan 375025, Armenia
| | - Tigran V. Chalikian
- Department
of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
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25
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Chiang HC, Levicky R. Effects of Chain-Chain Associations on Hybridization in DNA Brushes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:12603-12610. [PMID: 27934512 DOI: 10.1021/acs.langmuir.6b02990] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Hybridization of solution nucleic acids to DNA brushes is widely encountered in diagnostic and materials science applications. Typically, brush chain lengths of ten or more nucleotides are used to provide the needed sequence specificity and binding affinity. At these lengths, coincidental occurrence of complementary regions is expected to lead to associations between the nominally single-stranded brush chains due to intra- or interchain base pairing. This report investigates how these associations impact the brushes' hybridization activity toward complementary "target" sequences. Brushes were prepared from 20-mer chains with four-nucleotide-long "adhesive regions" through which neighboring chains could interact. The affinity and position of the adhesive region along the chain backbone were varied. DNA brushes were exposed to complementary solution targets, and the corresponding melting transitions were measured to estimate free energies of the brush-target hybridization. These results revealed that higher affinity adhesive regions more extensively suppressed brush hybridization relative to hybridization in solution. Associations near the middle of the chains were found to be more penalizing than those at the immobilized or the free end of the chains. Provided that the brush chains were close enough to associate, changes in brush density did not exert a significant effect on hybridization thermodynamics within the investigated coverage window. Comparison of the DNA brush results with those from commercial Affymetrix single-nucleotide-polymorphism (SNP) microarrays revealed agreement in the impact of chain associations on hybridization.
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Affiliation(s)
- Hao-Chun Chiang
- Department of Chemical and Biomolecular Engineering, New York University Tandon School of Engineering , 6 Metrotech Center, Brooklyn, New York 11201, United States
| | - Rastislav Levicky
- Department of Chemical and Biomolecular Engineering, New York University Tandon School of Engineering , 6 Metrotech Center, Brooklyn, New York 11201, United States
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26
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Nguyen JC, Dzowo YK, Wolfbrandt C, Townsend J, Kukatin S, Wang H, Resendiz MJE. Synthesis, Thermal Stability, Biophysical Properties, and Molecular Modeling of Oligonucleotides of RNA Containing 2'-O-2-Thiophenylmethyl Groups. J Org Chem 2016; 81:8947-8958. [PMID: 27584708 DOI: 10.1021/acs.joc.6b01615] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Dodecamers of RNA [CUACGGAAUCAU] were functionalized with C2'-O-2-thiophenylmethyl groups to obtain oligonucleotides 10-14 and 17. The modified nucleotides were incorporated into RNA strands via solid-phase synthesis. The biophysical properties of these ONs were used to quantify the effects of this modification on RNA:RNA and RNA:DNA duplexes. A combination of UV-vis and circular dichroism were used to determine thermal stabilities of all strands, which hybridized into A-form geometries. Destabilization of the double stranded RNA was measured as a function of number of consecutive modifications, reflected in decreased thermal denaturation values (ΔTm, ca. 2.5-11.5 °C). Van't Hoff plots on a duplex containing one modification (10:15) displayed a ca. ΔΔG° of +4 kcal/mol with respect to its canonical analogue. Interestingly, hybridization of two modified strands (13:17, containing a total of eight modifications) resulted in increased stability and a distinct secondary structure, reflected in its CD spectrum. Molecular modeling based on DFT calculations shed light on the nature of this stability, with induced changes in the torsional angle δ (C5'-C4'-C3'-O3) and phosphate-phosphate distances that are in agreement with a compacted structure. The described synthetic methodology and structural information will be useful in the design of thermodynamically stable structures containing chemically reactive modifications.
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Affiliation(s)
- Joseph C Nguyen
- Department of Chemistry, University of Colorado Denver , Science Building 1151 Arapahoe Street, Denver, Colorado 80204, United States
| | - Yannick Kokouvi Dzowo
- Department of Chemistry, University of Colorado Denver , Science Building 1151 Arapahoe Street, Denver, Colorado 80204, United States
| | - Carly Wolfbrandt
- Department of Chemistry, University of Colorado Denver , Science Building 1151 Arapahoe Street, Denver, Colorado 80204, United States
| | - Justin Townsend
- Department of Chemistry, University of Colorado Denver , Science Building 1151 Arapahoe Street, Denver, Colorado 80204, United States
| | - Stanislav Kukatin
- Department of Chemistry, University of Colorado Denver , Science Building 1151 Arapahoe Street, Denver, Colorado 80204, United States
| | - Haobin Wang
- Department of Chemistry, University of Colorado Denver , Science Building 1151 Arapahoe Street, Denver, Colorado 80204, United States
| | - Marino J E Resendiz
- Department of Chemistry, University of Colorado Denver , Science Building 1151 Arapahoe Street, Denver, Colorado 80204, United States
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27
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Kilburn D, Behrouzi R, Lee HT, Sarkar K, Briber RM, Woodson SA. Entropic stabilization of folded RNA in crowded solutions measured by SAXS. Nucleic Acids Res 2016; 44:9452-9461. [PMID: 27378777 PMCID: PMC5100557 DOI: 10.1093/nar/gkw597] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 06/21/2016] [Indexed: 01/29/2023] Open
Abstract
Non-coding RNAs must fold into specific structures that are stabilized by metal ions and other co-solutes in the cell's interior. Large crowder molecules such as PEG stabilize a bacterial group I ribozyme so that the RNA folds in low Mg2+ concentrations typical of the cell's interior. To understand the thermodynamic origins of stabilization by crowder molecules, small angle X-ray scattering was used to measure the folding and helix assembly of a bacterial group I ribozyme at different temperatures and in different MgCl2 and polyethylene glycol (PEG) concentrations. The resulting phase diagrams show that perturbations to folding by each variable do not overlap. A favorable enthalpy change drives the formation of compact, native-like structures, but requires Mg2+ ions at all temperatures studied (5–55°C). PEG reduces the entropic cost of helix assembly and increases correlations between RNA segments at all temperatures. The phase diagrams also revealed a semi-compact intermediate between the unfolded and folded ensemble that is locally more flexible than the unfolded state, as judged by SHAPE modification. These results suggest that environmental variables such as temperature and solute density will favor different types of RNA structures.
