1
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Skeparnias I, Bou-Nader C, Anastasakis DG, Fan L, Wang YX, Hafner M, Zhang J. Structural basis of MALAT1 RNA maturation and mascRNA biogenesis. Nat Struct Mol Biol 2024:10.1038/s41594-024-01340-4. [PMID: 38956168 DOI: 10.1038/s41594-024-01340-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Accepted: 05/29/2024] [Indexed: 07/04/2024]
Abstract
The metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) long noncoding RNA (lncRNA) has key roles in regulating transcription, splicing, tumorigenesis, etc. Its maturation and stabilization require precise processing by RNase P, which simultaneously initiates the biogenesis of a 3' cytoplasmic MALAT1-associated small cytoplasmic RNA (mascRNA). mascRNA was proposed to fold into a transfer RNA (tRNA)-like secondary structure but lacks eight conserved linking residues required by the canonical tRNA fold. Here we report crystal structures of human mascRNA before and after processing, which reveal an ultracompact, quasi-tRNA-like structure. Despite lacking all linker residues, mascRNA faithfully recreates the characteristic 'elbow' feature of tRNAs to recruit RNase P and ElaC homolog protein 2 (ELAC2) for processing, which exhibit distinct substrate specificities. Rotation and repositioning of the D-stem and anticodon regions preclude mascRNA from aminoacylation, avoiding interference with translation. Therefore, a class of metazoan lncRNA loci uses a previously unrecognized, unusually streamlined quasi-tRNA architecture to recruit select tRNA-processing enzymes while excluding others to drive bespoke RNA biogenesis, processing and maturation.
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Affiliation(s)
- Ilias Skeparnias
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Charles Bou-Nader
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Dimitrios G Anastasakis
- RNA Molecular Biology Laboratory, National Institute for Arthritis and Musculoskeletal and Skin Disease, Bethesda, MD, USA
| | - Lixin Fan
- Basic Science Program, Frederick National Laboratory for Cancer Research, Small-Angle X-Ray Scattering Core Facility of National Cancer Institute, Frederick, MD, USA
| | - Yun-Xing Wang
- Basic Science Program, Frederick National Laboratory for Cancer Research, Small-Angle X-Ray Scattering Core Facility of National Cancer Institute, Frederick, MD, USA
- Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - Markus Hafner
- RNA Molecular Biology Laboratory, National Institute for Arthritis and Musculoskeletal and Skin Disease, Bethesda, MD, USA
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA.
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2
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Alfano C, Fichou Y, Huber K, Weiss M, Spruijt E, Ebbinghaus S, De Luca G, Morando MA, Vetri V, Temussi PA, Pastore A. Molecular Crowding: The History and Development of a Scientific Paradigm. Chem Rev 2024; 124:3186-3219. [PMID: 38466779 PMCID: PMC10979406 DOI: 10.1021/acs.chemrev.3c00615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 02/13/2024] [Accepted: 02/26/2024] [Indexed: 03/13/2024]
Abstract
It is now generally accepted that macromolecules do not act in isolation but "live" in a crowded environment, that is, an environment populated by numerous different molecules. The field of molecular crowding has its origins in the far 80s but became accepted only by the end of the 90s. In the present issue, we discuss various aspects that are influenced by crowding and need to consider its effects. This Review is meant as an introduction to the theme and an analysis of the evolution of the crowding concept through time from colloidal and polymer physics to a more biological perspective. We introduce themes that will be more thoroughly treated in other Reviews of the present issue. In our intentions, each Review may stand by itself, but the complete collection has the aspiration to provide different but complementary perspectives to propose a more holistic view of molecular crowding.
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Affiliation(s)
- Caterina Alfano
- Structural
Biology and Biophysics Unit, Fondazione
Ri.MED, 90100 Palermo, Italy
| | - Yann Fichou
- CNRS,
Bordeaux INP, CBMN UMR 5248, IECB, University
of Bordeaux, F-33600 Pessac, France
| | - Klaus Huber
- Department
of Chemistry, University of Paderborn, 33098 Paderborn, Germany
| | - Matthias Weiss
- Experimental
Physics I, Physics of Living Matter, University
of Bayreuth, 95440 Bayreuth, Germany
| | - Evan Spruijt
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Simon Ebbinghaus
- Lehrstuhl
für Biophysikalische Chemie and Research Center Chemical Sciences
and Sustainability, Research Alliance Ruhr, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Giuseppe De Luca
- Dipartimento
di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche, Università degli Studi di Palermo, Viale delle Scienze, 90128 Palermo, Italy
| | | | - Valeria Vetri
- Dipartimento
di Fisica e Chimica − Emilio Segrè, Università degli Studi di Palermo, Viale delle Scienze, 90128 Palermo, Italy
| | | | - Annalisa Pastore
- King’s
College London, Denmark
Hill Campus, SE5 9RT London, United Kingdom
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3
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Anders AG, Tidwell ED, Gadkari VV, Koutmos M, Ruotolo BT. Collision-Induced Unfolding Reveals Disease-Associated Stability Shifts in Mitochondrial Transfer Ribonucleic Acids. J Am Chem Soc 2024; 146:4412-4420. [PMID: 38329282 DOI: 10.1021/jacs.3c09230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Ribonucleic acids (RNAs) remain challenging targets for structural biology, creating barriers to understanding their vast functions in cellular biology and fully realizing their applications in biotechnology. The inherent dynamism of RNAs creates numerous obstacles in capturing their biologically relevant higher-order structures (HOSs), and as a result, many RNA functions remain unknown. In this study, we describe the development of native ion mobility-mass spectrometry and collision-induced unfolding (CIU) for the structural characterization of a variety of RNAs. We evaluate the ability of these techniques to preserve native structural features in the gas phase across a wide range of functional RNAs. Finally, we apply these tools to study the elusive mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes-associated A3243G mutation. Our data demonstrate that our experimentally determined conditions preserve some solution-state memory of RNAs via the correlated complexity of CIU fingerprints and RNA HOS, the observation of predicted stability shifts in the control RNA samples, and the retention of predicted magnesium binding events in gas-phase RNA ions. Significant differences in collision cross section and stability are observed as a function of the A3243G mutation across a subset of the mitochondrial tRNA maturation pathway. We conclude by discussing the potential application of CIU for the development of RNA-based biotherapeutics and, more broadly, transcriptomic characterization.
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Affiliation(s)
- Anna G Anders
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Elizabeth D Tidwell
- Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Varun V Gadkari
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Markos Koutmos
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Brandon T Ruotolo
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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4
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Suddala KC, Yoo J, Fan L, Zuo X, Wang YX, Chung HS, Zhang J. Direct observation of tRNA-chaperoned folding of a dynamic mRNA ensemble. Nat Commun 2023; 14:5438. [PMID: 37673863 PMCID: PMC10482949 DOI: 10.1038/s41467-023-41155-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 08/24/2023] [Indexed: 09/08/2023] Open
Abstract
T-box riboswitches are multi-domain noncoding RNAs that surveil individual amino acid availabilities in most Gram-positive bacteria. T-boxes directly bind specific tRNAs, query their aminoacylation status to detect starvation, and feedback control the transcription or translation of downstream amino-acid metabolic genes. Most T-boxes rapidly recruit their cognate tRNA ligands through an intricate three-way stem I-stem II-tRNA interaction, whose establishment is not understood. Using single-molecule FRET, SAXS, and time-resolved fluorescence, we find that the free T-box RNA assumes a broad distribution of open, semi-open, and closed conformations that only slowly interconvert. tRNA directly binds all three conformers with distinct kinetics, triggers nearly instantaneous collapses of the open conformations, and returns the T-box RNA to their pre-binding conformations upon dissociation. This scissors-like dynamic behavior is enabled by a hinge-like pseudoknot domain which poises the T-box for rapid tRNA-induced domain closure. This study reveals tRNA-chaperoned folding of flexible, multi-domain mRNAs through a Venus flytrap-like mechanism.
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Affiliation(s)
- Krishna C Suddala
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 20892, USA
| | - Janghyun Yoo
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 20892, USA
| | - Lixin Fan
- Basic Science Program, Frederick National Laboratory for Cancer Research, Small-Angle X-Ray Scattering Core Facility of National Cancer Institute, Frederick, MD, 21702, USA
| | - Xiaobing Zuo
- X-ray Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Yun-Xing Wang
- Basic Science Program, Frederick National Laboratory for Cancer Research, Small-Angle X-Ray Scattering Core Facility of National Cancer Institute, Frederick, MD, 21702, USA
- Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Hoi Sung Chung
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 20892, USA.
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 20892, USA.
