1
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O'Brien BM, Moulick R, Jiménez-Avalos G, Rajasekaran N, Kaiser CM, Woodson SA. Stick-slip unfolding favors self-association of expanded HTT mRNA. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.31.596809. [PMID: 38895475 PMCID: PMC11185545 DOI: 10.1101/2024.05.31.596809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
In Huntington's Disease (HD) and related disorders, expansion of CAG trinucleotide repeats produces a toxic gain of function in affected neurons. Expanded huntingtin (expHTT) mRNA forms aggregates that sequester essential RNA binding proteins, dysregulating mRNA processing and translation. The physical basis of RNA aggregation has been difficult to disentangle owing to the heterogeneous structure of the CAG repeats. Here, we probe the folding and unfolding pathways of expHTT mRNA using single-molecule force spectroscopy. Whereas normal HTT mRNAs unfold reversibly and cooperatively, expHTT mRNAs with 20 or 40 CAG repeats slip and unravel non-cooperatively at low tension. Slippage of CAG base pairs is punctuated by concerted rearrangement of adjacent CCG trinucleotides, trapping partially folded structures that readily base pair with another RNA strand. We suggest that the conformational entropy of the CAG repeats, combined with stable CCG base pairs, creates a stick-slip behavior that explains the aggregation propensity of expHTT mRNA.
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Affiliation(s)
- Brett M O'Brien
- Chemical Biology Interface Program, Johns Hopkins University, Baltimore, MD 21218 USA
| | - Roumita Moulick
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218 USA
| | - Gabriel Jiménez-Avalos
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218 USA
| | | | - Christian M Kaiser
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218 USA
- Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, The Netherlands
| | - Sarah A Woodson
- Chemical Biology Interface Program, Johns Hopkins University, Baltimore, MD 21218 USA
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218 USA
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2
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González-García JS. A model for ribosome translocation based on the alternated displacement of its subunits. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2023:10.1007/s00249-023-01662-z. [PMID: 37291414 DOI: 10.1007/s00249-023-01662-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 05/03/2023] [Accepted: 05/21/2023] [Indexed: 06/10/2023]
Abstract
A meaningful dilemma in ribosome translocation arising from experimental facts is that, although the ribosome-mRNA interaction force always has a significant magnitude, the ribosome still moves to the next codon on the mRNA. How does the ribosome move to the next codon in the sequence while holding the mRNA tightly? The hypothesis proposed here is that ribosome subunits alternate the grip of the ribosome on the mRNA, freeing the other subunit of such interaction for a while, thus allowing its motion to the following codon. Based on this assumption, a single-loop cycle of ribosome configurations involving the relative position of its subunits is elaborated. When its dynamic is modeled as a Markov network, it gives expressions for the average ribosome translocation speed and stall force as functions of the equilibrium constants among the proposed ribosome configurations. The calculations have a reasonable agreement with experimental results, and the succession of molecular events considered here is consistent with current biomolecular concepts of the ribosome translocation process. Thus, the alternative displacements hypothesis developed in the present work suggests a feasible explanation of ribosome translocation.
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Affiliation(s)
- José S González-García
- Seminario de Bifurcaciones y Singularidades, Departamento de Matemáticas, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186 Col. Vicentina, 09340, Iztapalapa, Ciudad de México, México.
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3
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Wee LM, Tong AB, Florez Ariza AJ, Cañari-Chumpitaz C, Grob P, Nogales E, Bustamante CJ. A trailing ribosome speeds up RNA polymerase at the expense of transcript fidelity via force and allostery. Cell 2023; 186:1244-1262.e34. [PMID: 36931247 PMCID: PMC10135430 DOI: 10.1016/j.cell.2023.02.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 11/14/2022] [Accepted: 02/06/2023] [Indexed: 03/18/2023]
Abstract
In prokaryotes, translation can occur on mRNA that is being transcribed in a process called coupling. How the ribosome affects the RNA polymerase (RNAP) during coupling is not well understood. Here, we reconstituted the E. coli coupling system and demonstrated that the ribosome can prevent pausing and termination of RNAP and double the overall transcription rate at the expense of fidelity. Moreover, we monitored single RNAPs coupled to ribosomes and show that coupling increases the pause-free velocity of the polymerase and that a mechanical assisting force is sufficient to explain the majority of the effects of coupling. Also, by cryo-EM, we observed that RNAPs with a terminal mismatch adopt a backtracked conformation, while a coupled ribosome allosterically induces these polymerases toward a catalytically active anti-swiveled state. Finally, we demonstrate that prolonged RNAP pausing is detrimental to cell viability, which could be prevented by polymerase reactivation through a coupled ribosome.
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Affiliation(s)
- Liang Meng Wee
- QB3-Berkeley, Berkeley, CA, USA; Howard Hughes Medical Institute, University of California Berkeley, Berkeley, CA, USA
| | - Alexander B Tong
- QB3-Berkeley, Berkeley, CA, USA; Department of Chemistry, University of California Berkeley, Berkeley, CA, USA
| | - Alfredo Jose Florez Ariza
- QB3-Berkeley, Berkeley, CA, USA; Biophysics Graduate Group, University of California Berkeley, Berkeley, CA, USA
| | - Cristhian Cañari-Chumpitaz
- QB3-Berkeley, Berkeley, CA, USA; Department of Chemistry, University of California Berkeley, Berkeley, CA, USA; Howard Hughes Medical Institute, University of California Berkeley, Berkeley, CA, USA
| | - Patricia Grob
- QB3-Berkeley, Berkeley, CA, USA; Howard Hughes Medical Institute, University of California Berkeley, Berkeley, CA, USA; Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
| | - Eva Nogales
- QB3-Berkeley, Berkeley, CA, USA; Biophysics Graduate Group, University of California Berkeley, Berkeley, CA, USA; Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA; Howard Hughes Medical Institute, University of California Berkeley, Berkeley, CA, USA; Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Carlos J Bustamante
- QB3-Berkeley, Berkeley, CA, USA; Biophysics Graduate Group, University of California Berkeley, Berkeley, CA, USA; Department of Chemistry, University of California Berkeley, Berkeley, CA, USA; Department of Physics, University of California Berkeley, Berkeley, CA, USA; Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA; Kavli Energy Nanoscience Institute, Berkeley, CA, USA; Howard Hughes Medical Institute, University of California Berkeley, Berkeley, CA, USA; Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
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4
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Giuliodori AM, Belardinelli R, Duval M, Garofalo R, Schenckbecher E, Hauryliuk V, Ennifar E, Marzi S. Escherichia coli CspA stimulates translation in the cold of its own mRNA by promoting ribosome progression. Front Microbiol 2023; 14:1118329. [PMID: 36846801 PMCID: PMC9947658 DOI: 10.3389/fmicb.2023.1118329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 01/06/2023] [Indexed: 02/11/2023] Open
Abstract
Escherichia coli CspA is an RNA binding protein that accumulates during cold-shock and stimulates translation of several mRNAs-including its own. Translation in the cold of cspA mRNA involves a cis-acting thermosensor element, which enhances ribosome binding, and the trans-acting action of CspA. Using reconstituted translation systems and probing experiments we show that, at low temperature, CspA specifically promotes the translation of the cspA mRNA folded in the conformation less accessible to the ribosome, which is formed at 37°C but is retained upon cold shock. CspA interacts with its mRNA without inducing large structural rearrangements, but allowing the progression of the ribosomes during the transition from translation initiation to translation elongation. A similar structure-dependent mechanism may be responsible for the CspA-dependent translation stimulation observed with other probed mRNAs, for which the transition to the elongation phase is progressively facilitated during cold acclimation with the accumulation of CspA.
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Affiliation(s)
- Anna Maria Giuliodori
- School of Biosciences and Veterinary Medicine, University of Camerino, Camerino, Italy,*Correspondence: Anna Maria Giuliodori, ✉
| | - Riccardo Belardinelli
- Architecture et Réactivité de l’ARN, CNRS 9002, Université de Strasbourg, Strasbourg, France
| | - Melodie Duval
- Architecture et Réactivité de l’ARN, CNRS 9002, Université de Strasbourg, Strasbourg, France
| | - Raffaella Garofalo
- Architecture et Réactivité de l’ARN, CNRS 9002, Université de Strasbourg, Strasbourg, France
| | - Emma Schenckbecher
- Architecture et Réactivité de l’ARN, CNRS 9002, Université de Strasbourg, Strasbourg, France
| | - Vasili Hauryliuk
- Department of Experimental Medical Science, Lund University, Lund, Sweden,Institute of Technology, University of Tartu, Tartu, Estonia
| | - Eric Ennifar
- Architecture et Réactivité de l’ARN, CNRS 9002, Université de Strasbourg, Strasbourg, France
| | - Stefano Marzi
- Architecture et Réactivité de l’ARN, CNRS 9002, Université de Strasbourg, Strasbourg, France,Stefano Marzi, ✉
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5
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Haghizadeh A, Iftikhar M, Dandpat SS, Simpson T. Looking at Biomolecular Interactions through the Lens of Correlated Fluorescence Microscopy and Optical Tweezers. Int J Mol Sci 2023; 24:2668. [PMID: 36768987 PMCID: PMC9916863 DOI: 10.3390/ijms24032668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 12/19/2022] [Accepted: 01/26/2023] [Indexed: 02/01/2023] Open
Abstract
Understanding complex biological events at the molecular level paves the path to determine mechanistic processes across the timescale necessary for breakthrough discoveries. While various conventional biophysical methods provide some information for understanding biological systems, they often lack a complete picture of the molecular-level details of such dynamic processes. Studies at the single-molecule level have emerged to provide crucial missing links to understanding complex and dynamic pathways in biological systems, which are often superseded by bulk biophysical and biochemical studies. Latest developments in techniques combining single-molecule manipulation tools such as optical tweezers and visualization tools such as fluorescence or label-free microscopy have enabled the investigation of complex and dynamic biomolecular interactions at the single-molecule level. In this review, we present recent advances using correlated single-molecule manipulation and visualization-based approaches to obtain a more advanced understanding of the pathways for fundamental biological processes, and how this combination technique is facilitating research in the dynamic single-molecule (DSM), cell biology, and nanomaterials fields.
