1
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Tevonyan LL, Bazhulina NP, Kaluzhny DN. Enhancement of intrinsic guanine fluorescence by protonation in DNA of various structures. Biochimie 2024; 222:101-108. [PMID: 38447859 DOI: 10.1016/j.biochi.2024.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 02/24/2024] [Accepted: 03/03/2024] [Indexed: 03/08/2024]
Abstract
Understanding the diversity of DNA structure and functions in biology requires tools to study this biomolecule selectively and thoroughly. Fluorescence methods are powerful technique for non-invasive research. Due to the low quantum yield, the intrinsic fluorescence of nucleotides has not been considered for use in the detection and differentiation of nucleic acid bases. Here, we have studied the influence of protonation of nucleotides on their fluorescence properties. We show that protonation of ATP and GTP leads to enhanced intrinsic fluorescence. Fluorescence enhancement at acidic pH has been observed for double-stranded DNA and single-stranded oligonucleotides. The formation of G4 secondary structures apparently protected certain nucleotides from protonation, resulting in less pronounced fluorescence enhancement. Furthermore, acid-induced depurination under protonation was less noticeable in G4 structures than in double-stranded and single-stranded DNA. We show that changes in the intrinsic fluorescence of guanine can be used as a sensitive sensor for changes in the structure of the DNA and for the protonation of specific nucleotides.
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Affiliation(s)
- Liana L Tevonyan
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 32 Vavilov st., 119991, Moscow, Russia; Moscow Institute of Physics and Technology (National Research University), 9 Institutskiy per., Dolgoprudny, 141701, Moscow Region, Russia
| | - Natalia P Bazhulina
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 32 Vavilov st., 119991, Moscow, Russia
| | - Dmitry N Kaluzhny
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 32 Vavilov st., 119991, Moscow, Russia.
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2
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Megušar P, Miklavčič R, Korenč M, Ličen J, Vodopivec T, Černigoj U, Štrancar A, Sekirnik R. Scalable multimodal weak anion exchange chromatographic purification for stable mRNA drug substance. Electrophoresis 2023; 44:1978-1988. [PMID: 37828276 DOI: 10.1002/elps.202300106] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 09/15/2023] [Accepted: 09/18/2023] [Indexed: 10/14/2023]
Abstract
Messenger RNA (mRNA) has emerged as a modality with immense therapeutic potential. Recent innovations in production process of mRNA call for procedures to isolate pure mRNA drug substance (DS) with high yield, high capacity, scalability, and compatibility with GMP production systems. Novel RNA modalities, such as circular RNA (circRNA), have further driven the need for non-affinity capture possibilities which are already widely used in the biopharmaceutical industry, for example, in monoclonal antibody processing. The principle that multimodal ion exchange/hydrogen bonding chromatography can be used to separate mRNA from in vitro transcription components has recently been demonstrated. Here, we apply and refine this approach to be suitable for scalable purification of multiple mRNA constructs with sufficient yields, purity, and stability, for use in mRNA production process. Binding capacity of the PrimaS-modified monolithic chromatographic column for mRNA enabled up to 7 mg/mL product isolation in a single chromatographic run, with 98% recovery and room temperature stability of the eGFP mRNA demonstrated for up to 28 days. This approach is independent of construct size or the presence of polyadenylic acid tail and is applicable for capture of a wide variety of RNAs, including mRNA, self-amplifying RNA, circRNA, and with optimization also smaller RNAs such as transfer RNA and others.
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Affiliation(s)
| | - Rok Miklavčič
- Sartorius BIA Separations d.o.o., Ajdovščina, Slovenia
| | - Matevž Korenč
- Sartorius BIA Separations d.o.o., Ajdovščina, Slovenia
| | - Jure Ličen
- Sartorius BIA Separations d.o.o., Ajdovščina, Slovenia
| | | | - Urh Černigoj
- Sartorius BIA Separations d.o.o., Ajdovščina, Slovenia
| | - Aleš Štrancar
- Sartorius BIA Separations d.o.o., Ajdovščina, Slovenia
| | - Rok Sekirnik
- Sartorius BIA Separations d.o.o., Ajdovščina, Slovenia
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3
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Göç YB, Poziemski J, Smolińska W, Suwała D, Wieczorek G, Niedzialek D. Tracking Topological and Electronic Effects on the Folding and Stability of Guanine-Deficient RNA G-Quadruplexes, Engineered with a New Computational Tool for De Novo Quadruplex Folding. Int J Mol Sci 2022; 23:ijms231910990. [PMID: 36232294 PMCID: PMC9570295 DOI: 10.3390/ijms231910990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/09/2022] [Accepted: 09/13/2022] [Indexed: 11/16/2022] Open
Abstract
The initial aim of this work was to elucidate the mutual influence of different single-stranded segments (loops and caps) on the thermodynamic stability of RNA G-quadruplexes. To this end, we used a new NAB-GQ-builder software program, to construct dozens of two-tetrad G-quadruplex topologies, based on a designed library of sequences. Then, to probe the sequence–morphology–stability relationships of the designed topologies, we performed molecular dynamics simulations. Their results provide guidance for the design of G-quadruplexes with balanced structures, and in turn programmable physicochemical properties for applications as biomaterials. Moreover, by comparative examinations of the single-stranded segments of three oncogene promoter G-quadruplexes, we assess their druggability potential for future therapeutic strategies. Finally, on the basis of a thorough analysis at the quantum mechanical level of theory on a series of guanine assemblies, we demonstrate how a valence tautomerism, triggered by a coordination of cations, initiates the process of G-quadruplex folding, and we propose a sequential folding mechanism, otherwise dictated by the cancellation of the dipole moments on guanines.