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5
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DasGupta S, Zhang S, Szostak JW. Molecular Crowding Facilitates Ribozyme-Catalyzed RNA Assembly. ACS CENTRAL SCIENCE 2023; 9:1670-1678. [PMID: 37637737 PMCID: PMC10451029 DOI: 10.1021/acscentsci.3c00547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Indexed: 08/29/2023]
Abstract
Catalytic RNAs or ribozymes are considered to be central to primordial biology. Most ribozymes require moderate to high concentrations of divalent cations such as Mg2+ to fold into their catalytically competent structures and perform catalysis. However, undesirable effects of Mg2+ such as hydrolysis of reactive RNA building blocks and degradation of RNA structures are likely to undermine its beneficial roles in ribozyme catalysis. Further, prebiotic cell-like compartments bounded by fatty acid membranes are destabilized in the presence of Mg2+, making ribozyme function inside prebiotically relevant protocells a significant challenge. Therefore, we sought to identify conditions that would enable ribozymes to retain activity at low concentrations of Mg2+. Inspired by the ability of ribozymes to function inside crowded cellular environments with <1 mM free Mg2+, we tested molecular crowding as a potential mechanism to lower the Mg2+ concentration required for ribozyme-catalyzed RNA assembly. Here, we show that the ribozyme-catalyzed ligation of phosphorimidazolide RNA substrates is significantly enhanced in the presence of the artificial crowding agent polyethylene glycol. We also found that molecular crowding preserves ligase activity under denaturing conditions such as alkaline pH and the presence of urea. Additionally, we show that crowding-induced stimulation of RNA-catalyzed RNA assembly is not limited to phosphorimidazolide ligation but extends to the RNA-catalyzed polymerization of nucleoside triphosphates. RNA-catalyzed RNA ligation is also stimulated by the presence of prebiotically relevant small molecules such as ethylene glycol, ribose, and amino acids, consistent with a role for molecular crowding in primordial ribozyme function and more generally in the emergence of RNA-based cellular life.
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Affiliation(s)
- Saurja DasGupta
- Department
of Molecular Biology, Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Howard
Hughes Medical Institute, Massachusetts General
Hospital, Boston, Massachusetts 02114, United States
- Department
of Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Stephanie Zhang
- Department
of Molecular Biology, Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Department
of Chemistry and Chemical Biology, Harvard
University, Cambridge, Massachusetts 02138, United States
| | - Jack W. Szostak
- Department
of Molecular Biology, Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Howard
Hughes Medical Institute, Massachusetts General
Hospital, Boston, Massachusetts 02114, United States
- Department
of Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
- Department
of Chemistry and Chemical Biology, Harvard
University, Cambridge, Massachusetts 02138, United States
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6
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Schaffter SW, Wintenberg ME, Murphy TM, Strychalski EA. Design Approaches to Expand the Toolkit for Building Cotranscriptionally Encoded RNA Strand Displacement Circuits. ACS Synth Biol 2023; 12:1546-1561. [PMID: 37134273 DOI: 10.1021/acssynbio.3c00079] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Cotranscriptionally encoded RNA strand displacement (ctRSD) circuits are an emerging tool for programmable molecular computation, with potential applications spanning in vitro diagnostics to continuous computation inside living cells. In ctRSD circuits, RNA strand displacement components are continuously produced together via transcription. These RNA components can be rationally programmed through base pairing interactions to execute logic and signaling cascades. However, the small number of ctRSD components characterized to date limits circuit size and capabilities. Here, we characterize over 200 ctRSD gate sequences, exploring different input, output, and toehold sequences and changes to other design parameters, including domain lengths, ribozyme sequences, and the order in which gate strands are transcribed. This characterization provides a library of sequence domains for engineering ctRSD components, i.e., a toolkit, enabling circuits with up to 4-fold more inputs than previously possible. We also identify specific failure modes and systematically develop design approaches that reduce the likelihood of failure across different gate sequences. Lastly, we show the ctRSD gate design is robust to changes in transcriptional encoding, opening a broad design space for applications in more complex environments. Together, these results deliver an expanded toolkit and design approaches for building ctRSD circuits that will dramatically extend capabilities and potential applications.
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Affiliation(s)
- Samuel W Schaffter
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Molly E Wintenberg
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Terence M Murphy
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
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7
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Shin JH, Bonilla SL, Denny SK, Greenleaf WJ, Herschlag D. Dissecting the energetic architecture within an RNA tertiary structural motif via high-throughput thermodynamic measurements. Proc Natl Acad Sci U S A 2023; 120:e2220485120. [PMID: 36897989 PMCID: PMC10243134 DOI: 10.1073/pnas.2220485120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 02/01/2023] [Indexed: 03/12/2023] Open
Abstract
Structured RNAs and RNA/protein complexes perform critical cellular functions. They often contain structurally conserved tertiary contact "motifs," whose occurrence simplifies the RNA folding landscape. Prior studies have focused on the conformational and energetic modularity of intact motifs. Here, we turn to the dissection of one common motif, the 11nt receptor (11ntR), using quantitative analysis of RNA on a massively parallel array to measure the binding of all single and double 11ntR mutants to GAAA and GUAA tetraloops, thereby probing the energetic architecture of the motif. While the 11ntR behaves as a motif, its cooperativity is not absolute. Instead, we uncovered a gradient from high cooperativity amongst base-paired and neighboring residues to additivity between distant residues. As expected, substitutions at residues in direct contact with the GAAA tetraloop resulted in the largest decreases to binding, and energetic penalties of mutations were substantially smaller for binding to the alternate GUAA tetraloop, which lacks tertiary contacts present with the canonical GAAA tetraloop. However, we found that the energetic consequences of base partner substitutions are not, in general, simply described by base pair type or isostericity. We also found exceptions to the previously established stability-abundance relationship for 11ntR sequence variants. These findings of "exceptions to the rule" highlight the power of systematic high-throughput approaches to uncover novel variants for future study in addition to providing an energetic map of a functional RNA.
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Affiliation(s)
- John H. Shin
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA94305
- Department of Chemical Engineering, Stanford University, Stanford, CA94305
| | - Steve L. Bonilla
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO80045
| | - Sarah K. Denny
- Department of Genetics, Stanford University School of Medicine, Stanford, CA94305
- Scribe Therapeutics, Alameda, CA94501
| | - William J. Greenleaf
- Department of Genetics, Stanford University School of Medicine, Stanford, CA94305
- Department of Applied Physics, Stanford University, Stanford, CA94305
- Chan Zuckerberg Biohub, San Francisco, CA94158
| | - Daniel Herschlag
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA94305
- Department of Chemical Engineering, Stanford University, Stanford, CA94305
- ChEM-H Institute, Stanford University, Stanford, CA94305
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8
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Lai LB, Lai SM, Szymanski ES, Kapur M, Choi EK, Al-Hashimi HM, Ackerman SL, Gopalan V. Structural basis for impaired 5' processing of a mutant tRNA associated with defects in neuronal homeostasis. Proc Natl Acad Sci U S A 2022; 119:e2119529119. [PMID: 35238631 PMCID: PMC8915964 DOI: 10.1073/pnas.2119529119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 01/09/2022] [Indexed: 02/06/2023] Open
Abstract
SignificanceUnderstanding and treating neurological disorders are global priorities. Some of these diseases are engendered by mutations that cause defects in the cellular synthesis of transfer RNAs (tRNAs), which function as adapter molecules that translate messenger RNAs into proteins. During tRNA biogenesis, ribonuclease P catalyzes removal of the transcribed sequence upstream of the mature tRNA. Here, we focus on a cytoplasmic tRNAArgUCU that is expressed specifically in neurons and, when harboring a particular point mutation, contributes to neurodegeneration in mice. Our results suggest that this mutation favors stable alternative structures that are not cleaved by mouse ribonuclease P and motivate a paradigm that may help to understand the molecular basis for disease-associated mutations in other tRNAs.
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Affiliation(s)
- Lien B. Lai
- Department of Chemistry & Biochemistry, The Ohio State University, Columbus, OH 43210
- Center for RNA Biology, The Ohio State University, Columbus, OH 43210
| | - Stella M. Lai
- Department of Chemistry & Biochemistry, The Ohio State University, Columbus, OH 43210
- Center for RNA Biology, The Ohio State University, Columbus, OH 43210
| | - Eric S. Szymanski
- Department of Biochemistry, School of Medicine, Duke University, Durham, NC 27710
| | - Mridu Kapur
- Department of Cellular and Molecular Medicine, Section of Neurobiology, University of California San Diego, La Jolla, CA 92093
- Howard Hughes Medical Institute, University of California San Diego, La Jolla, CA 92093
| | - Edric K. Choi
- Department of Chemistry & Biochemistry, The Ohio State University, Columbus, OH 43210
- Center for RNA Biology, The Ohio State University, Columbus, OH 43210
| | - Hashim M. Al-Hashimi
- Department of Biochemistry, School of Medicine, Duke University, Durham, NC 27710
| | - Susan L. Ackerman
- Department of Cellular and Molecular Medicine, Section of Neurobiology, University of California San Diego, La Jolla, CA 92093
- Howard Hughes Medical Institute, University of California San Diego, La Jolla, CA 92093
| | - Venkat Gopalan
- Department of Chemistry & Biochemistry, The Ohio State University, Columbus, OH 43210
- Center for RNA Biology, The Ohio State University, Columbus, OH 43210
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9
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Multiplexed assessment of engineered bacterial constructs for intracellular β-galactosidase expression by redox amplification on catechol-chitosan modified nanoporous gold. Mikrochim Acta 2021; 189:4. [PMID: 34855041 DOI: 10.1007/s00604-021-05109-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Accepted: 11/11/2021] [Indexed: 10/19/2022]
Abstract
Synthetic biology approaches for rewiring of bacterial constructs to express particular intracellular factors upon induction with the target analyte are emerging as sensing paradigms for applications in environmental and in vivo monitoring. To aid in the design and optimization of bacterial constructs for sensing analytes, there is a need for lysis-free intracellular detection modalities that monitor the signal level and kinetics of expressed factors within different modified bacteria in a multiplexed manner, without requiring cumbersome surface immobilization. Herein, an electrochemical detection system on nanoporous gold that is electrofabricated with a biomaterial redox capacitor is presented for quantifying β-galactosidase expressed inside modified Escherichia coli constructs upon induction with dopamine. This nanostructure-mediated redox amplification approach on a microfluidic platform allows for multiplexed assessment of the expressed intracellular factors from different bacterial constructs suspended in distinct microchannels, with no need for cell lysis or immobilization. Since redox mediators present over the entire depth of the microchannel can interact with the electrode and with the E. coli construct in each channel, the platform exhibits high sensitivity and enables multiplexing. We envision its application in assessing synthetic biology-based approaches for comparing specificity, sensitivity, and signal response time upon induction with target analytes of interest.
