1
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Rissone P, Severino A, Pastor I, Ritort F. Universal cold RNA phase transitions. Proc Natl Acad Sci U S A 2024; 121:e2408313121. [PMID: 39150781 PMCID: PMC11348302 DOI: 10.1073/pnas.2408313121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Accepted: 07/12/2024] [Indexed: 08/18/2024] Open
Abstract
RNA's diversity of structures and functions impacts all life forms since primordia. We use calorimetric force spectroscopy to investigate RNA folding landscapes in previously unexplored low-temperature conditions. We find that Watson-Crick RNA hairpins, the most basic secondary structure elements, undergo a glass-like transition below [Formula: see text]C where the heat capacity abruptly changes and the RNA folds into a diversity of misfolded structures. We hypothesize that an altered RNA biochemistry, determined by sequence-independent ribose-water interactions, outweighs sequence-dependent base pairing. The ubiquitous ribose-water interactions lead to universal RNA phase transitions below TG, such as maximum stability at [Formula: see text]C where water density is maximum, and cold denaturation at [Formula: see text]C. RNA cold biochemistry may have a profound impact on RNA function and evolution.
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Affiliation(s)
- Paolo Rissone
- Small Biosystems Lab, Condensed Matter Physics Department, Universitat de Barcelona, Barcelona 08028, Spain
| | - Aurélien Severino
- Small Biosystems Lab, Condensed Matter Physics Department, Universitat de Barcelona, Barcelona 08028, Spain
| | - Isabel Pastor
- Small Biosystems Lab, Condensed Matter Physics Department, Universitat de Barcelona, Barcelona 08028, Spain
| | - Felix Ritort
- Small Biosystems Lab, Condensed Matter Physics Department, Universitat de Barcelona, Barcelona 08028, Spain
- Institut de Nanociència i Nanotecnologia, Universitat de Barcelona, Barcelona 08028, Spain
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2
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Zhang Y, Zhang J, Wan H, Wu Z, Xu H, Zhang Z, Wang Y, Wang J. New Insights into the Dependence of CPEB3 Ribozyme Cleavage on Mn 2+ and Mg 2. J Phys Chem Lett 2024; 15:2708-2714. [PMID: 38427973 DOI: 10.1021/acs.jpclett.3c03221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2024]
Abstract
CPEB3 ribozyme is a self-cleaving RNA that occurs naturally in mammals and requires divalent metal ions for efficient activity. Ribozymes exhibit preferences for specific metal ions, but the exact differences in the catalytic mechanisms of various metal ions on the CPEB3 ribozyme remain unclear. Our findings reveal that Mn2+ functions as a more effective cofactor for CPEB3 ribozyme catalysis compared to Mg2+, as confirmed by its stronger binding affinity to CPEB3 by EPR. Cleavage assays of CPEB3 mutants and molecular docking analyses further showed that excessive Mn2+ ions can bind to a second binding site near the catalytic site, hindering CPEB3 catalytic efficiency and contributing to the Mn2+ bell-shaped curve. These results implicate a pivotal role for the local nucleobase-Mn2+ interactions in facilitating RNA folding and modulating the directed attack of nucleophilic reagents. Our study provides new insights and experimental evidence for exploring the divalent cation dependent cleavage mechanism of the CPEB3 ribozyme.
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Affiliation(s)
- Yaoyao Zhang
- High Magnetic Field Laboratory, Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, China
- University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Jing Zhang
- High Magnetic Field Laboratory, Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, China
- University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Hengjia Wan
- High Magnetic Field Laboratory, Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, China
- University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Ziwei Wu
- High Magnetic Field Laboratory, Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, China
- University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Huangtao Xu
- High Magnetic Field Laboratory, Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - Zhe Zhang
- Institute for Systems and Physical Biology, Shenzhen Bay Laboratory, Shenzhen 518055, China
| | - Yujuan Wang
- High Magnetic Field Laboratory, Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, China
- International Magnetobiology Frontier Research Center (iMFRC), Science Island, Hefei 230031, China
| | - Junfeng Wang
- High Magnetic Field Laboratory, Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, China
- University of Science and Technology of China, Hefei, Anhui 230026, China
- School of Basic Medical Sciences, Anhui Medical University, Hefei, Anhui 230032, China
- International Magnetobiology Frontier Research Center (iMFRC), Science Island, Hefei 230031, China
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3
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Akhter S, Tang Z, Wang J, Haboro M, Holmstrom ED, Wang J, Miao Y. Mechanism of Ligand Binding to Theophylline RNA Aptamer. J Chem Inf Model 2024; 64:1017-1029. [PMID: 38226603 PMCID: PMC11058067 DOI: 10.1021/acs.jcim.3c01454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2024]
Abstract
Studying RNA-ligand interactions and quantifying their binding thermodynamics and kinetics are of particular relevance in the field of drug discovery. Here, we combined biochemical binding assays and accelerated molecular simulations to investigate ligand binding and dissociation in RNA using the theophylline-binding RNA as a model system. All-atom simulations using a Ligand Gaussian accelerated Molecular Dynamics method (LiGaMD) have captured repetitive binding and dissociation of theophylline and caffeine to RNA. Theophylline's binding free energy and kinetic rate constants align with our experimental data, while caffeine's binding affinity is over 10,000 times weaker, and its kinetics could not be determined. LiGaMD simulations allowed us to identify distinct low-energy conformations and multiple ligand binding pathways to RNA. Simulations revealed a "conformational selection" mechanism for ligand binding to the flexible RNA aptamer, which provides important mechanistic insights into ligand binding to the theophylline-binding model. Our findings suggest that compound docking using a structural ensemble of representative RNA conformations would be necessary for structure-based drug design of flexible RNA.
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Affiliation(s)
- Sana Akhter
- Computational Biology Program and Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66047, United States
| | - Zhichao Tang
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66047, United States
| | - Jinan Wang
- Computational Biology Program and Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66047, United States
| | - Mercy Haboro
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66047, United States
| | - Erik D Holmstrom
- Department of Molecular Biosciences and Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Jingxin Wang
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66047, United States
| | - Yinglong Miao
- Computational Biology Program and Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66047, United States
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4
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Suddala KC, Yoo J, Fan L, Zuo X, Wang YX, Chung HS, Zhang J. Direct observation of tRNA-chaperoned folding of a dynamic mRNA ensemble. Nat Commun 2023; 14:5438. [PMID: 37673863 PMCID: PMC10482949 DOI: 10.1038/s41467-023-41155-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 08/24/2023] [Indexed: 09/08/2023] Open
Abstract
T-box riboswitches are multi-domain noncoding RNAs that surveil individual amino acid availabilities in most Gram-positive bacteria. T-boxes directly bind specific tRNAs, query their aminoacylation status to detect starvation, and feedback control the transcription or translation of downstream amino-acid metabolic genes. Most T-boxes rapidly recruit their cognate tRNA ligands through an intricate three-way stem I-stem II-tRNA interaction, whose establishment is not understood. Using single-molecule FRET, SAXS, and time-resolved fluorescence, we find that the free T-box RNA assumes a broad distribution of open, semi-open, and closed conformations that only slowly interconvert. tRNA directly binds all three conformers with distinct kinetics, triggers nearly instantaneous collapses of the open conformations, and returns the T-box RNA to their pre-binding conformations upon dissociation. This scissors-like dynamic behavior is enabled by a hinge-like pseudoknot domain which poises the T-box for rapid tRNA-induced domain closure. This study reveals tRNA-chaperoned folding of flexible, multi-domain mRNAs through a Venus flytrap-like mechanism.
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Affiliation(s)
- Krishna C Suddala
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 20892, USA
| | - Janghyun Yoo
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 20892, USA
| | - Lixin Fan
- Basic Science Program, Frederick National Laboratory for Cancer Research, Small-Angle X-Ray Scattering Core Facility of National Cancer Institute, Frederick, MD, 21702, USA
| | - Xiaobing Zuo
- X-ray Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Yun-Xing Wang
- Basic Science Program, Frederick National Laboratory for Cancer Research, Small-Angle X-Ray Scattering Core Facility of National Cancer Institute, Frederick, MD, 21702, USA
- Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Hoi Sung Chung
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 20892, USA.
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 20892, USA.
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5
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Moderate activity of RNA chaperone maximizes the yield of self-spliced pre-RNA in vivo. Proc Natl Acad Sci U S A 2022; 119:e2209422119. [PMID: 36442111 PMCID: PMC9894238 DOI: 10.1073/pnas.2209422119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
CYT-19 is a DEAD-box protein whose adenosine-triphosphate (ATP)-dependent helicase activity facilitates the folding of group I introns in precursor RNA (pre-RNA) of Neurospora crassa (N. crassa). In the process, they consume a substantial amount of ATP. While much of the mechanistic insight into CYT-19 activity has been gained through the studies on the folding of Tetrahymena group I intron ribozyme, the more biologically relevant issue, namely the effect of CYT-19 on the self-splicing of pre-RNA, remains largely unexplored. Here, we employ a kinetic network model, based on the generalized iterative annealing mechanism (IAM), to investigate the relation between CYT-19 activity, rate of ribozyme folding, and the kinetics of the self-splicing reaction. The network rate parameters are extracted by analyzing the recent biochemical data for CYT-19-facilitated folding of Tetrahymena ribozyme. We then build extended models to explore the metabolism of pre-RNA. We show that the timescales of chaperone-mediated folding of group I ribozyme and self-splicing reaction compete with each other. As a consequence, in order to maximize the self-splicing yield of group I introns in pre-RNA, the chaperone activity must be sufficiently large to unfold the misfolded structures, but not too large to unfold the native structures prior to the self-splicing event. We discover that despite the promiscuous action on structured RNAs, the helicase activity of CYT-19 on group I ribozyme gives rise to self-splicing yields that are close to the maximum.
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6
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Wang K, He Y, Shen Y, Wang Y, Xu X, Song X, Sun T. Effect of pausing on the cotranscriptional folding kinetics of RNAs. Int J Biol Macromol 2022; 221:1345-1355. [PMID: 36115451 DOI: 10.1016/j.ijbiomac.2022.09.115] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 08/25/2022] [Accepted: 09/12/2022] [Indexed: 11/25/2022]
Abstract
The pausing event in RNA molecule folding that occurs during the cotranscription process plays a critical role in cellular RNA function. Based on Conformational Resampling through Kinetic Relaxation (CRKR), this paper investigates a method to reveal the specifics of pausing for RNA cotranscriptional folding of 117-nucleotide E. coli SRP RNA and 73-nucleotide HIV-1 TAR RNA. It can be inferred from the results that pausing events generate valid cotranscriptional conformational rearrangement to protect the function structures and influence the folding pathway, which is remarkably consistent with the experimental results. Additionally, different transcription speeds result in different levels of protection capability. The folding pathway or conformational rearrangement can also be affected by a change in transcription speed after pausing site. These findings illuminate that RNAs with functional structures undergo complex rearrangement folding in pausing events, and different RNAs prefer different speeds for specific folding pathways. Moreover, pausing in particular circumstances can be employed to regulate the population of final functional structures. In conclusion, this paper offers fresh perspectives on the pausing event in the cotranscriptional folding of RNAs.