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Affiliation(s)
- Yavuz Burak Göç
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland or
- Faculty of Chemistry, Biological & Chemical Research Center, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland
| | - Jakub Poziemski
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland or
| | - Weronika Smolińska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland or
- Faculty of Chemical and Process Engineering, Warsaw University of Technology, Waryńskiego 1, 00-645 Warsaw, Poland
| | - Dominik Suwała
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland or
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
| | - Grzegorz Wieczorek
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland or
- Molecure SA, Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Dorota Niedzialek
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland or
- Correspondence:
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4
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Perez FP, Bandeira JP, Perez Chumbiauca CN, Lahiri DK, Morisaki J, Rizkalla M. Multidimensional insights into the repeated electromagnetic field stimulation and biosystems interaction in aging and age-related diseases. J Biomed Sci 2022; 29:39. [PMID: 35698225 PMCID: PMC9190166 DOI: 10.1186/s12929-022-00825-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 06/07/2022] [Indexed: 11/25/2022] Open
Abstract
We provide a multidimensional sequence of events that describe the electromagnetic field (EMF) stimulation and biological system interaction. We describe this process from the quantum to the molecular, cellular, and organismal levels. We hypothesized that the sequence of events of these interactions starts with the oscillatory effect of the repeated electromagnetic stimulation (REMFS). These oscillations affect the interfacial water of an RNA causing changes at the quantum and molecular levels that release protons by quantum tunneling. Then protonation of RNA produces conformational changes that allow it to bind and activate Heat Shock Transcription Factor 1 (HSF1). Activated HSF1 binds to the DNA expressing chaperones that help regulate autophagy and degradation of abnormal proteins. This action helps to prevent and treat diseases such as Alzheimer’s and Parkinson’s disease (PD) by increasing clearance of pathologic proteins. This framework is based on multiple mathematical models, computer simulations, biophysical experiments, and cellular and animal studies. Results of the literature review and our research point towards the capacity of REMFS to manipulate various networks altered in aging (Reale et al. PloS one 9, e104973, 2014), including delay of cellular senescence (Perez et al. 2008, Exp Gerontol 43, 307-316) and reduction in levels of amyloid-β peptides (Aβ) (Perez et al. 2021, Sci Rep 11, 621). Results of these experiments using REMFS at low frequencies can be applied to the treatment of patients with age-related diseases. The use of EMF as a non-invasive therapeutic modality for Alzheimer’s disease, specifically, holds promise. It is also necessary to consider the complicated and interconnected genetic and epigenetic effects of the REMFS-biological system’s interaction while avoiding any possible adverse effects.
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Affiliation(s)
- Felipe P Perez
- Indiana University School of Medicine, Indianapolis, IN, USA. .,Division of General Internal Medicine and Geriatrics, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
| | - Joseph P Bandeira
- Indiana University School of Medicine, Indianapolis, IN, USA.,Division of General Internal Medicine and Geriatrics, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Cristina N Perez Chumbiauca
- Indiana University School of Medicine, Indianapolis, IN, USA.,Division of Rheumatology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Debomoy K Lahiri
- Indiana University School of Medicine, Indianapolis, IN, USA.,Department of Psychiatry, Institute of Psychiatric Research, Neuroscience Research Center, Indiana University School of Medicine, Indianapolis, IN, USA.,Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Jorge Morisaki
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Maher Rizkalla
- Department of Electrical and Computer Engineering, Indiana University-Purdue University, Indianapolis, IN, USA
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5
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Das S, Roy S, Bhattacharyya D. Understanding the role of non-Watson-Crick base pairs in DNA-protein recognition: Structural and energetic aspects using crystallographic database analysis and quantum chemical calculation. Biopolymers 2022; 113:e23492. [PMID: 35615897 DOI: 10.1002/bip.23492] [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: 02/16/2022] [Revised: 04/22/2022] [Accepted: 05/03/2022] [Indexed: 11/06/2022]
Abstract
Specific recognition of DNA base sequences by proteins is vital for life-cycles of all organisms. In a large number of crystal structures of protein-DNA complexes, DNA conformation significantly deviates from the canonical B-DNA structure. A key question is whether such alternate conformations exist prior to protein binding and one is selected for complexation or the structure observed is induced by protein binding. Non-canonical base pairs, such as Hoogsteen base pairs, are often observed in crystal structures of protein-DNA complexes. We decided to explore whether the occurrence of such non-canonical base pairs in protein-DNA complexes is induced by the protein or is selected from pre-existing conformations. Detailed quantum chemical calculations with dispersion-corrected density functional theory (DFT-D) indicated that most of the non-canonical base pairs with DNA bases are stable even in the absence of the interacting amino acids. However, the G:G Hoogsteen base pair, which also appears in the telomere structure, appears to be unstable in the absence of other stabilizing agents, such as positively charged amino acids. Thus, the stability of many of the non-canonical base pair containing duplexes may be close to the canonical B-DNA structure and hence energetically accessible in the ground state; suggesting that the selection from pre-existing conformations may be an important mechanism for observed non-canonical base pairs in protein-DNA complexes.
