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Ratajczyk EJ, Šulc P, Turberfield AJ, Doye JPK, Louis AA. Coarse-grained modeling of DNA-RNA hybrids. J Chem Phys 2024; 160:115101. [PMID: 38497475 DOI: 10.1063/5.0199558] [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: 11/17/2023] [Accepted: 01/26/2024] [Indexed: 03/19/2024] Open
Abstract
We introduce oxNA, a new model for the simulation of DNA-RNA hybrids that is based on two previously developed coarse-grained models-oxDNA and oxRNA. The model naturally reproduces the physical properties of hybrid duplexes, including their structure, persistence length, and force-extension characteristics. By parameterizing the DNA-RNA hydrogen bonding interaction, we fit the model's thermodynamic properties to experimental data using both average-sequence and sequence-dependent parameters. To demonstrate the model's applicability, we provide three examples of its use-calculating the free energy profiles of hybrid strand displacement reactions, studying the resolution of a short R-loop, and simulating RNA-scaffolded wireframe origami.
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Affiliation(s)
- Eryk J Ratajczyk
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
- Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot Hodgkin Building, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Petr Šulc
- School of Molecular Sciences and Center for Molecular Design and Biomimetics, The Biodesign Institute, Arizona State University, 1001 South McAllister Avenue, Tempe, Arizona 85281, USA
- School of Natural Sciences, Department of Bioscience, Technical University Munich, 85748 Garching, Germany
| | - Andrew J Turberfield
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
- Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot Hodgkin Building, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Jonathan P K Doye
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Ard A Louis
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP, United Kingdom
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2
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Shedding light on the base-pair opening dynamics of nucleic acids in living human cells. Nat Commun 2022; 13:7143. [PMID: 36446768 PMCID: PMC9708698 DOI: 10.1038/s41467-022-34822-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 11/03/2022] [Indexed: 11/30/2022] Open
Abstract
Base-pair opening is a fundamental property of nucleic acids that plays important roles in biological functions. However, studying the base-pair opening dynamics inside living cells has remained challenging. Here, to determine the base-pair opening kinetics inside living human cells, the exchange rate constant ([Formula: see text]) of the imino proton with the proton of solvent water involved in hairpin and G-quadruplex (GQ) structures is determined by the in-cell NMR technique. It is deduced on determination of [Formula: see text] values that at least some G-C base pairs of the hairpin structure and all G-G base-pairs of the GQ structure open more frequently in living human cells than in vitro. It is suggested that interactions with endogenous proteins could be responsible for the increase in frequency of base-pair opening. Our studies demonstrate a difference in dynamics of nucleic acids between in-cell and in vitro conditions.
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Zhao S, Li X, Wen Z, Zou M, Yu G, Liu X, Mao J, Zhang L, Xue Y, Fu R, Wang S. Dynamics of base pairs with low stability in RNA by solid-state nuclear magnetic resonance exchange spectroscopy. iScience 2022; 25:105322. [DOI: 10.1016/j.isci.2022.105322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 09/07/2022] [Accepted: 10/07/2022] [Indexed: 11/28/2022] Open
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4
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Yang J, Wang C, Luo L, Li Z, Xu B, Guo L, Xie J. Highly sensitive MALDI-MS measurement of active ricin: insight from more potential deoxynucleobase-hybrid oligonucleotide substrates. Analyst 2021; 146:2955-2964. [PMID: 33949380 DOI: 10.1039/d0an02205e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Herein, we report an improved MALDI-MS method for active ricin to contribute toward countermeasures against its real threat to the public. Compared with commonly used DNA or RNA substrates, the deoxynucleobase-hybrid oligonucleotide (RNA_dA, Rd) substrate containing functional Gd[combining low line]A[combining low line]GA loop was revealed as a substrate with more potential and used for the first time in ricin measurement via MALDI-MS. The Rd sequence greatly prompted ricin to exhibit its catalytic activity as rRNA N-glycosylase in ex vitro condition, which was supported by molecular docking simulation and enzymatic parameters depicted in MALDI-MS. Furthermore, we discovered that a highly pure matrix was the most crucial parameter for enhancing the sensitivity, which addressed the major obstacle encountered in the oligo(deoxy)nucleotide measurement, i.e., the interfering alkali metal ion-adducted signals in MALDI-MS. After the optimization of pH and enzymatic reaction buffer composition in this ex vitro condition, this method can provide a wide linearity of up to three orders of magnitude, i.e., 1-5000 ng mL-1, and a high sensitivity of 1 ng mL-1 without any enrichment. Denatured and active ricin could be distinctly differentiated, and the application to practical samples from one international exercise and a soft drink proved the feasibility of this new method. We believe this MALDI-MS method can contribute to the first response to ricin occurrence events in public safety and security, as well as pave a new way for a deep understanding of ricin and other type II ribosome inactivating proteins involved toxicology.
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Affiliation(s)
- Jiewei Yang
- State Key Laboratory of Toxicology and Medical Countermeasures, and Laboratory of Toxicant Analysis, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing, 100850, China.
| | - Chenyu Wang
- State Key Laboratory of Toxicology and Medical Countermeasures, and Laboratory of Toxicant Analysis, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing, 100850, China. and School of Pharmacy, Minzu University, Beijing, 100081, China
| | - Li Luo
- State Key Laboratory of Toxicology and Medical Countermeasures, and Laboratory of Toxicant Analysis, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing, 100850, China. and School of Public Health, Hebei Medical University, Shijiazhuang, Hebei Province 050017, China
| | - Zhi Li
- State Key Laboratory of Toxicology and Medical Countermeasures, and Laboratory of Toxicant Analysis, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing, 100850, China.
| | - Bin Xu
- State Key Laboratory of Toxicology and Medical Countermeasures, and Laboratory of Toxicant Analysis, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing, 100850, China.
| | - Lei Guo
- State Key Laboratory of Toxicology and Medical Countermeasures, and Laboratory of Toxicant Analysis, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing, 100850, China.
| | - Jianwei Xie
- State Key Laboratory of Toxicology and Medical Countermeasures, and Laboratory of Toxicant Analysis, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing, 100850, China.