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6
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Abstract
Translocation of transfer RNA (tRNA) and messenger RNA (mRNA) through the ribosome is catalyzed by the GTPase elongation factor G (EF-G) in bacteria. Although guanosine-5'-triphosphate (GTP) hydrolysis accelerates translocation and is required for dissociation of EF-G, its fundamental role remains unclear. Here, we used ensemble Förster resonance energy transfer (FRET) to monitor how inhibition of GTP hydrolysis impacts the structural dynamics of the ribosome. We used FRET pairs S12-S19 and S11-S13, which unambiguously report on rotation of the 30S head domain, and the S6-L9 pair, which measures intersubunit rotation. Our results show that, in addition to slowing reverse intersubunit rotation, as shown previously, blocking GTP hydrolysis slows forward head rotation. Surprisingly, blocking GTP hydrolysis completely abolishes reverse head rotation. We find that the S13-L33 FRET pair, which has been used in previous studies to monitor head rotation, appears to report almost exclusively on intersubunit rotation. Furthermore, we find that the signal from quenching of 3'-terminal pyrene-labeled mRNA, which is used extensively to follow mRNA translocation, correlates most closely with reverse intersubunit rotation. To account for our finding that blocking GTP hydrolysis abolishes a rotational event that occurs after the movements of mRNA and tRNAs are essentially complete, we propose that the primary role of GTP hydrolysis is to create an irreversible step in a mechanism that prevents release of EF-G until both the tRNAs and mRNA have moved by one full codon, ensuring productive translocation and maintenance of the translational reading frame.
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7
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Buck S, Pekarek L, Caliskan N. POTATO: Automated pipeline for batch analysis of optical tweezers data. Biophys J 2022; 121:2830-2839. [PMID: 35778838 PMCID: PMC9388390 DOI: 10.1016/j.bpj.2022.06.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 04/22/2022] [Accepted: 06/27/2022] [Indexed: 11/17/2022] Open
Abstract
Optical tweezers are a single-molecule technique that allows probing of intra- and intermolecular interactions that govern complex biological processes involving molecular motors, protein-nucleic acid interactions, and protein/RNA folding. Recent developments in instrumentation eased and accelerated optical tweezers data acquisition, but analysis of the data remains challenging. Here, to enable high-throughput data analysis, we developed an automated python-based analysis pipeline called POTATO (practical optical tweezers analysis tool). POTATO automatically processes the high-frequency raw data generated by force-ramp experiments and identifies (un)folding events using predefined parameters. After segmentation of the force-distance trajectories at the identified (un)folding events, sections of the curve can be fitted independently to a worm-like chain and freely jointed chain models, and the work applied on the molecule can be calculated by numerical integration. Furthermore, the tool allows plotting of constant force data and fitting of the Gaussian distance distribution over time. All these features are wrapped in a user-friendly graphical interface, which allows researchers without programming knowledge to perform sophisticated data analysis.
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Affiliation(s)
- Stefan Buck
- Helmholtz Institute for RNA-based Infection Research (HIRI), Würzburg, Germany
| | - Lukas Pekarek
- Helmholtz Institute for RNA-based Infection Research (HIRI), Würzburg, Germany
| | - Neva Caliskan
- Helmholtz Institute for RNA-based Infection Research (HIRI), Würzburg, Germany; Medical Faculty, Julius-Maximilians University Würzburg, Würzburg, Germany.
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8
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Translation initiation site of mRNA is selected through dynamic interaction with the ribosome. Proc Natl Acad Sci U S A 2022; 119:e2118099119. [PMID: 35605125 DOI: 10.1073/pnas.2118099119] [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: 11/18/2022] Open
Abstract
SignificanceRibosomes translate the genetic codes of messenger RNA (mRNA) to make proteins. Translation must begin at the correct initiation site; otherwise, abnormal proteins will be produced. Here, we show that a short ribosome-specific sequence in the upstream followed by an unstructured downstream sequence is a favorable initiation site. Those mRNAs lacking either of these two characteristics do not associate tightly with the ribosome. Initiator transfer RNA (tRNA) and initiation factors facilitate the binding. However, when the downstream site forms structures, initiation factor 3 triggers the dissociation of the accommodated initiator tRNA and the subsequent disassembly of the ribosome-mRNA complex. Thus, initiation factors help the ribosome distinguish unfavorable structured sequences that may not act as the mRNA translation initiation site.
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9
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Mallimadugula UL, Galburt EA. Parallel path mechanisms lead to nonmonotonic force-velocity curves and an optimum load for molecular motor function. Phys Rev E 2022; 105:034405. [PMID: 35428051 DOI: 10.1103/physreve.105.034405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 02/15/2022] [Indexed: 06/14/2023]
Abstract
Molecular motors convert chemical potential energy into mechanical work and perform a great number of critical biological functions. Examples include the polymerization and manipulation of nucleic acids, the generation of cellular motility and contractility, the formation and maintenance of cell shape, and the transport of materials within cells. The mechanisms underlying these molecular machines are varied, but are almost always considered in the context of a single kinetic pathway that describes motor stepping. However, the multidimensional nature of protein energy landscapes suggests the possibility of multiple reaction pathways connecting two states. Here we investigate the properties of a hypothetical molecular motor able to utilize parallel translocation mechanisms. We explore motor velocity and force dependence as a function of the energy landscape of each path and reveal the potential for such a mechanism to result in negative differential conductance. More specifically, regimes exist where increasing opposing force leads to increased velocity and an optimum load for motor function. We explore how the presence of this optimum depends on the rates of the individual paths and show that the distribution of stepping times characterized by the randomness parameter may be used to test for parallel path mechanisms. Last, we caution that experimental data consisting solely of measurements of velocity as a function of ATP concentration and force cannot be used to eliminate the possibility of such a parallel path mechanism.
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Affiliation(s)
- Upasana L Mallimadugula
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, Missouri 63108, USA
| | - Eric A Galburt
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, Missouri 63108, USA
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10
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van 't Spijker HM, Stackpole EE, Almeida S, Katsara O, Liu B, Shen K, Schneider RJ, Gao FB, Richter JD. Ribosome profiling reveals novel regulation of C9ORF72 GGGGCC repeat-containing RNA translation. RNA (NEW YORK, N.Y.) 2022; 28:123-138. [PMID: 34848561 PMCID: PMC8906550 DOI: 10.1261/rna.078963.121] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 10/31/2021] [Indexed: 06/13/2023]
Abstract
GGGGCC (G4C2) repeat expansion in the first intron of C9ORF72 causes amyotrophic lateral sclerosis and frontotemporal dementia. Repeat-containing RNA is translated into dipeptide repeat (DPR) proteins, some of which are neurotoxic. Using dynamic ribosome profiling, we identified three translation initiation sites in the intron upstream of (G4C2) repeats; these sites are detected irrespective of the presence or absence of the repeats. During translocation, ribosomes appear to be stalled on the repeats. An AUG in the preceding C9ORF72 exon initiates a uORF that inhibits downstream translation. Polysome isolation indicates that unspliced (G4C2) repeat-containing RNA is a substrate for DPR protein synthesis. (G4C2) repeat-containing RNA translation is 5' cap-independent but inhibited by the initiation factor DAP5, suggesting an interplay with uORF function. These results define novel translational mechanisms of expanded (G4C2) repeat-containing RNA in disease.
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Affiliation(s)
- Heleen M van 't Spijker
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, Massachusetts 01605, USA
| | - Emily E Stackpole
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, Massachusetts 01605, USA
| | - Sandra Almeida
- Department of Neurology, University of Massachusetts Chan Medical School, Worcester, Massachusetts 01605, USA
| | - Olga Katsara
- Department of Microbiology, New York University School of Medicine, New York, New York 10016, USA
| | - Botao Liu
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, Massachusetts 01605, USA
| | - Kuang Shen
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, Massachusetts 01605, USA
| | - Robert J Schneider
- Department of Microbiology, New York University School of Medicine, New York, New York 10016, USA
| | - Fen-Biao Gao
- Department of Neurology, University of Massachusetts Chan Medical School, Worcester, Massachusetts 01605, USA
| | - Joel D Richter
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, Massachusetts 01605, USA
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11
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Identifying Inhibitors of −1 Programmed Ribosomal Frameshifting in a Broad Spectrum of Coronaviruses. Viruses 2022; 14:v14020177. [PMID: 35215770 PMCID: PMC8876150 DOI: 10.3390/v14020177] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 12/30/2021] [Accepted: 01/10/2022] [Indexed: 02/06/2023] Open
Abstract
Recurrent outbreaks of novel zoonotic coronavirus (CoV) diseases in recent years have highlighted the importance of developing therapeutics with broad-spectrum activity against CoVs. Because all CoVs use −1 programmed ribosomal frameshifting (−1 PRF) to control expression of key viral proteins, the frameshift signal in viral mRNA that stimulates −1 PRF provides a promising potential target for such therapeutics. To test the viability of this strategy, we explored whether small-molecule inhibitors of −1 PRF in SARS-CoV-2 also inhibited −1 PRF in a range of bat CoVs—the most likely source of future zoonoses. Six inhibitors identified in new and previous screens against SARS-CoV-2 were evaluated against the frameshift signals from a panel of representative bat CoVs as well as MERS-CoV. Some drugs had strong activity against subsets of these CoV-derived frameshift signals, while having limited to no effect on −1 PRF caused by frameshift signals from other viruses used as negative controls. Notably, the serine protease inhibitor nafamostat suppressed −1 PRF significantly for multiple CoV-derived frameshift signals. These results suggest it is possible to find small-molecule ligands that inhibit −1 PRF specifically in a broad spectrum of CoVs, establishing frameshift signals as a viable target for developing pan-coronaviral therapeutics.
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12
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Joiret M, Kerff F, Rapino F, Close P, Geris L. Ribosome exit tunnel electrostatics. Phys Rev E 2022; 105:014409. [PMID: 35193250 DOI: 10.1103/physreve.105.014409] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 12/08/2021] [Indexed: 06/14/2023]
Abstract
The impact of ribosome exit tunnel electrostatics on the protein elongation rate or on forces acting upon the nascent polypeptide chain are currently not fully elucidated. In the past, researchers have measured the electrostatic potential inside the ribosome polypeptide exit tunnel at a limited number of spatial points, at least in rabbit reticulocytes. Here we present a basic electrostatic model of the exit tunnel of the ribosome, providing a quantitative physical description of the tunnel interaction with the nascent proteins at all centro-axial points inside the tunnel. We show that a strong electrostatic screening is due to water molecules (not mobile ions) attracted to the ribosomal nucleic acid phosphate moieties buried in the immediate vicinity of the tunnel wall. We also show how the tunnel wall components and local ribosomal protein protrusions impact on the electrostatic potential profile and impede charged amino acid residues from progressing through the tunnel, affecting the elongation rate in a range of -40% to +85% when compared to the average elongation rate. The time spent by the ribosome to decode the genetic encrypted message is constrained accordingly. We quantitatively derive, at single-residue resolution, the axial forces acting on the nascent peptide from its particular sequence embedded in the tunnel. The model sheds light on how the experimental data point measurements of the potential are linked to the local structural chemistry of the inner wall, shape, and size of the tunnel. The model consistently connects experimental observations coming from different fields in molecular biology, x-ray crystallography, physical chemistry, biomechanics, and synthetic and multiomics biology. Our model should be a valuable tool to gain insight into protein synthesis dynamics, translational control, and the role of the ribosome's mechanochemistry in the cotranslational protein folding.