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Affiliation(s)
- Soumi Das
- Department of Biophysics, Bose Institute, Kolkata, India
| | - Siddhartha Roy
- Department of Biophysics, Bose Institute, Kolkata, India
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6
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Moe MM, Benny J, Liu J. Collision-induced dissociation of homodimeric and heterodimeric radical cations of 9-methylguanine and 9-methyl-8-oxoguanine: correlation between intra-base pair proton transfer originating from the N1-H at a Watson-Crick edge and non-statistical dissociation. Phys Chem Chem Phys 2022; 24:9263-9276. [PMID: 35403654 DOI: 10.1039/d2cp00312k] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
It has been shown previously in protonated, deprotonated and ionized guanine-cytosine base pairs that intra-base pair proton transfer from the N1-H at the Watson-Crick edge of guanine to the complementary nucleobase prompts non-statistical dissociation of the base-pair system, and the dissociation of a proton-transferred base-pair structure is kinetically more favored than that of the starting, conventional base-pair structure. However, the fundamental chemistry underlying this anomalous and intriguing kinetics has not been completely revealed, which warrants the examination of more base-pair systems in different structural contexts in order to derive a generalized base-pair structure-kinetics correlation. The purpose of the present work is to expand the investigation to the non-canonical homodimeric and heterodimeric radical cations of 9-methylguanine (9MG) and 9-methyl-8-oxoguanine (9MOG), i.e., [9MG·9MG]˙+, [9MOG·9MG]˙+ and [9MOG·9MOG]˙+. Experimentally, collision-induced dissociation tandem mass spectrometry coupled with an electrospray ionization (ESI) source was used for the formation of base-pair radical cations, followed by detection of dissociation product ions and cross sections in the collisions with Xe gas under single ion-molecule collision conditions and as a function of the center-of-mass collision energy. Computationally, density functional theory and coupled cluster theory were used to calculate and identify probable base-pair structures and intra-base pair proton transfer and hydrogen transfer reactions, followed by kinetics modeling to explore the properties of dissociation transition states and kinetic factors. The significance of this work is twofold: it provides insight into base-pair opening kinetics in three biologically-important, non-canonical systems upon oxidative and ionization damage; and it links non-statistical dissociation to intra-base pair proton-transfer originating from the N1-H at the Watson-Crick edge of 8-oxoguanine, enhancing understanding towards the base-pair fragmentation assisted by proton transfer.
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Affiliation(s)
- May Myat Moe
- Department of Chemistry and Biochemistry, Queens College of the City University of New York, 65-30 Kissena Blvd., Queens, NY 11367, USA. .,Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, 365 5th Ave., New York, NY 10016, USA
| | - Jonathan Benny
- Department of Chemistry and Biochemistry, Queens College of the City University of New York, 65-30 Kissena Blvd., Queens, NY 11367, USA. .,Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, 365 5th Ave., New York, NY 10016, USA
| | - Jianbo Liu
- Department of Chemistry and Biochemistry, Queens College of the City University of New York, 65-30 Kissena Blvd., Queens, NY 11367, USA. .,Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, 365 5th Ave., New York, NY 10016, USA
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7
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Liao CC, Yau S. The Effects of Potential and pH on the Adsorption of Guanine on the Au(111) Electrode. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:2495-2501. [PMID: 35167284 DOI: 10.1021/acs.langmuir.1c02943] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The adsorption of nucleobase at a gold electrode has been a model system to study the interaction between biomolecule and metal, which is relevant to the development of sensors and molecular electronics. The current study has employed in situ scanning tunneling microscopy (STM) and voltammetry to investigate the adsorption configuration and spatial structure of guanine (G) on a well-defined Au(111) electrode in perchloric acid (HClO4) and neutral phosphate buffer solution (PBS) containing 50 μM G. Potential control had a profound effect on the adsorption of the G molecule on the Au(111) electrode. No adsorption of G was observed at a potential more negative than 0 V in HClO4 and -0.2 V (versus Ag/AgCl) in PBS; shifting potential positively triggered a rapid adsorption of G to yield a well-ordered G array. Different spatial structures of G admolecules were imaged with STM in HClO4 and PBS, suggesting that ions in the electrolyte were important in this adsorption event. Shifting potential positively caused a more compact G adlayer with molecules adopting a tilted orientation. Meanwhile, G molecules continued to deposit on the Au(111) electrode leading to a multilayer G film. These processes were reversible to the potential modulation. G admolecules on the Au(111) electrode could be irreversibly oxidized in 0.1 M PBS, which resulted in a prominent peak at 0.74 V in the voltammogram. This oxidation process could be used to analyze the G molecule in a sample.
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Affiliation(s)
- Chiu-Ching Liao
- Department of Chemistry, National Central University Chungli County, Taoyuan City 32001 Taiwan, ROC
| | - Shuehlin Yau
- Department of Chemistry, National Central University Chungli County, Taoyuan City 32001 Taiwan, ROC
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8
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Olajide OE, Donkor B, Hamid AM. Systematic Optimization of Ambient Ionization Ion Mobility Mass Spectrometry for Rapid Separation of Isomers. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:160-171. [PMID: 34910491 DOI: 10.1021/jasms.1c00311] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Current methods typically used for metabolite screening and disease diagnosis often require extensive sample preparation, which increases analysis time and associated costs. While ambient ionization techniques enable the analysis of various samples in complex matrices with little or no sample preparation in a short time (typically within a minute), their reduced selectivity, even when coupled with high-resolution mass spectrometers, limits their application in certain fields. In this study, we have optimized the coupling of paper spray (PS) and leaf spray (LS) ambient ionization techniques with a commercially available ion mobility mass spectrometer (IM-MS) and demonstrated the separation of geometric and constitutional isomers. Ambient ionization techniques allow simultaneous introduction and ionization of samples, while background noise and matrix interference from paper and leaf substrates are filtered out by IM separation, resulting in high sensitivity and selectivity of the PS-IM-MS and LS-IM-MS workflows. In addition, we introduced a novel approach to perform single-field collision cross section (CCS) measurements, which resulted in CCS values that differ by 0.15% and 0.25% from traditional stepped-field and single-field methods, respectively. In addition, we used advanced computational tools to confidently identify analyte structures by comparing CCS values from experimental IM measurements and theoretical calculations. These results suggest that the coupling of ambient ionization methods with ion mobility techniques enables rapid, sensitive, and highly selective analysis that can be used in different fields, such as agrochemical screening and disease diagnostics.