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5
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Brodolin K, Morichaud Z. Region 4 of the RNA polymerase σ subunit counteracts pausing during initial transcription. J Biol Chem 2021; 296:100253. [PMID: 33380428 PMCID: PMC7948647 DOI: 10.1074/jbc.ra120.016299] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 12/22/2020] [Accepted: 12/30/2020] [Indexed: 01/24/2023] Open
Abstract
All cellular genetic information is transcribed into RNA by multisubunit RNA polymerases (RNAPs). The basal transcription initiation factors of cellular RNAPs stimulate the initial RNA synthesis via poorly understood mechanisms. Here, we explored the mechanism employed by the bacterial factor σ in promoter-independent initial transcription. We found that the RNAP holoenzyme lacking the promoter-binding domain σ4 is ineffective in de novo transcription initiation and displays high propensity to pausing upon extension of RNAs 3 to 7 nucleotides in length. The nucleotide at the RNA 3' end determines the pause lifetime. The σ4 domain stabilizes short RNA:DNA hybrids and suppresses pausing by stimulating RNAP active-center translocation. The antipausing activity of σ4 is modulated by its interaction with the β subunit flap domain and by the σ remodeling factors AsiA and RbpA. Our results suggest that the presence of σ4 within the RNA exit channel compensates for the intrinsic instability of short RNA:DNA hybrids by increasing RNAP processivity, thus favoring productive transcription initiation. This "RNAP boosting" activity of the initiation factor is shaped by the thermodynamics of RNA:DNA interactions and thus, should be relevant for any factor-dependent RNAP.
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Affiliation(s)
- Konstantin Brodolin
- Institut de Recherche en Infectiologie de Montpellier, Centre national de la recherche scientifique, Univ Montpellier, Montpellier, France; Institut national de la santé et de la recherche médicale, Institut de Recherche en Infectiologie de Montpellier, Montpellier, France.
| | - Zakia Morichaud
- Institut de Recherche en Infectiologie de Montpellier, Centre national de la recherche scientifique, Univ Montpellier, Montpellier, France
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6
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Yang D, Liu W, Deng X, Xie W, Chen H, Zhong Z, Ma J. GC-Content Dependence of Elastic and Overstretching Properties of DNA:RNA Hybrid Duplexes. Biophys J 2020; 119:852-861. [PMID: 32738216 DOI: 10.1016/j.bpj.2020.06.034] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 05/22/2020] [Accepted: 06/18/2020] [Indexed: 01/25/2023] Open
Abstract
DNA:RNA hybrid duplex plays important roles in various biological processes. Both its structural stability and interactions with proteins are highly sequence dependent. In this study, we utilize homebuilt optical tweezers to investigate how GC contents in the sequence influence the structural and mechanical properties of DNA:RNA hybrid by measuring its contour length, elasticities, and overstretching dynamics. Our results support that the DNA:RNA hybrid adopts a conformation between the A- and B-form helix, and the GC content does not affect its structural and elastic parameters obviously when varying from 40 to 60% before the overstretching transition of DNA:RNA hybrid occurs. In the overstretching transition, however, our study unravels significant heterogeneity and strong sequence dependence, suggesting the presence of a highly dynamic competition between the two processes, namely the S-form duplex formation (nonhysteretic) and the unpeeling (hysteretic). Analyzing the components left in DNA:RNA hybrid after the overstretching transition suggests that the RNA strand is more easily unpeeled than the DNA strand, whereas an increase in the GC content from 40 to 60% can significantly reduce unpeeling. Large hysteresis is observed between the stretching and relaxation processes, which is also quantitatively correlated with the percentage of unpeeling in the DNA:RNA duplex. Increasing in both the salt concentration and GC content can effectively reduce the hysteresis with the latter being more significant. Together, our study reveals that the mechanical properties of DNA:RNA hybrid duplexes are significantly different from double-stranded DNA and double-stranded RNA, and its overstretching behavior is highly sequence dependent. These results should be taken into account in the future studies on DNA:RNA-hybrid-related functional structures and motor proteins.
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Affiliation(s)
- Dongni Yang
- School of Physics, Sun Yat-sen University, Guangzhou, Guangdong, China; State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Wenzhao Liu
- School of Physics, Sun Yat-sen University, Guangzhou, Guangdong, China; State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Xiangyu Deng
- State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Wei Xie
- State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Hu Chen
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen, Fujian, China
| | - Zhensheng Zhong
- School of Physics, Sun Yat-sen University, Guangzhou, Guangdong, China; State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou, Guangdong, China.
| | - Jie Ma
- School of Physics, Sun Yat-sen University, Guangzhou, Guangdong, China; State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou, Guangdong, China.