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10
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Progress toward SHAPE Constrained Computational Prediction of Tertiary Interactions in RNA Structure. Noncoding RNA 2021; 7:ncrna7040071. [PMID: 34842779 PMCID: PMC8628965 DOI: 10.3390/ncrna7040071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/29/2021] [Accepted: 11/02/2021] [Indexed: 01/04/2023] Open
Abstract
As more sequencing data accumulate and novel puzzling genetic regulations are discovered, the need for accurate automated modeling of RNA structure increases. RNA structure modeling from chemical probing experiments has made tremendous progress, however accurately predicting large RNA structures is still challenging for several reasons: RNA are inherently flexible and often adopt many energetically similar structures, which are not reliably distinguished by the available, incomplete thermodynamic model. Moreover, computationally, the problem is aggravated by the relevance of pseudoknots and non-canonical base pairs, which are hardly predicted efficiently. To identify nucleotides involved in pseudoknots and non-canonical interactions, we scrutinized the SHAPE reactivity of each nucleotide of the 188 nt long lariat-capping ribozyme under multiple conditions. Reactivities analyzed in the light of the X-ray structure were shown to report accurately the nucleotide status. Those that seemed paradoxical were rationalized by the nucleotide behavior along molecular dynamic simulations. We show that valuable information on intricate interactions can be deduced from probing with different reagents, and in the presence or absence of Mg2+. Furthermore, probing at increasing temperature was remarkably efficient at pointing to non-canonical interactions and pseudoknot pairings. The possibilities of following such strategies to inform structure modeling software are discussed.
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11
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Gunawardhana SM, Holmstrom ED. Apolar chemical environments compact unfolded RNAs and can promote folding. BIOPHYSICAL REPORTS 2021; 1. [PMID: 35382036 PMCID: PMC8978554 DOI: 10.1016/j.bpr.2021.100004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
It is well documented that the structure, and thus function, of nucleic acids depends on the chemical environment surrounding them, which often includes potential proteinaceous binding partners. The nonpolar amino acid side chains of these proteins will invariably alter the polarity of the local chemical environment around the nucleic acid. However, we are only beginning to understand how environmental polarity generally influences the structural and energetic properties of RNA folding. Here, we use a series of aqueous-organic cosolvent mixtures to systematically modulate the solvent polarity around two different RNA folding constructs that can form either secondary or tertiary structural elements. Using single-molecule Förster resonance energy transfer spectroscopy to simultaneously monitor the structural and energetic properties of these RNAs, we show that the unfolded conformations of both model RNAs become more compact in apolar environments characterized by dielectric constants less than that of pure water. In the case of tertiary structure formation, this compaction also gives rise to more energetically favorable folding. We propose that these physical changes arise from an enhanced accumulation of counterions in the low dielectric environment surrounding the unfolded RNA.
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Affiliation(s)
| | - Erik D Holmstrom
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas.,Department of Chemistry, University of Kansas, Lawrence, Kansas
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12
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Bou-Nader C, Muecksch F, Brown JB, Gordon JM, York A, Peng C, Ghirlando R, Summers MF, Bieniasz PD, Zhang J. HIV-1 matrix-tRNA complex structure reveals basis for host control of Gag localization. Cell Host Microbe 2021; 29:1421-1436.e7. [PMID: 34384537 PMCID: PMC8650744 DOI: 10.1016/j.chom.2021.07.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 05/24/2021] [Accepted: 07/19/2021] [Indexed: 10/20/2022]
Abstract
The HIV-1 virion structural polyprotein, Gag, is directed to particle assembly sites at the plasma membrane by its N-terminal matrix (MA) domain. MA also binds to host tRNAs. To understand the molecular basis of MA-tRNA interaction and its potential function, we present a co-crystal structure of HIV-1 MA-tRNALys3 complex. The structure reveals a specialized group of MA basic and aromatic residues preconfigured to recognize the distinctive structure of the tRNA elbow. Mutational, cross-linking, fluorescence, and NMR analyses show that the crystallographically defined interface drives MA-tRNA binding in solution and living cells. The structure indicates that MA is unlikely to bind tRNA and membrane simultaneously. Accordingly, single-amino-acid substitutions that abolish MA-tRNA binding caused striking redistribution of Gag to the plasma membrane and reduced HIV-1 replication. Thus, HIV-1 exploits host tRNAs to occlude a membrane localization signal and control the subcellular distribution of its major structural protein.
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Affiliation(s)
- Charles Bou-Nader
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Frauke Muecksch
- Laboratory of Retrovirology, The Rockefeller University, New York, NY 10065, USA
| | - Janae B Brown
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| | - Jackson M Gordon
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Ashley York
- Laboratory of Retrovirology, The Rockefeller University, New York, NY 10065, USA
| | - Chen Peng
- Laboratory of Retrovirology, The Rockefeller University, New York, NY 10065, USA
| | - Rodolfo Ghirlando
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Michael F Summers
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD 21250, USA; Howard Hughes Medical Institute, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| | - Paul D Bieniasz
- Laboratory of Retrovirology, The Rockefeller University, New York, NY 10065, USA; Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA.
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA.
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13
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Marathe IA, Lai SM, Zahurancik WJ, Poirier MG, Wysocki VH, Gopalan V. Protein cofactors and substrate influence Mg2+-dependent structural changes in the catalytic RNA of archaeal RNase P. Nucleic Acids Res 2021; 49:9444-9458. [PMID: 34387688 PMCID: PMC8450104 DOI: 10.1093/nar/gkab655] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/02/2021] [Accepted: 07/23/2021] [Indexed: 01/07/2023] Open
Abstract
The ribonucleoprotein (RNP) form of archaeal RNase P comprises one catalytic RNA and five protein cofactors. To catalyze Mg2+-dependent cleavage of the 5′ leader from pre-tRNAs, the catalytic (C) and specificity (S) domains of the RNase P RNA (RPR) cooperate to recognize different parts of the pre-tRNA. While ∼250–500 mM Mg2+ renders the archaeal RPR active without RNase P proteins (RPPs), addition of all RPPs lowers the Mg2+ requirement to ∼10–20 mM and improves the rate and fidelity of cleavage. To understand the Mg2+- and RPP-dependent structural changes that increase activity, we used pre-tRNA cleavage and ensemble FRET assays to characterize inter-domain interactions in Pyrococcus furiosus (Pfu) RPR, either alone or with RPPs ± pre-tRNA. Following splint ligation to doubly label the RPR (Cy3-RPRC domain and Cy5-RPRS domain), we used native mass spectrometry to verify the final product. We found that FRET correlates closely with activity, the Pfu RPR and RNase P holoenzyme (RPR + 5 RPPs) traverse different Mg2+-dependent paths to converge on similar functional states, and binding of the pre-tRNA by the holoenzyme influences Mg2+ cooperativity. Our findings highlight how Mg2+ and proteins in multi-subunit RNPs together favor RNA conformations in a dynamic ensemble for functional gains.
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Affiliation(s)
- Ila A Marathe
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA.,Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA.,Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Stella M Lai
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA.,Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA.,Resource for Native Mass Spectrometry-Guided Structural Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Walter J Zahurancik
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA.,Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Michael G Poirier
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA.,Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA.,Department of Physics, The Ohio State University, Columbus, OH 43210, USA
| | - Vicki H Wysocki
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA.,Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA.,Resource for Native Mass Spectrometry-Guided Structural Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Venkat Gopalan
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA.,Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA.,Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
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14
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Yamagami R, Sieg JP, Bevilacqua PC. Functional Roles of Chelated Magnesium Ions in RNA Folding and Function. Biochemistry 2021; 60:2374-2386. [PMID: 34319696 DOI: 10.1021/acs.biochem.1c00012] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
RNA regulates myriad cellular events such as transcription, translation, and splicing. To perform these essential functions, RNA often folds into complex tertiary structures in which its negatively charged ribose-phosphate backbone interacts with metal ions. Magnesium, the most abundant divalent metal ion in cells, neutralizes the backbone, thereby playing essential roles in RNA folding and function. This has been known for more than 50 years, and there are now thousands of in vitro studies, most of which have used ≥10 mM free Mg2+ ions to achieve optimal RNA folding and function. In the cell, however, concentrations of free Mg2+ ions are much lower, with most Mg2+ ions chelated by metabolites. In this Perspective, we curate data from a number of sources to provide extensive summaries of cellular concentrations of metabolites that bind Mg2+ and to estimate cellular concentrations of metabolite-chelated Mg2+ species, in the representative prokaryotic and eukaryotic systems Escherichia coli, Saccharomyces cerevisiae, and iBMK cells. Recent research from our lab and others has uncovered the fact that such weakly chelated Mg2+ ions can enhance RNA function, including its thermodynamic stability, chemical stability, and catalysis. We also discuss how metabolite-chelated Mg2+ complexes may have played roles in the origins of life. It is clear from this analysis that bound Mg2+ should not be simply considered non-RNA-interacting and that future RNA research, as well as protein research, could benefit from considering chelated magnesium.