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Affiliation(s)
- Duncan Kilburn
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Reza Behrouzi
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Hui-Ting Lee
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Krishnarjun Sarkar
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Robert M Briber
- Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742, USA
| | - Sarah A Woodson
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
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Minetti CASA, Remeta DP, Iden CR, Johnson F, Grollman AP, Breslauer KJ. Impact of thymine glycol damage on DNA duplex energetics: Correlations with lesion-induced biochemical and structural consequences. Biopolymers 2016; 103:491-508. [PMID: 25991500 DOI: 10.1002/bip.22680] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 05/08/2015] [Accepted: 05/12/2015] [Indexed: 11/08/2022]
Abstract
The magnitude and nature of lesion-induced energetic perturbations empirically correlate with mutagenicity/cytotoxicity profiles and can be predictive of lesion outcomes during polymerase-mediated replication in vitro. In this study, we assess the sequence and counterbase-dependent energetic impact of the Thymine glycol (Tg) lesion on a family of deoxyoligonucleotide duplexes. Tg damage arises from thymine and methyl-cytosine exposure to oxidizing agents or radiation-generated free-radicals. The Tg lesion blocks polymerase-mediated DNA replication in vitro and the unrepaired site elicits cytotoxic lethal consequences in vivo. Our combined calorimetric and spectroscopic characterization correlates Tg -induced energetic perturbations with biological and structural properties. Specifically, we incorporate a 5R-Tg isomer centered within the tridecanucleotide sequence 5'-GCGTACXCATGCG-3' (X = Tg or T) which is hybridized with the corresponding complementary sequence 5'-CGCATGNGTACGC-3' (N = A, G, T, C) to generate families of Tg -damaged (Tg ·N) and lesion-free (T·N) duplexes. We demonstrate that the magnitude and nature of the Tg destabilizing impact is dependent on counterbase identity (i.e., A ∼ G < T < C). The observation that a Tg lesion is less destabilizing when positioned opposite purines suggests that favorable counterbase stacking interactions may partially compensate lesion-induced perturbations. Moreover, the destabilizing energies of Tg ·N duplexes parallel their respective lesion-free T·N mismatch counterparts (i.e., G < T < C). Elucidation of Tg-induced destabilization relative to the corresponding undamaged mismatch energetics allows resolution of lesion-specific and sequence-dependent impacts. The Tg-induced energetic perturbations are consistent with its replication blocking properties and may serve as differential recognition elements for discrimination by the cellular repair machinery.
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Affiliation(s)
- Conceição A S A Minetti
- Department of Chemistry and Chemical Biology, Rutgers - The State University of New Jersey, Piscataway, NJ, 08854
| | - David P Remeta
- Department of Chemistry and Chemical Biology, Rutgers - The State University of New Jersey, Piscataway, NJ, 08854
| | - Charles R Iden
- Department of Pharmacological Sciences, School of Medicine, Stony Brook University, Stony Brook, NY, 11794
| | - Francis Johnson
- Department of Pharmacological Sciences, School of Medicine, Stony Brook University, Stony Brook, NY, 11794
| | - Arthur P Grollman
- Department of Pharmacological Sciences, School of Medicine, Stony Brook University, Stony Brook, NY, 11794
| | - Kenneth J Breslauer
- Department of Chemistry and Chemical Biology, Rutgers - The State University of New Jersey, Piscataway, NJ, 08854.,Rutgers Cancer Institute of New Jersey, New Brunswick, NJ, 08901
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29
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Chauca-Diaz AM, Choi YJ, Resendiz MJE. Biophysical properties and thermal stability of oligonucleotides of RNA containing 7,8-dihydro-8-hydroxyadenosine. Biopolymers 2016; 103:167-74. [PMID: 25363418 PMCID: PMC4302245 DOI: 10.1002/bip.22579] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Revised: 10/22/2014] [Accepted: 10/22/2014] [Indexed: 12/14/2022]
Abstract
Circular dichroism (CD) was used to assess the stabilization/destabilization imposed by oxidative lesion 7,8-dihydro-8-hydroxyadenosine (8-oxoA) on strands of RNA with different structural motifs. RNA:RNA homoduplex destabilization was observed in a position dependent manner using 10-mers as models that displayed differences between 12.7 and 15.1°C. We found that increasing the number of modifications resulted in depressed Tm values of about 12-15°C per lesion. The same effect was observed on RNA:DNA heteroduplex samples. We also tested the effects of this lesion in short hairpins containing the tetraloop UUCX (X = A, 8-oxoA). We found that the stem was hypersensitive to substitution of A by 8-oxoA and that it destabilized the structure by >23°C. Concomitant substitution at the stem and loop prevented formation of this secondary structure or lead to other less-stable hairpins. Incorporation of this lesion at the first base of the loop had no effect on either structure. Overall, we found that the effects of 8-oxoA on RNA structure are position dependent and that its stabilization may vary from sharp decreases to small increments, in some cases, leading to the formation of other more/less stable structures. These structural changes may have larger biological implications, particularly if the oxidatively modified RNA persists, thus leading to changes in RNA reactivity and function.