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7
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Liu JH, Xi K, Zhang X, Bao L, Zhang X, Tan ZJ. Structural Flexibility of DNA-RNA Hybrid Duplex: Stretching and Twist-Stretch Coupling. Biophys J 2019; 117:74-86. [PMID: 31164196 DOI: 10.1016/j.bpj.2019.05.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 04/25/2019] [Accepted: 05/17/2019] [Indexed: 12/21/2022] Open
Abstract
DNA-RNA hybrid (DRH) duplexes play essential roles during the replication of DNA and the reverse transcription of RNA viruses, and their flexibility is important for their biological functions. Recent experiments indicated that A-form RNA and B-form DNA have a strikingly different flexibility in stretching and twist-stretch coupling, and the structural flexibility of DRH duplex is of great interest, especially in stretching and twist-stretch coupling. In this work, we performed microsecond all-atom molecular dynamics simulations with new AMBER force fields to characterize the structural flexibility of DRH duplex in stretching and twist-stretch coupling. We have calculated all the helical parameters, stretch modulus, and twist-stretch coupling parameters for the DRH duplex. First, our analyses on structure suggest that the DRH duplex exhibits an intermediate conformation between A- and B-forms and closer to A-form, which can be attributed to the stronger rigidity of the RNA strand than the DNA strand. Second, our calculations show that the DRH duplex has the stretch modulus of 834 ± 34 pN and a very weak twist-stretch coupling. Our quantitative analyses indicate that, compared with DNA and RNA duplexes, the different flexibility of the DRH duplex in stretching and twist-stretch coupling is mainly attributed to its apparently different basepair inclination in the helical structure.
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Affiliation(s)
- Ju-Hui Liu
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Kun Xi
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Xi Zhang
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Lei Bao
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Xinghua Zhang
- College of Life Science, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China.
| | - Zhi-Jie Tan
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China.
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Koscielniak D, Wons E, Wilkowska K, Sektas M. Non-programmed transcriptional frameshifting is common and highly RNA polymerase type-dependent. Microb Cell Fact 2018; 17:184. [PMID: 30474557 PMCID: PMC6260861 DOI: 10.1186/s12934-018-1034-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 11/19/2018] [Indexed: 12/15/2022] Open
Abstract
Background The viral or host systems for a gene expression assume repeatability of the process and high quality of the protein product. Since level and fidelity of transcription primarily determines the overall efficiency, all factors contributing to their decrease should be identified and optimized. Among many observed processes, non-programmed insertion/deletion (indel) of nucleotide during transcription (slippage) occurring at homopolymeric A/T sequences within a gene can considerably impact its expression. To date, no comparative study of the most utilized Escherichia coli and T7 bacteriophage RNA polymerases (RNAP) propensity for this type of erroneous mRNA synthesis has been reported. To address this issue we evaluated the influence of shift-prone A/T sequences by assessing indel-dependent phenotypic changes. RNAP-specific expression profile was examined using two of the most potent promoters, ParaBAD of E. coli and φ10 of phage T7. Results Here we report on the first systematic study on requirements for efficient transcriptional slippage by T7 phage and cellular RNAPs considering three parameters: homopolymer length, template type, and frameshift directionality preferences. Using a series of out-of-frame gfp reporter genes fused to a variety of A/T homopolymeric sequences we show that T7 RNAP has an exceptional potential for generating frameshifts and is capable of slipping on as few as three adenine or four thymidine residues in a row, in a flanking sequence-dependent manner. In contrast, bacterial RNAP exhibits a relatively low ability to baypass indel mutations and requires a run of at least 7 tymidine and even more adenine residues. This difference comes from involvement of various intrinsic proofreading properties. Our studies demonstrate distinct preference towards a specific homopolymer in slippage induction. Whereas insertion slippage performed by T7 RNAP (but not deletion) occurs tendentiously on poly(A) rather than on poly(T) runs, strong bias towards poly(T) for the host RNAP is observed. Conclusions Intrinsic RNAP slippage properties involve trade-offs between accuracy, speed and processivity of transcription. Viral T7 RNAP manifests far greater inclinations to the transcriptional slippage than E. coli RNAP. This possibly plays an important role in driving bacteriophage adaptation and therefore could be considered as beneficial. However, from biotechnological and experimental viewpoint, this might create some problems, and strongly argues for employing bacterial expression systems, stocked with proofreading mechanisms. Electronic supplementary material The online version of this article (10.1186/s12934-018-1034-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Dawid Koscielniak
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308, Gdansk, Poland
| | - Ewa Wons
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308, Gdansk, Poland
| | - Karolina Wilkowska
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308, Gdansk, Poland
| | - Marian Sektas
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308, Gdansk, Poland.
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Künne T, Zhu Y, da Silva F, Konstantinides N, McKenzie RE, Jackson RN, Brouns S. Role of nucleotide identity in effective CRISPR target escape mutations. Nucleic Acids Res 2018; 46:10395-10404. [PMID: 30107450 PMCID: PMC6212716 DOI: 10.1093/nar/gky687] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 07/16/2018] [Accepted: 08/10/2018] [Indexed: 12/26/2022] Open
Abstract
Prokaryotes use primed CRISPR adaptation to update their memory bank of spacers against invading genetic elements that have escaped CRISPR interference through mutations in their protospacer target site. We previously observed a trend that nucleotide-dependent mismatches between crRNA and the protospacer strongly influence the efficiency of primed CRISPR adaptation. Here we show that guanine-substitutions in the target strand of the protospacer are highly detrimental to CRISPR interference and interference-dependent priming, while cytosine-substitutions are more readily tolerated. Furthermore, we show that this effect is based on strongly decreased binding affinity of the effector complex Cascade for guanine-mismatched targets, while cytosine-mismatched targets only minimally affect target DNA binding. Structural modeling of Cascade-bound targets with mismatches shows that steric clashes of mismatched guanines lead to unfavorable conformations of the RNA-DNA duplex. This effect has strong implications for the natural selection of target site mutations that lead to effective escape from type I CRISPR-Cas systems.