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Affiliation(s)
- Marc Joiret
- Biomechanics Research Unit, GIGA In Silico Medicine, Liège University, CHU-B34(+5) 1 Avenue de l'Hôpital, 4000 Liège, Belgium
| | - Frederic Kerff
- UR InBios, Centre d'Ingénierie des Protéines, Bât B6a, Allée du 6 Août, 19, B-4000 Liège, Belgium
| | - Francesca Rapino
- Cancer Signaling, GIGA Stem Cells, CHU-B34(+2) 1 Avenue de l'Hôpital, B-4000 Liège, Belgium
| | - Pierre Close
- Cancer Signaling, GIGA Stem Cells, CHU-B34(+2) 1 Avenue de l'Hôpital, B-4000 Liège, Belgium
| | - Liesbet Geris
- Biomechanics Research Unit, GIGA In Silico Medicine, Liège University, CHU-B34(+5) 1 Avenue de l'Hôpital, 4000 Liège, Belgium
- Skeletal Biology & Engineering Research Center, KU Leuven, ON I Herestraat 49 - box 813, 3000 Leuven, Belgium
- Biomechanics Section, KU Leuven, Celestijnenlaan 300C box 2419, B-3001 Heverlee, Belgium
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13
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Carbone CE, Loveland AB, Gamper HB, Hou YM, Demo G, Korostelev AA. Time-resolved cryo-EM visualizes ribosomal translocation with EF-G and GTP. Nat Commun 2021; 12:7236. [PMID: 34903725 PMCID: PMC8668904 DOI: 10.1038/s41467-021-27415-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 11/12/2021] [Indexed: 11/18/2022] Open
Abstract
During translation, a conserved GTPase elongation factor-EF-G in bacteria or eEF2 in eukaryotes-translocates tRNA and mRNA through the ribosome. EF-G has been proposed to act as a flexible motor that propels tRNA and mRNA movement, as a rigid pawl that biases unidirectional translocation resulting from ribosome rearrangements, or by various combinations of motor- and pawl-like mechanisms. Using time-resolved cryo-EM, we visualized GTP-catalyzed translocation without inhibitors, capturing elusive structures of ribosome•EF-G intermediates at near-atomic resolution. Prior to translocation, EF-G binds near peptidyl-tRNA, while the rotated 30S subunit stabilizes the EF-G GTPase center. Reverse 30S rotation releases Pi and translocates peptidyl-tRNA and EF-G by ~20 Å. An additional 4-Å translocation initiates EF-G dissociation from a transient ribosome state with highly swiveled 30S head. The structures visualize how nearly rigid EF-G rectifies inherent and spontaneous ribosomal dynamics into tRNA-mRNA translocation, whereas GTP hydrolysis and Pi release drive EF-G dissociation.
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Affiliation(s)
| | - Anna B Loveland
- RNA Therapeutics Institute, UMass Chan Medical School, Worcester, MA, USA
| | - Howard B Gamper
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Ya-Ming Hou
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Gabriel Demo
- RNA Therapeutics Institute, UMass Chan Medical School, Worcester, MA, USA.
- Central European Institute of Technology, Masaryk University, Kamenice 5, Brno, 625 00, Czech Republic.
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14
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Petrychenko V, Peng BZ, de A P Schwarzer AC, Peske F, Rodnina MV, Fischer N. Structural mechanism of GTPase-powered ribosome-tRNA movement. Nat Commun 2021; 12:5933. [PMID: 34635670 PMCID: PMC8505512 DOI: 10.1038/s41467-021-26133-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 09/17/2021] [Indexed: 11/25/2022] Open
Abstract
GTPases are regulators of cell signaling acting as molecular switches. The translational GTPase EF-G stands out, as it uses GTP hydrolysis to generate force and promote the movement of the ribosome along the mRNA. The key unresolved question is how GTP hydrolysis drives molecular movement. Here, we visualize the GTPase-powered step of ongoing translocation by time-resolved cryo-EM. EF-G in the active GDP-Pi form stabilizes the rotated conformation of ribosomal subunits and induces twisting of the sarcin-ricin loop of the 23 S rRNA. Refolding of the GTPase switch regions upon Pi release initiates a large-scale rigid-body rotation of EF-G pivoting around the sarcin-ricin loop that facilitates back rotation of the ribosomal subunits and forward swiveling of the head domain of the small subunit, ultimately driving tRNA forward movement. The findings demonstrate how a GTPase orchestrates spontaneous thermal fluctuations of a large RNA-protein complex into force-generating molecular movement.
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MESH Headings
- Binding Sites
- Biomechanical Phenomena
- Cryoelectron Microscopy
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Guanosine Triphosphate/chemistry
- Guanosine Triphosphate/metabolism
- Hydrolysis
- Kinetics
- Models, Molecular
- Peptide Elongation Factor G/chemistry
- Peptide Elongation Factor G/genetics
- Peptide Elongation Factor G/metabolism
- Protein Binding
- Protein Biosynthesis
- Protein Conformation, alpha-Helical
- Protein Conformation, beta-Strand
- Protein Folding
- Protein Interaction Domains and Motifs
- RNA, Messenger/chemistry
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Ribosomal, 23S/chemistry
- RNA, Ribosomal, 23S/genetics
- RNA, Ribosomal, 23S/metabolism
- RNA, Transfer/chemistry
- RNA, Transfer/genetics
- RNA, Transfer/metabolism
- Ribosomes/metabolism
- Ribosomes/ultrastructure
- Thermodynamics
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Affiliation(s)
- Valentyn Petrychenko
- Department of Structural Dynamics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Bee-Zen Peng
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Ana C de A P Schwarzer
- Department of Structural Dynamics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
| | - Frank Peske
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Marina V Rodnina
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
| | - Niels Fischer
- Department of Structural Dynamics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
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15
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Rieu M, Valle-Orero J, Ducos B, Allemand JF, Croquette V. Single-molecule kinetic locking allows fluorescence-free quantification of protein/nucleic-acid binding. Commun Biol 2021; 4:1083. [PMID: 34526657 PMCID: PMC8443601 DOI: 10.1038/s42003-021-02606-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 08/25/2021] [Indexed: 11/09/2022] Open
Abstract
Fluorescence-free micro-manipulation of nucleic acids (NA) allows the functional characterization of DNA/RNA processing proteins, without the interference of labels, but currently fails to detect and quantify their binding. To overcome this limitation, we developed a method based on single-molecule force spectroscopy, called kinetic locking, that allows a direct in vitro visualization of protein binding while avoiding any kind of chemical disturbance of the protein’s natural function. We validate kinetic locking by measuring accurately the hybridization energy of ultrashort nucleotides (5, 6, 7 bases) and use it to measure the dynamical interactions of Escherichia coli/E. coli RecQ helicase with its DNA substrate. Rieu et al. present a magnetic tweezers based single-molecule manipulation method, called kinetic locking, for direct detection of biomolecular binding without use of fluorescent probes. By measuring dynamical interactions of E. coli RecQ helicase with its DNA substrate, authors show that this method holds promise for studying DNA-DNA and DNA-protein interactions while avoiding the need for labelling.
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Affiliation(s)
- Martin Rieu
- Laboratoire de physique de l'Ecole Normale Supérieure (LPENS), ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, Paris, France. .,Institut de Biologie de l'Ecole Normale Supérieure (IBENS), ENS, Université PSL, CNRS, INSERM, Paris, France.
| | - Jessica Valle-Orero
- Laboratoire de physique de l'Ecole Normale Supérieure (LPENS), ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, Paris, France.,Institut de Biologie de l'Ecole Normale Supérieure (IBENS), ENS, Université PSL, CNRS, INSERM, Paris, France
| | - Bertrand Ducos
- Laboratoire de physique de l'Ecole Normale Supérieure (LPENS), ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, Paris, France.,Institut de Biologie de l'Ecole Normale Supérieure (IBENS), ENS, Université PSL, CNRS, INSERM, Paris, France
| | - Jean-François Allemand
- Laboratoire de physique de l'Ecole Normale Supérieure (LPENS), ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, Paris, France.,Institut de Biologie de l'Ecole Normale Supérieure (IBENS), ENS, Université PSL, CNRS, INSERM, Paris, France
| | - Vincent Croquette
- Laboratoire de physique de l'Ecole Normale Supérieure (LPENS), ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, Paris, France.,Institut de Biologie de l'Ecole Normale Supérieure (IBENS), ENS, Université PSL, CNRS, INSERM, Paris, France.,ESPCI Paris, Université PSL, 10 rue Vauquelin, 75005, Paris, France
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16
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Bao C, Ermolenko DN. Ribosome as a Translocase and Helicase. BIOCHEMISTRY (MOSCOW) 2021; 86:992-1002. [PMID: 34488575 PMCID: PMC8294220 DOI: 10.1134/s0006297921080095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
During protein synthesis, ribosome moves along mRNA to decode one codon after the other. Ribosome translocation is induced by a universally conserved protein, elongation factor G (EF-G) in bacteria and elongation factor 2 (EF-2) in eukaryotes. EF-G-induced translocation results in unwinding of the intramolecular secondary structures of mRNA by three base pairs at a time that renders the translating ribosome a processive helicase. Professor Alexander Sergeevich Spirin has made numerous seminal contributions to understanding the molecular mechanism of translocation. Here, we review Spirin's insights into the ribosomal translocation and recent advances in the field that stemmed from Spirin's pioneering work. We also discuss key remaining challenges in studies of translocase and helicase activities of the ribosome.
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Affiliation(s)
- Chen Bao
- Department of Biochemistry & Biophysics, School of Medicine and Dentistry and Center for RNA Biology, University of Rochester, Rochester, NY, USA.
| | - Dmitri N Ermolenko
- Department of Biochemistry & Biophysics, School of Medicine and Dentistry and Center for RNA Biology, University of Rochester, Rochester, NY, USA.