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Affiliation(s)
- Ryota Yamagami
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.,Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Jacob P Sieg
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.,Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Philip C Bevilacqua
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.,Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.,Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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15
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It is time to crowd your cell culture media - Physicochemical considerations with biological consequences. Biomaterials 2021; 275:120943. [PMID: 34139505 DOI: 10.1016/j.biomaterials.2021.120943] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 05/24/2021] [Accepted: 05/29/2021] [Indexed: 12/12/2022]
Abstract
In vivo, the interior and exterior of cells is populated by various macromolecules that create an extremely crowded milieu. Yet again, in vitro eukaryotic cell culture is conducted in dilute culture media that hardly imitate the native tissue density. Herein, the concept of macromolecular crowding is discussed in both intracellular and extracellular context. Particular emphasis is given on how the physicochemical properties of the crowding molecules govern and determine kinetics, equilibria and mechanism of action of biochemical and biological reactions, processes and functions. It is evidenced that we are still at the beginning of appreciating, let alone effectively implementing, the potential of macromolecular crowding in permanently differentiated and stem cell culture systems.
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16
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Raghunath M, Zeugolis DI. Transforming eukaryotic cell culture with macromolecular crowding. Trends Biochem Sci 2021; 46:805-811. [PMID: 33994289 DOI: 10.1016/j.tibs.2021.04.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 04/07/2021] [Accepted: 04/16/2021] [Indexed: 01/10/2023]
Abstract
In multicellular organisms, the intracellular and extracellular spaces are considerably packed with a diverse range of macromolecular species. Yet, standard eukaryotic cell culture is performed in dilute, and deprived of macromolecules culture media, that barely imitate the density and complex macromolecular composition of tissues. Essentially, we drown cells in a sea of media and then expect them to perform physiologically. Herein, we argue the use of macromolecular crowding (MMC) in eukaryotic cell culture for regenerative medicine and drug discovery purposes.
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Affiliation(s)
- Michael Raghunath
- Center for Cell Biology and Tissue Engineering, Institute for Chemistry and Biotechnology, Zurich University of Applied Sciences, Wädenswil, Switzerland
| | - Dimitrios I Zeugolis
- Regenerative, Modular, and Developmental Engineering Laboratory (REMODEL), National University of Ireland Galway (NUI Galway), Galway, Ireland; Science Foundation Ireland (SFI) Centre for Research in Medical Devices (CÚRAM), National University of Ireland Galway (NUI Galway), Galway, Ireland; Regenerative, Modular, and Developmental Engineering Laboratory (REMODEL), Faculty of Biomedical Sciences, Università della Svizzera Italiana (USI), Lugano, Switzerland; Regenerative, Modular, and Developmental Engineering Laboratory (REMODEL), School of Mechanical and Materials Engineering, University College Dublin (UCD), Dublin, Ireland.
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17
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Feng C, Tan YL, Cheng YX, Shi YZ, Tan ZJ. Salt-Dependent RNA Pseudoknot Stability: Effect of Spatial Confinement. Front Mol Biosci 2021; 8:666369. [PMID: 33928126 PMCID: PMC8078894 DOI: 10.3389/fmolb.2021.666369] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 03/17/2021] [Indexed: 12/27/2022] Open
Abstract
Macromolecules, such as RNAs, reside in crowded cell environments, which could strongly affect the folded structures and stability of RNAs. The emergence of RNA-driven phase separation in biology further stresses the potential functional roles of molecular crowding. In this work, we employed the coarse-grained model that was previously developed by us to predict 3D structures and stability of the mouse mammary tumor virus (MMTV) pseudoknot under different spatial confinements over a wide range of salt concentrations. The results show that spatial confinements can not only enhance the compactness and stability of MMTV pseudoknot structures but also weaken the dependence of the RNA structure compactness and stability on salt concentration. Based on our microscopic analyses, we found that the effect of spatial confinement on the salt-dependent RNA pseudoknot stability mainly comes through the spatial suppression of extended conformations, which are prevalent in the partially/fully unfolded states, especially at low ion concentrations. Furthermore, our comprehensive analyses revealed that the thermally unfolding pathway of the pseudoknot can be significantly modulated by spatial confinements, since the intermediate states with more extended conformations would loss favor when spatial confinements are introduced.
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Affiliation(s)
- Chenjie Feng
- Key Laboratory of Artificial Micro and Nano-structures of Ministry of Education, Center for Theoretical Physics, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Ya-Lan Tan
- Key Laboratory of Artificial Micro and Nano-structures of Ministry of Education, Center for Theoretical Physics, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Yu-Xuan Cheng
- Key Laboratory of Artificial Micro and Nano-structures of Ministry of Education, Center for Theoretical Physics, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Ya-Zhou Shi
- Research Center of Nonlinear Science, School of Mathematics and Computer Science, Wuhan Textile University, Wuhan, China
| | - Zhi-Jie Tan
- Key Laboratory of Artificial Micro and Nano-structures of Ministry of Education, Center for Theoretical Physics, School of Physics and Technology, Wuhan University, Wuhan, China
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18
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Fiorentini D, Cappadone C, Farruggia G, Prata C. Magnesium: Biochemistry, Nutrition, Detection, and Social Impact of Diseases Linked to Its Deficiency. Nutrients 2021; 13:1136. [PMID: 33808247 PMCID: PMC8065437 DOI: 10.3390/nu13041136] [Citation(s) in RCA: 107] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 03/23/2021] [Accepted: 03/26/2021] [Indexed: 12/11/2022] Open
Abstract
Magnesium plays an important role in many physiological functions. Habitually low intakes of magnesium and in general the deficiency of this micronutrient induce changes in biochemical pathways that can increase the risk of illness and, in particular, chronic degenerative diseases. The assessment of magnesium status is consequently of great importance, however, its evaluation is difficult. The measurement of serum magnesium concentration is the most commonly used and readily available method for assessing magnesium status, even if serum levels have no reliable correlation with total body magnesium levels or concentrations in specific tissues. Therefore, this review offers an overview of recent insights into magnesium from multiple perspectives. Starting from a biochemical point of view, it aims at highlighting the risk due to insufficient uptake (frequently due to the low content of magnesium in the modern western diet), at suggesting strategies to reach the recommended dietary reference values, and at focusing on the importance of detecting physiological or pathological levels of magnesium in various body districts, in order to counteract the social impact of diseases linked to magnesium deficiency.
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Affiliation(s)
| | | | - Giovanna Farruggia
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum—University of Bologna, 40126 Bologna, Italy; (D.F.); (C.C.); (C.P.)
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19
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Zeugolis DI. Bioinspired in vitro microenvironments to control cell fate: focus on macromolecular crowding. Am J Physiol Cell Physiol 2021; 320:C842-C849. [PMID: 33656930 DOI: 10.1152/ajpcell.00380.2020] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The development of therapeutic regenerative medicine and accurate drug discovery cell-based products requires effective, with respect to obtaining sufficient numbers of viable, proliferative, and functional cell populations, cell expansion ex vivo. Unfortunately, traditional cell culture systems fail to recapitulate the multifaceted tissue milieu in vitro, resulting in cell phenotypic drift, loss of functionality, senescence, and apoptosis. Substrate-, environment-, and media-induced approaches are under intense investigation as a means to maintain cell phenotype and function while in culture. In this context, herein, the potential of macromolecular crowding, a biophysical phenomenon with considerable biological consequences, is discussed.
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Affiliation(s)
- Dimitrios I Zeugolis
- Regenerative, Modular, and Developmental Engineering Laboratory (REMODEL), Biomedical Sciences Building, National University of Ireland Galway, Galway, Ireland.,Science Foundation Ireland (SFI) Centre for Research in Medical Devices (CÚRAM), Biomedical Sciences Building, National University of Ireland Galway, Galway, Ireland.,Faculty of Biomedical Sciences, Regenerative, Modular, and Developmental Engineering Laboratory (REMODEL), Università della Svizzera Italiana, Lugano, Switzerland.,Regenerative, Modular & Developmental Engineering Laboratory (REMODEL), School of Mechanical and Materials Engineering, University College Dublin, Dublin, Ireland
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20
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Roden C, Gladfelter AS. RNA contributions to the form and function of biomolecular condensates. Nat Rev Mol Cell Biol 2021; 22:183-195. [PMID: 32632317 PMCID: PMC7785677 DOI: 10.1038/s41580-020-0264-6] [Citation(s) in RCA: 294] [Impact Index Per Article: 98.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/04/2020] [Indexed: 01/08/2023]
Abstract
Biomolecular condensation partitions cellular contents and has important roles in stress responses, maintaining homeostasis, development and disease. Many nuclear and cytoplasmic condensates are rich in RNA and RNA-binding proteins (RBPs), which undergo liquid-liquid phase separation (LLPS). Whereas the role of RBPs in condensates has been well studied, less attention has been paid to the contribution of RNA to LLPS. In this Review, we discuss the role of RNA in biomolecular condensation and highlight considerations for designing condensate reconstitution experiments. We focus on RNA properties such as composition, length, structure, modifications and expression level. These properties can modulate the biophysical features of native condensates, including their size, shape, viscosity, liquidity, surface tension and composition. We also discuss the role of RNA-protein condensates in development, disease and homeostasis, emphasizing how their properties and function can be determined by RNA. Finally, we discuss the multifaceted cellular functions of biomolecular condensates, including cell compartmentalization through RNA transport and localization, supporting catalytic processes, storage and inheritance of specific molecules, and buffering noise and responding to stress.