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Affiliation(s)
- Orobola E Olajide
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312, United States
| | - Benedicta Donkor
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312, United States
| | - Ahmed M Hamid
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312, United States
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9
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Liu Y, Ma C, Leonen CJA, Chatterjee C, Nováková G, Marek A, Tureček F. Tackling a Curious Case: Generation of Charge-Tagged Guanosine Radicals by Gas-Phase Electron Transfer and Their Characterization by UV-vis Photodissociation Action Spectroscopy and Theory. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:772-785. [PMID: 33567214 PMCID: PMC8579407 DOI: 10.1021/jasms.0c00459] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We report the generation of gas-phase riboguanosine radicals that were tagged at ribose with a fixed-charge 6-(trimethylammonium)hexane-1-aminocarbonyl group. The radical generation relied on electron transfer from fluoranthene anion to noncovalent dibenzocrown-ether dication complexes which formed nucleoside cation radicals upon one-electron reduction and crown-ether ligand loss. The cation radicals were characterized by collision-induced dissociation (CID), photodissociation (UVPD), and UV-vis action spectroscopy. Identification of charge-tagged guanosine radicals was challenging because of spontaneous dissociations by loss of a hydrogen atom and guanine that occurred upon storing the ions in the ion trap without further excitation. The loss of H proceeded from an exchangeable position on N-7 in guanine that was established by deuterium labeling and was the lowest energy dissociation of the guanosine radicals according to transition-state energy calculations. Rate constant measurements revealed an inverse isotope effect on the loss of either hydrogen or deuterium with rate constants kH = 0.25-0.26 s-1 and kD = 0.39-0.54 s-1. We used time-dependent density functional theory calculations, including thermal vibronic effects, to predict the absorption spectra of several protomeric radical isomers. The calculated spectra of low-energy N-7-H guanine-radical tautomers closely matched the action spectra. Transition-state-theory calculations of the rate constants for the loss of H-7 and guanine agreed with the experimental rate constants for a narrow range of ion effective temperatures. Our calculations suggest that the observed inverse isotope effect does not arise from the isotope-dependent differences in the transition-state energies. Instead, it may be caused by the dynamics of post-transition-state complexes preceding the product separation.
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Affiliation(s)
- Yue Liu
- Department of Chemistry, Bagley Hall, Box 351700, University of Washington, Seattle, Washington 98195-1700, United States
| | - Congcong Ma
- Department of Chemistry, Bagley Hall, Box 351700, University of Washington, Seattle, Washington 98195-1700, United States
| | - Calvin J A Leonen
- Department of Chemistry, Bagley Hall, Box 351700, University of Washington, Seattle, Washington 98195-1700, United States
| | - Champak Chatterjee
- Department of Chemistry, Bagley Hall, Box 351700, University of Washington, Seattle, Washington 98195-1700, United States
| | - Gabriela Nováková
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
| | - Aleš Marek
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
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10
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Cabaj MK, Dominiak PM. Frequency and hydrogen bonding of nucleobase homopairs in small molecule crystals. Nucleic Acids Res 2020; 48:8302-8319. [PMID: 32725210 PMCID: PMC7470937 DOI: 10.1093/nar/gkaa629] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 07/10/2020] [Accepted: 07/16/2020] [Indexed: 11/16/2022] Open
Abstract
We used the high resolution and accuracy of the Cambridge Structural Database (CSD) to provide detailed information regarding base pairing interactions of selected nucleobases. We searched for base pairs in which nucleobases interact with each other through two or more hydrogen bonds and form more or less planar structures. The investigated compounds were either free forms or derivatives of adenine, guanine, hypoxanthine, thymine, uracil and cytosine. We divided our findings into categories including types of pairs, protonation patterns and whether they are formed by free bases or substituted ones. We found base pair types that are exclusive to small molecule crystal structures, some that can be found only in RNA containing crystal structures and many that are native to both environments. With a few exceptions, nucleobase protonation generally followed a standard pattern governed by pKa values. The lengths of hydrogen bonds did not depend on whether the nucleobases forming a base pair were charged or not. The reasons why particular nucleobases formed base pairs in a certain way varied significantly.