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MESH Headings
- Base Pairing
- Base Sequence
- CRISPR-Associated Proteins/genetics
- CRISPR-Associated Proteins/metabolism
- CRISPR-Cas Systems
- Clustered Regularly Interspaced Short Palindromic Repeats
- Cytosine/chemistry
- Cytosine/metabolism
- DNA Helicases/genetics
- DNA Helicases/metabolism
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- DNA, Bacterial/metabolism
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Escherichia coli Proteins/genetics
- Escherichia coli Proteins/metabolism
- Guanine/chemistry
- Guanine/metabolism
- Mutation
- Plasmids/chemistry
- Plasmids/metabolism
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Guide, CRISPR-Cas Systems/chemistry
- RNA, Guide, CRISPR-Cas Systems/genetics
- RNA, Guide, CRISPR-Cas Systems/metabolism
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Affiliation(s)
- Tim Künne
- Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
- Laboratory of Food Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
| | - Yifan Zhu
- Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Fausia da Silva
- Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Nico Konstantinides
- Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Rebecca E McKenzie
- Kavli Institute of Nanoscience, Department of Bionanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Ryan N Jackson
- Department of Chemistry and Biochemistry, Utah State University, 0300 Old Main Hill, Logan, UT, USA
| | - Stan JJ Brouns
- Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
- Kavli Institute of Nanoscience, Department of Bionanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
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10
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Zhou KI, Clark WC, Pan DW, Eckwahl MJ, Dai Q, Pan T. Pseudouridines have context-dependent mutation and stop rates in high-throughput sequencing. RNA Biol 2018; 15:892-900. [PMID: 29683381 PMCID: PMC6161689 DOI: 10.1080/15476286.2018.1462654] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 04/02/2018] [Accepted: 04/03/2018] [Indexed: 01/28/2023] Open
Abstract
The abundant RNA modification pseudouridine (Ψ) has been mapped transcriptome-wide by chemically modifying pseudouridines with carbodiimide and detecting the resulting reverse transcription stops in high-throughput sequencing. However, these methods have limited sensitivity and specificity, in part due to the use of reverse transcription stops. We sought to use mutations rather than just stops in sequencing data to identify pseudouridine sites. Here, we identify reverse transcription conditions that allow read-through of carbodiimide-modified pseudouridine (CMC-Ψ), and we show that pseudouridines in carbodiimide-treated human ribosomal RNA have context-dependent mutation and stop rates in high-throughput sequencing libraries prepared under these conditions. Furthermore, accounting for the context-dependence of mutation and stop rates can enhance the detection of pseudouridine sites. Similar approaches could contribute to the sequencing-based detection of many RNA modifications.
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Affiliation(s)
- Katherine I. Zhou
- Medical Scientist Training Program, The University of Chicago, Chicago, Illinois, USA
| | - Wesley C. Clark
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois, USA
| | - David W. Pan
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois, USA
| | - Matthew J. Eckwahl
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois, USA
| | - Qing Dai
- Department of Chemistry, The University of Chicago, Chicago, Illinois, USA
| | - Tao Pan
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois, USA
- Institute of Biophysical Dynamics, The University of Chicago, Chicago, Illinois, USA
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11
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Huang Y, Russu IM. Dynamic and Energetic Signatures of Adenine Tracts in a rA-dT RNA-DNA Hybrid and in Homologous RNA-DNA, RNA-RNA, and DNA-DNA Double Helices. Biochemistry 2017; 56:2446-2454. [PMID: 28430414 DOI: 10.1021/acs.biochem.6b01122] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nuclear magnetic resonance spectroscopy and proton exchange are being used to characterize the opening reactions of individual base pairs in the RNA-DNA hybrid 5'-rGCGAUAAAAAGGCC-3'/5'-dGGCCTTTTTATCGC-3'. The hybrid contains a central tract of five rA-dT base pairs. The rates and the equilibrium constant of the opening reaction for each base pair are determined from the dependence of the exchange rates of imino protons on ammonia concentration, at 10 °C. The results are compared to those previously obtained by our laboratory for three homologous duplexes of the same base sequence (except for the appropriate T/U substitution), containing tracts of dA-rU, rA-rU, or dA-dT base pairs. The rA-dT tract is distinguished by an enhanced propensity of the base pairs to exist in the extrahelical state. The opening rates of rA-dT base pairs also exhibit a strong dependence on the location of the base pair in the structure; namely, as one advances into the tract, the opening rates of rA-dT base pairs gradually decrease. The local stability of each rA-dT base pair within the tract is the same as that of the corresponding rA-rU base pair in the homologous RNA-only duplex but differs from the stabilities of dA-dT and dA-rU base pairs in the other two duplexes (namely, dA-dT > rA-dT > dA-rU). These results demonstrate that, in nucleic acid double helices with the same base sequence, the opening dynamics and the energetics of individual base pairs are strongly influenced by the nature of the strand and by the structural context of the base pair.