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Affiliation(s)
- Christine Roden
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- The Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Amy S Gladfelter
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- The Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA.
- Whitman Center, Marine Biology Laboratory, Woods Hole, MA, USA.
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21
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Abstract
RNA enzymes or ribozymes catalyze some of the most important reactions in biology and are thought to have played a central role in the origin and evolution of life on earth. Catalytic function in RNA has evolved in crowded cellular environments that are different from dilute solutions in which most in vitro assays are performed. The presence of molecules such as amino acids, polypeptides, alcohols, and sugars in the cell introduces forces that modify the kinetics and thermodynamics of ribozyme-catalyzed reactions. Synthetic molecules are routinely used in in vitro studies to better approximate the properties of biomolecules under in vivo conditions. This review discusses the various forces that operate within simulated crowded solutions in the context of RNA structure, folding, and catalysis. It also explores ideas about how crowding could have been beneficial to the evolution of functional RNAs and the development of primitive cellular systems in a prebiotic milieu.
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Affiliation(s)
- Saurja DasGupta
- Howard Hughes Medical Institute, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
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22
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Ge X, Xu J. Macromolecular crowding effects on transcription and translation are regulated by free magnesium ion. Biotechnol Appl Biochem 2020; 67:117-122. [PMID: 31576614 PMCID: PMC7263881 DOI: 10.1002/bab.1827] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 09/28/2019] [Indexed: 12/21/2022]
Abstract
Cell-free metabolic engineering is an emerging and promising alternative platform for the production of fuels and chemicals. In recent years, macromolecular crowding effect, which is an important function in living cells but ignored in cell-free systems, has been transferred to cell-free protein synthesis (CFPS). However, inhibitory effects of crowding agents on CFPS were frequently observed, and the mechanism is unclear. In this study, free Mg2+ was found to be a key factor that can regulate the macromolecular crowding effect on in vitro transcription, in vitro translation, and coupled transcript/translation. Addition of crowding agents (20% of Ficoll-70 or Ficoll-400) enhanced in vitro transcription at an index of free Mg2+ concentration (IFMC) below 2 mM but inhibited the transcription when the IFMC was higher than 2 mM. Similarly, Ficoll-400 enhanced in vitro translation and coupled transcription/translation at a lower IFMC (0.1-2 mM) and inhibited the reactions at higher IFMC (>2 mM). Based on the results, CFPS systems could be further optimized by adjusting the content of crowding agents and the IFMC. Besides, the results also indicate that macromolecular crowding effect is important for maintaining the efficiency of in vivo transcription and translation which occur at a low intracellular IFMC (<1 mM).
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Affiliation(s)
- Xumeng Ge
- Arkansas Biosciences Institute and College of Agriculture and Technology, Arkansas State University, Jonesboro, AR, USA
- Quasar Energy Group, Independence, OH, USA
| | - Jianfeng Xu
- Arkansas Biosciences Institute and College of Agriculture and Technology, Arkansas State University, Jonesboro, AR, USA
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23
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Tripathi K, Menon GI, Vemparala S. Confined crowded polymers near attractive surfaces. J Chem Phys 2019; 151:244901. [PMID: 31893876 DOI: 10.1063/1.5115284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present results from molecular dynamics simulations of a spherically confined neutral polymer in the presence of crowding particles, studying polymer shapes and conformations as a function of the strength of the attraction to the confining wall, solvent quality, and the density of crowders. The conformations of the polymer under good solvent conditions are weakly dependent on crowder particle density, even when the polymer is strongly confined. In contrast, under poor solvent conditions, when the polymer assumes a collapsed conformation when unconfined, it can exhibit transitions to two different adsorbed phases, when either the interaction with the wall or the density of crowder particles is changed. One such transition involves a desorbed collapsed phase change to an adsorbed extended phase as the attraction of the polymer towards the confining wall is increased. Such an adsorbed extended phase can exhibit a second transition to an ordered adsorbed collapsed phase as the crowder particle density is increased. The ordered adsorbed collapsed phase of the polymer differs significantly in its structure from the desorbed collapsed phase. We revisit the earlier understanding of the adsorption of confined polymers on attractive surfaces in light of our results.
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Affiliation(s)
- Kamal Tripathi
- The Institute of Mathematical Sciences, C.I.T. Campus, Taramani, Chennai 600113, India
| | - Gautam I Menon
- The Institute of Mathematical Sciences, C.I.T. Campus, Taramani, Chennai 600113, India
| | - Satyavani Vemparala
- The Institute of Mathematical Sciences, C.I.T. Campus, Taramani, Chennai 600113, India
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24
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Messina KJ, Kierzek R, Tracey MA, Bevilacqua PC. Small Molecule Rescue and Glycosidic Conformational Analysis of the Twister Ribozyme. Biochemistry 2019; 58:4857-4868. [PMID: 31742390 PMCID: PMC6901379 DOI: 10.1021/acs.biochem.9b00742] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The number of self-cleaving ribozymes has increased sharply in recent years, giving rise to elaborations of the four known ribozyme catalytic strategies, α, β, γ, and δ. One such extension is utilized by the twister ribozyme, which is hypothesized to conduct δ, or general acid catalysis, via N3 of the syn adenine +1 nucleobase indirectly via buffer catalysis at biological pH and directly at lower pH. Herein, we test the δ catalysis role of A1 via chemical rescue and the catalytic relevance of the syn orientation of the nucleobase by conformational analysis. Using inhibited twister ribozyme variants with A1(N3) deaza or A1 abasic modifications, we observe >100-fold chemical rescue effects in the presence of protonatable biological small molecules such as imidazole and histidine, similar to observed rescue values previously reported for C75U/C76Δ in the HDV ribozyme. Brønsted plots for the twister variants support a model in which small molecules rescue catalytic activity via a proton transfer mechanism, suggesting that A1 in the wild type is involved in proton transfer, most likely general acid catalysis. Additionally, through glycosidic conformational analysis in an appropriate background that accommodates the bromine atom, we observe that an 8BrA1-modified twister ribozyme is up to 10-fold faster than a nonmodified A1 ribozyme, supporting crystallographic data that show that A1 is syn when conducting proton transfer. Overall, this study provides functional evidence that the nucleotide immediately downstream of the cleavage site participates directly or indirectly in general acid-base catalysis in the twister ribozyme while occupying the syn conformation.
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Affiliation(s)
- Kyle J. Messina
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802
- Center for RNA Molecular Biology, Pennsylvania State University, University Park, PA 16802
| | - Ryszard Kierzek
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland
| | - Matthew A. Tracey
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802
- Current Address: Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104
| | - Philip C. Bevilacqua
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802
- Center for RNA Molecular Biology, Pennsylvania State University, University Park, PA 16802
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802
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25
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Single-nucleotide control of tRNA folding cooperativity under near-cellular conditions. Proc Natl Acad Sci U S A 2019; 116:23075-23082. [PMID: 31666318 DOI: 10.1073/pnas.1913418116] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
RNA folding is often studied by renaturing full-length RNA in vitro and tracking folding transitions. However, the intracellular transcript folds as it emerges from the RNA polymerase. Here, we investigate the folding pathways and stability of numerous late-transcriptional intermediates of yeast and Escherichia coli transfer RNAs (tRNAs). Transfer RNA is a highly regulated functional RNA that undergoes multiple steps of posttranscriptional processing and is found in very different lengths during its lifetime in the cell. The precursor transcript is extended on both the 5' and 3' ends of the cloverleaf core, and these extensions get trimmed before addition of the 3'-CCA and aminoacylation. We studied the thermodynamics and structures of the precursor tRNA and of late-transcriptional intermediates of the cloverleaf structure. We examined RNA folding at both the secondary and tertiary structural levels using multiple biochemical and biophysical approaches. Our findings suggest that perhaps nature has selected for a single-base addition to control folding to the functional 3D structure. In near-cellular conditions, yeast tRNAPhe and E. coli tRNAAla transcripts fold in a single, cooperative transition only when nearly all of the nucleotides in the cloverleaf are transcribed by indirectly enhancing folding cooperativity. Furthermore, native extensions on the 5' and 3' ends do not interfere with cooperative core folding. This highly controlled cooperative folding has implications for recognition of tRNA by processing and modification enzymes and quality control of tRNA in cells.