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Affiliation(s)
- Ana M Chauca-Diaz
- Department of Chemistry, University of Colorado Denver, Science Building, 1151 Arapahoe St, Denver, CO, 80204
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30
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Tetracycline determines the conformation of its aptamer at physiological magnesium concentrations. Biophys J 2016; 107:2962-2971. [PMID: 25517161 DOI: 10.1016/j.bpj.2014.11.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 10/16/2014] [Accepted: 11/03/2014] [Indexed: 12/12/2022] Open
Abstract
Synthetic riboswitches are versatile tools for the study and manipulation of biological systems. Yet, the underlying mechanisms governing its structural properties and regulation under physiological conditions are poorly studied. We performed spectroscopic and calorimetric experiments to explore the folding kinetics and thermodynamics of the tetracycline-binding aptamer, which can be employed as synthetic riboswitch, in the range of physiological magnesium concentrations. The dissociation constant of the ligand-aptamer complex was found to strongly depend on the magnesium concentration. At physiological magnesium concentrations, tetracycline induces a significant conformational shift from a compact, but heterogeneous intermediate state toward the completely formed set of tertiary interactions defining the regulation-competent structure. Thus, the switching functionality of the tetracycline-binding aptamer appears to include both a conformational rearrangement toward the regulation-competent structure and its thermodynamic stabilization.
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31
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Vaitiekunas P, Crane-Robinson C, Privalov PL. The energetic basis of the DNA double helix: a combined microcalorimetric approach. Nucleic Acids Res 2015; 43:8577-89. [PMID: 26304541 PMCID: PMC4787831 DOI: 10.1093/nar/gkv812] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 07/24/2015] [Accepted: 07/28/2015] [Indexed: 12/23/2022] Open
Abstract
Microcalorimetric studies of DNA duplexes and their component single strands showed that association enthalpies of unfolded complementary strands into completely folded duplexes increase linearly with temperature and do not depend on salt concentration, i.e. duplex formation results in a constant heat capacity decrement, identical for CG and AT pairs. Although duplex thermostability increases with CG content, the enthalpic and entropic contributions of an AT pair to duplex formation exceed that of a CG pair when compared at the same temperature. The reduced contribution of AT pairs to duplex stabilization comes not from their lower enthalpy, as previously supposed, but from their larger entropy contribution. This larger enthalpy and particularly the greater entropy results from water fixed by the AT pair in the minor groove. As the increased entropy of an AT pair exceeds that of melting ice, the water molecule fixed by this pair must affect those of its neighbors. Water in the minor groove is, thus, orchestrated by the arrangement of AT groups, i.e. is context dependent. In contrast, water hydrating exposed nonpolar surfaces of bases is responsible for the heat capacity increment on dissociation and, therefore, for the temperature dependence of all thermodynamic characteristics of the double helix.
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Affiliation(s)
| | | | - Peter L Privalov
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
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32
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Fakhfakh K, Hughesman CB, Louise Creagh A, Kao V, Haynes C. Calorimetric and Spectroscopic Analysis of the Thermal Stability of Short Duplex DNA-Containing Sugar and Base-Modified Nucleotides. Methods Enzymol 2015; 567:97-127. [PMID: 26794352 DOI: 10.1016/bs.mie.2015.08.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Base- and sugar-modified analogs of DNA and RNA are finding ever expanding use in medicine and biotechnology as tools to better tailor structured oligonucleotides by altering their thermal stability, nuclease resistance, base-pairing specificity, antisense activity, or cellular uptake. Proper deployment of these chemical modifications generally requires knowledge of how each affects base-pairing properties and thermal stabilities. Here, we describe in detail how differential scanning calorimetry and UV spectroscopy may be used to quantify the melting thermodynamics of short dsDNA containing chemically modified nucleosides in one or both strands. Insights are provided into why and how the presence of highly stable base pairs containing modified nucleosides can alter the nature of calorimetry or melting spectroscopy data, and how each experiment must therefore be conducted to ensure high-quality melting thermodynamics data are obtained. Strengths and weaknesses of the two methods when applied to chemically modified duplexes are also addressed.
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Affiliation(s)
- Kareem Fakhfakh
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada; Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, British Columbia, Canada
| | - Curtis B Hughesman
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
| | - A Louise Creagh
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada; Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, British Columbia, Canada
| | - Vincent Kao
- Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, British Columbia, Canada
| | - Charles Haynes
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada; Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, British Columbia, Canada; RES'EAU Water Research Network, Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, British Columbia, Canada.