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Affiliation(s)
- Yuegao Huang
- Department of Chemistry and Molecular Biophysics Program, Wesleyan University , Middletown, Connecticut 06459, United States
| | - Irina M Russu
- Department of Chemistry and Molecular Biophysics Program, Wesleyan University , Middletown, Connecticut 06459, United States
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12
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Farasat I, Salis HM. A Biophysical Model of CRISPR/Cas9 Activity for Rational Design of Genome Editing and Gene Regulation. PLoS Comput Biol 2016; 12:e1004724. [PMID: 26824432 PMCID: PMC4732943 DOI: 10.1371/journal.pcbi.1004724] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Accepted: 12/23/2015] [Indexed: 12/26/2022] Open
Abstract
The ability to precisely modify genomes and regulate specific genes will greatly accelerate several medical and engineering applications. The CRISPR/Cas9 (Type II) system binds and cuts DNA using guide RNAs, though the variables that control its on-target and off-target activity remain poorly characterized. Here, we develop and parameterize a system-wide biophysical model of Cas9-based genome editing and gene regulation to predict how changing guide RNA sequences, DNA superhelical densities, Cas9 and crRNA expression levels, organisms and growth conditions, and experimental conditions collectively control the dynamics of dCas9-based binding and Cas9-based cleavage at all DNA sites with both canonical and non-canonical PAMs. We combine statistical thermodynamics and kinetics to model Cas9:crRNA complex formation, diffusion, site selection, reversible R-loop formation, and cleavage, using large amounts of structural, biochemical, expression, and next-generation sequencing data to determine kinetic parameters and develop free energy models. Our results identify DNA supercoiling as a novel mechanism controlling Cas9 binding. Using the model, we predict Cas9 off-target binding frequencies across the lambdaphage and human genomes, and explain why Cas9's off-target activity can be so high. With this improved understanding, we propose several rules for designing experiments for minimizing off-target activity. We also discuss the implications for engineering dCas9-based genetic circuits.
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Affiliation(s)
- Iman Farasat
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Howard M. Salis
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Biological Engineering, Pennsylvania State University, University Park, Pennsylvania, United States of America
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13
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Szulik M, Pallan PS, Nocek B, Voehler M, Banerjee S, Brooks S, Joachimiak A, Egli M, Eichman BF, Stone MP. Differential stabilities and sequence-dependent base pair opening dynamics of Watson-Crick base pairs with 5-hydroxymethylcytosine, 5-formylcytosine, or 5-carboxylcytosine. Biochemistry 2015; 54:1294-305. [PMID: 25632825 PMCID: PMC4325598 DOI: 10.1021/bi501534x] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
5-Hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC) form during active demethylation of 5-methylcytosine (5mC) and are implicated in epigenetic regulation of the genome. They are differentially processed by thymine DNA glycosylase (TDG), an enzyme involved in active demethylation of 5mC. Three modified Dickerson-Drew dodecamer (DDD) sequences, amenable to crystallographic and spectroscopic analyses and containing the 5'-CG-3' sequence associated with genomic cytosine methylation, containing 5hmC, 5fC, or 5caC placed site-specifically into the 5'-T(8)X(9)G(10)-3' sequence of the DDD, were compared. The presence of 5caC at the X(9) base increased the stability of the DDD, whereas 5hmC or 5fC did not. Both 5hmC and 5fC increased imino proton exchange rates and calculated rate constants for base pair opening at the neighboring base pair A(5):T(8), whereas 5caC did not. At the oxidized base pair G(4):X(9), 5fC exhibited an increase in the imino proton exchange rate and the calculated kop. In all cases, minimal effects to imino proton exchange rates occurred at the neighboring base pair C(3):G(10). No evidence was observed for imino tautomerization, accompanied by wobble base pairing, for 5hmC, 5fC, or 5caC when positioned at base pair G(4):X(9); each favored Watson-Crick base pairing. However, both 5fC and 5caC exhibited intranucleobase hydrogen bonding between their formyl or carboxyl oxygens, respectively, and the adjacent cytosine N(4) exocyclic amines. The lesion-specific differences observed in the DDD may be implicated in recognition of 5hmC, 5fC, or 5caC in DNA by TDG. However, they do not correlate with differential excision of 5hmC, 5fC, or 5caC by TDG, which may be mediated by differences in transition states of the enzyme-bound complexes.
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Affiliation(s)
- Marta
W. Szulik
- Department
of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt
Ingram Cancer Center, and Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Pradeep S. Pallan
- Department
of Biochemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt
Ingram Cancer Center, and Center for Structural Biology, School of
Medicine, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Boguslaw Nocek
- Bioscience
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Markus Voehler
- Department
of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt
Ingram Cancer Center, and Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Surajit Banerjee
- Northeastern
Collaborative Access Team and Department of Chemistry and Chemical
Biology, Cornell University, Argonne National
Laboratory, Argonne, Illinois 60439, United
States
| | - Sonja Brooks
- Department
of Biological Sciences, Vanderbilt Institute of Chemical Biology,
and Center for Structural Biology, Vanderbilt
University, Nashville, Tennessee 37235, United States
| | - Andrzej Joachimiak
- Bioscience
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Martin Egli
- Department
of Biochemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt
Ingram Cancer Center, and Center for Structural Biology, School of
Medicine, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Brandt F. Eichman
- Department
of Biological Sciences, Vanderbilt Institute of Chemical Biology,
and Center for Structural Biology, Vanderbilt
University, Nashville, Tennessee 37235, United States
| | - Michael P. Stone
- Department
of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt
Ingram Cancer Center, and Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235, United States,(M.P.S.) Tel.: 615-322-2589; E-mail:
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14
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Molodtsov V, Anikin M, McAllister WT. The presence of an RNA:DNA hybrid that is prone to slippage promotes termination by T7 RNA polymerase. J Mol Biol 2014; 426:3095-3107. [PMID: 24976131 DOI: 10.1016/j.jmb.2014.06.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 06/20/2014] [Accepted: 06/23/2014] [Indexed: 11/17/2022]
Abstract
Intrinsic termination signals for multisubunit bacterial RNA polymerases (RNAPs) encode a GC-rich stem-loop structure followed by a polyuridine [poly(U)] tract, and it has been proposed that steric clash of the stem-loop with the exit pore of the RNAP imposes a shearing force on the RNA in the downstream RNA:DNA hybrid, resulting in misalignment of the active site. The structurally unrelated T7 RNAP terminates at a similar type of signal (TΦ), suggesting a common mechanism for termination. In the absence of a hairpin (passive conditions), T7 RNAP slips efficiently in both homopolymeric A and U tracts, and we have found that replacement of the U tract in TΦ with a slippage-prone A tract still allows efficient termination. Under passive conditions, incorporation of a single G residue following a poly(U) tract (which is the situation during termination at TΦ) results in a "locked" complex that is unable to extend the transcript. Our results support a model in which transmission of the shearing force generated by steric clash of the hairpin with the exit pore is promoted by the presence of a slippery tracts downstream, resulting in alterations in the active site and the formation of a locked complex that represents an early step in the termination pathway.