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26
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Yamagami R, Huang R, Bevilacqua PC. Cellular Concentrations of Nucleotide Diphosphate-Chelated Magnesium Ions Accelerate Catalysis by RNA and DNA Enzymes. Biochemistry 2019; 58:3971-3979. [PMID: 31512860 DOI: 10.1021/acs.biochem.9b00578] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
RNAs are involved in myriad cellular events. In general, RNA function is affected by cellular conditions. For instance, molecular crowding promotes RNA folding through compaction of the RNA. Metabolites generally destabilize RNA secondary structure, which improves RNA folding cooperativity and increases the fraction of functional RNA. Our recent studies demonstrate that cellular concentrations of amino acid-chelated magnesium (aaCM) stimulate RNA folding and catalysis while protecting RNAs from magnesium ion-induced degradation. However, effects of other cellular magnesium ion chelators on RNA function have not been tested. Herein, we report that nucleotide diphosphate-chelated magnesium, which is of intermediate strength, promotes RNA catalysis much like aaCM. Nucleotides are some of the major metabolites in cells and have one to three phosphates, which have increasingly tight binding of magnesium. On the basis of binding calculations, ∼85% ATP, ∼40% ADP, and only 5% AMP are estimated to possess a magnesium ion under cellular conditions of 0.50 mM Mg2+free. We tested the self-cleaving activity of the hammerhead ribozyme in the presence of these chelated magnesium species. Our results indicate that NTP-chelated magnesium and NMP-chelated magnesium do not appreciably stimulate RNA catalysis, whereas NDP-chelated magnesium promotes RNA catalysis up to 6.5-fold. Inspired by NDP, we observed similar stimulatory effects for several other Mg2+ diphosphate-containing metabolites, including UDP-GlcNAC and UDP-Glc; in addition, we found similar effects for a DNAzyme. Thus, rate stimulatory effects are general with respect to the diphosphate and nucleic acid enzyme. These results implicate magnesium-chelated diphosphate metabolites as general facilitators of RNA function inside cells.
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Affiliation(s)
- Ryota Yamagami
- Department of Chemistry , Pennsylvania State University , University Park , Pennsylvania 16802 , United States.,Center for RNA Molecular Biology , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Ruochuan Huang
- Department of Chemistry , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Philip C Bevilacqua
- Department of Chemistry , Pennsylvania State University , University Park , Pennsylvania 16802 , United States.,Center for RNA Molecular Biology , Pennsylvania State University , University Park , Pennsylvania 16802 , United States.,Department of Biochemistry and Molecular Biology , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
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27
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Welty R, Pabit SA, Katz AM, Calvey GD, Pollack L, Hall KB. Divalent ions tune the kinetics of a bacterial GTPase center rRNA folding transition from secondary to tertiary structure. RNA (NEW YORK, N.Y.) 2018; 24:1828-1838. [PMID: 30254137 PMCID: PMC6239185 DOI: 10.1261/rna.068361.118] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 09/20/2018] [Indexed: 05/22/2023]
Abstract
Folding of an RNA from secondary to tertiary structure often depends on divalent ions for efficient electrostatic charge screening (nonspecific association) or binding (specific association). To measure how different divalent cations modify folding kinetics of the 60 nucleotide Ecoli rRNA GTPase center, we combined stopped-flow fluorescence in the presence of Mg2+, Ca2+, or Sr2+ together with time-resolved small angle X-ray scattering (SAXS) in the presence of Mg2+ to observe the folding process. Immediately upon addition of each divalent ion, the RNA undergoes a transition from an extended state with secondary structure to a more compact structure. Subsequently, specific divalent ions modulate populations of intermediates in conformational ensembles along the folding pathway with transition times longer than 10 msec. Rate constants for the five folding transitions act on timescales from submillisecond to tens of seconds. The sensitivity of RNA tertiary structure to divalent cation identity affects all but the fastest events in RNA folding, and allowed us to identify those states that prefer Mg2+ The GTPase center RNA appears to have optimized its folding trajectory to specifically utilize this most abundant intracellular divalent ion.
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Affiliation(s)
- Robb Welty
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | - Suzette A Pabit
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - Andrea M Katz
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - George D Calvey
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - Lois Pollack
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - Kathleen B Hall
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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28
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mRNAs and lncRNAs intrinsically form secondary structures with short end-to-end distances. Nat Commun 2018; 9:4328. [PMID: 30337527 PMCID: PMC6193969 DOI: 10.1038/s41467-018-06792-z] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 09/20/2018] [Indexed: 12/17/2022] Open
Abstract
The 5' and 3' termini of RNA play important roles in many cellular processes. Using Förster resonance energy transfer (FRET), we show that mRNAs and lncRNAs have an intrinsic propensity to fold in the absence of proteins into structures in which the 5' end and 3' end are ≤7 nm apart irrespective of mRNA length. Computational estimates suggest that the inherent proximity of the ends is a universal property of most mRNA and lncRNA sequences. Only guanosine-depleted RNA sequences with low sequence complexity are unstructured and exhibit end-to-end distances expected for the random coil conformation of RNA. While the biological implications remain to be explored, short end-to-end distances could facilitate the binding of protein factors that regulate translation initiation by bridging mRNA 5' and 3' ends. Furthermore, our studies provide the basis for measuring, computing and manipulating end-to-end distances and secondary structure in RNA in research and biotechnology.
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29
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Denny SK, Bisaria N, Yesselman JD, Das R, Herschlag D, Greenleaf WJ. High-Throughput Investigation of Diverse Junction Elements in RNA Tertiary Folding. Cell 2018; 174:377-390.e20. [PMID: 29961580 PMCID: PMC6053692 DOI: 10.1016/j.cell.2018.05.038] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 03/07/2018] [Accepted: 05/15/2018] [Indexed: 12/21/2022]
Abstract
RNAs fold into defined tertiary structures to function in critical biological processes. While quantitative models can predict RNA secondary structure stability, we are still unable to predict the thermodynamic stability of RNA tertiary structure. Here, we probe conformational preferences of diverse RNA two-way junctions to develop a predictive model for the formation of RNA tertiary structure. We quantitatively measured tertiary assembly energetics of >1,000 of RNA junctions inserted in multiple structural scaffolds to generate a "thermodynamic fingerprint" for each junction. Thermodynamic fingerprints enabled comparison of junction conformational preferences, revealing principles for how sequence influences 3-dimensional conformations. Utilizing fingerprints of junctions with known crystal structures, we generated ensembles for related junctions that predicted their thermodynamic effects on assembly formation. This work reveals sequence-structure-energetic relationships in RNA, demonstrates the capacity for diverse compensation strategies within tertiary structures, and provides a path to quantitative modeling of RNA folding energetics based on "ensemble modularity."
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Affiliation(s)
| | - Namita Bisaria
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Joseph David Yesselman
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Rhiju Das
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - Daniel Herschlag
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Chemistry, Stanford University, Stanford, CA 94305, USA; Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA; ChEM-H Institute, Stanford University, Stanford, CA 94305, USA.
| | - William James Greenleaf
- Program in Biophysics, Stanford University, Stanford, CA 94305, USA; Department of Applied Physics, Stanford University, Stanford, CA 94305, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA.
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30
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Miner JC, García AE. Concentration-dependent and configuration-dependent interactions of monovalent ions with an RNA tetraloop. J Chem Phys 2018; 148:222837. [PMID: 29907048 DOI: 10.1063/1.5019939] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Monovalent salt solutions have strongly coupled interactions with biopolymers, from large polyelectrolytes to small RNA oligomers. High salt concentrations have been known to induce transitions in the structure of RNA, producing non-canonical configurations and even driving RNA to precipitate out of solution. Using all-atom molecular dynamics simulations, we model a monovalent salt species (KCL) at high concentrations (0.1-3m) and calculate the equilibrium distributions of water and ions around a small tetraloop-forming RNA oligomer in a variety of structural arrangements: folded A-RNA (canonical) and Z-RNA (non-canonical) tetraloops and unfolded configurations. From these data, we calculate the ion preferential binding coefficients and Donnan coefficients for the RNA oligomer as a function of concentration and structure. We find that cation accumulation is highest around non-canonical Z-RNA configurations at concentrations below 0.5m, while unfolded configurations accumulate the most co-ions in all concentrations. By contrast, canonical A-RNA structures consistently show the lowest accumulations for all ion species. Water distributions vary markedly with RNA configuration but show little dependency on KCL concentration. Based on Donnan coefficient calculations, the net charge of the solution at the surface of the RNA decreases linearly as a function of salt concentration and becomes net-neutral near 2.5-3m KCL for folded configurations, while unfolded configurations still show a positive solution charge. Our findings show that all-atom molecular dynamics can describe the equilibrium distributions of monovalent salt in the presence of small RNA oligomers at KCL concentrations where ion correlation effects become important. Furthermore, these results provide valuable insights into the distributions of water and ions near the RNA oligomer surface as a function of structural configuration.
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Affiliation(s)
- Jacob Carlson Miner
- Theoretical Biology and Biophysics, MS K710, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Angel Enrique García
- Center for Nonlinear Studies, MS B258, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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31
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Hancock R. Crowding, Entropic Forces, and Confinement: Crucial Factors for Structures and Functions in the Cell Nucleus. BIOCHEMISTRY (MOSCOW) 2018; 83:326-337. [PMID: 29626920 DOI: 10.1134/s0006297918040041] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The view of the cell nucleus as a crowded system of colloid particles and that chromosomes are giant self-avoiding polymers is stimulating rapid advances in our understanding of its structure and activities, thanks to concepts and experimental methods from colloid, polymer, soft matter, and nano sciences and to increased computational power for simulating macromolecules and polymers. This review summarizes current understanding of some characteristics of the molecular environment in the nucleus, of how intranuclear compartments are formed, and of how the genome is highly but precisely compacted, and underlines the crucial, subtle, and sometimes unintuitive effects on structures and reactions of entropic forces caused by the high concentration of macromolecules in the nucleus.