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Affiliation(s)
- Kang Wang
- Department of Physics, Zhejiang University of Science and Technology, Hangzhou, Zhejiang 310008, China
| | - Yunan He
- Department of Physics, Zhejiang University of Science and Technology, Hangzhou, Zhejiang 310008, China
| | - Yu Shen
- Department of Physics, Zhejiang University of Science and Technology, Hangzhou, Zhejiang 310008, China
| | - Yan Wang
- Department of Physics, Zhejiang University of Science and Technology, Hangzhou, Zhejiang 310008, China
| | - Xiaojun Xu
- Institute of Bioinformatics and Medical Engineering, Jiangsu University of Technology, Changzhou, Jiangsu 213001, China
| | - Xiaohui Song
- Eye Center, The Second Affiliated Hospital Zhejiang University, School of Medicine, Hangzhou, Zhejiang 310000, China.
| | - Tingting Sun
- Department of Physics, Zhejiang University of Science and Technology, Hangzhou, Zhejiang 310008, China.
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7
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Opuu V, Merleau NSC, Messow V, Smerlak M. RAFFT: Efficient prediction of RNA folding pathways using the fast Fourier transform. PLoS Comput Biol 2022; 18:e1010448. [PMID: 36026505 PMCID: PMC9455880 DOI: 10.1371/journal.pcbi.1010448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 09/08/2022] [Accepted: 07/28/2022] [Indexed: 11/18/2022] Open
Abstract
We propose a novel heuristic to predict RNA secondary structure formation pathways that has two components: (i) a folding algorithm and (ii) a kinetic ansatz. This heuristic is inspired by the kinetic partitioning mechanism, by which molecules follow alternative folding pathways to their native structure, some much faster than others. Similarly, our algorithm RAFFT starts by generating an ensemble of concurrent folding pathways ending in multiple metastable structures, which is in contrast with traditional thermodynamic approaches that find single structures with minimal free energies. When we constrained the algorithm to predict only 50 structures per sequence, near-native structures were found for RNA molecules of length ≤ 200 nucleotides. Our heuristic has been tested on the coronavirus frameshifting stimulation element (CFSE): an ensemble of 68 distinct structures allowed us to produce complete folding kinetic trajectories, whereas known methods require evaluating millions of sub-optimal structures to achieve this result. Thanks to the fast Fourier transform on which RAFFT (RNA folding Algorithm wih Fast Fourier Transform) is based, these computations are efficient, with complexity O ( L 2logL ).
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Affiliation(s)
- Vaitea Opuu
- Max Planck Institute for Mathematics in the Sciences, Leipzig, Germany
- * E-mail:
| | | | - Vincent Messow
- Max Planck Institute for Mathematics in the Sciences, Leipzig, Germany
| | - Matteo Smerlak
- Max Planck Institute for Mathematics in the Sciences, Leipzig, Germany
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8
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Somero GN. Solutions: how adaptive changes in cellular fluids enable marine life to cope with abiotic stressors. MARINE LIFE SCIENCE & TECHNOLOGY 2022; 4:389-413. [PMID: 37073170 PMCID: PMC10077225 DOI: 10.1007/s42995-022-00140-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 06/15/2022] [Indexed: 05/03/2023]
Abstract
The seas confront organisms with a suite of abiotic stressors that pose challenges for physiological activity. Variations in temperature, hydrostatic pressure, and salinity have potential to disrupt structures, and functions of all molecular systems on which life depends. During evolution, sequences of nucleic acids and proteins are adaptively modified to "fit" these macromolecules for function under the particular abiotic conditions of the habitat. Complementing these macromolecular adaptations are alterations in compositions of solutions that bathe macromolecules and affect stabilities of their higher order structures. A primary result of these "micromolecular" adaptations is preservation of optimal balances between conformational rigidity and flexibility of macromolecules. Micromolecular adaptations involve several families of organic osmolytes, with varying effects on macromolecular stability. A given type of osmolyte generally has similar effects on DNA, RNA, proteins and membranes; thus, adaptive regulation of cellular osmolyte pools has a global effect on macromolecules. These effects are mediated largely through influences of osmolytes and macromolecules on water structure and activity. Acclimatory micromolecular responses are often critical in enabling organisms to cope with environmental changes during their lifetimes, for example, during vertical migration in the water column. A species' breadth of environmental tolerance may depend on how effectively it can vary the osmolyte composition of its cellular fluids in the face of stress. Micromolecular adaptations remain an under-appreciated aspect of evolution and acclimatization. Further study can lead to a better understanding of determinants of environmental tolerance ranges and to biotechnological advances in designing improved stabilizers for biological materials.
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Affiliation(s)
- George N. Somero
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950 USA
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9
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Pujari N, Saundh SL, Acquah FA, Mooers BHM, Ferré-D’Amaré AR, Leung AKW. Engineering Crystal Packing in RNA Structures I: Past and Future Strategies for Engineering RNA Packing in Crystals. CRYSTALS 2021; 11:952. [PMID: 34745656 PMCID: PMC8570644 DOI: 10.3390/cryst11080952] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
X-ray crystallography remains a powerful method to gain atomistic insights into the catalytic and regulatory functions of RNA molecules. However, the technique requires the preparation of diffraction-quality crystals. This is often a resource- and time-consuming venture because RNA crystallization is hindered by the conformational heterogeneity of RNA, as well as the limited opportunities for stereospecific intermolecular interactions between RNA molecules. The limited success at crystallization explains in part the smaller number of RNA-only structures in the Protein Data Bank. Several approaches have been developed to aid the formation of well-ordered RNA crystals. The majority of these are construct-engineering techniques that aim to introduce crystal contacts to favor the formation of well-diffracting crystals. A typical example is the insertion of tetraloop-tetraloop receptor pairs into non-essential RNA segments to promote intermolecular association. Other methods of promoting crystallization involve chaperones and crystallization-friendly molecules that increase RNA stability and improve crystal packing. In this review, we discuss the various techniques that have been successfully used to facilitate crystal packing of RNA molecules, recent advances in construct engineering, and directions for future research in this vital aspect of RNA crystallography.
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Affiliation(s)
- Narsimha Pujari
- Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada
| | - Stephanie L. Saundh
- Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada
| | - Francis A. Acquah
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Blaine H. M. Mooers
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Adrian R. Ferré-D’Amaré
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, Bethesda, MD 20892, USA
| | - Adelaine Kwun-Wai Leung
- Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada
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10
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The Role of RNA Secondary Structure in Regulation of Gene Expression in Bacteria. Int J Mol Sci 2021; 22:ijms22157845. [PMID: 34360611 PMCID: PMC8346122 DOI: 10.3390/ijms22157845] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/10/2021] [Accepted: 07/12/2021] [Indexed: 11/28/2022] Open
Abstract
Due to the high exposition to changing environmental conditions, bacteria have developed many mechanisms enabling immediate adjustments of gene expression. In many cases, the required speed and plasticity of the response are provided by RNA-dependent regulatory mechanisms. This is possible due to the very high dynamics and flexibility of an RNA structure, which provide the necessary sensitivity and specificity for efficient sensing and transduction of environmental signals. In this review, we will discuss the current knowledge about known bacterial regulatory mechanisms which rely on RNA structure. To better understand the structure-driven modulation of gene expression, we describe the basic theory on RNA structure folding and dynamics. Next, we present examples of multiple mechanisms employed by RNA regulators in the control of bacterial transcription and translation.
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11
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Laouer K, Schmid M, Wien F, Changenet P, Hache F. Folding Dynamics of DNA G-Quadruplexes Probed by Millisecond Temperature Jump Circular Dichroism. J Phys Chem B 2021; 125:8088-8098. [PMID: 34279936 DOI: 10.1021/acs.jpcb.1c01993] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
G-quadruplexes play important roles in cellular regulatory functions, but despite significant experimental and theoretical efforts, their folding mechanisms remain poorly understood. In this context, we developed a T-jump experiment to access the thermal denaturation and renaturation dynamics of short intramolecular G-quadruplexes in vitro, on the time scale of a few hundred milliseconds. With this new setup, we compared the thermal denaturation and renaturation kinetics of three antiparallel topologies made of the human telomeric sequences d[(5'-GGG(TTAGGG)3-3']/Na+ and d[5'-AGGG(TTAGGG)3-3']/Na+ and the thrombin-binding aptamer sequence d[5'-GGTTGGTGTGGTTGG-3']/K+, with those of the parallel topology made of the human CEB25 minisatellite d[5'-AAGGGTGGGTGTAAGTGTGGGTGGGT-3']/Na+. In all cases, exponential kinetics of the order of several hundred milliseconds were observed. Measurements performed for different initial temperatures revealed distinct denaturation and renaturation dynamics, ruling out a simple two-state mechanism. The parallel topology, in which all guanines adopt an anti conformation, displays much slower dynamics than antiparallel topologies associated with very low activation barriers. This behavior can be explained by the constrained conformational space due to the presence of the single-base propeller loops that likely hinders the movement of the coiled DNA strand and reduces the contribution of the entropy during the renaturation process at high temperatures.
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Affiliation(s)
- K Laouer
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS -INSERM, Institut Polytechnique de Paris, 91128 Cedex Palaiseau, France
| | - M Schmid
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS -INSERM, Institut Polytechnique de Paris, 91128 Cedex Palaiseau, France
| | - F Wien
- L'orme des merisiers, Synchrotron SOLEIL, 91192 Gif sur Yvette, France
| | - P Changenet
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS -INSERM, Institut Polytechnique de Paris, 91128 Cedex Palaiseau, France
| | - F Hache
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS -INSERM, Institut Polytechnique de Paris, 91128 Cedex Palaiseau, France
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12
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Wu C, Shan Y, Wang S, Liu F. Dynamically probing ATP-dependent RNA helicase A-assisted RNA structure conversion using single molecule fluorescence resonance energy transfer. Protein Sci 2021; 30:1157-1168. [PMID: 33837988 DOI: 10.1002/pro.4081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 04/08/2021] [Indexed: 12/16/2022]
Abstract
RNA helicase A (RHA) as a member of DExH-box subgroup of helicase superfamily II, participates in diverse biological processes involved in RNA metabolism in organisms, and these RNA-mediated biological processes rely on RNA structure conversion. However, how RHA regulate the RNA structure conversion was still unknown. In order to unveil the mechanism of RNA structure conversion mediated by RHA, single molecule fluorescence resonance energy transfer was adopted to in our assay, and substrates RNA were from internal ribosome entry site of foot-and-mouth disease virus genome. We first found that the RNA structure conversion by RHA against thermodynamic equilibrium in vitro, and the process of dsRNA YZ converted to dsRNA XY through a tripartite intermediate state. In addition, the rate of the RNA structure conversion and the distribution of dsRNA YZ and XY were affected by ATP concentrations. Our study provides real-time insight into ATP-dependent RHA-assisted RNA structure conversion at the single molecule level, the mechanism displayed by RHA may help in understand how RHA contributes to many biological functions, and the basic mechanistic features illustrated in our work also underlay more complex protein-assisted RNA structure conversions.