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Affiliation(s)
- Vadim Molodtsov
- Graduate Program in Cell and Molecular Biology, Rowan University School of Osteopathic Medicine, 42 East Laurel Road, UDP 2200, Stratford, NJ 08084, USA; Department of Cell Biology, Rowan University School of Osteopathic Medicine, 42 East Laurel Road, UDP 2200, Stratford, NJ 08084, USA
| | - Michael Anikin
- Department of Cell Biology, Rowan University School of Osteopathic Medicine, 42 East Laurel Road, UDP 2200, Stratford, NJ 08084, USA
| | - William T McAllister
- Department of Cell Biology, Rowan University School of Osteopathic Medicine, 42 East Laurel Road, UDP 2200, Stratford, NJ 08084, USA.
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15
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Parks AR, Court C, Lubkowska L, Jin DJ, Kashlev M, Court DL. Bacteriophage λ N protein inhibits transcription slippage by Escherichia coli RNA polymerase. Nucleic Acids Res 2014; 42:5823-9. [PMID: 24711367 PMCID: PMC4027172 DOI: 10.1093/nar/gku203] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Transcriptional slippage is a class of error in which ribonucleic acid (RNA) polymerase incorporates nucleotides out of register, with respect to the deoxyribonucleic acid (DNA) template. This phenomenon is involved in gene regulation mechanisms and in the development of diverse diseases. The bacteriophage λ N protein reduces transcriptional slippage within actively growing cells and in vitro. N appears to stabilize the RNA/DNA hybrid, particularly at the 5′ end, preventing loss of register between transcript and template. This report provides the first evidence of a protein that directly influences transcriptional slippage, and provides a clue about the molecular mechanism of transcription termination and N-mediated antitermination.
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Affiliation(s)
- Adam R Parks
- Molecular Control and Genetics Section, Gene Regulation and Chromosome Biology, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD 21702-1201, USA
| | - Carolyn Court
- Molecular Control and Genetics Section, Gene Regulation and Chromosome Biology, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD 21702-1201, USA
| | - Lucyna Lubkowska
- Molecular Control and Genetics Section, Gene Regulation and Chromosome Biology, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD 21702-1201, USA
| | - Ding J Jin
- Molecular Control and Genetics Section, Gene Regulation and Chromosome Biology, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD 21702-1201, USA
| | - Mikhail Kashlev
- Molecular Control and Genetics Section, Gene Regulation and Chromosome Biology, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD 21702-1201, USA
| | - Donald L Court
- Molecular Control and Genetics Section, Gene Regulation and Chromosome Biology, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD 21702-1201, USA
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16
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Suresh G, Priyakumar UD. DNA–RNA hybrid duplexes with decreasing pyrimidine content in the DNA strand provide structural snapshots for the A- to B-form conformational transition of nucleic acids. Phys Chem Chem Phys 2014; 16:18148-55. [DOI: 10.1039/c4cp02478h] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A gradual increase in the deoxypyrimidine content in DNA–RNA hybrids leads to B- to A-form nucleic acid transition. Possible factors that govern nuclease activity on hybrid duplexes are presented.
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Affiliation(s)
- Gorle Suresh
- Centre for Computational Natural Sciences and Bioinformatics
- International Institute of Information Technology
- Hyderabad 500 032, India
| | - U. Deva Priyakumar
- Centre for Computational Natural Sciences and Bioinformatics
- International Institute of Information Technology
- Hyderabad 500 032, India
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17
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Szulik MW, Voehler MW, Ganguly M, Gold B, Stone MP. Site-specific stabilization of DNA by a tethered major groove amine, 7-aminomethyl-7-deaza-2'-deoxyguanosine. Biochemistry 2013; 52:7659-68. [PMID: 24131376 PMCID: PMC3812902 DOI: 10.1021/bi400695r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
A cationic
7-aminomethyl-7-deaza-2′-deoxyguanosine (7amG)
was incorporated site-specifically into the self-complementary duplex
d(G1A2G3A4X5C6G7C8T9C10T11C12)2 (X = 7amG). This construct placed two positively charged amines adjacent
to the major groove edges of two symmetry-related guanines, providing
a model for probing how cation binding in the major groove modulates
the structure and stability of DNA. Molecular dynamics calculations
restrained by nuclear magnetic resonance (NMR) data revealed that
the tethered cationic amines were in plane with the modified base
pairs. The tethered amines did not form salt bridges to the phosphodiester
backbone. There was also no indication of the amines being capable
of hydrogen bonding to flanking DNA bases. NMR spectroscopy as a function
of temperature revealed that the X5 imino resonance remained
sharp at 55 °C. Additionally, two 5′-neighboring base
pairs, A4:T9 and G3:C10, were stabilized with respect to the exchange of their imino protons
with solvent. The equilibrium constant for base pair opening at the
A4:T9 base pair determined by magnetization
transfer from water in the absence and presence of added ammonia base
catalyst decreased for the modified duplex compared to that of the
A4:T9 base pair in the unmodified duplex, which
confirmed that the overall fraction of the A4:T9 base pair in the open state of the modified duplex decreased. This
was also observed for the G3:C10 base pair,
where αKop for the G3:C10 base pair in the modified duplex was 3.0 × 106 versus 4.1 × 106 for the same base pair in
the unmodified duplex. In contrast, equilibrium constants for base
pair opening at the X5:C8 and C6:G7 base pairs did not change at 15 °C. These results argue
against the notion that electrostatic interactions with DNA are entirely
entropic and suggest that major groove cations can stabilize DNA via
enthalpic contributions to the free energy of duplex formation.