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17
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Structural dynamics of single SARS-CoV-2 pseudoknot molecules reveal topologically distinct conformers. Nat Commun 2021; 12:4749. [PMID: 34362921 PMCID: PMC8346527 DOI: 10.1038/s41467-021-25085-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 07/21/2021] [Indexed: 11/08/2022] Open
Abstract
The RNA pseudoknot that stimulates programmed ribosomal frameshifting in SARS-CoV-2 is a possible drug target. To understand how it responds to mechanical tension applied by ribosomes, thought to play a key role during frameshifting, we probe its structural dynamics using optical tweezers. We find that it forms multiple structures: two pseudoknotted conformers with different stability and barriers, and alternative stem-loop structures. The pseudoknotted conformers have distinct topologies, one threading the 5′ end through a 3-helix junction to create a knot-like fold, the other with unthreaded 5′ end, consistent with structures observed via cryo-EM and simulations. Refolding of the pseudoknotted conformers starts with stem 1, followed by stem 3 and lastly stem 2; Mg2+ ions are not required, but increase pseudoknot mechanical rigidity and favor formation of the knot-like conformer. These results resolve the SARS-CoV-2 frameshift signal folding mechanism and highlight its conformational heterogeneity, with important implications for structure-based drug-discovery efforts. The RNA pseudoknot of SARS-CoV-2 promotes -1 programmed ribosomal frameshifting. Here the authors use single molecule force spectroscopy to study the folding of this pseudoknot, showing that it forms at least two different pseudoknot conformers with distinct fold topologies.
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18
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Hsu CF, Chang KC, Chen YL, Hsieh PS, Lee AI, Tu JY, Chen YT, Wen JD. Formation of frameshift-stimulating RNA pseudoknots is facilitated by remodeling of their folding intermediates. Nucleic Acids Res 2021; 49:6941-6957. [PMID: 34161580 PMCID: PMC8266650 DOI: 10.1093/nar/gkab512] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 05/27/2021] [Accepted: 06/04/2021] [Indexed: 12/15/2022] Open
Abstract
Programmed –1 ribosomal frameshifting is an essential regulation mechanism of translation in viruses and bacteria. It is stimulated by mRNA structures inside the coding region. As the structure is unfolded repeatedly by consecutive translating ribosomes, whether it can refold properly each time is important in performing its function. By using single-molecule approaches and molecular dynamics simulations, we found that a frameshift-stimulating RNA pseudoknot folds sequentially through its upstream stem S1 and downstream stem S2. In this pathway, S2 folds from the downstream side and tends to be trapped in intermediates. By masking the last few nucleotides to mimic their gradual emergence from translating ribosomes, S2 can be directed to fold from the upstream region. The results show that the intermediates are greatly suppressed, suggesting that mRNA refolding may be modulated by ribosomes. Moreover, masking the first few nucleotides of S1 favors the folding from S2 and yields native pseudoknots, which are stable enough to retrieve the masked nucleotides. We hypothesize that translating ribosomes can remodel an intermediate mRNA structure into a stable conformation, which may in turn stimulate backward slippage of the ribosome. This supports an interactive model of ribosomal frameshifting and gives an insightful account addressing previous experimental observations.
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Affiliation(s)
- Chiung-Fang Hsu
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei 10617, Taiwan
| | - Kai-Chun Chang
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei 10617, Taiwan
| | - Yi-Lan Chen
- Genome and Systems Biology Degree Program, National Taiwan University and Academia Sinica, Taipei 10617, Taiwan
| | - Po-Szu Hsieh
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei 10617, Taiwan
| | - An-I Lee
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei 10617, Taiwan
| | - Jui-Yun Tu
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei 10617, Taiwan
| | - Yu-Ting Chen
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei 10617, Taiwan
| | - Jin-Der Wen
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei 10617, Taiwan.,Genome and Systems Biology Degree Program, National Taiwan University and Academia Sinica, Taipei 10617, Taiwan
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19
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Mechanical strength of RNA knot in Zika virus protects against cellular defenses. Nat Chem Biol 2021; 17:975-981. [PMID: 34253909 DOI: 10.1038/s41589-021-00829-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 06/03/2021] [Indexed: 12/21/2022]
Abstract
Unusual knot-like structures recently discovered in viral exoribonuclease-resistant RNAs (xrRNAs) prevent digestion by host RNases to create subgenomic RNAs enhancing infection and pathogenicity. xrRNAs are proposed to prevent digestion through mechanical resistance to unfolding. However, their unfolding force has not been measured, and the factors determining RNase resistance are unclear. Furthermore, how these knots fold remains unknown. Unfolding a Zika virus xrRNA with optical tweezers revealed that it was the most mechanically stable RNA yet observed. The knot formed by threading the 5' end into a three-helix junction before pseudoknot interactions closed a ring around it. The pseudoknot and tertiary contacts stabilizing the threaded 5' end were both required to generate extreme force resistance, whereas removing a 5'-end contact produced a low-force knot lacking RNase resistance. These results indicate mechanical resistance plays a central functional role, with the fraction of molecules forming extremely high-force knots determining the RNase resistance level.
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20
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Chang KC, Wen JD. Programmed -1 ribosomal frameshifting from the perspective of the conformational dynamics of mRNA and ribosomes. Comput Struct Biotechnol J 2021; 19:3580-3588. [PMID: 34257837 PMCID: PMC8246090 DOI: 10.1016/j.csbj.2021.06.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 06/11/2021] [Accepted: 06/12/2021] [Indexed: 11/01/2022] Open
Abstract
Programmed -1 ribosomal frameshifting (-1 PRF) is a translation mechanism that regulates the relative expression level of two proteins encoded on the same messenger RNA (mRNA). This regulation is commonly used by viruses such as coronaviruses and retroviruses but rarely by host human cells, and for this reason, it has long been considered as a therapeutic target for antiviral drug development. Understanding the molecular mechanism of -1 PRF is one step toward this goal. Minus-one PRF occurs with a certain efficiency when translating ribosomes encounter the specialized mRNA signal consisting of the frameshifting site and a downstream stimulatory structure, which impedes translocation of the ribosome. The impeded ribosome can still undergo profound conformational changes to proceed with translocation; however, some of these changes may be unique and essential to frameshifting. In addition, most stimulatory structures exhibit conformational dynamics and sufficient mechanical strength, which, when under the action of ribosomes, may in turn further promote -1 PRF efficiency. In this review, we discuss how the dynamic features of ribosomes and mRNA stimulatory structures may influence the occurrence of -1 PRF and propose a hypothetical frameshifting model that recapitulates the role of conformational dynamics.
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Affiliation(s)
- Kai-Chun Chang
- Department of Bioengineering and Therapeutic Sciences, Schools of Medicine and Pharmacy, University of California, San Francisco, CA 94158, United States
| | - Jin-Der Wen
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei 10617, Taiwan
- Genome and Systems Biology Degree Program, National Taiwan University and Academia Sinica, Taipei 10617, Taiwan
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21
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Richter JD, Zhao X. The molecular biology of FMRP: new insights into fragile X syndrome. Nat Rev Neurosci 2021; 22:209-222. [PMID: 33608673 PMCID: PMC8094212 DOI: 10.1038/s41583-021-00432-0] [Citation(s) in RCA: 136] [Impact Index Per Article: 45.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2021] [Indexed: 01/31/2023]
Abstract
Fragile X mental retardation protein (FMRP) is the product of the fragile X mental retardation 1 gene (FMR1), a gene that - when epigenetically inactivated by a triplet nucleotide repeat expansion - causes the neurodevelopmental disorder fragile X syndrome (FXS). FMRP is a widely expressed RNA-binding protein with activity that is essential for proper synaptic plasticity and architecture, aspects of neural function that are known to go awry in FXS. Although the neurophysiology of FXS has been described in remarkable detail, research focusing on the molecular biology of FMRP has only scratched the surface. For more than two decades, FMRP has been well established as a translational repressor; however, recent whole transcriptome and translatome analyses in mouse and human models of FXS have shown that FMRP is involved in the regulation of nearly all aspects of gene expression. The emerging mechanistic details of the mechanisms by which FMRP regulates gene expression may offer ways to design new therapies for FXS.
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Affiliation(s)
- Joel D Richter
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, USA.
| | - Xinyu Zhao
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA. .,Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA.
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22
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Bustamante CJ, Chemla YR, Liu S, Wang MD. Optical tweezers in single-molecule biophysics. NATURE REVIEWS. METHODS PRIMERS 2021; 1:25. [PMID: 34849486 PMCID: PMC8629167 DOI: 10.1038/s43586-021-00021-6] [Citation(s) in RCA: 112] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/12/2021] [Indexed: 12/15/2022]
Abstract
Optical tweezers have become the method of choice in single-molecule manipulation studies. In this Primer, we first review the physical principles of optical tweezers and the characteristics that make them a powerful tool to investigate single molecules. We then introduce the modifications of the method to extend the measurement of forces and displacements to torques and angles, and to develop optical tweezers with single-molecule fluorescence detection capabilities. We discuss force and torque calibration of these instruments, their various modes of operation and most common experimental geometries. We describe the type of data obtained in each experimental design and their analyses. This description is followed by a survey of applications of these methods to the studies of protein-nucleic acid interactions, protein/RNA folding and molecular motors. We also discuss data reproducibility, the factors that lead to the data variability among different laboratories and the need to develop field standards. We cover the current limitations of the methods and possible ways to optimize instrument operation, data extraction and analysis, before suggesting likely areas of future growth.