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Affiliation(s)
- Chengcheng Wu
- Joint International Research Laboratory of Animal Health and Food Safety of Ministry of Education & Single Molecule Nanometry Laboratory (Sinmolab), Nanjing Agricultural University, Nanjing, China
| | - Yanke Shan
- Joint International Research Laboratory of Animal Health and Food Safety of Ministry of Education & Single Molecule Nanometry Laboratory (Sinmolab), Nanjing Agricultural University, Nanjing, China
| | - Shouyu Wang
- Joint International Research Laboratory of Animal Health and Food Safety of Ministry of Education & Single Molecule Nanometry Laboratory (Sinmolab), Nanjing Agricultural University, Nanjing, China.,Computational Optics Laboratory, Jiangnan University, Wuxi, China
| | - Fei Liu
- Joint International Research Laboratory of Animal Health and Food Safety of Ministry of Education & Single Molecule Nanometry Laboratory (Sinmolab), Nanjing Agricultural University, Nanjing, China
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13
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Wang F, Sun LZ, Sun T, Chang S, Xu X. Helix-Based RNA Landscape Partition and Alternative Secondary Structure Determination. ACS OMEGA 2019; 4:15407-15413. [PMID: 31572840 PMCID: PMC6761681 DOI: 10.1021/acsomega.9b01430] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 09/03/2019] [Indexed: 06/10/2023]
Abstract
RNA is a versatile macromolecule with the ability to fold into and interconvert between multiple functional conformations. The elucidation of the RNA folding landscape, especially the knowledge of alternative structures, is critical to uncover the physical mechanism of RNA functions. Here, we introduce a helix-based strategy for RNA folding landscape partition and alternative secondary structure determination. The benchmark test of 27 RNAs involving alternative stable structures shows that the model has the ability to divide the whole landscape into distinct partitions at the secondary structure level and predict the representative structures for each partition. Furthermore, the predicted structures and equilibrium populations of metastable conformations for the 2'dG-sensing riboswitch reveal the allosteric conformational switch on transcript length, which is consistent with the experimental study, indicating the importance of metastable states for RNA-based gene regulation. The model delivers a starting point for the landscape-based strategy toward the RNA folding mechanism and functions.
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Affiliation(s)
- Fengfei Wang
- Institute
of Bioinformatics and Medical Engineering, School of Mathematics and
Physics, Jiangsu University of Technology, Changzhou, Jiangsu 213001, China
| | - Li-Zhen Sun
- Department
of Applied Physics, Zhejiang University
of Technology, Hangzhou, Zhejiang 310023, China
| | - Tingting Sun
- Department
of Physics, Zhejiang University of Science
and Technology, Hangzhou, Zhejiang 310023, China
| | - Shan Chang
- Institute
of Bioinformatics and Medical Engineering, School of Mathematics and
Physics, Jiangsu University of Technology, Changzhou, Jiangsu 213001, China
| | - Xiaojun Xu
- Institute
of Bioinformatics and Medical Engineering, School of Mathematics and
Physics, Jiangsu University of Technology, Changzhou, Jiangsu 213001, China
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14
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Yonkunas MJ, Baird NJ. A highly ordered, nonprotective MALAT1 ENE structure is adopted prior to triplex formation. RNA (NEW YORK, N.Y.) 2019; 25:975-984. [PMID: 31113838 PMCID: PMC6633196 DOI: 10.1261/rna.069906.118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Accepted: 05/13/2019] [Indexed: 05/06/2023]
Abstract
The 3' end of the ∼7 kb lncRNA MALAT1 contains an evolutionarily and structurally conserved element for nuclear expression (ENE) which confers protection from cellular degradation pathways. Formation of an ENE triple helix is required to support transcript accumulation, leading to persistent oncogenic activity of MALAT1 in multiple cancer types. Though the specific mechanism of triplex-mediated protection remains unknown, the MALAT1 ENE triplex has been identified as a promising target for therapeutic intervention. Interestingly, a maturation step of the nascent lncRNA 3' end is required prior to triplex formation. We hypothesize that disruption of the maturation or folding process may be a viable mechanism of inhibition. To assess putative cotranscriptional ENE conformations prior to triplex formation, we perform microsecond MD simulations of a partially folded ENE conformation and the ENE triplex. We identify a highly ordered ENE structure prior to triplex formation. Extensive formation of U•U base pairs within the large U-rich internal loops produces a global rod-like architecture. We present a three-dimensional structure of the isolated ENE motif, the global features of which are consistent with small angle X-ray scattering (SAXS) experiments. Our structural model represents a nonprotective conformation of the MALAT1 ENE, providing a molecular description useful for future mechanistic and inhibition studies. We anticipate that targeting stretches of U•U pairs within the ENE motif will prove advantageous for the design of therapeutics targeting this oncogenic lncRNA.
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Affiliation(s)
- Michael J Yonkunas
- Department of Chemistry & Biochemistry, University of the Sciences, Philadelphia, Pennsylvania 19104, USA
| | - Nathan J Baird
- Department of Chemistry & Biochemistry, University of the Sciences, Philadelphia, Pennsylvania 19104, USA
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15
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Hanspach G, Trucks S, Hengesbach M. Strategic labelling approaches for RNA single-molecule spectroscopy. RNA Biol 2019; 16:1119-1132. [PMID: 30874475 DOI: 10.1080/15476286.2019.1593093] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Most single-molecule techniques observing RNA in vitro or in vivo require fluorescent labels that have to be connected to the RNA of interest. In recent years, a plethora of methods has been developed to achieve site-specific labelling, in many cases under near-native conditions. Here, we review chemical as well as enzymatic labelling methods that are compatible with single-molecule fluorescence spectroscopy or microscopy and show how these can be combined to offer a large variety of options to site-specifically place one or more labels in an RNA of interest. By either chemically forming a covalent bond or non-covalent hybridization, these techniques are prerequisites to perform state-of-the-art single-molecule experiments.
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Affiliation(s)
- Gerd Hanspach
- a Goethe-University Frankfurt, Institute for Organic Chemistry and Chemical Biology , Frankfurt , Germany
| | - Sven Trucks
- a Goethe-University Frankfurt, Institute for Organic Chemistry and Chemical Biology , Frankfurt , Germany
| | - Martin Hengesbach
- a Goethe-University Frankfurt, Institute for Organic Chemistry and Chemical Biology , Frankfurt , Germany
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16
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Chen YL, Sutton JL, Pollack L. How the Conformations of an Internal Junction Contribute to Fold an RNA Domain. J Phys Chem B 2018; 122:11363-11372. [PMID: 30285445 DOI: 10.1021/acs.jpcb.8b07262] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Like proteins, some RNAs fold to compact structures. We can model functional RNAs as a series of short, rigid, base-paired elements, connected by non-base-paired nucleotides that serve as junctions. These connecting regions bend and twist, facilitating the formation of tertiary contacts that stabilize compact states. Here, we explore the roles of salt and junction sequence in determining the structures of a ubiquitous connector: an asymmetric internal loop. We focus on the J5/5a junction from the widely studied P4-P6 domain of the Tetrahymena ribozyme. Following the addition of magnesium ions to fold P4-P6, this junction bends dramatically, bringing the two halves of the RNA domain together for tertiary contact engagement. Using single-molecule fluorescence resonance energy transfer (smFRET), we examine the role of sequence and salt on model RNA constructs that contain these junction regions. We explore the wild-type J5/5a junction as well as two sequence variants. These junctions display distinct, salt-dependent conformations. Small-angle X-ray scattering (SAXS) measurements verify that these effects persist in the full-length P4-P6 domain. These measurements underscore the importance of junction sequence and interactions with ions in facilitating RNA folding.
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Affiliation(s)
- Yen-Lin Chen
- School of Applied and Engineering Physics , Cornell University , Ithaca , New York 14853 , United States
| | - Julie L Sutton
- School of Applied and Engineering Physics , Cornell University , Ithaca , New York 14853 , United States
| | - Lois Pollack
- School of Applied and Engineering Physics , Cornell University , Ithaca , New York 14853 , United States
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17
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Abstract
The past decades have witnessed tremendous developments in our understanding of RNA biology. At the core of these advances have been studies aimed at discerning RNA structure and at understanding the forces that influence the RNA folding process. It is easy to take the present state of understanding for granted, but there is much to be learned by considering the path to our current understanding, which has been tortuous, with the birth and death of models, the adaptation of experimental tools originally developed for characterization of protein structure and catalysis, and the development of novel tools for probing RNA. In this review we tour the stages of RNA folding studies, considering them as "epochs" that can be generalized across scientific disciplines. These epochs span from the discovery of catalytic RNA, through biophysical insights into the putative primordial RNA World, to characterization of structured RNAs, the building and testing of models, and, finally, to the development of models with the potential to yield generalizable predictive and quantitative models for RNA conformational, thermodynamic, and kinetic behavior. We hope that this accounting will aid others as they navigate the many fascinating questions about RNA and its roles in biology, in the past, present, and future.
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Affiliation(s)
- Daniel Herschlag
- Department of Biochemistry, Stanford University, Stanford, California 94305
- Department of Chemical Engineering, Stanford University, Stanford, California 94305
- Department of Chemistry, Stanford University, Stanford, California 94305
- Stanford ChEM-H (Chemistry, Engineering, and Medicine for Human Health), Stanford, California 94305
| | - Steve Bonilla
- Department of Biochemistry, Stanford University, Stanford, California 94305
- Department of Chemical Engineering, Stanford University, Stanford, California 94305
| | - Namita Bisaria
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142
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18
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Bruetzel LK, Walker PU, Gerling T, Dietz H, Lipfert J. Time-Resolved Small-Angle X-ray Scattering Reveals Millisecond Transitions of a DNA Origami Switch. NANO LETTERS 2018; 18:2672-2676. [PMID: 29554806 DOI: 10.1021/acs.nanolett.8b00592] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Self-assembled DNA structures enable creation of specific shapes at the nanometer-micrometer scale with molecular resolution. The construction of functional DNA assemblies will likely require dynamic structures that can undergo controllable conformational changes. DNA devices based on shape complementary stacking interactions have been demonstrated to undergo reversible conformational changes triggered by changes in ionic environment or temperature. An experimentally unexplored aspect is how quickly conformational transitions of large synthetic DNA origami structures can actually occur. Here, we use time-resolved small-angle X-ray scattering to monitor large-scale conformational transitions of a two-state DNA origami switch in free solution. We show that the DNA device switches from its open to its closed conformation upon addition of MgCl2 in milliseconds, which is close to the theoretical diffusive speed limit. In contrast, measurements of the dimerization of DNA origami bricks reveal much slower and concentration-dependent assembly kinetics. DNA brick dimerization occurs on a time scale of minutes to hours suggesting that the kinetics depend on local concentration and molecular alignment.