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33
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Fakhfakh K, Marais O, Cheng XBJ, Castañeda JR, Hughesman CB, Haynes C. Molecular thermodynamics of LNA:LNA base pairs and the hyperstabilizing effect of 5′-proximal LNA:DNA base pairs. AIChE J 2015. [DOI: 10.1002/aic.14916] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Kareem Fakhfakh
- Michael Smith Laboratories, University of British Columbia; Vancouver BC Canada
- Dept. of Chemical and Biological Engineering; University of British Columbia; Vancouver BC Canada
| | - Olivia Marais
- Dept. of Chemical and Biological Engineering; University of British Columbia; Vancouver BC Canada
| | - Xin Bo Justin Cheng
- Dept. of Chemical and Biological Engineering; University of British Columbia; Vancouver BC Canada
| | - Jorge Real Castañeda
- Dept. of Chemical and Biological Engineering; University of British Columbia; Vancouver BC Canada
| | - Curtis B. Hughesman
- Michael Smith Laboratories, University of British Columbia; Vancouver BC Canada
| | - Charles Haynes
- Michael Smith Laboratories, University of British Columbia; Vancouver BC Canada
- Dept. of Chemical and Biological Engineering; University of British Columbia; Vancouver BC Canada
- RES'EAU Water Research Network, Dept. of Chemical and Biological Engineering; University of British Columbia; Vancouver BC Canada
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34
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Rayan G, Macgregor RB. A look at the effect of sequence complexity on pressure destabilisation of DNA polymers. Biophys Chem 2015; 199:34-8. [DOI: 10.1016/j.bpc.2015.02.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 02/11/2015] [Accepted: 02/13/2015] [Indexed: 11/16/2022]
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35
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Hughesman C, Fakhfakh K, Bidshahri R, Lund HL, Haynes C. A new general model for predicting melting thermodynamics of complementary and mismatched B-form duplexes containing locked nucleic acids: application to probe design for digital PCR detection of somatic mutations. Biochemistry 2015; 54:1338-52. [PMID: 25654628 DOI: 10.1021/bi500905b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Advances in real-time polymerase chain reaction (PCR), as well as the emergence of digital PCR (dPCR) and useful modified nucleotide chemistries, including locked nucleic acids (LNAs), have created the potential to improve and expand clinical applications of PCR through their ability to better quantify and differentiate amplification products, but fully realizing this potential will require robust methods for designing dual-labeled hydrolysis probes and predicting their hybridization thermodynamics as a function of their sequence, chemistry, and template complementarity. We present here a nearest-neighbor thermodynamic model that accurately predicts the melting thermodynamics of a short oligonucleotide duplexed either to its perfect complement or to a template containing mismatched base pairs. The model may be applied to pure-DNA duplexes or to duplexes for which one strand contains any number and pattern of LNA substitutions. Perturbations to duplex stability arising from mismatched DNA:DNA or LNA:DNA base pairs are treated at the Gibbs energy level to maintain statistical significance in the regressed model parameters. This approach, when combined with the model's accounting of the temperature dependencies of the melting enthalpy and entropy, permits accurate prediction of T(m) values for pure-DNA homoduplexes or LNA-substituted heteroduplexes containing one or two independent mismatched base pairs. Terms accounting for changes in solution conditions and terminal addition of fluorescent dyes and quenchers are then introduced so that the model may be used to accurately predict and thereby tailor the T(m) of a pure-DNA or LNA-substituted hydrolysis probe when duplexed either to its perfect-match template or to a template harboring a noncomplementary base. The model, which builds on classic nearest-neighbor thermodynamics, should therefore be of use to clinicians and biologists who require probes that distinguish and quantify two closely related alleles in either a quantitative PCR or dPCR assay. This potential is demonstrated by using the model to design allele-specific probes that completely discriminate and quantify clinically relevant mutant alleles (BRAF V600E and KIT D816V) in a dPCR assay.
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Affiliation(s)
- Curtis Hughesman
- Michael Smith Laboratories, University of British Columbia , Vancouver, BC, Canada V6T 1Z4
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36
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Halvorsen K, Agris PF. Cross-platform comparison of nucleic acid hybridization: toward quantitative reference standards. Anal Biochem 2014; 465:127-33. [PMID: 25124363 DOI: 10.1016/j.ab.2014.08.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 07/14/2014] [Accepted: 08/02/2014] [Indexed: 11/18/2022]
Abstract
Measuring interactions between biological molecules is vitally important to both basic and applied research as well as development of pharmaceuticals. Although a wide and growing range of techniques is available to measure various kinetic and thermodynamic properties of interacting biomolecules, it can be difficult to compare data across techniques of different laboratories and personnel or even across different instruments using the same technique. Here we evaluate relevant biological interactions based on complementary DNA and RNA oligonucleotides that could be used as reference standards for many experimental systems. We measured thermodynamics of duplex formation using isothermal titration calorimetry, differential scanning calorimetry, and ultraviolet-visible (UV-vis) monitored denaturation/renaturation. These standards can be used to validate results, compare data from disparate techniques, act as a teaching tool for laboratory classes, or potentially to calibrate instruments. The RNA and DNA standards have many attractive features, including low cost, high purity, easily measurable concentrations, and minimal handling concerns, making them ideal for use as a reference material.
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Affiliation(s)
- Ken Halvorsen
- The RNA Institute, University at Albany-SUNY, Albany, NY 12222, USA.
| | - Paul F Agris
- The RNA Institute, University at Albany-SUNY, Albany, NY 12222, USA; Department of Biological Sciences, University at Albany-SUNY, Albany, NY 12222, USA
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37
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Košutić M, Jud L, Da Veiga C, Frener M, Fauster K, Kreutz C, Ennifar E, Micura R. Surprising base pairing and structural properties of 2'-trifluoromethylthio-modified ribonucleic acids. J Am Chem Soc 2014; 136:6656-63. [PMID: 24766131 PMCID: PMC4021565 DOI: 10.1021/ja5005637] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
![]()
The chemical synthesis of ribonucleic
acids (RNA) with novel chemical
modifications is largely driven by the motivation to identify eligible
functional probes for the various applications in life sciences. To
this end, we have a strong focus on the development of novel fluorinated
RNA derivatives that are powerful in NMR spectroscopic analysis of
RNA folding and RNA ligand interactions. Here, we report on the synthesis
of 2′-SCF3 pyrimidine nucleoside containing oligoribonucleotides
and the comprehensive investigation of their structure and base pairing
properties. While this modification has a modest impact on thermodynamic
stability when it resides in single-stranded regions, it was found
to be destabilizing to a surprisingly high extent when located in
double helical regions. Our NMR spectroscopic investigations on short
single-stranded RNA revealed a strong preference for C2′-endo
conformation of the 2′-SCF3 ribose unit. Together
with a recent computational study (L. Li, J. W. Szostak, J.