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Affiliation(s)
- R Hancock
- Biosystems Group, Biotechnology Centre, Silesian University of Technology, Poland and Laval University Cancer Research Centre, Québec, G1R2J6, Canada.
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32
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Cellular conditions of weakly chelated magnesium ions strongly promote RNA stability and catalysis. Nat Commun 2018; 9:2149. [PMID: 29858572 PMCID: PMC5984629 DOI: 10.1038/s41467-018-04415-1] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 04/23/2018] [Indexed: 01/06/2023] Open
Abstract
Most RNA folding studies have been performed under non-physiological conditions of high concentrations (≥10 mM) of Mg2+free, while actual cellular concentrations of Mg2+free are only ~1 mM in a background of greater than 50 mM Mg2+total. To uncover cellular behavior of RNA, we devised cytoplasm mimic systems that include biological concentrations of amino acids, which weakly chelate Mg2+. Amino acid-chelated Mg2+ (aaCM) of ~15 mM dramatically increases RNA folding and prevents RNA degradation. Furthermore, aaCM enhance self-cleavage of several different ribozymes, up to 100,000-fold at Mg2+free of just 0.5 mM, indirectly through RNA compaction. Other metabolites that weakly chelate magnesium offer similar beneficial effects, which implies chelated magnesium may enhance RNA function in the cell in the same way. Overall, these results indicate that the states of Mg2+ should not be limited to free and bound only, as weakly bound Mg2+ strongly promotes RNA function under cellular conditions.
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33
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Leamy KA, Yennawar NH, Bevilacqua PC. Molecular Mechanism for Folding Cooperativity of Functional RNAs in Living Organisms. Biochemistry 2018; 57:2994-3002. [PMID: 29733204 PMCID: PMC6726375 DOI: 10.1021/acs.biochem.8b00345] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A diverse set of organisms has adapted to live under extreme conditions. The molecular origin of the stability is unclear, however. It is not known whether the adaptation of functional RNAs, which have intricate tertiary structures, arises from strengthening of tertiary or secondary structure. Herein we evaluate effects of sequence changes on the thermostability of tRNAphe using experimental and computational approaches. To separate out effects of secondary and tertiary structure on thermostability, we modify base pairing strength in the acceptor stem, which does not participate in tertiary structure. In dilute solution conditions, strengthening secondary structure leads to non-two-state thermal denaturation curves and has small effects on thermostability, or the temperature at which tertiary structure and function are lost. In contrast, under cellular conditions with crowding and Mg2+-chelated amino acids, where two-state cooperative unfolding is maintained, strengthening secondary structure enhances thermostability. Investigation of stabilities of each tRNA stem across 44 organisms with a range of optimal growing temperatures revealed that organisms that grow in warmer environments have more stable stems. We also used Shannon entropies to identify positions of higher and lower information content, or sequence conservation, in tRNAphe and found that secondary structures have modest information content allowing them to drive thermal adaptation, while tertiary structures have maximal information content hindering them from participating in thermal adaptation. Base-paired regions with no tertiary structure and modest information content thus offer a facile evolutionary route to enhancing the thermostability of functional RNA by the simple molecular rules of base pairing.
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Affiliation(s)
- Kathleen A Leamy
- Department of Chemistry , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
- Center for RNA Molecular Biology , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Neela H Yennawar
- Huck Institutes of the Life Sciences , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Philip C Bevilacqua
- Department of Chemistry , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
- Center for RNA Molecular Biology , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
- Department of Biochemistry and Molecular Biology , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
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34
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Poudyal R, Cakmak FP, Keating CD, Bevilacqua PC. Physical Principles and Extant Biology Reveal Roles for RNA-Containing Membraneless Compartments in Origins of Life Chemistry. Biochemistry 2018; 57:2509-2519. [PMID: 29560725 PMCID: PMC7276092 DOI: 10.1021/acs.biochem.8b00081] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
This Perspective focuses on RNA in biological and nonbiological compartments resulting from liquid-liquid phase separation (LLPS), with an emphasis on origins of life. In extant cells, intracellular liquid condensates, many of which are rich in RNAs and intrinsically disordered proteins, provide spatial regulation of biomolecular interactions that can result in altered gene expression. Given the diversity of biogenic and abiogenic molecules that undergo LLPS, such membraneless compartments may have also played key roles in prebiotic chemistries relevant to the origins of life. The RNA World hypothesis posits that RNA may have served as both a genetic information carrier and a catalyst during the origin of life. Because of its polyanionic backbone, RNA can undergo LLPS by complex coacervation in the presence of polycations. Phase separation could provide a mechanism for concentrating monomers for RNA synthesis and selectively partition longer RNAs with enzymatic functions, thus driving prebiotic evolution. We introduce several types of LLPS that could lead to compartmentalization and discuss potential roles in template-mediated non-enzymatic polymerization of RNA and other related biomolecules, functions of ribozymes and aptamers, and benefits or penalties imparted by liquid demixing. We conclude that tiny liquid droplets may have concentrated precious biomolecules and acted as bioreactors in the RNA World.
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Affiliation(s)
- Raghav Poudyal
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center for RNA Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Fatma Pir Cakmak
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Christine D. Keating
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Philip C. Bevilacqua
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center for RNA Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, United States
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35
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Leonard KN, Blose JM. Effects of osmolytes and macromolecular crowders on stable GAAA tetraloops and their preference for a CG closing base pair. PeerJ 2018; 6:e4236. [PMID: 29456882 PMCID: PMC5815330 DOI: 10.7717/peerj.4236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 12/15/2017] [Indexed: 11/20/2022] Open
Abstract
Osmolytes and macromolecular crowders have the potential to influence the stability of secondary structure motifs and alter preferences for conserved nucleic acid sequences in vivo. To further understand the cellular function of RNA we observed the effects of a model osmolyte, polyethylene glycol (PEG) 200, and a model macromolecular crowding agent, PEG 8000, on the GAAA tetraloop motif. GAAA tetraloops are conserved, stable tetraloops, and are critical participants in RNA tertiary structure. They also have a thermodynamic preference for a CG closing base pair. The thermal denaturation of model hairpins containing GAAA loops was monitored using UV-Vis spectroscopy in the presence and absence of PEG 200 or PEG 8000. Both of the cosolutes tested influenced the thermodynamic preference for a CG base pair by destabilizing the loop with a CG closing base pair relative to the loop with a GC closing base pair. This result also extended to a related DNA triloop, which provides further evidence that the interactions between the loop and closing base pair are identical for the d(GCA) triloop and the GAAA tetraloop. Our results suggest that in the presence of model PEG molecules, loops with a GC closing base pair may retain some preferential interactions with the cosolutes that are lost in the presence of the CG closing base pair. These results reveal that relatively small structural changes could influence how neutral cosolutes tune the stability and function of secondary structure motifs in vivo.
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Affiliation(s)
- Kaethe N. Leonard
- Department of Chemistry and Biochemistry, State University of New York, The College at Brockport, Brockport, NY, United States of America
| | - Joshua M. Blose
- Department of Chemistry and Biochemistry, State University of New York, The College at Brockport, Brockport, NY, United States of America
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36
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Tanaka M, Matsumoto T, Iida H. Attenuation of guanine oxidation via DNA-mediated electron transfer in a crowded environment using small cosolutes. Org Biomol Chem 2018; 16:6695-6702. [DOI: 10.1039/c8ob02003e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Guanine oxidation induced by photoirradiation on a pyrene-modified oligonucleotide was investigated under molecular crowding using small cosolutes such as glycerol.
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Affiliation(s)
- Makiko Tanaka
- Department of Engineering Science
- Graduate School of Informatics and Engineering
- The University of Electro-Communications
- Chofu
- Japan
| | - Takayuki Matsumoto
- Department of Engineering Science
- Graduate School of Informatics and Engineering
- The University of Electro-Communications
- Chofu
- Japan
| | - Hiroki Iida
- Department of Engineering Science
- Graduate School of Informatics and Engineering
- The University of Electro-Communications
- Chofu
- Japan
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37
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Daher M, Widom JR, Tay W, Walter NG. Soft Interactions with Model Crowders and Non-canonical Interactions with Cellular Proteins Stabilize RNA Folding. J Mol Biol 2017; 430:509-523. [PMID: 29128594 DOI: 10.1016/j.jmb.2017.10.030] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 10/22/2017] [Accepted: 10/30/2017] [Indexed: 12/18/2022]
Abstract
Living cells contain diverse biopolymers, creating a heterogeneous crowding environment, the impact of which on RNA folding is poorly understood. Here, we have used single-molecule fluorescence resonance energy transfer to monitor tertiary structure formation of the hairpin ribozyme as a model to probe the effects of polyethylene glycol and yeast cell extract as crowding agents. As expected, polyethylene glycol stabilizes the docked, catalytically active state of the ribozyme, in part through excluded volume effects; unexpectedly, we found evidence that it additionally displays soft, non-specific interactions with the ribozyme. Yeast extract has a profound effect on folding at protein concentrations 1000-fold lower than found intracellularly, suggesting the dominance of specific interactions over volume exclusion. Gel shift assays and affinity pull-down followed by mass spectrometry identified numerous non-canonical RNA-binding proteins that stabilize ribozyme folding; the apparent chaperoning activity of these ubiquitous proteins significantly compensates for the low-counterion environment of the cell.