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Affiliation(s)
- Linda K Bruetzel
- Department of Physics, Nanosystems Initiative Munich, and Center for Nanoscience , LMU Munich , Amalienstrasse 54 , 80799 Munich , Germany
| | - Philipp U Walker
- Department of Physics, Nanosystems Initiative Munich, and Center for Nanoscience , LMU Munich , Amalienstrasse 54 , 80799 Munich , Germany
| | - Thomas Gerling
- Physik Department , Institute for Advanced Study, Technische Universität München , Am Coulombwall 4a , 85748 Garching , Germany
| | - Hendrik Dietz
- Physik Department , Institute for Advanced Study, Technische Universität München , Am Coulombwall 4a , 85748 Garching , Germany
| | - Jan Lipfert
- Department of Physics, Nanosystems Initiative Munich, and Center for Nanoscience , LMU Munich , Amalienstrasse 54 , 80799 Munich , Germany
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19
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Woods CT, Laederach A. Classification of RNA structure change by 'gazing' at experimental data. Bioinformatics 2018; 33:1647-1655. [PMID: 28130241 PMCID: PMC5447233 DOI: 10.1093/bioinformatics/btx041] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 01/20/2017] [Indexed: 11/12/2022] Open
Abstract
Motivation Mutations (or Single Nucleotide Variants) in folded RiboNucleic Acid structures that cause local or global conformational change are riboSNitches. Predicting riboSNitches is challenging, as it requires making two, albeit related, structure predictions. The data most often used to experimentally validate riboSNitch predictions is Selective 2' Hydroxyl Acylation by Primer Extension, or SHAPE. Experimentally establishing a riboSNitch requires the quantitative comparison of two SHAPE traces: wild-type (WT) and mutant. Historically, SHAPE data was collected on electropherograms and change in structure was evaluated by 'gel gazing.' SHAPE data is now routinely collected with next generation sequencing and/or capillary sequencers. We aim to establish a classifier capable of simulating human 'gazing' by identifying features of the SHAPE profile that human experts agree 'looks' like a riboSNitch. Results We find strong quantitative agreement between experts when RNA scientists 'gaze' at SHAPE data and identify riboSNitches. We identify dynamic time warping and seven other features predictive of the human consensus. The classSNitch classifier reported here accurately reproduces human consensus for 167 mutant/WT comparisons with an Area Under the Curve (AUC) above 0.8. When we analyze 2019 mutant traces for 17 different RNAs, we find that features of the WT SHAPE reactivity allow us to improve thermodynamic structure predictions of riboSNitches. This is significant, as accurate RNA structural analysis and prediction is likely to become an important aspect of precision medicine. Availability and Implementation The classSNitch R package is freely available at http://classsnitch.r-forge.r-project.org . Contact alain@email.unc.edu. Supplementary information Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Chanin Tolson Woods
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Curriculum in Bioinformatics and Computational Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Alain Laederach
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Curriculum in Bioinformatics and Computational Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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20
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Single-molecule FRET studies on the cotranscriptional folding of a thiamine pyrophosphate riboswitch. Proc Natl Acad Sci U S A 2017; 115:331-336. [PMID: 29279370 DOI: 10.1073/pnas.1712983115] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Because RNAs fold as they are being synthesized, their transcription rate can affect their folding. Here, we report the results of single-molecule fluorescence studies that characterize the ligand-dependent cotranscriptional folding of the Escherichia coli thiM riboswitch that regulates translation. We found that the riboswitch aptamer folds into the "off" conformation independent of its ligand, but switches to the "on" conformation during transcriptional pausing near the translational start codon. Ligand binding maintains the riboswitch in the off conformation during transcriptional pauses. We expect our assay will permit the controlled study of the two main physical mechanisms that regulate cotranscriptional folding: transcriptional pausing and transcriptional speed.
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21
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Woods CT, Lackey L, Williams B, Dokholyan NV, Gotz D, Laederach A. Comparative Visualization of the RNA Suboptimal Conformational Ensemble In Vivo. Biophys J 2017. [PMID: 28625696 PMCID: PMC5529173 DOI: 10.1016/j.bpj.2017.05.031] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
When a ribonucleic acid (RNA) molecule folds, it often does not adopt a single, well-defined conformation. The folding energy landscape of an RNA is highly dependent on its nucleotide sequence and molecular environment. Cellular molecules sometimes alter the energy landscape, thereby changing the ensemble of likely low-energy conformations. The effects of these energy landscape changes on the conformational ensemble are particularly challenging to visualize for large RNAs. We have created a robust approach for visualizing the conformational ensemble of RNAs that is well suited for in vitro versus in vivo comparisons. Our method creates a stable map of conformational space for a given RNA sequence. We first identify single point mutations in the RNA that maximally sample suboptimal conformational space based on the ensemble’s partition function. Then, we cluster these diverse ensembles to identify the most diverse partition functions for Boltzmann stochastic sampling. By using, to our knowledge, a novel nestedness distance metric, we iteratively add mutant suboptimal ensembles to converge on a stable 2D map of conformational space. We then compute the selective 2′ hydroxyl acylation by primer extension (SHAPE)-directed ensemble for the RNA folding under different conditions, and we project these ensembles on the map to visualize. To validate our approach, we established a conformational map of the Vibrio vulnificus add adenine riboswitch that reveals five classes of structures. In the presence of adenine, projection of the SHAPE-directed sampling correctly identified the on-conformation; without the ligand, only off-conformations were visualized. We also collected the whole-transcript in vitro and in vivo SHAPE-MaP for human β-actin messenger RNA that revealed similar global folds in both conditions. Nonetheless, a comparison of in vitro and in vivo data revealed that specific regions exhibited significantly different SHAPE-MaP profiles indicative of structural rearrangements, including rearrangement consistent with binding of the zipcode protein in a region distal to the stop codon.
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Affiliation(s)
- Chanin T Woods
- Curriculum in Bioinformatics and Computational Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Lela Lackey
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Benfeard Williams
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Nikolay V Dokholyan
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - David Gotz
- Carolina Health Informatics Program, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; School of Information and Library Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Alain Laederach
- Curriculum in Bioinformatics and Computational Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
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22
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Bell DR, Cheng SY, Salazar H, Ren P. Capturing RNA Folding Free Energy with Coarse-Grained Molecular Dynamics Simulations. Sci Rep 2017; 7:45812. [PMID: 28393861 PMCID: PMC5385882 DOI: 10.1038/srep45812] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 03/06/2017] [Indexed: 01/25/2023] Open
Abstract
We introduce a coarse-grained RNA model for molecular dynamics simulations, RACER (RnA CoarsE-gRained). RACER achieves accurate native structure prediction for a number of RNAs (average RMSD of 2.93 Å) and the sequence-specific variation of free energy is in excellent agreement with experimentally measured stabilities (R2 = 0.93). Using RACER, we identified hydrogen-bonding (or base pairing), base stacking, and electrostatic interactions as essential driving forces for RNA folding. Also, we found that separating pairing vs. stacking interactions allowed RACER to distinguish folded vs. unfolded states. In RACER, base pairing and stacking interactions each provide an approximate stability of 3-4 kcal/mol for an A-form helix. RACER was developed based on PDB structural statistics and experimental thermodynamic data. In contrast with previous work, RACER implements a novel effective vdW potential energy function, which led us to re-parameterize hydrogen bond and electrostatic potential energy functions. Further, RACER is validated and optimized using a simulated annealing protocol to generate potential energy vs. RMSD landscapes. Finally, RACER is tested using extensive equilibrium pulling simulations (0.86 ms total) on eleven RNA sequences (hairpins and duplexes).
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Affiliation(s)
- David R. Bell
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
| | - Sara Y. Cheng
- Department of Physics, University of Texas at Austin, Austin, Texas 78712, United States
| | - Heber Salazar
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
| | - Pengyu Ren
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
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23
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Coey A, Larsen K, Puglisi JD, Viani Puglisi E. Heterogeneous structures formed by conserved RNA sequences within the HIV reverse transcription initiation site. RNA (NEW YORK, N.Y.) 2016; 22:1689-1698. [PMID: 27613581 PMCID: PMC5066621 DOI: 10.1261/rna.056804.116] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 08/03/2016] [Indexed: 06/06/2023]
Abstract
Reverse transcription is a key process in the early steps of HIV infection. This process initiates within a specific complex formed by the 5' UTR of the HIV genomic RNA (vRNA) and a host primer tRNALys3 Using nuclear magnetic resonance (NMR) spectroscopy and single-molecule fluorescence spectroscopy, we detect two distinct conformers adopted by the tRNA/vRNA initiation complex. We directly show that an interaction between the conserved 8-nucleotide viral RNA primer activation signal (PAS) and the primer tRNA occurs in one of these conformers. This intermolecular PAS interaction likely induces strain on a vRNA intramolecular helix, which must be broken for reverse transcription to initiate. We propose a mechanism by which this vRNA/tRNA conformer relieves the kinetic block formed by the vRNA intramolecular helix to initiate reverse transcription.
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Affiliation(s)
- Aaron Coey
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305-5126, USA
- Biophysics Program, Stanford University School of Medicine, Stanford, California 94305-5126, USA
| | - Kevin Larsen
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305-5126, USA
- Biophysics Program, Stanford University School of Medicine, Stanford, California 94305-5126, USA
| | - Joseph D Puglisi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305-5126, USA
| | - Elisabetta Viani Puglisi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305-5126, USA
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24
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Börner R, Kowerko D, Miserachs HG, Schaffer MF, Sigel RK. Metal ion induced heterogeneity in RNA folding studied by smFRET. Coord Chem Rev 2016. [DOI: 10.1016/j.ccr.2016.06.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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25
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Watters KE, Strobel EJ, Yu AM, Lis JT, Lucks JB. Cotranscriptional folding of a riboswitch at nucleotide resolution. Nat Struct Mol Biol 2016; 23:1124-1131. [PMID: 27798597 PMCID: PMC5497173 DOI: 10.1038/nsmb.3316] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 10/05/2016] [Indexed: 12/19/2022]
Abstract
RNAs can begin to fold immediately after emerging from RNA polymerase during transcription. Interactions between nascent RNAs and ligands during cotranscriptional folding can direct the formation of alternative RNA structures, a feature exploited by non-coding RNAs called riboswitches to make gene regulatory decisions. Despite their importance, cotranscriptional folding pathways have yet to be uncovered with sufficient resolution to reveal how cotranscriptional folding governs RNA structure and function. To access cotranscriptional folding at nucleotide resolution, we extend selective 2’-hydroxyl acylation analyzed by primer extension sequencing (SHAPE-Seq) to measure structural information of nascent RNAs during transcription. With cotranscriptional SHAPE-Seq, we determine how the B. cereus crcB fluoride riboswitch cotranscriptional folding pathway undergoes a ligand-dependent bifurcation that delays or promotes terminator formation via a series of coordinated structural transitions. Our results directly link cotranscriptional RNA folding to a genetic decision and establish a framework for cotranscriptional analysis of RNA structure at nucleotide resolution.