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Affiliation(s)
- Małgorzata Katarzyna Cabaj
- Biological and Chemical Research Centre, Department of Chemistry, University of Warsaw, ul. Żwirki i Wigury 101, 02-089 Warszawa, Poland
| | - Paulina Maria Dominiak
- Biological and Chemical Research Centre, Department of Chemistry, University of Warsaw, ul. Żwirki i Wigury 101, 02-089 Warszawa, Poland
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11
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Energy of the CH⋯O H-bonds and others specific contacts in the quercetin molecule: QM/QTAIM approximation formulas. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.113456] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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12
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Huang SR, Liu Y, Tureček F. UV–vis Photodissociation Action Spectroscopy Reveals Cytosine–Guanine Hydrogen Transfer in DNA Tetranucleotide Cation Radicals upon One-Electron Reduction. J Phys Chem B 2020; 124:3505-3517. [DOI: 10.1021/acs.jpcb.0c01693] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Shu R. Huang
- Department of Chemistry, Bagley Hall, Box
351700, University of Washington, Seattle, Washington 98195-1700, United States
| | - Yue Liu
- Department of Chemistry, Bagley Hall, Box
351700, University of Washington, Seattle, Washington 98195-1700, United States
| | - František Tureček
- Department of Chemistry, Bagley Hall, Box
351700, University of Washington, Seattle, Washington 98195-1700, United States
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13
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Cheng R, Loire E, Martens J, Fridgen TD. An IRMPD spectroscopic and computational study of protonated guanine-containing mismatched base pairs in the gas phase. Phys Chem Chem Phys 2020; 22:2999-3007. [DOI: 10.1039/c9cp06393e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Infrared multiple photon dissociation spectroscopy has been used to probe the structures of the three protonated base-pair mismatches containing 9-ethylguanine (9eG) in the gas phase. Some of these protonated base-pairs have been identified in RNA.
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Affiliation(s)
- Ruodi Cheng
- Department of Chemistry
- Memorial University
- St. John's
- Canada
| | - Estelle Loire
- Laboratoire Chimie Physique – CLIO
- Campus Universite d’Orsay
- France
| | - Jonathan Martens
- Radboud University
- Institute for Molecules and Materials
- FELIX Laboratory
- Nijmegen
- The Netherlands
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14
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Liu Y, Huang SR, Tureček F. Guanine–adenine interactions in DNA tetranucleotide cation radicals revealed by UV/vis photodissociation action spectroscopy and theory. Phys Chem Chem Phys 2020; 22:16831-16842. [DOI: 10.1039/d0cp02362k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Hydrogen-rich cation radicals (GATT + 2H)+˙ and (AGTT + 2H)+˙ represent oligonucleotide models of charged hydrogen atom adducts to DNA.
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Affiliation(s)
- Yue Liu
- Department of Chemistry
- University of Washington
- Seattle
- USA
| | - Shu R. Huang
- Department of Chemistry
- University of Washington
- Seattle
- USA
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15
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Porter JE, Chapagain P, Fernandez-Lima F. Single-stranded DNA structural diversity: TAGGGT from monomers to dimers to tetramer formation. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2019; 33 Suppl 2:60-65. [PMID: 30506977 DOI: 10.1002/rcm.8367] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 11/27/2018] [Accepted: 11/27/2018] [Indexed: 06/09/2023]
Abstract
RATIONALE DNA quadruplex structures have emerged as novel drug targets due to their role in preventing abnormal gene transcription and maintaining telomere stability. Trapped Ion Mobility Spectrometry-Mass Spectrometry (TIMS-MS), combined with theoretical modeling, is a powerful tool for studying the kinetic intermediates of DNA complexes formed in solution and interrogated in the gas phase after desolvation. METHODS A TAGGGT ssDNA sequence was purchased and studied in 10 mM ammonium acetate using nanospray electrospray ionization (nESI)-TIMS-MS in positive and negative ion mode. Collisional cross section (CCS) profiles were measured using internal calibration (Tune Mix). Theoretical structures were proposed based on molecular dynamics, charge location and geometry optimization for the most intense IMS bands based on the number of TAGGGT units, adduct form and charge states. RESULTS A distribution of monomeric, dimeric and tetrameric TAGGGT structures were formed in solution and separated in the gas phase based on their mobility and m/z value (e.g., [M + 2H]+2 , [2M + 3H]+3 , [M - 2H]-2 , [2M - 3H]-3 , [4M + 4H]+4 , [4M + 3H + NH4 ]+4 , [4M + 2H + 2NH4 ]+4 and [4M + H + 3NH4 ]+4 ). The high mobility resolution of the TIMS-MS analyzer permitted the observation of multiple CCS bands per molecular ion form. Comparison with theoretical candidate structures suggests that monomeric TAGGGT species are stabilized by A-T and G+ -G interactions, with the size of the conformer influenced by the proton location. In the case of the TAGGGT quadruplex, the protonated species displayed a broad CCS distribution, while six discrete conformers were stabilized by the presence of ammonium ions (n = 1-3). CONCLUSIONS This is the first observation of multiple conformations of TAGGGT complexes (n = 1, 2 and 4) in 10 mM ammonium acetate. Candidate structures with intramolecular interactions of the form of G+ -G and traditional A-T base pairing agreed with the experimental trends. Our results demonstrate the structural diversity of TAGGGT monomers, dimers and tetramers in the gas phase beyond the previously reported solution structure, using 10 mM ammonium acetate to replicate biological conditions.