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Affiliation(s)
- Carlos J. Bustamante
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, CA, USA
- Department of Chemistry, University of California, Berkeley, CA, USA
- Kavli Energy NanoScience Institute, University of California, Berkeley, CA, USA
- Howard Hughes Medical Institute, University of California, Berkeley, CA, USA
| | - Yann R. Chemla
- Department of Physics, Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Shixin Liu
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, NY, USA
| | - Michelle D. Wang
- Department of Physics, Laboratory of Atomic and Solid State Physics, Howard Hughes Medical Institute, Cornell University, Ithaca, NY, USA
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23
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Dutta A, Schütz GM, Chowdhury D. Stochastic thermodynamics and modes of operation of a ribosome: A network theoretic perspective. Phys Rev E 2021; 101:032402. [PMID: 32289926 DOI: 10.1103/physreve.101.032402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 02/14/2020] [Indexed: 12/29/2022]
Abstract
The ribosome is one of the largest and most complex macromolecular machines in living cells. It polymerizes a protein in a step-by-step manner as directed by the corresponding nucleotide sequence on the template messenger RNA (mRNA) and this process is referred to as "translation" of the genetic message encoded in the sequence of mRNA transcript. In each successful chemomechanical cycle during the (protein) elongation stage, the ribosome elongates the protein by a single subunit, called amino acid, and steps forward on the template mRNA by three nucleotides called a codon. Therefore, a ribosome is also regarded as a molecular motor for which the mRNA serves as the track, its step size is that of a codon and two molecules of GTP and one molecule of ATP hydrolyzed in that cycle serve as its fuel. What adds further complexity is the existence of competing pathways leading to distinct cycles, branched pathways in each cycle, and futile consumption of fuel that leads neither to elongation of the nascent protein nor forward stepping of the ribosome on its track. We investigate a model formulated in terms of the network of discrete chemomechanical states of a ribosome during the elongation stage of translation. The model is analyzed using a combination of stochastic thermodynamic and kinetic analysis based on a graph-theoretic approach. We derive the exact solution of the corresponding master equations. We represent the steady state in terms of the cycles of the underlying network and discuss the energy transduction processes. We identify the various possible modes of operation of a ribosome in terms of its average velocity and mean rate of GTP hydrolysis. We also compute entropy production as functions of the rates of the interstate transitions and the thermodynamic cost for accuracy of the translation process.
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Affiliation(s)
- Annwesha Dutta
- Department of Physics, Indian Institute of Technology, Kanpur 208016, India
| | - Gunter M Schütz
- Institute of Complex Systems II, Forschungszentrum Jülich, 52425 Jülich, Germany
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24
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Halma MTJ, Ritchie DB, Woodside MT. Conformational Shannon Entropy of mRNA Structures from Force Spectroscopy Measurements Predicts the Efficiency of -1 Programmed Ribosomal Frameshift Stimulation. PHYSICAL REVIEW LETTERS 2021; 126:038102. [PMID: 33543960 DOI: 10.1103/physrevlett.126.038102] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Accepted: 12/15/2020] [Indexed: 06/12/2023]
Abstract
-1 programmed ribosomal frameshifting (-1 PRF) is stimulated by structures in messenger RNA (mRNA), but the factors determining -1 PRF efficiency are unclear. We show that -1 PRF efficiency varies directly with the conformational heterogeneity of the stimulatory structure, quantified as the Shannon entropy of the state occupancy, for a panel of stimulatory structures with efficiencies from 2% to 80%. The correlation is force dependent and vanishes at forces above those applied by the ribosome. These results support the hypothesis that heterogeneous conformational dynamics are a key factor in stimulating -1 PRF.
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Affiliation(s)
- Matthew T J Halma
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - Dustin B Ritchie
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - Michael T Woodside
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
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25
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Rodnina MV, Peske F, Peng BZ, Belardinelli R, Wintermeyer W. Converting GTP hydrolysis into motion: versatile translational elongation factor G. Biol Chem 2020; 401:131-142. [PMID: 31600135 DOI: 10.1515/hsz-2019-0313] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 08/24/2019] [Indexed: 12/16/2022]
Abstract
Elongation factor G (EF-G) is a translational GTPase that acts at several stages of protein synthesis. Its canonical function is to catalyze tRNA movement during translation elongation, but it also acts at the last step of translation to promote ribosome recycling. Moreover, EF-G has additional functions, such as helping the ribosome to maintain the mRNA reading frame or to slide over non-coding stretches of the mRNA. EF-G has an unconventional GTPase cycle that couples the energy of GTP hydrolysis to movement. EF-G facilitates movement in the GDP-Pi form. To convert the energy of hydrolysis to movement, it requires various ligands in the A site, such as a tRNA in translocation, an mRNA secondary structure element in ribosome sliding, or ribosome recycling factor in post-termination complex disassembly. The ligand defines the direction and timing of EF-G-facilitated motion. In this review, we summarize recent advances in understanding the mechanism of EF-G action as a remarkable force-generating GTPase.
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Affiliation(s)
- Marina V Rodnina
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Frank Peske
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Bee-Zen Peng
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Riccardo Belardinelli
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Wolfgang Wintermeyer
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
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26
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Sharma S, Subramani S, Popa I. Does protein unfolding play a functional role in vivo? FEBS J 2020; 288:1742-1758. [PMID: 32761965 DOI: 10.1111/febs.15508] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/09/2020] [Accepted: 08/03/2020] [Indexed: 12/21/2022]
Abstract
Unfolding and refolding of multidomain proteins under force have yet to be recognized as a major mechanism of function for proteins in vivo. In this review, we discuss the inherent properties of multidomain proteins under a force vector from a structural and functional perspective. We then characterize three main systems where multidomain proteins could play major roles through mechanical unfolding: muscular contraction, cellular mechanotransduction, and bacterial adhesion. We analyze how key multidomain proteins for each system can produce a gain-of-function from the perspective of a fine-tuned quantized response, a molecular battery, delivery of mechanical work through refolding, elasticity tuning, protection and exposure of cryptic sites, and binding-induced mechanical changes. Understanding how mechanical unfolding and refolding affect function will have important implications in designing mechano-active drugs against conditions such as muscular dystrophy, cancer, or novel antibiotics.
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Affiliation(s)
- Sabita Sharma
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Smrithika Subramani
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Ionel Popa
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
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27
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Simpson LJ, Tzima E, Reader JS. Mechanical Forces and Their Effect on the Ribosome and Protein Translation Machinery. Cells 2020; 9:cells9030650. [PMID: 32156009 PMCID: PMC7140433 DOI: 10.3390/cells9030650] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 03/03/2020] [Accepted: 03/04/2020] [Indexed: 12/12/2022] Open
Abstract
Mechanical forces acting on biological systems, at both the macroscopic and microscopic levels, play an important part in shaping cellular phenotypes. There is a growing realization that biomolecules that respond to force directly applied to them, or via mechano-sensitive signalling pathways, can produce profound changes to not only transcriptional pathways, but also in protein translation. Forces naturally occurring at the molecular level can impact the rate at which the bacterial ribosome translates messenger RNA (mRNA) transcripts and influence processes such as co-translational folding of a nascent protein as it exits the ribosome. In eukaryotes, force can also be transduced at the cellular level by the cytoskeleton, the cell’s internal filamentous network. The cytoskeleton closely associates with components of the translational machinery such as ribosomes and elongation factors and, as such, is a crucial determinant of localized protein translation. In this review we will give (1) a brief overview of protein translation in bacteria and eukaryotes and then discuss (2) how mechanical forces are directly involved with ribosomes during active protein synthesis and (3) how eukaryotic ribosomes and other protein translation machinery intimately associates with the mechanosensitive cytoskeleton network.
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28
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Choi J, O’Loughlin S, Atkins JF, Puglisi JD. The energy landscape of -1 ribosomal frameshifting. SCIENCE ADVANCES 2020; 6:eaax6969. [PMID: 31911945 PMCID: PMC6938710 DOI: 10.1126/sciadv.aax6969] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 11/04/2019] [Indexed: 05/02/2023]
Abstract
Maintenance of translational reading frame ensures the fidelity of information transfer during protein synthesis. Yet, programmed ribosomal frameshifting sequences within the coding region promote a high rate of reading frame change at predetermined sites thus enriching genomic information density. Frameshifting is typically stimulated by the presence of 3' messenger RNA (mRNA) structures, but how these mRNA structures enhance -1 frameshifting remains debatable. Here, we apply single-molecule and ensemble approaches to formulate a mechanistic model of ribosomal -1 frameshifting. Our model suggests that the ribosome is intrinsically susceptible to frameshift before its translocation and this transient state is prolonged by the presence of a precisely positioned downstream mRNA structure. We challenged this model using temperature variation in vivo, which followed the prediction made based on in vitro results. Our results provide a quantitative framework for analyzing other frameshifting enhancers and a potential approach to control gene expression dynamically using programmed frameshifting.
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Affiliation(s)
- Junhong Choi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305-5126, USA
- Department of Applied Physics, Stanford University, Stanford, CA 94305-4090, USA
| | - Sinéad O’Loughlin
- Schools of Biochemistry and Microbiology, University College Cork, Western Gateway Building, Western Road, Cork, Ireland
| | - John F. Atkins
- Schools of Biochemistry and Microbiology, University College Cork, Western Gateway Building, Western Road, Cork, Ireland
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112-5330, USA
| | - Joseph D. Puglisi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305-5126, USA
- Corresponding author.
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29
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Yin H, Gavriliuc M, Lin R, Xu S, Wang Y. Modulation and Visualization of EF-G Power Stroke During Ribosomal Translocation. Chembiochem 2019; 20:2927-2935. [PMID: 31194278 PMCID: PMC6888950 DOI: 10.1002/cbic.201900276] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Indexed: 11/30/2022]
Abstract
During ribosome translocation, the elongation factor EF‐G undergoes large conformational change while maintaining its contact with the moving tRNA. We previously measured a power stroke accompanying EF‐G catalysis, which was consistent with structural studies. However, the role of power stroke in translocation fidelity remains unclear. Here, we report quantitative measurements of the power strokes of structurally modified EF‐Gs by using two different techniques and reveal the correlation between power stroke and translocation efficiency and fidelity. We discovered that the reduced power stroke only lowered the percentage of translocation but did not introduce translocation error. The established force ‐structure–function correlation for EF‐G indicates that power stroke drives ribosomal translocation, but the mRNA reading frame is probably maintained by ribosome itself. Furthermore, the microscope detection method reported here can be simply implemented for other biochemical applications.