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Affiliation(s)
- Kyle E Watters
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York, USA
| | - Eric J Strobel
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York, USA
| | - Angela M Yu
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York, USA.,Tri-Institutional Training Program in Computational Biology and Medicine at Cornell University, Ithaca, New York, USA; Weill Cornell Medical College, New York, New York, USA; and Memorial Sloan-Kettering Cancer Center, New York, New York, USA.,Computational Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, USA
| | - John T Lis
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, USA
| | - Julius B Lucks
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York, USA.,Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois, USA
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26
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Kinetic and thermodynamic framework for P4-P6 RNA reveals tertiary motif modularity and modulation of the folding preferred pathway. Proc Natl Acad Sci U S A 2016; 113:E4956-65. [PMID: 27493222 DOI: 10.1073/pnas.1525082113] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The past decade has seen a wealth of 3D structural information about complex structured RNAs and identification of functional intermediates. Nevertheless, developing a complete and predictive understanding of the folding and function of these RNAs in biology will require connection of individual rate and equilibrium constants to structural changes that occur in individual folding steps and further relating these steps to the properties and behavior of isolated, simplified systems. To accomplish these goals we used the considerable structural knowledge of the folded, unfolded, and intermediate states of P4-P6 RNA. We enumerated structural states and possible folding transitions and determined rate and equilibrium constants for the transitions between these states using single-molecule FRET with a series of mutant P4-P6 variants. Comparisons with simplified constructs containing an isolated tertiary contact suggest that a given tertiary interaction has a stereotyped rate for breaking that may help identify structural transitions within complex RNAs and simplify the prediction of folding kinetics and thermodynamics for structured RNAs from their parts. The preferred folding pathway involves initial formation of the proximal tertiary contact. However, this preference was only ∼10 fold and could be reversed by a single point mutation, indicating that a model akin to a protein-folding contact order model will not suffice to describe RNA folding. Instead, our results suggest a strong analogy with a modified RNA diffusion-collision model in which tertiary elements within preformed secondary structures collide, with the success of these collisions dependent on whether the tertiary elements are in their rare binding-competent conformations.
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27
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Xue Y, Gracia B, Herschlag D, Russell R, Al-Hashimi HM. Visualizing the formation of an RNA folding intermediate through a fast highly modular secondary structure switch. Nat Commun 2016; 7:ncomms11768. [PMID: 27292179 PMCID: PMC4909931 DOI: 10.1038/ncomms11768] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 04/26/2016] [Indexed: 12/28/2022] Open
Abstract
Intermediates play important roles in RNA folding but can be difficult to characterize when short-lived or not significantly populated. By combining (15)N relaxation dispersion NMR with chemical probing, we visualized a fast (kex=k1+k-1≈423 s(-1)) secondary structural switch directed towards a low-populated (∼3%) partially folded intermediate in tertiary folding of the P5abc subdomain of the 'Tetrahymena' group I intron ribozyme. The secondary structure switch changes the base-pairing register across the P5c hairpin, creating a native-like structure, and occurs at rates of more than two orders of magnitude faster than tertiary folding. The switch occurs robustly in the absence of tertiary interactions, Mg(2+) or even when the hairpin is excised from the three-way junction. Fast, highly modular secondary structural switches may be quite common during RNA tertiary folding where they may help smoothen the folding landscape by allowing folding to proceed efficiently via additional pathways.
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Affiliation(s)
- Yi Xue
- Department of Biochemistry, Duke Center for RNA Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Brant Gracia
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712, USA
| | - Daniel Herschlag
- Department of Biochemistry, Beckman Center, Stanford University, Stanford, California 94305, USA.,Department of Chemistry, Stanford University, Stanford, California 94305, USA.,Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA.,Chemistry, Engineering, and Medicine for Human Health (ChEM-H) Institute, Stanford University, Stanford, California 94305, USA
| | - Rick Russell
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712, USA
| | - Hashim M Al-Hashimi
- Department of Biochemistry, Duke Center for RNA Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.,Department of Chemistry, Duke University, Durham, Stanford, North Carolina 27710, USA
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28
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Wei G, Xi W, Nussinov R, Ma B. Protein Ensembles: How Does Nature Harness Thermodynamic Fluctuations for Life? The Diverse Functional Roles of Conformational Ensembles in the Cell. Chem Rev 2016; 116:6516-51. [PMID: 26807783 PMCID: PMC6407618 DOI: 10.1021/acs.chemrev.5b00562] [Citation(s) in RCA: 253] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
All soluble proteins populate conformational ensembles that together constitute the native state. Their fluctuations in water are intrinsic thermodynamic phenomena, and the distributions of the states on the energy landscape are determined by statistical thermodynamics; however, they are optimized to perform their biological functions. In this review we briefly describe advances in free energy landscape studies of protein conformational ensembles. Experimental (nuclear magnetic resonance, small-angle X-ray scattering, single-molecule spectroscopy, and cryo-electron microscopy) and computational (replica-exchange molecular dynamics, metadynamics, and Markov state models) approaches have made great progress in recent years. These address the challenging characterization of the highly flexible and heterogeneous protein ensembles. We focus on structural aspects of protein conformational distributions, from collective motions of single- and multi-domain proteins, intrinsically disordered proteins, to multiprotein complexes. Importantly, we highlight recent studies that illustrate functional adjustment of protein conformational ensembles in the crowded cellular environment. We center on the role of the ensemble in recognition of small- and macro-molecules (protein and RNA/DNA) and emphasize emerging concepts of protein dynamics in enzyme catalysis. Overall, protein ensembles link fundamental physicochemical principles and protein behavior and the cellular network and its regulation.
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Affiliation(s)
- Guanghong Wei
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Department of Physics, Fudan University, Shanghai, P. R. China
| | - Wenhui Xi
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Department of Physics, Fudan University, Shanghai, P. R. China
| | - Ruth Nussinov
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702, USA
- Sackler Inst. of Molecular Medicine Department of Human Genetics and Molecular Medicine Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Buyong Ma
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702, USA
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29
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Xu X, Yu T, Chen SJ. Understanding the kinetic mechanism of RNA single base pair formation. Proc Natl Acad Sci U S A 2016; 113:116-21. [PMID: 26699466 PMCID: PMC4711849 DOI: 10.1073/pnas.1517511113] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
RNA functions are intrinsically tied to folding kinetics. The most elementary step in RNA folding is the closing and opening of a base pair. Understanding this elementary rate process is the basis for RNA folding kinetics studies. Previous studies mostly focused on the unfolding of base pairs. Here, based on a hybrid approach, we investigate the folding process at level of single base pairing/stacking. The study, which integrates molecular dynamics simulation, kinetic Monte Carlo simulation, and master equation methods, uncovers two alternative dominant pathways: Starting from the unfolded state, the nucleotide backbone first folds to the native conformation, followed by subsequent adjustment of the base conformation. During the base conformational rearrangement, the backbone either retains the native conformation or switches to nonnative conformations in order to lower the kinetic barrier for base rearrangement. The method enables quantification of kinetic partitioning among the different pathways. Moreover, the simulation reveals several intriguing ion binding/dissociation signatures for the conformational changes. Our approach may be useful for developing a base pair opening/closing rate model.
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Affiliation(s)
- Xiaojun Xu
- Department of Physics, University of Missouri, Columbia, MO 65211; Department of Biochemistry, University of Missouri, Columbia, MO 65211; Informatics Institute, University of Missouri, Columbia, MO 65211
| | - Tao Yu
- Department of Physics, University of Missouri, Columbia, MO 65211; Department of Biochemistry, University of Missouri, Columbia, MO 65211; Informatics Institute, University of Missouri, Columbia, MO 65211; Department of Physics, Jianghan University, Wuhan, Hubei 430056, China
| | - Shi-Jie Chen
- Department of Physics, University of Missouri, Columbia, MO 65211; Department of Biochemistry, University of Missouri, Columbia, MO 65211; Informatics Institute, University of Missouri, Columbia, MO 65211;
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30
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Cordero P, Das R. Rich RNA Structure Landscapes Revealed by Mutate-and-Map Analysis. PLoS Comput Biol 2015; 11:e1004473. [PMID: 26566145 PMCID: PMC4643908 DOI: 10.1371/journal.pcbi.1004473] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2015] [Accepted: 07/20/2015] [Indexed: 11/19/2022] Open
Abstract
Landscapes exhibiting multiple secondary structures arise in natural RNA molecules that modulate gene expression, protein synthesis, and viral infection [corrected]. We report herein that high-throughput chemical experiments can isolate an RNA's multiple alternative secondary structures as they are stabilized by systematic mutagenesis (mutate-and-map, M2) and that a computational algorithm, REEFFIT, enables unbiased reconstruction of these states' structures and populations. In an in silico benchmark on non-coding RNAs with complex landscapes, M2-REEFFIT recovers 95% of RNA helices present with at least 25% population while maintaining a low false discovery rate (10%) and conservative error estimates. In experimental benchmarks, M2-REEFFIT recovers the structure landscapes of a 35-nt MedLoop hairpin, a 110-nt 16S rRNA four-way junction with an excited state, a 25-nt bistable hairpin, and a 112-nt three-state adenine riboswitch with its expression platform, molecules whose characterization previously required expert mutational analysis and specialized NMR or chemical mapping experiments. With this validation, M2-REEFFIT enabled tests of whether artificial RNA sequences might exhibit complex landscapes in the absence of explicit design. An artificial flavin mononucleotide riboswitch and a randomly generated RNA sequence are found to interconvert between three or more states, including structures for which there was no design, but that could be stabilized through mutations. These results highlight the likely pervasiveness of rich landscapes with multiple secondary structures in both natural and artificial RNAs and demonstrate an automated chemical/computational route for their empirical characterization.
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Affiliation(s)
- Pablo Cordero
- Biomedical Informatics Program, Stanford University, Stanford, California, United States of America
- Biochemistry Department, Stanford University, Stanford, California, United States of America
| | - Rhiju Das
- Biomedical Informatics Program, Stanford University, Stanford, California, United States of America
- Biochemistry Department, Stanford University, Stanford, California, United States of America
- Physics Department, Stanford University, Stanford, California, United States of America
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31
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Kutchko KM, Sanders W, Ziehr B, Phillips G, Solem A, Halvorsen M, Weeks KM, Moorman N, Laederach A. Multiple conformations are a conserved and regulatory feature of the RB1 5' UTR. RNA (NEW YORK, N.Y.) 2015; 21:1274-85. [PMID: 25999316 PMCID: PMC4478346 DOI: 10.1261/rna.049221.114] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Accepted: 03/27/2015] [Indexed: 05/22/2023]
Abstract
Folding to a well-defined conformation is essential for the function of structured ribonucleic acids (RNAs) like the ribosome and tRNA. Structured elements in the untranslated regions (UTRs) of specific messenger RNAs (mRNAs) are known to control expression. The importance of unstructured regions adopting multiple conformations, however, is still poorly understood. High-resolution SHAPE-directed Boltzmann suboptimal sampling of the Homo sapiens Retinoblastoma 1 (RB1) 5' UTR yields three distinct conformations compatible with the experimental data. Private single nucleotide variants (SNVs) identified in two patients with retinoblastoma each collapse the structural ensemble to a single but distinct well-defined conformation. The RB1 5' UTRs from Bos taurus (cow) and Trichechus manatus latirostris (manatee) are divergent in sequence from H. sapiens (human) yet maintain structural compatibility with high-probability base pairs. SHAPE chemical probing of the cow and manatee RB1 5' UTRs reveals that they also adopt multiple conformations. Luciferase reporter assays reveal that 5' UTR mutations alter RB1 expression. In a traditional model of disease, causative SNVs disrupt a key structural element in the RNA. For the subset of patients with heritable retinoblastoma-associated SNVs in the RB1 5' UTR, the absence of multiple structures is likely causative of the cancer. Our data therefore suggest that selective pressure will favor multiple conformations in eukaryotic UTRs to regulate expression.