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Affiliation(s)
- Jacob E Porter
- Department of Chemistry & Biochemistry, Florida International University, Miami, FL, USA
| | - Prem Chapagain
- Department of Physics, Florida International University, Miami, FL, USA
- Biomolecular Sciences Institute, Florida International University, Miami, FL, USA
| | - Francisco Fernandez-Lima
- Department of Chemistry & Biochemistry, Florida International University, Miami, FL, USA
- Biomolecular Sciences Institute, Florida International University, Miami, FL, USA
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16
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Halder A, Data D, Seelam PP, Bhattacharyya D, Mitra A. Estimating Strengths of Individual Hydrogen Bonds in RNA Base Pairs: Toward a Consensus between Different Computational Approaches. ACS OMEGA 2019; 4:7354-7368. [PMID: 31459834 PMCID: PMC6648064 DOI: 10.1021/acsomega.8b03689] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Accepted: 04/12/2019] [Indexed: 06/10/2023]
Abstract
Noncoding RNA molecules are composed of a large variety of noncanonical base pairs that shape up their functionally competent folded structures. Each base pair is composed of at least two interbase hydrogen bonds (H-bonds). It is expected that the characteristic geometry and stability of different noncanonical base pairs are determined collectively by the properties of these interbase H-bonds. We have studied the ground-state electronic properties [using density functional theory (DFT) and DFT-D3-based methods] of all the 118 normal base pairs and 36 modified base pairs, belonging to 12 different geometric families (cis and trans of WW, WH, HH, WS, HS, and SS) that occur in a nonredundant set of high-resolution RNA crystal structures. Having addressed some of the limitations of the earlier approaches, we provide here a comprehensive compilation of the average energies of different types of interbase H-bonds (E HB). We have also characterized each interbase H-bond using 13 different parameters that describe its geometry, charge distribution at its bond critical point (BCP), and n → σ*-type charge transfer from filled π orbitals of the H-bond acceptor to the empty antibonding orbital of the H-bond donor. On the basis of the extent of their linear correlation with the H-bonding energy, we have shortlisted five parameters to model linear equations for predicting E HB values. They are (i) electron density at the BCP: ρ, (ii) its Laplacian: ∇2ρ, (iii) stabilization energy due to n → σ*-type charge transfer: E(2), (iv) donor-hydrogen distance, and (v) hydrogen-acceptor distance. We have performed single variable and multivariable linear regression analysis over the normal base pairs and have modeled sets of linear relationships between these five parameters and E HB. Performance testing of our model over the set of modified base pairs shows promising results, at least for the moderately strong H-bonds.
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Affiliation(s)
- Antarip Halder
- Center
for Computational Natural Sciences and Bioinformatics (CCNSB), International Institute of Information Technology
(IIIT-H), Gachibowli, Hyderabad 500032, India
| | - Dhruv Data
- Center
for Computational Natural Sciences and Bioinformatics (CCNSB), International Institute of Information Technology
(IIIT-H), Gachibowli, Hyderabad 500032, India
| | - Preethi P. Seelam
- Center
for Computational Natural Sciences and Bioinformatics (CCNSB), International Institute of Information Technology
(IIIT-H), Gachibowli, Hyderabad 500032, India
| | - Dhananjay Bhattacharyya
- Computational
Science Division, Saha Institute of Nuclear
Physics(SINP), 1/AF,
Bidhannagar, Kolkata 700064, India
| | - Abhijit Mitra
- Center
for Computational Natural Sciences and Bioinformatics (CCNSB), International Institute of Information Technology
(IIIT-H), Gachibowli, Hyderabad 500032, India
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17
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Halder A, Vemuri S, Roy R, Katuri J, Bhattacharyya D, Mitra A. Evidence for Hidden Involvement of N3-Protonated Guanine in RNA Structure and Function. ACS OMEGA 2019; 4:699-709. [PMID: 30775644 PMCID: PMC6372247 DOI: 10.1021/acsomega.8b02908] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 12/25/2018] [Indexed: 05/05/2023]
Abstract
Charged nucleobases have been found to occur in several known RNA molecules and are considered essential for their structure and function. The mechanism of their involvement is however not yet fully understood. Revelation of the role of N7-protonated guanine, in modulating the geometry and stability of noncanonical base pairs formed through its unprotonated edges [Watson-Crick (WC) and sugar], has triggered the need to evaluate the feasibility of similar roles of other protonated nucleobases [Halder et al., Phys Chem Chem Phys, 2015, 17, 26249]. In this context, N3 protonation of guanine makes an interesting case as its influence on the charge distribution of the WC edge is similar to that of N7 protonation, though its thermodynamic cost of protonation is significantly higher. In this work, we have carried out structural bioinformatics analyses and quantum mechanics-based calculations to show that N3 protonation of guanine may take place in a cellular environment, at least in the G:C W:W Trans and G:G W:H Cis base pairs. Our results provide a reasonable starting point for future investigations in order to address the larger mechanistic question.