Am. Chem. Soc. 2014, 136, 2858–2865)
that estimated the extent of destabilization caused by a single C2′-endo
nucleotide within a native RNA duplex to amount to 6 kcal mol−1 because of disruption of the planar base pair structure,
these findings support the notion that the intrinsic preference for
C2′-endo conformation of 2′-SCF3 nucleosides
is most likely responsible for the pronounced destabilization of double
helices. Importantly, we were able to crystallize 2′-SCF3 modified RNAs and solved their X-ray structures at atomic
resolution. Interestingly, the 2′-SCF3 containing
nucleosides that were engaged in distinct mismatch arrangements, but
also in a standard Watson–Crick base pair, adopted the same
C3′-endo ribose conformations as observed in the structure
of the unmodified RNA. Likely, strong crystal packing interactions
account for this observation. In all structures, the fluorine atoms
made surprisingly close contacts to the oxygen atoms of the corresponding
pyrimidine nucleobase (O2), and the 2′-SCF3 moieties
participated in defined water-bridged hydrogen-bonding networks in
the minor groove. All these features allow a rationalization of the
structural determinants of the 2′-SCF3 nucleoside
modification and correlate them to base pairing properties.
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Affiliation(s)
- Marija Košutić
- Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck , 6020 Innsbruck, Austria
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38
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Son I, Shek YL, Dubins DN, Chalikian TV. Hydration Changes Accompanying Helix-to-Coil DNA Transitions. J Am Chem Soc 2014; 136:4040-7. [DOI: 10.1021/ja5004137] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Ikbae Son
- Department of Pharmaceutical
Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - Yuen Lai Shek
- Department of Pharmaceutical
Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - David N. Dubins
- Department of Pharmaceutical
Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - Tigran V. Chalikian
- Department of Pharmaceutical
Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
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39
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Andronescu M, Condon A, Turner DH, Mathews DH. The determination of RNA folding nearest neighbor parameters. Methods Mol Biol 2014; 1097:45-70. [PMID: 24639154 DOI: 10.1007/978-1-62703-709-9_3] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The stability of RNA secondary structure can be predicted using a set of nearest neighbor parameters. These parameters are widely used by algorithms that predict secondary structure. This contribution introduces the UV optical melting experiments that are used to determine the folding stability of short RNA strands. It explains how the nearest neighbor parameters are chosen and how the values are fit to the data. A sample nearest neighbor calculation is provided. The contribution concludes with new methods that use the database of sequences with known structures to determine parameter values.
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Affiliation(s)
- Mirela Andronescu
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
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40
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Elmas A, Jajamovich GH, Wang X, Samoilov MS. Designing DNA barcodes orthogonal in melting temperature by simulated annealing optimization. Nucleic Acid Ther 2013; 23:140-51. [PMID: 23557118 DOI: 10.1089/nat.2012.0394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Molecular barcode arrays are widely employed in the analysis of large strain libraries, whereby probes linked to unique oligonucleotides ("antitags") are used to detect selected DNA targets ("tags") by highly specific hybridization. One of the major problems for such screen designs is thus insuring a high degree of probe-target specificity and a low level of nonspecific binding (in sum, "orthogonality") across the entire tag population ("collection"). Several approaches have been previously proposed for designing orthogonal DNA tags by-among others-focusing on their individual or pair-wise structures, such as Smith Waterman sequence similarity, the widely used nearest neighbor method, and full thermodynamic estimates of sequences. However, these methods generally involve imposing various heuristic constraints ("design rules") on possible tag/antitag (TaT) sequences in order to achieve probe-target specificity across the collection. The resulting lack of freedom in considering all putative sequences can lead to potentially suboptimal designs and to the ensuing reduction in the degree of orthogonality within the constructed TaT collections. Here, we demonstrate that a randomized-search algorithm based on simulated annealing optimization can be used in order to substantially free the design process from the limitations of sequence constraints-allowing for the elucidation of potentially more optimal DNA tag collections. The designed sets of DNA oligonucleotides are optimized for the highest degree of orthogonality as quantified by melting temperature Tm-an experimentally relevant system property, which could also be used as a theoretically meaningful thermodynamic metric for optimizing TaT binding specificity. That is, this work describes an approach to constructing tag/antitag libraries, which offer the greatest melting temperature separation between specific probe-target duplexes and other nonspecific structures. The proposed method finds, with high probability, the global solution that maximizes the difference in Tm between the specific and nonspecific tag-antitag hybridizations across a collection of given size for TaTs of specified length. An application of this approach is demonstrated using 2 different DNA probe sets.