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Affiliation(s)
- Heng Yin
- Department of Chemistry, University of Houston, Houston, TX, 77204, USA
| | - Miriam Gavriliuc
- Department of Biology and Biochemistry, University of Houston, Houston, TX, 77204, USA
| | - Ran Lin
- Department of Biology and Biochemistry, University of Houston, Houston, TX, 77204, USA
| | - Shoujun Xu
- Department of Chemistry, University of Houston, Houston, TX, 77204, USA
| | - Yuhong Wang
- Department of Biology and Biochemistry, University of Houston, Houston, TX, 77204, USA
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30
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Desai VP, Frank F, Lee A, Righini M, Lancaster L, Noller HF, Tinoco I, Bustamante C. Co-temporal Force and Fluorescence Measurements Reveal a Ribosomal Gear Shift Mechanism of Translation Regulation by Structured mRNAs. Mol Cell 2019; 75:1007-1019.e5. [PMID: 31471187 DOI: 10.1016/j.molcel.2019.07.024] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 06/12/2019] [Accepted: 07/15/2019] [Indexed: 11/18/2022]
Abstract
The movement of ribosomes on mRNA is often interrupted by secondary structures that present mechanical barriers and play a central role in translation regulation. We investigate how ribosomes couple their internal conformational changes with the activity of translocation factor EF-G to unwind mRNA secondary structures using high-resolution optical tweezers with single-molecule fluorescence capability. We find that hairpin opening occurs during EF-G-catalyzed translocation and is driven by the forward rotation of the small subunit head. Modulating the magnitude of the hairpin barrier by force shows that ribosomes respond to strong barriers by shifting their operation to an alternative 7-fold-slower kinetic pathway prior to translocation. Shifting into a slow gear results from an allosteric switch in the ribosome that may allow it to exploit thermal fluctuations to overcome mechanical barriers. Finally, we observe that ribosomes occasionally open the hairpin in two successive sub-codon steps, revealing a previously unobserved translocation intermediate.
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Affiliation(s)
- Varsha P Desai
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA; Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Filipp Frank
- Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Antony Lee
- Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Physics, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Maurizio Righini
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA; Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, QB3, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Laura Lancaster
- Department of Molecular, Cell, and Developmental Biology and Center for Molecular Biology of RNA, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Harry F Noller
- Department of Molecular, Cell, and Developmental Biology and Center for Molecular Biology of RNA, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Ignacio Tinoco
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Carlos Bustamante
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA; Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Physics, University of California, Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, QB3, University of California, Berkeley, Berkeley, CA 94720, USA; Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Kavli Energy Nanoscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA.
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31
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Wu B, Zhang H, Sun R, Peng S, Cooperman BS, Goldman YE, Chen C. Translocation kinetics and structural dynamics of ribosomes are modulated by the conformational plasticity of downstream pseudoknots. Nucleic Acids Res 2019; 46:9736-9748. [PMID: 30011005 PMCID: PMC6182138 DOI: 10.1093/nar/gky636] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 07/03/2018] [Indexed: 11/21/2022] Open
Abstract
Downstream stable mRNA secondary structures can stall elongating ribosomes by impeding the concerted movements of tRNAs and mRNA on the ribosome during translocation. The addition of a downstream mRNA structure, such as a stem-loop or a pseudoknot, is essential to induce -1 programmed ribosomal frameshifting (-1 PRF). Interestingly, previous studies revealed that -1 PRF efficiencies correlate with conformational plasticity of pseudoknots, defined as their propensity to form incompletely folded structures, rather than with the mechanical properties of pseudoknots. To elucidate the detailed molecular mechanisms of translocation and -1 PRF, we applied several smFRET assays to systematically examine how translocation rates and conformational dynamics of ribosomes were affected by different pseudoknots. Our results show that initial pseudoknot-unwinding significantly inhibits late-stage translocation and modulates conformational dynamics of ribosomal post-translocation complexes. The effects of pseudoknots on the structural dynamics of ribosomes strongly correlate with their abilities to induce -1 PRF. Our results lead us to propose a kinetic scheme for translocation which includes an initial power-stroke step and a following thermal-ratcheting step. This scheme provides mechanistic insights on how selective modulation of late-stage translocation by pseudoknots affects -1 PRF. Overall our findings advance current understanding of translocation and ribosome-induced mRNA structure unwinding.
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Affiliation(s)
- Bo Wu
- School of Life Sciences; Tsinghua-Peking Joint Center for Life Sciences; Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China
| | - Haibo Zhang
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA.,Spark Therapeutics, 3737 Market Street, Philadelphia, PA, 19104, USA
| | - Ruirui Sun
- School of Life Sciences; Tsinghua-Peking Joint Center for Life Sciences; Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China
| | - Sijia Peng
- School of Life Sciences; Tsinghua-Peking Joint Center for Life Sciences; Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China
| | - Barry S Cooperman
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Yale E Goldman
- Pennsylvania Muscle Institute, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Chunlai Chen
- School of Life Sciences; Tsinghua-Peking Joint Center for Life Sciences; Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China
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32
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Tomko EJ, Galburt EA. Single-molecule approach for studying RNAP II transcription initiation using magnetic tweezers. Methods 2019; 159-160:35-44. [PMID: 30898685 DOI: 10.1016/j.ymeth.2019.03.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 03/12/2019] [Accepted: 03/14/2019] [Indexed: 11/19/2022] Open
Abstract
The initiation of transcription underlies the ability of cells to modulate genome expression as a function of both internal and external signals and the core process of initiation has features that are shared across all domains of life. Specifically, initiation can be sub-divided into promoter recognition, promoter opening, and promoter escape. However, the molecular players and mechanisms used are significantly different in Eukaryotes and Bacteria. In particular, bacterial initiation requires only the formation of RNA polymerase (RNAP) holoenzyme and proceeds as a series of spontaneous conformational changes while eukaryotic initiation requires the formation of the 31-subunit pre-initiation complex (PIC) and often requires ATP hydrolysis by the Ssl2/XPB subunit of the general transcription factor TFIIH. Our mechanistic view of this process in Eukaryotes has recently been improved through a combination of structural and single-molecule approaches which are providing a detailed picture of the structural dynamics that lead to the production of an elongation competent RNAP II and thus, an RNA transcript. Here we provide the methodological details of our single-molecule magnetic tweezers studies of transcription initiation using purified factors from Saccharomyces cerevisiae.
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Affiliation(s)
- Eric J Tomko
- Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO 63110, United States
| | - Eric A Galburt
- Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO 63110, United States.
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33
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Opron K, Burton ZF. Ribosome Structure, Function, and Early Evolution. Int J Mol Sci 2018; 20:ijms20010040. [PMID: 30583477 PMCID: PMC6337491 DOI: 10.3390/ijms20010040] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 12/03/2018] [Accepted: 12/16/2018] [Indexed: 11/16/2022] Open
Abstract
Ribosomes are among the largest and most dynamic molecular motors. The structure and dynamics of translation initiation and elongation are reviewed. Three ribosome motions have been identified for initiation and translocation. A swivel motion between the head/beak and the body of the 30S subunit was observed. A tilting dynamic of the head/beak versus the body of the 30S subunit was detected using simulations. A reversible ratcheting motion was seen between the 30S and the 50S subunits that slide relative to one another. The 30S⁻50S intersubunit contacts regulate translocation. IF2, EF-Tu, and EF-G are homologous G-protein GTPases that cycle on and off the same site on the ribosome. The ribosome, aminoacyl-tRNA synthetase (aaRS) enzymes, transfer ribonucleic acid (tRNA), and messenger ribonucleic acid (mRNA) form the core of information processing in cells and are coevolved. Surprisingly, class I and class II aaRS enzymes, with distinct and incompatible folds, are homologs. Divergence of class I and class II aaRS enzymes and coevolution of the genetic code are described by analysis of ancient archaeal species.
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Affiliation(s)
- Kristopher Opron
- Bioinformatics Core, University of Michigan, Ann Arbor, MI 48109-0674, USA.
| | - Zachary F Burton
- Department of Biochemistry and Molecular Biology, 603 Wilson Rd., Michigan State University, MI 48824-1319, USA.
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34
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Yang L, Zhong Z, Tong C, Jia H, Liu Y, Chen G. Single-Molecule Mechanical Folding and Unfolding of RNA Hairpins: Effects of Single A-U to A·C Pair Substitutions and Single Proton Binding and Implications for mRNA Structure-Induced -1 Ribosomal Frameshifting. J Am Chem Soc 2018; 140:8172-8184. [PMID: 29884019 DOI: 10.1021/jacs.8b02970] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A wobble A·C pair can be protonated at near physiological pH to form a more stable wobble A+·C pair. Here, we constructed an RNA hairpin (rHP) and three mutants with one A-U base pair substituted with an A·C mismatch on the top (near the loop, U22C), middle (U25C), and bottom (U29C) positions of the stem, respectively. Our results on single-molecule mechanical (un)folding using optical tweezers reveal the destabilization effect of A-U to A·C pair substitution and protonation-dependent enhancement of mechanical stability facilitated through an increased folding rate, or decreased unfolding rate, or both. Our data show that protonation may occur rapidly upon the formation of an apparent mechanical folding transition state. Furthermore, we measured the bulk -1 ribosomal frameshifting efficiencies of the hairpins by a cell-free translation assay. For the mRNA hairpins studied, -1 frameshifting efficiency correlates with mechanical unfolding force at equilibrium and folding rate at around 15 pN. U29C has a frameshifting efficiency similar to that of rHP (∼2%). Accordingly, the bottom 2-4 base pairs of U29C may not form under a stretching force at pH 7.3, which is consistent with the fact that the bottom base pairs of the hairpins may be disrupted by ribosome at the slippery site. U22C and U25C have a similar frameshifting efficiency (∼1%), indicating that both unfolding and folding rates of an mRNA hairpin in a crowded environment may affect frameshifting. Our data indicate that mechanical (un)folding of RNA hairpins may mimic how mRNAs unfold and fold in the presence of translating ribosomes.
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Affiliation(s)
- Lixia Yang
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Zhensheng Zhong
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371.,School of Physics, and State Key Laboratory of Optoelectronic Materials and Technologies , Sun Yat-sen University , Guangzhou 510275 , People's Republic of China
| | - Cailing Tong
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Huan Jia
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Yiran Liu
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
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35
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Jia H, Wang Y, Xu S. Super-resolution force spectroscopy reveals ribosomal motion at sub-nucleotide steps. Chem Commun (Camb) 2018; 54:5883-5886. [PMID: 29785422 DOI: 10.1039/c8cc02658k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Probing biomolecular motion beyond a single nucleotide is technically challenging but fundamentally significant. We have developed super-resolution force spectroscopy (SURFS) with 0.5 pN force resolution and revealed that the ribosome moves by half a nucleotide upon the formation of the pre-translocation complex, which is beyond the resolution of other techniques.
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Affiliation(s)
- Haina Jia
- Department of Chemistry, University of Houston, Houston, TX 77204, USA.