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Affiliation(s)
- Antarip Halder
- Center
for Computational Natural Sciences and Bioinformatics (CCNSB), International Institute of Information Technology,
Hyderabad (IIIT-H), Gachibowli, Hyderabad 500032, Telangana, India
| | - Saurabh Vemuri
- Center
for Computational Natural Sciences and Bioinformatics (CCNSB), International Institute of Information Technology,
Hyderabad (IIIT-H), Gachibowli, Hyderabad 500032, Telangana, India
| | - Rohit Roy
- Center
for Computational Natural Sciences and Bioinformatics (CCNSB), International Institute of Information Technology,
Hyderabad (IIIT-H), Gachibowli, Hyderabad 500032, Telangana, India
| | - Jayanth Katuri
- Center
for Computational Natural Sciences and Bioinformatics (CCNSB), International Institute of Information Technology,
Hyderabad (IIIT-H), Gachibowli, Hyderabad 500032, Telangana, India
| | - Dhananjay Bhattacharyya
- Computational
Science Division, Saha Institute of Nuclear
Physics (SINP), 1/AF,
Bidhannagar, Kolkata 700064, India
| | - Abhijit Mitra
- Center
for Computational Natural Sciences and Bioinformatics (CCNSB), International Institute of Information Technology,
Hyderabad (IIIT-H), Gachibowli, Hyderabad 500032, Telangana, India
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18
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Liu Y, Korn JA, Dang A, Tureček F. Hydrogen-Rich Cation Radicals of DNA Dinucleotides: Generation and Structure Elucidation by UV-Vis Action Spectroscopy. J Phys Chem B 2018; 122:9665-9680. [PMID: 30269486 DOI: 10.1021/acs.jpcb.8b07925] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Hydrogen-rich DNA dinucleotide cation radicals (dGG + 2H)+•, (dCG + 2H)+•, and (dGC + 2H)+• represent transient species comprising protonated and hydrogen atom adducted nucleobase rings that serve as models for proton and radical migrations in ionized DNA. These DNA cation radicals were generated in the gas phase by electron-transfer dissociation of dinucleotide dication-crown-ether complexes and characterized by UV-vis photodissociation action spectra, ab initio calculations of structures and relative energies, and time-dependent density functional theory calculations of UV-vis absorption spectra. Theoretical calculations indicate that (dGG + 2H)+• cation radicals formed by electron transfer underwent an exothermic conformational collapse that was accompanied by guanine ring stacking and facile internucleobase hydrogen atom transfer, forming 3'-guanine C-8-H radicals. In contrast, exothermic hydrogen transfer from the 5'-cytosine radical onto the guanine ring in (dCG + 2H)+• was kinetically hampered, resulting in the formation of a mixture of 5'-cytosine and 3'-guanine radicals. Conformational folding and nucleobase stacking were energetically unfavorable in (dGC + 2H)+• that retained its structure of a 3'-cytosine radical, as formed by one-electron reduction of the dication. Hydrogen-rich guanine (G + H)• and cytosine (C + H)• radicals were calculated to have vastly different basicities in water, as illustrated by the respective p Ka values of 20.0 and 4.6, which is pertinent to their different abilities to undergo proton-transfer reactions in solution.
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Affiliation(s)
- Yang Liu
- Department of Chemistry, Bagley Hall , University of Washington , P.O. Box 351700, Seattle , Washington 98195-1700 , United States
| | - Joseph A Korn
- Department of Chemistry, Bagley Hall , University of Washington , P.O. Box 351700, Seattle , Washington 98195-1700 , United States
| | - Andy Dang
- Department of Chemistry, Bagley Hall , University of Washington , P.O. Box 351700, Seattle , Washington 98195-1700 , United States
| | - František Tureček
- Department of Chemistry, Bagley Hall , University of Washington , P.O. Box 351700, Seattle , Washington 98195-1700 , United States
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19
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Kumar P, Cabaj MK, Pazio A, Dominiak PM. Protonated nucleobases are not fully ionized in their chloride salt crystals and form metastable base pairs further stabilized by the surrounding anions. IUCRJ 2018; 5:449-469. [PMID: 30002846 PMCID: PMC6038959 DOI: 10.1107/s2052252518006346] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 04/25/2018] [Indexed: 06/08/2023]
Abstract
This paper presents experimental charge-density studies of cytosinium chloride, adeninium chloride hemihydrate and guaninium dichloride crystals based on ultra-high-resolution X-ray diffraction data and extensive theoretical calculations. The results confirm that the cohesive energies of the studied systems are dominated by contributions from intermolecular electrostatic interactions, as expected for ionic crystals. Electrostatic interaction energies (Ees) usually constitute 95% of the total interaction energy. The Ees energies in this study were several times larger in absolute value when compared, for example, with dimers of neutral nucleobases. However, they were not as large as some theoretical calculations have predicted. This was because the molecules appeared not to be fully ionized in the studied crystals. Apart from charge transfer from chlorine to the protonated nucleobases, small but visible charge redistribution within the nucleobase cations was observed. Some dimers of singly protonated bases in the studied crystals, namely a cytosinium-cytosinium trans sugar/sugar edge pair and an adeninium-adeninium trans Hoogsteen/Hoogsteen edge pair, exhibited attractive interactions (negative values of Ees) or unusually low repulsion despite identical molecular charges. The pairs are metastable as a result of strong hydrogen bonding between bases which overcompensates the overall cation-cation repulsion, the latter being weakened due to charge transfer and molecular charge-density polarization.
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Affiliation(s)
- Prashant Kumar
- Biological and Chemical Research Center, Department of Chemistry, University of Warsaw, ul. Żwirki i Wigury 101, Warszawa 02-089, Poland
| | - Malgorzata Katarzyna Cabaj
- Biological and Chemical Research Center, Department of Chemistry, University of Warsaw, ul. Żwirki i Wigury 101, Warszawa 02-089, Poland
| | - Aleksandra Pazio
- Biological and Chemical Research Center, Department of Chemistry, University of Warsaw, ul. Żwirki i Wigury 101, Warszawa 02-089, Poland
| | - Paulina Maria Dominiak
- Biological and Chemical Research Center, Department of Chemistry, University of Warsaw, ul. Żwirki i Wigury 101, Warszawa 02-089, Poland
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20
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Halder A, Roy R, Bhattacharyya D, Mitra A. Consequences of Mg2+ binding on the geometry and stability of RNA base pairs. Phys Chem Chem Phys 2018; 20:21934-21948. [DOI: 10.1039/c8cp03602k] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Quantum chemical calculations reveal the role of magnesium in stabilizing the geometries of intrinsically unstable RNA base pairs.