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Affiliation(s)
- Katrina M Kutchko
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA Curriculum in Bioinformatics and Computational Biology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Wes Sanders
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA
| | - Ben Ziehr
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina 27599, USA Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Gabriela Phillips
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA
| | - Amanda Solem
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA
| | - Matthew Halvorsen
- Institute for Genomic Medicine, Columbia University Medical Center, New York, New York 10032, USA
| | - Kevin M Weeks
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA
| | - Nathaniel Moorman
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina 27599, USA Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Alain Laederach
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA
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32
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Li Y, Zhong C, Zhang S. Finding consensus stable local optimal structures for aligned RNA sequences and its application to discovering riboswitch elements. ACTA ACUST UNITED AC 2015; 10:498-518. [PMID: 24989865 DOI: 10.1504/ijbra.2014.062997] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Many non-coding RNAs (ncRNAs) can fold into alternate native structures and perform different biological functions. The computational prediction of an ncRNA's alternate native structures can be conducted by analysing the ncRNA's energy landscape. Previously, we have developed a computational approach, RNASLOpt, to predict alternate native structures for a single RNA. In this paper, in order to improve the accuracy of the prediction, we incorporate structural conservation information among a family of related ncRNA sequences to the prediction. We propose a comparative approach, RNAConSLOpt, to produce all possible consensus SLOpt stack configurations that are conserved on the consensus energy landscape of a family of related ncRNAs. Benchmarking tests show that RNAConSLOpt can reduce the number of candidate structures compared with RNASLOpt, and can predict ncRNAs' alternate native structures accurately. Moreover, an application of the proposed pipeline to bacteria in Bacillus genus has discovered several novel riboswitch candidates.
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Affiliation(s)
- Yuan Li
- Department of Electrical Engineering and Computer Science, University of Central Florida, Orlando, Florida 32816, USA
| | - Cuncong Zhong
- Department of Electrical Engineering and Computer Science, University of Central Florida, Orlando, Florida 32816, USA
| | - Shaojie Zhang
- Department of Electrical Engineering and Computer Science, University of Central Florida, Orlando, Florida 32816, USA
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33
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Chillón I, Marcia M, Legiewicz M, Liu F, Somarowthu S, Pyle AM. Native Purification and Analysis of Long RNAs. Methods Enzymol 2015; 558:3-37. [PMID: 26068736 PMCID: PMC4477701 DOI: 10.1016/bs.mie.2015.01.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The purification and analysis of long noncoding RNAs (lncRNAs) in vitro is a challenge, particularly if one wants to preserve elements of functional structure. Here, we describe a method for purifying lncRNAs that preserves the cotranscriptionally derived structure. The protocol avoids the misfolding that can occur during denaturation-renaturation protocols, thus facilitating the folding of long RNAs to a native-like state. This method is simple and does not require addition of tags to the RNA or the use of affinity columns. LncRNAs purified using this type of native purification protocol are amenable to biochemical and biophysical analysis. Here, we describe how to study lncRNA global compaction in the presence of divalent ions at equilibrium using sedimentation velocity analytical ultracentrifugation and analytical size-exclusion chromatography as well as how to use these uniform RNA species to determine robust lncRNA secondary structure maps by chemical probing techniques like selective 2'-hydroxyl acylation analyzed by primer extension and dimethyl sulfate probing.
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Affiliation(s)
- Isabel Chillón
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut, USA; Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
| | - Marco Marcia
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut, USA
| | - Michal Legiewicz
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut, USA
| | - Fei Liu
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut, USA
| | - Srinivas Somarowthu
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut, USA
| | - Anna Marie Pyle
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut, USA; Howard Hughes Medical Institute, Chevy Chase, Maryland, USA; Department of Chemistry, Yale University, New Haven, Connecticut, USA.
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34
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Nussinov R, Tsai CJ, Liu J. Principles of allosteric interactions in cell signaling. J Am Chem Soc 2014; 136:17692-701. [PMID: 25474128 PMCID: PMC4291754 DOI: 10.1021/ja510028c] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Indexed: 02/07/2023]
Abstract
Linking cell signaling events to the fundamental physicochemical basis of the conformational behavior of single molecules and ultimately to cellular function is a key challenge facing the life sciences. Here we outline the emerging principles of allosteric interactions in cell signaling, with emphasis on the following points. (1) Allosteric efficacy is not a function of the chemical composition of the allosteric pocket but reflects the extent of the population shift between the inactive and active states. That is, the allosteric effect is determined by the extent of preferred binding, not by the overall binding affinity. (2) Coupling between the allosteric and active sites does not decide the allosteric effect; however, it does define the propagation pathways, the allosteric binding sites, and key on-path residues. (3) Atoms of allosteric effectors can act as "driver" or "anchor" and create attractive "pulling" or repulsive "pushing" interactions. Deciphering, quantifying, and integrating the multiple co-occurring events present daunting challenges to our scientific community.
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Affiliation(s)
- Ruth Nussinov
- Cancer
and Inflammation Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research,
National Cancer Institute, Frederick, Maryland 21702, United States
- Sackler
Institute of Molecular Medicine, Department of Human Genetics and
Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Chung-Jung Tsai
- Cancer
and Inflammation Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research,
National Cancer Institute, Frederick, Maryland 21702, United States
| | - Jin Liu
- Department
of Biophysics, University of Texas Southwestern
Medical Center, 5323
Harry Hines Boulevard, Dallas, Texas 75390, United
States
- Department
of Chemistry, Center for Drug Discovery, Design, and Delivery (CD4),
and Center for Scientific Computation, Southern
Methodist University, 3215 Daniel Avenue, Dallas, Texas 75275, United
States
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35
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Sowa SW, Vazquez-Anderson J, Clark CA, De La Peña R, Dunn K, Fung EK, Khoury MJ, Contreras LM. Exploiting post-transcriptional regulation to probe RNA structures in vivo via fluorescence. Nucleic Acids Res 2014; 43:e13. [PMID: 25416800 PMCID: PMC4333371 DOI: 10.1093/nar/gku1191] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
While RNA structures have been extensively characterized in vitro, very few techniques exist to probe RNA structures inside cells. Here, we have exploited mechanisms of post-transcriptional regulation to synthesize fluorescence-based probes that assay RNA structures in vivo. Our probing system involves the co-expression of two constructs: (i) a target RNA and (ii) a reporter containing a probe complementary to a region in the target RNA attached to an RBS-sequestering hairpin and fused to a sequence encoding the green fluorescent protein (GFP). When a region of the target RNA is accessible, the area can interact with its complementary probe, resulting in fluorescence. By using this system, we observed varied patterns of structural accessibility along the length of the Tetrahymena group I intron. We performed in vivo DMS footprinting which, along with previous footprinting studies, helped to explain our probing results. Additionally, this novel approach represents a valuable tool to differentiate between RNA variants and to detect structural changes caused by subtle mutations. Our results capture some differences from traditional footprinting assays that could suggest that probing in vivo via oligonucleotide hybridization facilitates the detection of folding intermediates. Importantly, our data indicate that intracellular oligonucleotide probing can be a powerful complement to existing RNA structural probing methods.
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Affiliation(s)
- Steven W Sowa
- Microbiology Graduate Program, University of Texas at Austin, 100 E. 24th Street, A6500, Austin, TX 78712, USA
| | - Jorge Vazquez-Anderson
- McKetta Department of Chemical Engineering, University of Texas at Austin, 200 E. Dean Keeton St., Stop C0400, Austin, TX 78712, USA
| | - Chelsea A Clark
- McKetta Department of Chemical Engineering, University of Texas at Austin, 200 E. Dean Keeton St., Stop C0400, Austin, TX 78712, USA
| | - Ricardo De La Peña
- McKetta Department of Chemical Engineering, University of Texas at Austin, 200 E. Dean Keeton St., Stop C0400, Austin, TX 78712, USA
| | - Kaitlin Dunn
- McKetta Department of Chemical Engineering, University of Texas at Austin, 200 E. Dean Keeton St., Stop C0400, Austin, TX 78712, USA
| | - Emily K Fung
- McKetta Department of Chemical Engineering, University of Texas at Austin, 200 E. Dean Keeton St., Stop C0400, Austin, TX 78712, USA
| | - Mark J Khoury
- McKetta Department of Chemical Engineering, University of Texas at Austin, 200 E. Dean Keeton St., Stop C0400, Austin, TX 78712, USA
| | - Lydia M Contreras
- McKetta Department of Chemical Engineering, University of Texas at Austin, 200 E. Dean Keeton St., Stop C0400, Austin, TX 78712, USA
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36
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Tian S, Cordero P, Kladwang W, Das R. High-throughput mutate-map-rescue evaluates SHAPE-directed RNA structure and uncovers excited states. RNA (NEW YORK, N.Y.) 2014; 20:1815-26. [PMID: 25183835 PMCID: PMC4201832 DOI: 10.1261/rna.044321.114] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The three-dimensional conformations of noncoding RNAs underpin their biochemical functions but have largely eluded experimental characterization. Here, we report that integrating a classic mutation/rescue strategy with high-throughput chemical mapping enables rapid RNA structure inference with unusually strong validation. We revisit a 16S rRNA domain for which SHAPE (selective 2'-hydroxyl acylation with primer extension) and limited mutational analysis suggested a conformational change between apo- and holo-ribosome conformations. Computational support estimates, data from alternative chemical probes, and mutate-and-map (M(2)) experiments highlight issues of prior methodology and instead give a near-crystallographic secondary structure. Systematic interrogation of single base pairs via a high-throughput mutation/rescue approach then permits incisive validation and refinement of the M(2)-based secondary structure. The data further uncover the functional conformation as an excited state (20 ± 10% population) accessible via a single-nucleotide register shift. These results correct an erroneous SHAPE inference of a ribosomal conformational change, expose critical limitations of conventional structure mapping methods, and illustrate practical steps for more incisively dissecting RNA dynamic structure landscapes.