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36
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Choi J, Grosely R, Prabhakar A, Lapointe CP, Wang J, Puglisi JD. How Messenger RNA and Nascent Chain Sequences Regulate Translation Elongation. Annu Rev Biochem 2018; 87:421-449. [PMID: 29925264 PMCID: PMC6594189 DOI: 10.1146/annurev-biochem-060815-014818] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Translation elongation is a highly coordinated, multistep, multifactor process that ensures accurate and efficient addition of amino acids to a growing nascent-peptide chain encoded in the sequence of translated messenger RNA (mRNA). Although translation elongation is heavily regulated by external factors, there is clear evidence that mRNA and nascent-peptide sequences control elongation dynamics, determining both the sequence and structure of synthesized proteins. Advances in methods have driven experiments that revealed the basic mechanisms of elongation as well as the mechanisms of regulation by mRNA and nascent-peptide sequences. In this review, we highlight how mRNA and nascent-peptide elements manipulate the translation machinery to alter the dynamics and pathway of elongation.
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Affiliation(s)
- Junhong Choi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305-5126, USA; , , , , ,
- Department of Applied Physics, Stanford University, Stanford, California 94305-4090, USA
| | - Rosslyn Grosely
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305-5126, USA; , , , , ,
| | - Arjun Prabhakar
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305-5126, USA; , , , , ,
- Program in Biophysics, Stanford University, Stanford, California 94305, USA
| | - Christopher P Lapointe
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305-5126, USA; , , , , ,
| | - Jinfan Wang
- Department of Structural Biology, 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; , , , , ,
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37
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Lai WJC, Ermolenko DN. Ensemble and single-molecule FRET studies of protein synthesis. Methods 2017; 137:37-48. [PMID: 29247758 DOI: 10.1016/j.ymeth.2017.12.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 11/30/2017] [Accepted: 12/11/2017] [Indexed: 11/29/2022] Open
Abstract
Protein synthesis is a complex, multi-step process that involves large conformational changes of the ribosome and protein factors of translation. Over the last decade, Förster resonance energy transfer (FRET) has become instrumental for studying structural rearrangements of the translational apparatus. Here, we discuss the design of ensemble and single-molecule (sm) FRET assays of translation. We describe a number of experimental strategies that can be used to introduce fluorophores into the ribosome, tRNA, mRNA and protein factors of translation. Alternative approaches to tethering of translation components to the microscope slide in smFRET experiments are also reviewed. Finally, we discuss possible challenges in the interpretation of FRET data and ways to address these challenges.
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Affiliation(s)
- Wan-Jung C Lai
- Department of Biochemistry and Biophysics & Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, United States
| | - Dmitri N Ermolenko
- Department of Biochemistry and Biophysics & Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, United States.
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38
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Furuta K, Furuta A. Re-engineering of protein motors to understand mechanisms biasing random motion and generating collective dynamics. Curr Opin Biotechnol 2017; 51:39-46. [PMID: 29179022 DOI: 10.1016/j.copbio.2017.11.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2017] [Revised: 11/12/2017] [Accepted: 11/14/2017] [Indexed: 11/25/2022]
Abstract
A considerable amount of insight into the mechanisms of protein-based biomolecular motors has been accumulated over decades of research. However, our knowledge about the design principles of these motors is still limited. Even less is known about the design of multi-motor systems that perform various functions within the cell. Here we focus on constructive (or synthetic) approaches to biomolecular motors that could make a breakthrough in our understanding. Recent achievements include studies at different hierarchical levels of complexity: re-engineering of individual motors, construction of multi-motor systems, and generation of large-scale complex behaviour. We then propose a strategy where the collective behaviour can be repeatedly tested upon modifying individual motors, which may provide important clues about how biomolecular motors and their systems are designed.
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Affiliation(s)
- Ken'ya Furuta
- Advanced ICT Research Institute, National Institute of Information and Communications Technology, Kobe, Hyogo 651-2492, Japan.
| | - Akane Furuta
- Advanced ICT Research Institute, National Institute of Information and Communications Technology, Kobe, Hyogo 651-2492, Japan
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39
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Ribosome structural dynamics in translocation: yet another functional role for ribosomal RNA. Q Rev Biophys 2017; 50:e12. [DOI: 10.1017/s0033583517000117] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractRibosomes are remarkable ribonucleoprotein complexes that are responsible for protein synthesis in all forms of life. They polymerize polypeptide chains programmed by nucleotide sequences in messenger RNA in a mechanism mediated by transfer RNA. One of the most challenging problems in the ribosome field is to understand the mechanism of coupled translocation of mRNA and tRNA during the elongation phase of protein synthesis. In recent years, the results of structural, biophysical and biochemical studies have provided extensive evidence that translocation is based on the structural dynamics of the ribosome itself. Detailed structural analysis has shown that ribosome dynamics, like aminoacyl-tRNA selection and catalysis of peptide bond formation, is made possible by the properties of ribosomal RNA.
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40
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Prabhakar A, Choi J, Wang J, Petrov A, Puglisi JD. Dynamic basis of fidelity and speed in translation: Coordinated multistep mechanisms of elongation and termination. Protein Sci 2017; 26:1352-1362. [PMID: 28480640 DOI: 10.1002/pro.3190] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 05/03/2017] [Indexed: 12/11/2022]
Abstract
As the universal machine that transfers genetic information from RNA to protein, the ribosome synthesizes proteins with remarkably high fidelity and speed. This is a result of the accurate and efficient decoding of mRNA codons via multistep mechanisms during elongation and termination stages of translation. These mechanisms control how the correct sense codon is recognized by a tRNA for peptide elongation, how the next codon is presented to the decoding center without change of frame during translocation, and how the stop codon is discriminated for timely release of the nascent peptide. These processes occur efficiently through coupling of chemical energy expenditure, ligand interactions, and conformational changes. Understanding this coupling in detail required integration of many techniques that were developed in the past two decades. This multidisciplinary approach has revealed the dynamic nature of translational control and uncovered how external cellular factors such as tRNA abundance and mRNA modifications affect the synthesis of the protein product. Insights from these studies will aid synthetic biology and therapeutic approaches to translation.
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Affiliation(s)
- Arjun Prabhakar
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California, 94305.,Program in Biophysics, Stanford University, Stanford, California, 94305
| | - Junhong Choi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California, 94305.,Department of Applied Physics, Stanford University, Stanford, California, 94305
| | - Jinfan Wang
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California, 94305
| | - Alexey Petrov
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California, 94305
| | - Joseph D Puglisi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California, 94305
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41
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Recurring RNA structural motifs underlie the mechanics of L1 stalk movement. Nat Commun 2017; 8:14285. [PMID: 28176782 PMCID: PMC5309774 DOI: 10.1038/ncomms14285] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 12/15/2016] [Indexed: 01/19/2023] Open
Abstract
The L1 stalk of the large ribosomal subunit undergoes large-scale movements coupled to the translocation of deacylated tRNA during protein synthesis. We use quantitative comparative structural analysis to localize the origins of L1 stalk movement and to understand its dynamic interactions with tRNA and other structural elements of the ribosome. Besides its stacking interactions with the tRNA elbow, stalk movement is directly linked to intersubunit rotation, rotation of the 30S head domain and contact of the acceptor arm of deacylated tRNA with helix 68 of 23S rRNA. Movement originates from pivoting at stacked non-canonical base pairs in a Family A three-way junction and bending in an internal G-U-rich zone. Use of these same motifs as hinge points to enable such dynamic events as rotation of the 30S subunit head domain and in flexing of the anticodon arm of tRNA suggests that they represent general strategies for movement of functional RNAs. Translocation of the tRNA on the ribosome is associated with large-scale molecular movements of the ribosomal L1 stalk. Here the authors identify the key determinants that allow these dramatic movements, and suggest they represent general strategies used to enable large-scale motions in functional RNAs.
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42
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Zhong Z, Yang L, Zhang H, Shi J, Vandana JJ, Lam DTUH, Olsthoorn RCL, Lu L, Chen G. Mechanical unfolding kinetics of the SRV-1 gag-pro mRNA pseudoknot: possible implications for -1 ribosomal frameshifting stimulation. Sci Rep 2016; 6:39549. [PMID: 28000744 PMCID: PMC5175198 DOI: 10.1038/srep39549] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 11/24/2016] [Indexed: 12/19/2022] Open
Abstract
Minus-one ribosomal frameshifting is a translational recoding mechanism widely utilized by many RNA viruses to generate accurate ratios of structural and catalytic proteins. An RNA pseudoknot structure located in the overlapping region of the gag and pro genes of Simian Retrovirus type 1 (SRV-1) stimulates frameshifting. However, the experimental characterization of SRV-1 pseudoknot (un)folding dynamics and the effect of the base triple formation is lacking. Here, we report the results of our single-molecule nanomanipulation using optical tweezers and theoretical simulation by steered molecular dynamics. Our results directly reveal that the energetic coupling between loop 2 and stem 1 via minor-groove base triple formation enhances the mechanical stability. The terminal base pair in stem 1 (directly in contact with a translating ribosome at the slippery site) also affects the mechanical stability of the pseudoknot. The -1 frameshifting efficiency is positively correlated with the cooperative one-step unfolding force and inversely correlated with the one-step mechanical unfolding rate at zero force. A significantly improved correlation was observed between -1 frameshifting efficiency and unfolding rate at forces of 15-35 pN, consistent with the fact that the ribosome is a force-generating molecular motor with helicase activity. No correlation was observed between thermal stability and -1 frameshifting efficiency.
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Affiliation(s)
- Zhensheng Zhong
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore
| | - Lixia Yang
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore
| | - Haiping Zhang
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551 Singapore
| | - Jiahao Shi
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore
| | - J. Jeya Vandana
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore
| | - Do Thuy Uyen Ha Lam
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore
- St Andrew’s Junior College, 5 Sorby Adams Drive, 357691 Singapore
| | - René C. L. Olsthoorn
- Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
| | - Lanyuan Lu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551 Singapore
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore
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43
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Shakiba B, Dayeri M, Mohammad-Rafiee F. Modeling of ribosome dynamics on a ds-mRNA under an external load. J Chem Phys 2016; 145:025101. [PMID: 27421425 DOI: 10.1063/1.4958321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Protein molecules in cells are synthesized by macromolecular machines called ribosomes. According to the recent experimental data, we reduce the complexity of the ribosome and propose a model to express its activity in six main states. Using our model, we study the translation rate in different biological relevant situations in the presence of external force and the translation through the RNA double stranded region in the absence or presence of the external force. In the present study, we give a quantitative theory for translation rate and show that the ribosome behaves more like a Brownian Ratchet motor. Our findings could shed some light on understanding behaviors of the ribosome in biological conditions.