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Affiliation(s)
- Marta W Szulik
- Department of Chemistry and Center for Structural Biology, Vanderbilt University , Nashville, Tennessee 37235, United States
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18
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Chen YJ, Liu P, Nielsen AAK, Brophy JAN, Clancy K, Peterson T, Voigt CA. Characterization of 582 natural and synthetic terminators and quantification of their design constraints. Nat Methods 2013; 10:659-64. [DOI: 10.1038/nmeth.2515] [Citation(s) in RCA: 344] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 05/06/2013] [Indexed: 01/20/2023]
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19
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Pramanik S, Nagatoishi S, Saxena S, Bhattacharyya J, Sugimoto N. Conformational flexibility influences degree of hydration of nucleic acid hybrids. J Phys Chem B 2011; 115:13862-72. [PMID: 21992117 DOI: 10.1021/jp207856p] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Four nucleic acid duplexes-DNA/RNA hybrid, RNA/DNA hybrid, RNA duplex, and DNA duplex-were studied under molecular crowding conditions of osmolytes. Destabilization of duplexes (ΔΔG°(25)) indicated that the ΔΔG°(25) values of hybrids were intermediate between those of DNA and RNA duplexes. In the presence of polyethylene glycol 200, the ΔΔG°(25) values were estimated to be +3.0, +3.5, +3.5, and +4.1 kcal mol(-1) for the DNA duplex, DNA/RNA hybrid, RNA/DNA hybrid, and RNA duplex, respectively. Differences in the number of water molecules taken up (-Δn(w)) upon duplex formations between 0 and 37 °C (Δ(-Δn(w))) were estimated to be 44.8 and 59.7 per duplex structure for the DNA/RNA and RNA/DNA hybrids, respectively. While the Δ(-Δn(w)) value for the DNA/RNA hybrid was intermediate between those of the DNA (26.1) and RNA (59.2) duplexes, the value for RNA/DNA hybrid was close to that of RNA duplex. These differences in the thermodynamic parameters and hydration are probably a consequence of the enhanced global flexibility of the RNA/DNA hybrid structure relative to the DNA/RNA hybrid structure observed in molecular dynamics simulations. This molecular crowding study provides information not only on hydration but also on the flexibility of the conformation of nucleic acid duplexes.
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Affiliation(s)
- Smritimoy Pramanik
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 7-1-20 Minatojima-minamimachi, Kobe 650-0047, Japan
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20
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Huang Y, Weng X, Russu IM. Enhanced base-pair opening in the adenine tract of a RNA double helix. Biochemistry 2011; 50:1857-63. [PMID: 21250663 DOI: 10.1021/bi1014997] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Proton exchange and nuclear magnetic resonance spectroscopy are being used to characterize the kinetics and energetics of base-pair opening in two nucleic acid double helices. One is the RNA duplex 5'-r(GCGAUAAAAAGGCC)-3'/5'-r(GGCCUUUUUAUCGC)-3', which contains a central tract of five AU base pairs. The other is the homologous DNA duplex with a central tract of five AT base pairs. The rates and the equilibrium constants of the opening reaction of each base pair are measured from the dependence of the exchange rates of imino protons on ammonia concentration, at 10 °C. The results reveal that the tract of AU base pairs in the RNA duplex differs from the homologous tract of AT base pairs in DNA in several ways. The rates of opening of AU base pairs in RNA are high and increase progressively along the tract, reaching their largest values at the 3'-end of the tract. In contrast, the opening rates of AT base pairs in DNA are much lower than those of AU base pairs. Within the tract, the largest opening rate is observed for the AT base pair at the 5'-end of the tract. These differences in opening kinetics are paralleled by differences in the stabilities of individual base pairs. All AU base pairs in the RNA are less stable than the AT base pairs in the DNA. The presence of the tract enhances these differences by increasing the stability of AT base pairs in DNA while decreasing the stability of AU base pairs in RNA. Due to these divergent trends, along the tracts, the AU base pairs become progressively less stable than AT base pairs. These findings demonstrate that tracts of AU base pairs in RNA have specific dynamic and energetic signatures that distinguish them from similar tracts of AT base pairs in DNA.