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Affiliation(s)
- Abdulkadir Elmas
- Department of Electrical Engineering, Columbia University , New York, NY 10027, USA
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41
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Escobedo G, Arjona-Román JL, Meléndez-Pérez R, Suárez-Álvarez K, Guzmán C, Aguirre-García J, Gutiérrez-Reyes G, Vivas O, Varela-Fascinetto G, Rodríguez-Romero A, Robles-Díaz G, Kershenobich D. Liver exhibits thermal variations according to the stage of fibrosis progression: A novel use of modulated-differential scanning calorimetry for research in hepatology. Hepatol Res 2013; 43:785-94. [PMID: 23252661 DOI: 10.1111/hepr.12026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2012] [Revised: 11/09/2012] [Accepted: 11/13/2012] [Indexed: 02/08/2023]
Abstract
AIM Liver fibrosis results in a disproportion of the hepatic composition and architecture, characterized by a progressive accumulation of fibrillar proteins at the liver parenchyma. Modulated-differential scanning calorimetry (mDSC) is an experimental methodology able to determine the specific thermal signature from any biological substance, based on the variation in heat flow and heat capacity. As these physicochemical properties are directly influenced by compositional and structural changes, we decided to study the thermal behavior of the liver during fibrosis using mDSC. METHODS Liver fibrosis was induced in rats by bile duct ligation or carbon tetrachloride administration. Degree of liver fibrosis was determined by histological examination using the Masson-trichrome stain, accompanied by hepatic expression of α-smooth muscle actin. The thermal analysis was performed in a modulated-differential scanning calorimeter using 20 mg of fresh liver mass. RESULTS The liver showed a characteristic thermal signature in control animals, which progressively differed among mild (F1), moderate (F2) and advanced (F3-F4) liver fibrosis. For heat flow, the hepatic thermal signature from F3-F4 rats exhibited significant differences when compared with F1, F2 and controls. In terms of heat capacity, liver specimens provided a specific thermal signature for each stage of disease, characterized by a transition temperature onset at 95°C for controls, whereas in F1, F2 and F3-F4 animals this temperature significantly decreased to 93°C, 84°C and 75°C, respectively. CONCLUSION Because the liver shows a differential thermal signature according to the degree of fibrosis, mDSC could be a novel tool in the study of liver fibrosis progression.
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Affiliation(s)
- Galileo Escobedo
- Unit of Experimental Medicine, General Hospital of Mexico, México D.F., México; Laboratory for Liver, Pancreas and Motility, Department of Experimental Medicine, School of Medicine, General Hospital of Mexico, México D.F., México
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42
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Denesyuk NA, Thirumalai D. Coarse-grained model for predicting RNA folding thermodynamics. J Phys Chem B 2013; 117:4901-11. [PMID: 23527587 DOI: 10.1021/jp401087x] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We present a thermodynamically robust coarse-grained model to simulate folding of RNA in monovalent salt solutions. The model includes stacking, hydrogen bond, and electrostatic interactions as fundamental components in describing the stability of RNA structures. The stacking interactions are parametrized using a set of nucleotide-specific parameters, which were calibrated against the thermodynamic measurements for single-base stacks and base-pair stacks. All hydrogen bonds are assumed to have the same strength, regardless of their context in the RNA structure. The ionic buffer is modeled implicitly, using the concept of counterion condensation and the Debye-Hückel theory. The three adjustable parameters in the model were determined by fitting the experimental data for two RNA hairpins and a pseudoknot. A single set of parameters provides good agreement with thermodynamic data for the three RNA molecules over a wide range of temperatures and salt concentrations. In the process of calibrating the model, we establish the extent of counterion condensation onto the single-stranded RNA backbone. The reduced backbone charge is independent of the ionic strength and is 60% of the RNA bare charge at 37 °C. Our model can be used to predict the folding thermodynamics for any RNA molecule in the presence of monovalent ions.
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Affiliation(s)
- Natalia A Denesyuk
- Department of Chemistry and Biochemistry and Biophysics Program, Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, United States
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43
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Belozerova I, Levicky R. Melting thermodynamics of reversible DNA/ligand complexes at interfaces. J Am Chem Soc 2012; 134:18667-76. [PMID: 23046441 PMCID: PMC3498581 DOI: 10.1021/ja3066368] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A variety of solution methods exist for analysis of interactions between small molecule ligands and nucleic acids; however, accomplishing this task economically at the scale of hundreds to thousands of sequences remains challenging. Surface assays offer a prospective solution through array-based multiplexing, capable of mapping out the full sequence context of a DNA/ligand interaction in a single experiment. However, relative to solution assays, accurate quantification of DNA/ligand interactions in a surface format must contend with limited understanding of molecular activities and interactions at a solid-liquid interface. We report a surface adaptation of a solution method in which shifts in duplex stability, induced by ligand binding and quantified from melting transitions, are used for thermodynamic analysis of DNA/ligand interactions. The results are benchmarked against solution calorimetric data. Equilibrium operation is confirmed through superposition of denaturation/hybridization transitions triggered by heating and cooling. The antibiotic compound netropsin, which undergoes electrostatic and sequence-specific minor groove interactions with DNA, is used as a prototypical small molecule. DNA/netropsin interactions are investigated as a function of ionic strength and drug concentration through electrochemical tracing of surface melt transitions. Comparison with solution values finds excellent agreement in free energy, though reliable separation into enthalpic and entropic contributions proves more difficult. The results establish key guidelines for analysis of DNA-ligand interactions via reversible melting denaturation at surfaces.