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Affiliation(s)
- Bahareh Shakiba
- Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan 45137-66731, Iran
| | - Maryam Dayeri
- Department of Biological Sciences, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan 45137-66731, Iran
| | - Farshid Mohammad-Rafiee
- Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan 45137-66731, Iran
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Elongation factor G initiates translocation through a power stroke. Proc Natl Acad Sci U S A 2016; 113:7515-20. [PMID: 27313204 DOI: 10.1073/pnas.1602668113] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
During the translocation step of prokaryotic protein synthesis, elongation factor G (EF-G), a guanosine triphosphatase (GTPase), binds to the ribosomal PRE-translocation (PRE) complex and facilitates movement of transfer RNAs (tRNAs) and messenger RNA (mRNA) by one codon. Energy liberated by EF-G's GTPase activity is necessary for EF-G to catalyze rapid and precise translocation. Whether this energy is used mainly to drive movements of the tRNAs and mRNA or to foster EF-G dissociation from the ribosome after translocation has been a long-lasting debate. Free EF-G, not bound to the ribosome, adopts quite different structures in its GTP and GDP forms. Structures of EF-G on the ribosome have been visualized at various intermediate steps along the translocation pathway, using antibiotics and nonhydolyzable GTP analogs to block translocation and to prolong the dwell time of EF-G on the ribosome. However, the structural dynamics of EF-G bound to the ribosome have not yet been described during normal, uninhibited translocation. Here, we report the rotational motions of EF-G domains during normal translocation detected by single-molecule polarized total internal reflection fluorescence (polTIRF) microscopy. Our study shows that EF-G has a small (∼10°) global rotational motion relative to the ribosome after GTP hydrolysis that exerts a force to unlock the ribosome. This is followed by a larger rotation within domain III of EF-G before its dissociation from the ribosome.
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45
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Hori N, Denesyuk NA, Thirumalai D. Salt Effects on the Thermodynamics of a Frameshifting RNA Pseudoknot under Tension. J Mol Biol 2016; 428:2847-59. [PMID: 27315694 DOI: 10.1016/j.jmb.2016.06.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 06/06/2016] [Accepted: 06/07/2016] [Indexed: 12/24/2022]
Abstract
Because of the potential link between -1 programmed ribosomal frameshifting and response of a pseudoknot (PK) RNA to force, a number of single-molecule pulling experiments have been performed on PKs to decipher the mechanism of programmed ribosomal frameshifting. Motivated in part by these experiments, we performed simulations using a coarse-grained model of RNA to describe the response of a PK over a range of mechanical forces (fs) and monovalent salt concentrations (Cs). The coarse-grained simulations quantitatively reproduce the multistep thermal melting observed in experiments, thus validating our model. The free energy changes obtained in simulations are in excellent agreement with experiments. By varying f and C, we calculated the phase diagram that shows a sequence of structural transitions, populating distinct intermediate states. As f and C are changed, the stem-loop tertiary interactions rupture first, followed by unfolding of the 3'-end hairpin (I⇌F). Finally, the 5'-end hairpin unravels, producing an extended state (E⇌I). A theoretical analysis of the phase boundaries shows that the critical force for rupture scales as (logCm)(α) with α=1(0.5) for E⇌I (I⇌F) transition. This relation is used to obtain the preferential ion-RNA interaction coefficient, which can be quantitatively measured in single-molecule experiments, as done previously for DNA hairpins. A by-product of our work is the suggestion that the frameshift efficiency is likely determined by the stability of the 5'-end hairpin that the ribosome first encounters during translation.
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Affiliation(s)
- Naoto Hori
- Biophysics Program, Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA
| | - Natalia A Denesyuk
- Biophysics Program, Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA
| | - D Thirumalai
- Biophysics Program, Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA.
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46
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Abeyrathne PD, Koh CS, Grant T, Grigorieff N, Korostelev AA. Ensemble cryo-EM uncovers inchworm-like translocation of a viral IRES through the ribosome. eLife 2016; 5. [PMID: 27159452 PMCID: PMC4896748 DOI: 10.7554/elife.14874] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 05/08/2016] [Indexed: 12/17/2022] Open
Abstract
Internal ribosome entry sites (IRESs) mediate cap-independent translation of viral mRNAs. Using electron cryo-microscopy of a single specimen, we present five ribosome structures formed with the Taura syndrome virus IRES and translocase eEF2•GTP bound with sordarin. The structures suggest a trajectory of IRES translocation, required for translation initiation, and provide an unprecedented view of eEF2 dynamics. The IRES rearranges from extended to bent to extended conformations. This inchworm-like movement is coupled with ribosomal inter-subunit rotation and 40S head swivel. eEF2, attached to the 60S subunit, slides along the rotating 40S subunit to enter the A site. Its diphthamide-bearing tip at domain IV separates the tRNA-mRNA-like pseudoknot I (PKI) of the IRES from the decoding center. This unlocks 40S domains, facilitating head swivel and biasing IRES translocation via hitherto-elusive intermediates with PKI captured between the A and P sites. The structures suggest missing links in our understanding of tRNA translocation.
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Affiliation(s)
| | - Cha San Koh
- RNA Therapeutics Institute, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, United States
| | - Timothy Grant
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Nikolaus Grigorieff
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Andrei A Korostelev
- RNA Therapeutics Institute, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, United States
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Ling C, Ermolenko DN. Structural insights into ribosome translocation. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 7:620-36. [PMID: 27117863 PMCID: PMC4990484 DOI: 10.1002/wrna.1354] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 03/15/2016] [Accepted: 03/18/2016] [Indexed: 11/23/2022]
Abstract
During protein synthesis, tRNA and mRNA are translocated from the A to P to E sites of the ribosome thus enabling the ribosome to translate one codon of mRNA after the other. Ribosome translocation along mRNA is induced by the universally conserved ribosome GTPase, elongation factor G (EF‐G) in bacteria and elongation factor 2 (EF‐2) in eukaryotes. Recent structural and single‐molecule studies revealed that tRNA and mRNA translocation within the ribosome is accompanied by cyclic forward and reverse rotations between the large and small ribosomal subunits parallel to the plane of the intersubunit interface. In addition, during ribosome translocation, the ‘head’ domain of small ribosomal subunit undergoes forward‐ and back‐swiveling motions relative to the rest of the small ribosomal subunit around the axis that is orthogonal to the axis of intersubunit rotation. tRNA/mRNA translocation is also coupled to the docking of domain IV of EF‐G into the A site of the small ribosomal subunit that converts the thermally driven motions of the ribosome and tRNA into the forward translocation of tRNA/mRNA inside the ribosome. Despite recent and enormous progress made in the understanding of the molecular mechanism of ribosome translocation, the sequence of structural rearrangements of the ribosome, EF‐G and tRNA during translocation is still not fully established and awaits further investigation. WIREs RNA 2016, 7:620–636. doi: 10.1002/wrna.1354 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Clarence Ling
- Department of Biochemistry and Biophysics & Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA
| | - Dmitri N Ermolenko
- Department of Biochemistry and Biophysics & Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA
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48
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Salsi E, Farah E, Ermolenko DN. EF-G Activation by Phosphate Analogs. J Mol Biol 2016; 428:2248-58. [PMID: 27063503 DOI: 10.1016/j.jmb.2016.03.032] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 03/25/2016] [Accepted: 03/29/2016] [Indexed: 01/31/2023]
Abstract
Elongation factor G (EF-G) is a universally conserved translational GTPase that promotes the translocation of tRNA and mRNA through the ribosome. EF-G binds to the ribosome in a GTP-bound form and subsequently catalyzes GTP hydrolysis. The contribution of the ribosome-stimulated GTP hydrolysis by EF-G to tRNA/mRNA translocation remains debated. Here, we show that while EF-G•GDP does not stably bind to the ribosome and induce translocation, EF-G•GDP in complex with phosphate group analogs BeF3(-) and AlF4(-) promotes the translocation of tRNA and mRNA. Furthermore, the rates of mRNA translocation induced by EF-G in the presence of GTP and a non-hydrolyzable analog of GTP, GDP•BeF3(-) are similar. Our results are consistent with the model suggesting that GTP hydrolysis is not directly coupled to mRNA/tRNA translocation. Hence, GTP binding is required to induce the activated, translocation-competent conformation of EF-G while GTP hydrolysis triggers EF-G release from the ribosome.
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Affiliation(s)
- Enea Salsi
- Department of Biochemistry and Biophysics & Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA
| | - Elie Farah
- Department of Biochemistry and Biophysics & Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA
| | - Dmitri N Ermolenko
- Department of Biochemistry and Biophysics & Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA.
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-1 Programmed Ribosomal Frameshifting as a Force-Dependent Process. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2016; 139:45-72. [PMID: 26970190 PMCID: PMC7102820 DOI: 10.1016/bs.pmbts.2015.11.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
-1 Programmed ribosomal frameshifting is a translational recoding event in which ribosomes slip backward along messenger RNA presumably due to increased tension disrupting the codon-anticodon interaction at the ribosome's coding site. Single-molecule physical methods and recent experiments characterizing the physical properties of mRNA's slippery sequence as well as the mechanical stability of downstream mRNA structure motifs that give rise to frameshifting are discussed. Progress in technology, experimental assays, and data analysis methods hold promise for accurate physical modeling and quantitative understanding of -1 programmed ribosomal frameshifting.
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Mechanical insights into ribosomal progression overcoming RNA G-quadruplex from periodical translation suppression in cells. Sci Rep 2016; 6:22719. [PMID: 26948955 PMCID: PMC4780275 DOI: 10.1038/srep22719] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 02/18/2016] [Indexed: 01/10/2023] Open
Abstract
G-quadruplexes formed on DNA and RNA can be roadblocks to movement of polymerases and ribosome on template nucleotides. Although folding and unfolding processes of the G-quadruplexes are deliberately studied in vitro, how the mechanical and physical properties of the G-quadruplexes affect intracellular biological systems is still unclear. In this study, mRNAs with G-quadruplex forming sequences located either in the 5′ untranslated region (UTR) or in the open reading frame (ORF) were constructed to evaluate positional effects of the G-quadruplex on translation suppression in cells. Periodic fluctuation of translation suppression was observed at every three nucleotides within the ORF but not within the 5′ UTR. The results suggested that difference in motion of ribosome at the 5′ UTR and the ORF determined the ability of the G-quadruplex structure to act as a roadblock to translation in cells and provided mechanical insights into ribosomal progression to overcome the roadblock.
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