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Affiliation(s)
- Yuegao Huang
- Department of Chemistry and Molecular Biophysics Program, Wesleyan University, Middletown, Connecticut 06459, United States
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21
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Rinnenthal J, Klinkert B, Narberhaus F, Schwalbe H. Direct observation of the temperature-induced melting process of the Salmonella fourU RNA thermometer at base-pair resolution. Nucleic Acids Res 2010; 38:3834-47. [PMID: 20211842 PMCID: PMC2887971 DOI: 10.1093/nar/gkq124] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 01/28/2010] [Accepted: 02/10/2010] [Indexed: 11/13/2022] Open
Abstract
In prokaryotes, RNA thermometers regulate a number of heat shock and virulence genes. These temperature sensitive RNA elements are usually located in the 5'-untranslated regions of the regulated genes. They repress translation initiation by base pairing to the Shine-Dalgarno sequence at low temperatures. We investigated the thermodynamic stability of the temperature labile hairpin 2 of the Salmonella fourU RNA thermometer over a broad temperature range and determined free energy, enthalpy and entropy values for the base-pair opening of individual nucleobases by measuring the temperature dependence of the imino proton exchange rates via NMR spectroscopy. Exchange rates were analyzed for the wild-type (wt) RNA and the A8C mutant. The wt RNA was found to be stabilized by the extraordinarily stable G14-C25 base pair. The mismatch base pair in the wt RNA thermometer (A8-G31) is responsible for the smaller cooperativity of the unfolding transition in the wt RNA. Enthalpy and entropy values for the base-pair opening events exhibit linear correlation for both RNAs. The slopes of these correlations coincide with the melting points of the RNAs determined by CD spectroscopy. RNA unfolding occurs at a temperature where all nucleobases have equal thermodynamic stabilities. Our results are in agreement with a consecutive zipper-type unfolding mechanism in which the stacking interaction is responsible for the observed cooperativity. Furthermore, remote effects of the A8C mutation affecting the stability of nucleobase G14 could be identified. According to our analysis we deduce that this effect is most probably transduced via the hydration shell of the RNA.
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Affiliation(s)
- Jörg Rinnenthal
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max-von-Laue-Strasse 7, D-60438 Frankfurt/Main and Microbial Biology, Ruhr-Universität Bochum, Universitätsstrasse 150, NDEF06/783, 44780 Bochum, Germany
| | - Birgit Klinkert
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max-von-Laue-Strasse 7, D-60438 Frankfurt/Main and Microbial Biology, Ruhr-Universität Bochum, Universitätsstrasse 150, NDEF06/783, 44780 Bochum, Germany
| | - Franz Narberhaus
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max-von-Laue-Strasse 7, D-60438 Frankfurt/Main and Microbial Biology, Ruhr-Universität Bochum, Universitätsstrasse 150, NDEF06/783, 44780 Bochum, Germany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max-von-Laue-Strasse 7, D-60438 Frankfurt/Main and Microbial Biology, Ruhr-Universität Bochum, Universitätsstrasse 150, NDEF06/783, 44780 Bochum, Germany
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22
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Huang Y, Weng X, Russu IM. Structural energetics of the adenine tract from an intrinsic transcription terminator. J Mol Biol 2010; 397:677-88. [PMID: 20132823 DOI: 10.1016/j.jmb.2010.01.068] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 01/25/2010] [Accepted: 01/27/2010] [Indexed: 11/26/2022]
Abstract
Intrinsic transcription termination sites generally contain a tract of adenines in the DNA template that yields a tract of uracils at the 3' end of the nascent RNA. To understand how this base sequence contributes to termination of transcription, we have investigated two nucleic acid structures. The first is the RNA-DNA hybrid that contains the uracil tract 5'-rUUUUUAU-3' from the tR2 intrinsic terminator of bacteriophage lambda. The second is the homologous DNA-DNA duplex that contains the adenine tract 5'-dATAAAAA-3'. This duplex is present at the tR2 site when the DNA is not transcribed. The opening and the stability of each rU-dA/dT-dA base pair in the two structures are characterized by imino proton exchange and nuclear magnetic resonance spectroscopy. The results reveal concerted opening of the central rU-dA base pairs in the RNA-DNA hybrid. Furthermore, the stability profile of the adenine tract in the RNA-DNA hybrid is very different from that of the tract in the template DNA-DNA duplex. In the RNA-DNA hybrid, the stabilities of rU-dA base pairs range from 4.3 to 6.5 kcal/mol (at 10 degrees C). The sites of lowest stability are identified at the central positions of the tract. In the template DNA-DNA duplex, the dT-dA base pairs are more stable than the corresponding rU-dA base pairs in the hybrid by 0.9 to 4.6 kcal/mol and, in contrast to the RNA-DNA hybrid, the central base pairs have the highest stability. These results suggest that the central rU-dA/dT-dA base pairs in the adenine tract make the largest energetic contributions to transcription termination by promoting both the dissociation of the RNA transcript and the closing of the transcription bubble. The results also suggest that the high stability of dT-dA base pairs in the DNA provides a signal for the pausing of RNA polymerase at the termination site.
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Affiliation(s)
- Yuegao Huang
- Department of Chemistry, Wesleyan University, Middletown, CT 06459, USA
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23
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Abstract
Transcription stimulates the genetic instability of trinucleotide repeat sequences. However, the mechanisms leading to transcription-dependent repeat length variation are unclear. We demonstrate, using biochemical and genetic approaches, that the formation of stable RNA.DNA hybrids enhances the instability of CTG.CAG repeat tracts. In vitro transcribed CG-rich repeating sequences, unlike AT-rich repeats and nonrepeating sequences, form stable, ribonuclease A-resistant structures. These RNA.DNA hybrids are eliminated by ribonuclease H treatment. Mutation in the rnhA1 gene that decreases the activity of ribonuclease HI stimulates the instability of CTG.CAG repeats in E. coli. Importantly, the effect of ribonuclease HI depletion on repeat instability requires active transcription. We also showed that transcription-dependent CTG.CAG repeat instability in human cells is stimulated by siRNA knockdown of RNase H1 and H2. In addition, we used bisulfite modification, which detects single-stranded DNA, to demonstrate that the nontemplate DNA strand at transcribed CTG.CAG repeats remains partially single-stranded in human genomic DNA, thus indicating that it is displaced by an RNA.DNA hybrid. These studies demonstrate that persistent hybrids between the nascent RNA transcript and the template DNA strand at CTG.CAG tracts promote instability of DNA trinucleotide repeats.
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