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Affiliation(s)
- Irina Belozerova
- Department of Chemical & Biomolecular Engineering, Polytechnic Institute of New York University, Brooklyn, 11201, United States
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44
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Ren P, Chun J, Thomas DG, Schnieders MJ, Marucho M, Zhang J, Baker NA. Biomolecular electrostatics and solvation: a computational perspective. Q Rev Biophys 2012; 45:427-91. [PMID: 23217364 PMCID: PMC3533255 DOI: 10.1017/s003358351200011x] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
An understanding of molecular interactions is essential for insight into biological systems at the molecular scale. Among the various components of molecular interactions, electrostatics are of special importance because of their long-range nature and their influence on polar or charged molecules, including water, aqueous ions, proteins, nucleic acids, carbohydrates, and membrane lipids. In particular, robust models of electrostatic interactions are essential for understanding the solvation properties of biomolecules and the effects of solvation upon biomolecular folding, binding, enzyme catalysis, and dynamics. Electrostatics, therefore, are of central importance to understanding biomolecular structure and modeling interactions within and among biological molecules. This review discusses the solvation of biomolecules with a computational biophysics view toward describing the phenomenon. While our main focus lies on the computational aspect of the models, we provide an overview of the basic elements of biomolecular solvation (e.g. solvent structure, polarization, ion binding, and non-polar behavior) in order to provide a background to understand the different types of solvation models.
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Affiliation(s)
- Pengyu Ren
- Department of Biomedical Engineering, The University of Texas at Austin
| | | | | | | | - Marcelo Marucho
- Department of Physics and Astronomy, The University of Texas at San Antonio
| | - Jiajing Zhang
- Department of Biomedical Engineering, The University of Texas at Austin
| | - Nathan A. Baker
- To whom correspondence should be addressed. Pacific Northwest National Laboratory, PO Box 999, MSID K7-29, Richland, WA 99352. Phone: +1-509-375-3997,
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45
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Ge D, Wang X, Williams K, Levicky R. Thermostable DNA immobilization and temperature effects on surface hybridization. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:8446-8455. [PMID: 22578171 PMCID: PMC3368703 DOI: 10.1021/la301165a] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Monolayer films of nucleic acids on solid supports are encountered in a range of diagnostic and bioanalytical applications. These applications often rely on elevated temperatures to improve performance; moreover, studies at elevated temperatures can provide fundamental information on layer organization and functionality. To support such applications, this study compares thermostability of oligonucleotide monolayers immobilized to gold by first coating the gold with a nanometer-thick film (an "anchor layer") of a polymercaptosiloxane, to which DNA oligonucleotides are subsequently tethered through maleimide-thiol conjugation, with thermostability of monolayers formed via widely used attachment through a terminal thiol moiety on the DNA. The temperature range covered is from 25 to 90 °C. After confirming stability of immobilization and, more importantly, retention of hybridization activity even under the harshest conditions investigated, these thermostable films are used to demonstrate measurements of (1) reversible surface melting transitions and (2) temperature dependence of competitive hybridization, when fully matched and mismatched sequences compete for binding to immobilized DNA oligonucleotides. The competitive hybridization experiments reveal a pronounced impact of temperature on rates of approach to equilibrium, with kinetic freezing into nonequilibrium states close to room temperature and rapid approach to equilibrium at elevated temperatures. Modeling of competitive surface hybridization equilibria using thermodynamic parameters derived from surface melting transitions of the individual sequences is also discussed.
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46
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Thermodynamic and kinetic analysis of an RNA kissing interaction and its resolution into an extended duplex. Biophys J 2012; 102:1097-107. [PMID: 22404932 DOI: 10.1016/j.bpj.2011.12.052] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Revised: 12/22/2011] [Accepted: 12/30/2011] [Indexed: 11/22/2022] Open
Abstract
Kissing hairpin interactions form when the loop residues of two hairpins have Watson-Crick complementarity. In a unimolecular context, kissing interactions are important for tertiary folding and pseudoknot formation, whereas in a bimolecular context, they provide a basis for molecular recognition. In some cases, kissing complexes can be a prelude to strand displacement reactions where the two hairpins resolve to form a stable extended intermolecular duplex. The kinetics and thermodynamics of kissing-complex formation and their subsequent strand-displacement reactions are poorly understood. Here, biophysical techniques including isothermal titration calorimetry, surface plasmon resonance, and single-molecule fluorescence have been employed to probe the factors that govern the stability of kissing complexes and their subsequent structural rearrangements. We show that the general understanding of RNA duplex formation can be extended to kissing complexes but that kissing complexes display an unusual level of stability relative to simple duplexes of the same sequence. These interactions form and break many times at room temperature before becoming committed to a slow, irreversible forward transition to the strand-displaced form. Furthermore, using smFRET we show that the primary difference between stable and labile kissing complexes is based almost completely on their off rates. Both stable and labile complexes form at the same rate within error, but less stable species dissociate rapidly, allowing us to understand how these complexes can help generate specificity along a folding pathway or during a gene regulation event.
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47
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Ozel AB, Srivannavit O, Rouillard JM, Gulari AE. Target concentration dependence of DNA melting temperature on oligonucleotide microarrays. Biotechnol Prog 2012; 28:556-66. [PMID: 22275183 DOI: 10.1002/btpr.1505] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2011] [Revised: 11/08/2011] [Indexed: 01/12/2023]
Abstract
The design of microarrays is currently based on studies focusing on DNA hybridization reaction in bulk solution. However, the presence of a surface to which the probe strand is attached can make the solution-based approximations invalid, resulting in sub-optimum hybridization conditions. To determine the effect of surfaces on DNA duplex formation, the authors studied the dependence of DNA melting temperature (T(m)) on target concentration. An automated system was developed to capture the melting profiles of a 25-mer perfect-match probe-target pair initially hybridized at 23°C. Target concentrations ranged from 0.0165 to 15 nM with different probe amounts (0.03-0.82 pmol on a surface area of 10(18) Å(2)), a constant probe density (5 × 10(12) molecules/cm(2)) and spacer length (15 dT). The authors found that T(m) for duplexes anchored to a surface is lower than in-solution, and this difference increases with increasing target concentration. In a representative set, a target concentration increase from 0.5 to 15 nM with 0.82 pmol of probe on the surface resulted in a T(m) decrease of 6°C when compared with a 4°C increase in solution. At very low target concentrations, a multi-melting process was observed in low temperature domains of the curves. This was attributed to the presence of truncated or mismatch probes.