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Affiliation(s)
- Antarip Halder
- Center for Computational Natural Sciences and Bioinformatics (CCNSB)
- International Institute of Information Technology (IIIT-H)
- Hyderabad 500032
- India
| | - Rohit Roy
- Center for Computational Natural Sciences and Bioinformatics (CCNSB)
- International Institute of Information Technology (IIIT-H)
- Hyderabad 500032
- India
| | | | - Abhijit Mitra
- Center for Computational Natural Sciences and Bioinformatics (CCNSB)
- International Institute of Information Technology (IIIT-H)
- Hyderabad 500032
- India
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21
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Seelam PP, Sharma P, Mitra A. Structural landscape of base pairs containing post-transcriptional modifications in RNA. RNA (NEW YORK, N.Y.) 2017; 23:847-859. [PMID: 28341704 PMCID: PMC5435857 DOI: 10.1261/rna.060749.117] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 03/23/2017] [Indexed: 05/20/2023]
Abstract
Base pairs involving post-transcriptionally modified nucleobases are believed to play important roles in a wide variety of functional RNAs. Here we present our attempts toward understanding the structural and functional role of naturally occurring modified base pairs using a combination of X-ray crystal structure database analysis, sequence analysis, and advanced quantum chemical methods. Our bioinformatics analysis reveals that despite their presence in all major secondary structural elements, modified base pairs are most prevalent in tRNA crystal structures and most commonly involve guanine or uridine modifications. Further, analysis of tRNA sequences reveals additional examples of modified base pairs at structurally conserved tRNA regions and highlights the conservation patterns of these base pairs in three domains of life. Comparison of structures and binding energies of modified base pairs with their unmodified counterparts, using quantum chemical methods, allowed us to classify the base modifications in terms of the nature of their electronic structure effects on base-pairing. Analysis of specific structural contexts of modified base pairs in RNA crystal structures revealed several interesting scenarios, including those at the tRNA:rRNA interface, antibiotic-binding sites on the ribosome, and the three-way junctions within tRNA. These scenarios, when analyzed in the context of available experimental data, allowed us to correlate the occurrence and strength of modified base pairs with their specific functional roles. Overall, our study highlights the structural importance of modified base pairs in RNA and points toward the need for greater appreciation of the role of modified bases and their interactions, in the context of many biological processes involving RNA.
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Affiliation(s)
- Preethi P Seelam
- Center for Computational Natural Sciences and Bioinformatics, International Institute of Information Technology Hyderabad (IIIT-H), Gachibowli, Hyderabad, Telangana 500032, India
| | - Purshotam Sharma
- Computational Biochemistry Laboratory, Department of Chemistry and Centre for Advanced Studies in Chemistry, Panjab University, Chandigarh 160014, India
| | - Abhijit Mitra
- Center for Computational Natural Sciences and Bioinformatics, International Institute of Information Technology Hyderabad (IIIT-H), Gachibowli, Hyderabad, Telangana 500032, India
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22
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Halder A, Roy R, Bhattacharyya D, Mitra A. How Does Mg 2+ Modulate the RNA Folding Mechanism: A Case Study of the G:C W:W Trans Basepair. Biophys J 2017; 113:277-289. [PMID: 28506525 DOI: 10.1016/j.bpj.2017.04.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 04/18/2017] [Accepted: 04/21/2017] [Indexed: 12/30/2022] Open
Abstract
Reverse Watson-Crick G:C basepairs (G:C W:W Trans) occur frequently in different functional RNAs. This is one of the few basepairs whose gas-phase-optimized isolated geometry is inconsistent with the corresponding experimental geometry. Several earlier studies indicate that through post-transcriptional modification, direct protonation, or coordination with Mg2+, accumulation of positive charge near N7 of guanine can stabilize the experimental geometry. Interestingly, recent studies reveal significant variation in the position of putatively bound Mg2+. This, in conjunction with recently raised doubts regarding some of the Mg2+ assignments near the imino nitrogen of guanine, is suggestive of the existence of multiple Mg2+ binding modes for this basepair. Our detailed investigation of Mg2+-bound G:C W:W Trans pairs occurring in high-resolution RNA crystal structures shows that they are found in 14 different contexts, eight of which display Mg2+ binding at the Hoogsteen edge of guanine. Further examination of occurrences in these eight contexts led to the characterization of three different Mg2+ binding modes: 1) direct binding via N7 coordination, 2) direct binding via O6 coordination, and 3) binding via hydrogen-bonding interaction with the first-shell water molecules. In the crystal structures, the latter two modes are associated with a buckled and propeller-twisted geometry of the basepair. Interestingly, respective optimized geometries of these different Mg2+ binding modes (optimized using six different DFT functionals) are consistent with their corresponding experimental geometries. Subsequent interaction energy calculations at the MP2 level, and decomposition of its components, suggest that for G:C W:W Trans , Mg2+ binding can fine tune the basepair geometries without compromising with their stability. Our results, therefore, underline the importance of the mode of binding of Mg2+ ions in shaping RNA structure, folding and function.
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Affiliation(s)
- Antarip Halder
- Center for Computational Natural Sciences and Bioinformatics (CCNSB), International Institute of Information Technology (IIIT-H), Gachibowli, Hyderabad, India
| | - Rohit Roy
- Center for Computational Natural Sciences and Bioinformatics (CCNSB), International Institute of Information Technology (IIIT-H), Gachibowli, Hyderabad, India
| | | | - Abhijit Mitra
- Center for Computational Natural Sciences and Bioinformatics (CCNSB), International Institute of Information Technology (IIIT-H), Gachibowli, Hyderabad, India.
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