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Affiliation(s)
- Siqi Tian
- Department of Biochemistry, Stanford University, Stanford, California 94305, USA
| | - Pablo Cordero
- Biomedical Informatics Program, Stanford University, Stanford, California 94305, USA
| | - Wipapat Kladwang
- Department of Physics, Stanford University, Stanford, California 94305, USA
| | - Rhiju Das
- Department of Biochemistry, Stanford University, Stanford, California 94305, USA Biomedical Informatics Program, Stanford University, Stanford, California 94305, USA Department of Physics, Stanford University, Stanford, California 94305, USA
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37
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Gleitsman KR, Herschlag DH. A kinetic and thermodynamic framework for the Azoarcus group I ribozyme reaction. RNA (NEW YORK, N.Y.) 2014; 20:1732-1746. [PMID: 25246656 PMCID: PMC4201826 DOI: 10.1261/rna.044362.114] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 07/15/2014] [Indexed: 06/01/2023]
Abstract
Determination of quantitative thermodynamic and kinetic frameworks for ribozymes derived from the Azoarcus group I intron and comparisons to their well-studied analogs from the Tetrahymena group I intron reveal similarities and differences between these RNAs. The guanosine (G) substrate binds to the Azoarcus and Tetrahymena ribozymes with similar equilibrium binding constants and similar very slow association rate constants. These and additional literature observations support a model in which the free ribozyme is not conformationally competent to bind G and in which the probability of assuming the binding-competent state is determined by tertiary interactions of peripheral elements. As proposed previously, the slow binding of guanosine may play a role in the specificity of group I intron self-splicing, and slow binding may be used analogously in other biological processes. The internal equilibrium between ribozyme-bound substrates and products is similar for these ribozymes, but the Azoarcus ribozyme does not display the coupling in the binding of substrates that is observed with the Tetrahymena ribozyme, suggesting that local preorganization of the active site and rearrangements within the active site upon substrate binding are different for these ribozymes. Our results also confirm the much greater tertiary binding energy of the 5'-splice site analog with the Azoarcus ribozyme, binding energy that presumably compensates for the fewer base-pairing interactions to allow the 5'-exon intermediate in self splicing to remain bound subsequent to 5'-exon cleavage and prior to exon ligation. Most generally, these frameworks provide a foundation for design and interpretation of experiments investigating fundamental properties of these and other structured RNAs.
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Affiliation(s)
- Kristin R Gleitsman
- Department of Biochemistry, Stanford University, Stanford, California 94305-5307, USA
| | - Daniel H Herschlag
- Department of Biochemistry, Stanford University, Stanford, California 94305-5307, USA
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38
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Structural studies of a double-stranded RNA from trypanosome RNA editing by small-angle X-ray scattering. Methods Mol Biol 2014; 1240:165-89. [PMID: 25352145 DOI: 10.1007/978-1-4939-1896-6_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
We used small-angle X-ray scattering (SAXS) to evaluate the solution structure of a double-stranded RNA with 32 base pairs. We wanted to compare the solution structure to the crystal structure to assess the impact of the crystal lattice on the overall conformation of the RNA. The RNA was designed to self-anneal and form a head-to-head fusion of two identical mRNA/oligo(U) tail domains (the U-helix) from a trypanosome RNA editing substrate formed by the annealing of a guide RNA to a pre-edited mRNA. This substrate is from the U insertion/deletion RNA editing system of trypanosomes. Each strand in the fusion RNA had 16 purines from the pre-mRNA followed by 16 uracils (Us) from the U-tail at the 3' end of the guide RNA. The strands were designed to form a double helix with blunt ends, but each strand had the potential to form hairpins and single-stranded RNA helices. Hairpins could form by the 3' oligouridylate tract folding back to hybridize with the 5' oligopurine tract and forming an intervening loop. Single-stranded helices could form by the stacking of bases in the polypurine tract. Some of the 16 Us 3' to the polypurine tract may have been unstacked and in random coils. Our SAXS studies showed that the RNA formed a mix of single-stranded structures in the absence of MgCl2. In the presence of MgCl2 at concentrations similar to those in the crystal, the solution structure was consistent with the double-stranded, blunt-ended structure, in agreement with the crystal structure. Here we describe the preparation of RNA samples, data collection with an in-house SAXS instrument designed for biological samples, and the processing and modeling of the scattering data.
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39
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Global analysis of riboswitches by small-angle X-ray scattering and calorimetry. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:1020-1029. [PMID: 24769285 DOI: 10.1016/j.bbagrm.2014.04.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 04/10/2014] [Accepted: 04/13/2014] [Indexed: 11/22/2022]
Abstract
Riboswitches are phylogenetically widespread non-coding mRNA domains that directly bind cellular metabolites and regulate transcription, translation, RNA stability or splicing via alternative RNA structures modulated by ligand binding. The details of ligand recognition by many riboswitches have been elucidated using X-ray crystallography and NMR. However, the global dynamics of riboswitch-ligand interactions and their thermodynamic driving forces are less understood. By compiling the work of many laboratories investigating riboswitches using small-angle X-ray scattering (SAXS) and isothermal titration calorimetry (ITC), we uncover general trends and common themes. There is a pressing need for community-wide consensus experimental conditions to allow results of riboswitch studies to be compared rigorously. Nonetheless, our meta-analysis reveals considerable diversity in the extent to which ligand binding reorganizes global riboswitch structures. It also demonstrates a wide spectrum of enthalpy-entropy compensation regimes across riboswitches that bind a diverse set of ligands, giving rise to a relatively narrow range of physiologically relevant free energies and ligand affinities. From the strongly entropy-driven binding of glycine to the predominantly enthalpy-driven binding of c-di-GMP to their respective riboswitches, these distinct thermodynamic signatures reflect the versatile strategies employed by RNA to adapt to the chemical natures of diverse ligands. Riboswitches have evolved to use a combination of long-range tertiary interactions, conformational selection, and induced fit to work with distinct ligand structure, charge, and solvation properties. This article is part of a Special Issue entitled: Riboswitches.
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40
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Mitchell D, Russell R. Folding pathways of the Tetrahymena ribozyme. J Mol Biol 2014; 426:2300-12. [PMID: 24747051 DOI: 10.1016/j.jmb.2014.04.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 04/09/2014] [Accepted: 04/11/2014] [Indexed: 01/01/2023]
Abstract
Like many structured RNAs, the Tetrahymena group I intron ribozyme folds through multiple pathways and intermediates. Under standard conditions in vitro, a small fraction reaches the native state (N) with kobs ≈ 0.6 min(-1), while the remainder forms a long-lived misfolded conformation (M) thought to differ in topology. These alternative outcomes reflect a pathway that branches late in folding, after disruption of a trapped intermediate (Itrap). Here we use catalytic activity to probe the folding transitions from Itrap to the native and misfolded states. We show that mutations predicted to weaken the core helix P3 do not increase the rate of folding from Itrap but they increase the fraction that reaches the native state rather than forming the misfolded state. Thus, P3 is disrupted during folding to the native state but not to the misfolded state, and P3 disruption occurs after the rate-limiting step. Interestingly, P3-strengthening mutants also increase native folding. Additional experiments show that these mutants are rapidly committed to folding to the native state, although they reach the native state with approximately the same rate constant as the wild-type ribozyme (~1 min(-1)). Thus, the P3-strengthening mutants populate a distinct pathway that includes at least one intermediate but avoids the M state, most likely because P3 and the correct topology are formed early. Our results highlight multiple pathways in RNA folding and illustrate how kinetic competitions between rapid events can have long-lasting effects because the "choice" is enforced by energy barriers that grow larger as folding progresses.
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Affiliation(s)
- David Mitchell
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Rick Russell
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
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41
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Tsai CJ, Nussinov R. The free energy landscape in translational science: how can somatic mutations result in constitutive oncogenic activation? Phys Chem Chem Phys 2014; 16:6332-41. [PMID: 24445437 PMCID: PMC7667491 DOI: 10.1039/c3cp54253j] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The free energy landscape theory has transformed the field of protein folding. The significance of perceiving function in terms of conformational heterogeneity is gradually shifting the interest in the community from folding to function. From the free energy landscape standpoint the principles are unchanged: rather than considering the entire protein conformational landscape, the focus is on the ensemble around the bottom of the folding funnel. The protein can be viewed as populating one of two states: active or inactive. The basins of the two states are separated by a surmountable barrier, which allows the conformations to switch between the states. Unless the protein is a repressor, under physiological conditions it typically populates the inactive state. Ligand binding (or post-translational modification) triggers a switch to the active state. Constitutive allosteric mutations work by shifting the population from the inactive to the active state and keeping it there. This can happen by either destabilizing the inactive state, stabilizing the active state, or both. Identification of the mechanism through which they work is important since it may assist in drug discovery. Here we spotlight the usefulness of the free energy landscape in translational science, illustrating how oncogenic mutations can work in key proteins from the EGFR/Ras/Raf/Erk/Mek pathway, the main signaling pathway in cancer. Finally, we delineate the key components which are needed in order to trace the mechanism of allosteric events.
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Affiliation(s)
- Chung-Jung Tsai
- Leidos Biomedical Research, Inc., Cancer and Inflammation Program, National Cancer Institute, Frederick, MD 21702, USA.
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42
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Abstract
Ions surround nucleic acids in what is referred to as an ion atmosphere. As a result, the folding and dynamics of RNA and DNA and their complexes with proteins and with each other cannot be understood without a reasonably sophisticated appreciation of these ions' electrostatic interactions. However, the underlying behavior of the ion atmosphere follows physical rules that are distinct from the rules of site binding that biochemists are most familiar and comfortable with. The main goal of this review is to familiarize nucleic acid experimentalists with the physical concepts that underlie nucleic acid-ion interactions. Throughout, we provide practical strategies for interpreting and analyzing nucleic acid experiments that avoid pitfalls from oversimplified or incorrect models. We briefly review the status of theories that predict or simulate nucleic acid-ion interactions and experiments that test these theories. Finally, we describe opportunities for going beyond phenomenological fits to a next-generation, truly predictive understanding of nucleic acid-ion interactions.
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Affiliation(s)
- Jan Lipfert
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, Netherlands;
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Strulson CA, Yennawar NH, Rambo RP, Bevilacqua PC. Molecular crowding favors reactivity of a human ribozyme under physiological ionic conditions. Biochemistry 2013; 52:8187-97. [PMID: 24187989 PMCID: PMC3882164 DOI: 10.1021/bi400816s] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In an effort to relate RNA folding to function under cellular-like conditions, we monitored the self-cleavage reaction of the human hepatitis delta virus-like CPEB3 ribozyme in the background of physiological ionic concentrations and various crowding and cosolute agents. We found that at physiological free Mg(2+) concentrations (∼0.1-0.5 mM), both crowders and cosolutes stimulate the rate of self-cleavage, up to ∼6-fold, but that in 10 mM Mg(2+) (conditions widely used for in vitro ribozyme studies) these same additives have virtually no effect on the self-cleavage rate. We further observe a dependence of the self-cleavage rate on crowder size, wherein the level of rate stimulation is diminished for crowders larger than the size of the unfolded RNA. Monitoring effects of crowding and cosolute agents on rates in biological amounts of urea revealed additive-promoted increases at both low and high Mg(2+) concentrations, with a maximal stimulation of more than 10-fold and a rescue of the rate to its urea-free values. Small-angle X-ray scattering experiments reveal a structural basis for this stimulation in that higher-molecular weight crowding agents favor a more compact form of the ribozyme in 0.5 mM Mg(2+) that is essentially equivalent to the form under standard ribozyme conditions of 10 mM Mg(2+) without a crowder. This finding suggests that at least a portion of the rate enhancement arises from favoring the native RNA tertiary structure. We conclude that cellular-like crowding supports ribozyme reactivity by favoring a compact form of the ribozyme, but only under physiological ionic and cosolute conditions.