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Affiliation(s)
- Ayse Bilge Ozel
- Dept. of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
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48
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Burnouf D, Ennifar E, Guedich S, Puffer B, Hoffmann G, Bec G, Disdier F, Baltzinger M, Dumas P. kinITC: a new method for obtaining joint thermodynamic and kinetic data by isothermal titration calorimetry. J Am Chem Soc 2011; 134:559-65. [PMID: 22126339 DOI: 10.1021/ja209057d] [Citation(s) in RCA: 138] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Isothermal titration calorimetry (ITC) is the method of choice for obtaining thermodynamic data on a great variety of systems. Here we show that modern ITC apparatus and new processing methods allow researchers to obtain a complete kinetic description of systems more diverse than previously thought, ranging from simple ligand binding to complex RNA folding. We illustrate these new features with a simple case (HIV-1 reverse transcriptase/inhibitor interaction) and with the more complex case of the folding of a riboswitch triggered by the binding of its ligand. The originality of the new kinITC method lies in its ability to dissect, both thermodynamically and kinetically, the two components: primary ligand binding and subsequent RNA folding. We are not aware of another single method that can yield, in a simple way, such deep insight into a composite process. Our study also rationalizes common observations from daily ITC use.
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Affiliation(s)
- Dominique Burnouf
- Architecture et Réactivité de l'ARN, Biophysique et Biologie Structurale, Institut de Biologie Moléculaire et Cellulaire du CNRS, Université de Strasbourg, 15, rue René Descartes, 67084 Strasbourg, France
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49
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Owczarzy R, You Y, Groth CL, Tataurov AV. Stability and mismatch discrimination of locked nucleic acid-DNA duplexes. Biochemistry 2011; 50:9352-67. [PMID: 21928795 PMCID: PMC3201676 DOI: 10.1021/bi200904e] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Locked nucleic acids (LNA; symbols of bases, +A, +C,
+G, and +T) are introduced into chemically synthesized oligonucleotides
to increase duplex stability and specificity. To understand these
effects, we have determined thermodynamic parameters of consecutive
LNA nucleotides. We present guidelines for the design of LNA oligonucleotides
and introduce free online software that predicts the stability of
any LNA duplex oligomer. Thermodynamic analysis shows that the single
strand–duplex transition is characterized by a favorable enthalpic
change and by an unfavorable loss of entropy. A single LNA modification
confines the local conformation of nucleotides, causing a smaller,
less unfavorable entropic loss when the single strand is restricted
to the rigid duplex structure. Additional LNAs adjacent to the initial
modification appear to enhance stacking and H-bonding interactions
because they increase the enthalpic contributions to duplex stabilization.
New nearest-neighbor parameters correctly forecast the positive and
negative effects of LNAs on mismatch discrimination. Specificity is
enhanced in a majority of sequences and is dependent on mismatch type
and adjacent base pairs; the largest discriminatory boost occurs for
the central +C·C mismatch within the +T+C+C sequence and the
+A·G mismatch within the +T+A+G sequence. LNAs do not affect
specificity in some sequences and even impair it for many +G·T
and +C·A mismatches. The level of mismatch discrimination decreases
the most for the central +G·T mismatch within the +G+G+C sequence
and the +C·A mismatch within the +G+C+G sequence. We hypothesize
that these discrimination changes are not unique features of LNAs
but originate from the shift of the duplex conformation from B-form
to A-form.
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Affiliation(s)
- Richard Owczarzy
- Department of Molecular Genetics and Biophysics, Integrated DNA Technologies, Coralville, Iowa 52241, United States.
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50
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Ouldridge TE, Louis AA, Doye JPK. Structural, mechanical, and thermodynamic properties of a coarse-grained DNA model. J Chem Phys 2011; 134:085101. [PMID: 21361556 DOI: 10.1063/1.3552946] [Citation(s) in RCA: 312] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We explore in detail the structural, mechanical, and thermodynamic properties of a coarse-grained model of DNA similar to that recently introduced in a study of DNA nanotweezers [T. E. Ouldridge, A. A. Louis, and J. P. K. Doye, Phys. Rev. Lett. 134, 178101 (2010)]. Effective interactions are used to represent chain connectivity, excluded volume, base stacking, and hydrogen bonding, naturally reproducing a range of DNA behavior. The model incorporates the specificity of Watson-Crick base pairing, but otherwise neglects sequence dependence of interaction strengths, resulting in an "average base" description of DNA. We quantify the relation to experiment of the thermodynamics of single-stranded stacking, duplex hybridization, and hairpin formation, as well as structural properties such as the persistence length of single strands and duplexes, and the elastic torsional and stretching moduli of double helices. We also explore the model's representation of more complex motifs involving dangling ends, bulged bases and internal loops, and the effect of stacking and fraying on the thermodynamics of the duplex formation transition.
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