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Affiliation(s)
- Christopher A. Strulson
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
- Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Neela H. Yennawar
- Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Robert P. Rambo
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720
| | - Philip C. Bevilacqua
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
- Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
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Gajda MJ, Martinez Zapien D, Uchikawa E, Dock-Bregeon AC. Modeling the structure of RNA molecules with small-angle X-ray scattering data. PLoS One 2013; 8:e78007. [PMID: 24223750 PMCID: PMC3817170 DOI: 10.1371/journal.pone.0078007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 09/08/2013] [Indexed: 11/19/2022] Open
Abstract
We propose a novel fragment assembly method for low-resolution modeling of RNA and show how it may be used along with small-angle X-ray solution scattering (SAXS) data to model low-resolution structures of particles having as many as 12 independent secondary structure elements. We assessed this model-building procedure by using both artificial data on a previously proposed benchmark and publicly available data. With the artificial data, SAXS-guided models show better similarity to native structures than ROSETTA decoys. The publicly available data showed that SAXS-guided models can be used to reinterpret RNA structures previously deposited in the Protein Data Bank. Our approach allows for fast and efficient building of de novo models of RNA using approximate secondary structures that can be readily obtained from existing bioinformatic approaches. We also offer a rigorous assessment of the resolving power of SAXS in the case of small RNA structures, along with a small multimetric benchmark of the proposed method.
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Affiliation(s)
- Michal Jan Gajda
- NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Niedersachsen, Germany
- Hamburg Outstation, European Molecular Biology Laboratories, Hamburg, Germany
| | - Denise Martinez Zapien
- Laboratoire de Biologie et Génomique Structurales, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, Bas-Rhin, France
| | - Emiko Uchikawa
- Laboratoire de Biologie et Génomique Structurales, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, Bas-Rhin, France
| | - Anne-Catherine Dock-Bregeon
- Laboratoire de Biologie et Génomique Structurales, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, Bas-Rhin, France
- Génomique Fonctionnelle, Institut de Biologie de l’École Normale Supérieure, Paris, Île-de-France, France
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Lin YC, Lin BL, Setiawan T, Chang CC, Yen CF, Chang WH. A Single Molecule FRET Study of Formation of RNA Polymerase II Elongation Complex on Passivated Surface. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.201000074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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46
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Evolutionary evidence for alternative structure in RNA sequence co-variation. PLoS Comput Biol 2013; 9:e1003152. [PMID: 23935473 PMCID: PMC3723493 DOI: 10.1371/journal.pcbi.1003152] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 06/05/2013] [Indexed: 02/06/2023] Open
Abstract
Sequence conservation and co-variation of base pairs are hallmarks of structured RNAs. For certain RNAs (e.g. riboswitches), a single sequence must adopt at least two alternative secondary structures to effectively regulate the message. If alternative secondary structures are important to the function of an RNA, we expect to observe evolutionary co-variation supporting multiple conformations. We set out to characterize the evolutionary co-variation supporting alternative conformations in riboswitches to determine the extent to which alternative secondary structures are conserved. We found strong co-variation support for the terminator, P1, and anti-terminator stems in the purine riboswitch by extending alignments to include terminator sequences. When we performed Boltzmann suboptimal sampling on purine riboswitch sequences with terminators we found that these sequences appear to have evolved to favor specific alternative conformations. We extended our analysis of co-variation to classic alignments of group I/II introns, tRNA, and other classes of riboswitches. In a majority of these RNAs, we found evolutionary evidence for alternative conformations that are compatible with the Boltzmann suboptimal ensemble. Our analyses suggest that alternative conformations are selected for and thus likely play functional roles in even the most structured of RNAs. RNA (Ribonucleic Acid) is a messenger of genetic information, master regulator, and catalyst in the cell. To carry out its function, RNA can fold into complex three-dimensional structures. Certain classes of RNAs, called riboswitches, adopt at least two alternative structures to act as a switch. We set out to detect the evolutionary signal for alternative structures in riboswitches as we hypothesize that these RNA sequences must have evolved to allow both conformations. We find that indeed such signals exist when we compare the sequences of riboswitches from multiple species. When we extend this analysis to other RNA regulators in the cell that are not thought of as switches, we detect equivalent evolutionary support for alternative structures. Viewed through the lens of evolutionary structure conservation RNA sequences appear to have adapted to adopt multiple conformations.
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Mitchell D, Jarmoskaite I, Seval N, Seifert S, Russell R. The long-range P3 helix of the Tetrahymena ribozyme is disrupted during folding between the native and misfolded conformations. J Mol Biol 2013; 425:2670-86. [PMID: 23702292 DOI: 10.1016/j.jmb.2013.05.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 05/07/2013] [Accepted: 05/09/2013] [Indexed: 02/07/2023]
Abstract
RNAs are prone to misfolding, but how misfolded structures are formed and resolved remains incompletely understood. The Tetrahymena group I intron ribozyme folds in vitro to a long-lived misfolded conformation (M) that includes extensive native structure but is proposed to differ in topology from the native state (N). A leading model predicts that exchange of the topologies requires unwinding of the long-range, core helix P3, despite the presence of P3 in both conformations. To test this model, we constructed 16 mutations to strengthen or weaken P3. Catalytic activity and in-line probing showed that nearly all of the mutants form the M state before folding to N. The P3-weakening mutations accelerated refolding from M (3- to 30-fold) and the P3-strengthening mutations slowed refolding (6- to 1400-fold), suggesting that P3 indeed unwinds transiently. Upon depletion of Mg(2+), the mutations had analogous effects on unfolding from N to intermediates that subsequently fold to M. The magnitudes for the P3-weakening mutations were larger than in refolding from M, and small-angle X-ray scattering showed that the ribozyme expands rapidly to intermediates from which P3 is disrupted subsequently. These results are consistent with previous results indicating unfolding of native peripheral structure during refolding from M, which probably permits rearrangement of the core. Together, our results demonstrate that exchange of the native and misfolded conformations requires loss of a core helix in addition to peripheral structure. Further, the results strongly suggest that misfolding arises from a topological error within the ribozyme core, and a specific topology is proposed.
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Affiliation(s)
- David Mitchell
- Department of Chemistry and Biochemistry, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
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Kruse E, Voigt C, Leeder WM, Göringer HU. RNA helicases involved in U-insertion/deletion-type RNA editing. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:835-41. [PMID: 23587716 DOI: 10.1016/j.bbagrm.2013.04.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 04/04/2013] [Accepted: 04/08/2013] [Indexed: 12/20/2022]
Abstract
Mitochondrial pre-messenger RNAs in kinetoplastid protozoa such as the disease-causing African trypanosomes are substrates of a unique RNA editing reaction. The process is characterized by the site-specific insertion and deletion of exclusively U nucleotides and converts nonfunctional pre-mRNAs into translatable transcripts. Similar to other RNA-based metabolic pathways, RNA editing is catalyzed by a macromolecular protein complex, the editosome. Editosomes provide a reactive surface for the individual steps of the catalytic cycle and involve as key players a specific class of small, non-coding RNAs termed guide (g)RNAs. gRNAs basepair proximal to an editing site and act as quasi templates in the U-insertion/deletion reaction. Next to the editosome several accessory proteins and complexes have been identified, which contribute to different steps of the reaction. This includes matchmaking-type RNA/RNA annealing factors as well as RNA helicases of the archetypical DEAD- and DExH/D-box families. Here we summarize the current structural, genetic and biochemical knowledge of the two characterized "editing RNA helicases" and provide an outlook onto dynamic processes within the editing reaction cycle. This article is part of a Special Issue entitled: The Biology of RNA helicases - Modulation for life.
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Chen C, Mitra S, Jonikas M, Martin J, Brenowitz M, Laederach A. Understanding the role of three-dimensional topology in determining the folding intermediates of group I introns. Biophys J 2013; 104:1326-37. [PMID: 23528092 DOI: 10.1016/j.bpj.2013.02.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Revised: 01/28/2013] [Accepted: 02/07/2013] [Indexed: 11/30/2022] Open
Abstract
Many RNA molecules exert their biological function only after folding to unique three-dimensional structures. For long, noncoding RNA molecules, the complexity of finding the native topology can be a major impediment to correct folding to the biologically active structure. An RNA molecule may fold to a near-native structure but not be able to continue to the correct structure due to a topological barrier such as crossed strands or incorrectly stacked helices. Achieving the native conformation thus requires unfolding and refolding, resulting in a long-lived intermediate. We investigate the role of topology in the folding of two phylogenetically related catalytic group I introns, the Twort and Azoarcus group I ribozymes. The kinetic models describing the Mg(2+)-mediated folding of these ribozymes were previously determined by time-resolved hydroxyl (∙OH) radical footprinting. Two intermediates formed by parallel intermediates were resolved for each RNA. These data and analytical ultracentrifugation compaction analyses are used herein to constrain coarse-grained models of these folding intermediates as we investigate the role of nonnative topology in dictating the lifetime of the intermediates. Starting from an ensemble of unfolded conformations, we folded the RNA molecules by progressively adding native constraints to subdomains of the RNA defined by the ∙OH time-progress curves to simulate folding through the different kinetic pathways. We find that nonnative topologies (arrangement of helices) occur frequently in the folding simulations despite using only native constraints to drive the reaction, and that the initial conformation, rather than the folding pathway, is the major determinant of whether the RNA adopts nonnative topology during folding. From these analyses we conclude that biases in the initial conformation likely determine the relative flux through parallel RNA folding pathways.
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Affiliation(s)
- Chunxia Chen
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
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Doetsch M, Stampfl S, Fürtig B, Beich-Frandsen M, Saxena K, Lybecker M, Schroeder R. Study of E. coli Hfq's RNA annealing acceleration and duplex destabilization activities using substrates with different GC-contents. Nucleic Acids Res 2012; 41:487-97. [PMID: 23104381 PMCID: PMC3592463 DOI: 10.1093/nar/gks942] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Folding of RNA molecules into their functional three-dimensional structures is often supported by RNA chaperones, some of which can catalyse the two elementary reactions helix disruption and helix formation. Hfq is one such RNA chaperone, but its strand displacement activity is controversial. Whereas some groups found Hfq to destabilize secondary structures, others did not observe such an activity with their RNA substrates. We studied Hfq’s activities using a set of short RNAs of different thermodynamic stabilities (GC-contents from 4.8% to 61.9%), but constant length. We show that Hfq’s strand displacement as well as its annealing activity are strongly dependent on the substrate’s GC-content. However, this is due to Hfq’s preferred binding of AU-rich sequences and not to the substrate’s thermodynamic stability. Importantly, Hfq catalyses both annealing and strand displacement with comparable rates for different substrates, hinting at RNA strand diffusion and annealing nucleation being rate-limiting for both reactions. Hfq’s strand displacement activity is a result of the thermodynamic destabilization of the RNA through preferred single-strand binding whereas annealing acceleration is independent from Hfq’s thermodynamic influence. Therefore, the two apparently disparate activities annealing acceleration and duplex destabilization are not in energetic conflict with each other.
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Affiliation(s)
- Martina Doetsch
- Department for Biochemistry, Max F Perutz Laboratories, Dr-Bohrgasse 9, 1030 Vienna, Austria
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