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Affiliation(s)
- May Daher
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA; Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Julia R Widom
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA; Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Wendy Tay
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA; Program in Chemical Biology, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Nils G Walter
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA; Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI 48109-1055, USA.
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38
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Whittum ME, Blose JM. Effects of osmolytes on stable UUCG tetraloops and their preference for a CG closing base pair. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2017; 36:583-597. [PMID: 29035162 DOI: 10.1080/15257770.2017.1375518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Osmolytes have the potential to affect the stability of secondary structure motifs and alter preferences for conserved nucleic acid sequences in the cell. To contribute to the understanding of the in vivo function of RNA we observed the effects of different classes of osmolytes on the UNCG tetraloop motif. UNCG tetraloops are the most common and stable of the RNA tetraloops and are nucleation sites for RNA folding. They also have a significant thermodynamic preference for a CG closing base pair. The thermal denaturation of model hairpins containing UUCG loops was monitored using UV-Vis spectroscopy in the presence of osmolytes with different chemical properties. Interestingly, all of the osmolytes tested destabilized the hairpins, but all had little effect on the thermodynamic preference for a CG base pair, except for polyethylene glycol (PEG) 200. PEG 200 destabilized the loop with the CG closing base pair relative to the loop with a GC closing base pair. The destabilization was linear with increasing concentrations of PEG 200, and the slope of this relationship was not perturbed by changes in the hairpin stem outside of the closing pair. This result suggests that in the presence of PEG 200, the UUCG loop with a GC closing base pair may retain some preferential interactions with the cosolute that are lost in the presence of the CG closing base pair. These results reveal that relatively small structural changes may influence how osmolytes tune the stability, and thus the function of a secondary structure motif in vivo.
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Affiliation(s)
- Michelle E Whittum
- a Department of Chemistry and Biochemistry, The College at Brockport , State University of New York , Brockport , New York , USA
| | - Joshua M Blose
- a Department of Chemistry and Biochemistry, The College at Brockport , State University of New York , Brockport , New York , USA
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39
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Choi EK, Ulanowicz KA, Nguyen YAH, Frandsen JK, Mitton-Fry RM. SHAPE analysis of the htrA RNA thermometer from Salmonella enterica. RNA (NEW YORK, N.Y.) 2017; 23:1569-1581. [PMID: 28739676 PMCID: PMC5602114 DOI: 10.1261/rna.062299.117] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 07/18/2017] [Indexed: 06/07/2023]
Abstract
RNA thermometers regulate expression of some genes involved in virulence of pathogenic bacteria such as Yersinia, Neisseria, and Salmonella They often function through temperature-dependent conformational changes that alter accessibility of the ribosome-binding site. The 5'-untranslated region (UTR) of the htrA mRNA from Salmonella enterica contains a very short RNA thermometer. We have systematically characterized the structure and dynamics of this thermometer at single-nucleotide resolution using SHAPE (selective 2'-hydroxyl acylation analyzed by primer extension) assays. Our results confirm that the htrA thermometer adopts the predicted hairpin conformation at low temperatures, with conformational change occurring over a physiological temperature regime. Detailed SHAPE melting curves for individual nucleotides suggest that the thermometer unfolds in a cooperative fashion, with nucleotides from both upper and lower portions of the stem gaining flexibility at a common transition temperature. Intriguingly, analysis of an extended htrA 5' UTR sequence revealed not only the presence of the RNA thermometer, but also an additional, stable upstream structure. We generated and analyzed point mutants of the htrA thermometer, revealing elements that modulate its stability, allowing the hairpin to melt under the slightly elevated temperatures experienced during the infection of a warm-blooded host. This work sheds light on structure-function relationships in htrA and related thermometers, and it also illustrates the utility of SHAPE assays for detailed study of RNA thermometer systems.
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Affiliation(s)
- Edric K Choi
- Department of Chemistry and Biochemistry, Denison University, Granville, Ohio 43023, USA
| | - Kelsey A Ulanowicz
- Department of Chemistry and Biochemistry, Denison University, Granville, Ohio 43023, USA
| | - Yen Anh H Nguyen
- Department of Chemistry and Biochemistry, Denison University, Granville, Ohio 43023, USA
| | - Jane K Frandsen
- Department of Chemistry and Biochemistry, Denison University, Granville, Ohio 43023, USA
| | - Rachel M Mitton-Fry
- Department of Chemistry and Biochemistry, Denison University, Granville, Ohio 43023, USA
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40
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Quantitative tests of a reconstitution model for RNA folding thermodynamics and kinetics. Proc Natl Acad Sci U S A 2017; 114:E7688-E7696. [PMID: 28839094 DOI: 10.1073/pnas.1703507114] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Decades of study of the architecture and function of structured RNAs have led to the perspective that RNA tertiary structure is modular, made of locally stable domains that retain their structure across RNAs. We formalize a hypothesis inspired by this modularity-that RNA folding thermodynamics and kinetics can be quantitatively predicted from separable energetic contributions of the individual components of a complex RNA. This reconstitution hypothesis considers RNA tertiary folding in terms of ΔGalign, the probability of aligning tertiary contact partners, and ΔGtert, the favorable energetic contribution from the formation of tertiary contacts in an aligned state. This hypothesis predicts that changes in the alignment of tertiary contacts from different connecting helices and junctions (ΔGHJH) or from changes in the electrostatic environment (ΔG+/-) will not affect the energetic perturbation from a mutation in a tertiary contact (ΔΔGtert). Consistent with these predictions, single-molecule FRET measurements of folding of model RNAs revealed constant ΔΔGtert values for mutations in a tertiary contact embedded in different structural contexts and under different electrostatic conditions. The kinetic effects of these mutations provide further support for modular behavior of RNA elements and suggest that tertiary mutations may be used to identify rate-limiting steps and dissect folding and assembly pathways for complex RNAs. Overall, our model and results are foundational for a predictive understanding of RNA folding that will allow manipulation of RNA folding thermodynamics and kinetics. Conversely, the approaches herein can identify cases where an independent, additive model cannot be applied and so require additional investigation.
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41
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Nakano SI, Sugimoto N. Model studies of the effects of intracellular crowding on nucleic acid interactions. MOLECULAR BIOSYSTEMS 2017; 13:32-41. [PMID: 27819369 DOI: 10.1039/c6mb00654j] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Molecular interactions and reactions in living cells occur with high concentrations of background molecules and ions. Many research studies have shown that intracellular molecules have characteristics different from those obtained using simple aqueous solutions. To better understand the behavior of biomolecules in intracellular environments, biophysical experiments were conducted under cell-mimicking conditions in a test tube. It has been shown that the molecular environments at the physiological level of macromolecular crowding, spatial confinement, water activity and dielectric constant, have significant effects on the interactions of DNA and RNA for hybridization, higher-order folding, and catalytic activity. The experimental approaches using in vitro model systems are useful to reveal the origin of the environmental effects and to bridge the gap between the behaviors of nucleic acids in vitro and in vivo. This paper highlights the model experiments used to evaluate the influences of intracellular environment on nucleic acid interactions.
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Affiliation(s)
- Shu-Ichi Nakano
- Department of Nanobiochemistry, Faculty of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, 7-1-20, Minatojima-minamimachi, Chuo-ku, Kobe, 650-0047, Japan.
| | - Naoki Sugimoto
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 7-1-20, Minatojima-minamimachi, Chuo-ku, Kobe, 650-0047, Japan. and Graduate School of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, 7-1-20, Minatojima-minamimachi, Chuo-ku, Kobe, 650-0047, Japan
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42
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The 2D Structure of the T. brucei Preedited RPS12 mRNA Is Not Affected by Macromolecular Crowding. J Nucleic Acids 2017; 2017:6067345. [PMID: 28698807 PMCID: PMC5494072 DOI: 10.1155/2017/6067345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 04/04/2017] [Indexed: 11/17/2022] Open
Abstract
Mitochondrial transcript maturation in African trypanosomes requires RNA editing to convert sequence-deficient pre-mRNAs into translatable mRNAs. The different pre-mRNAs have been shown to adopt highly stable 2D folds; however, it is not known whether these structures resemble the in vivo folds given the extreme "crowding" conditions within the mitochondrion. Here, we analyze the effects of macromolecular crowding on the structure of the mitochondrial RPS12 pre-mRNA. We use high molecular mass polyethylene glycol as a macromolecular cosolute and monitor the structure of the RNA globally and with nucleotide resolution. We demonstrate that crowding has no impact on the 2D fold and we conclude that the MFE structure in dilute solvent conditions represents a good proxy for the folding of the pre-mRNA in its mitochondrial solvent context.
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43
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Leamy KA, Yennawar NH, Bevilacqua PC. Cooperative RNA Folding under Cellular Conditions Arises From Both Tertiary Structure Stabilization and Secondary Structure Destabilization. Biochemistry 2017; 56:3422-3433. [PMID: 28657303 DOI: 10.1021/acs.biochem.7b00325] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
RNA folding has been studied extensively in vitro, typically under dilute solution conditions and abiologically high salt concentrations of 1 M Na+ or 10 mM Mg2+. The cellular environment is very different, with 20-40% crowding and only 10-40 mM Na+, 140 mM K+, and 0.5-2.0 mM Mg2+. As such, RNA structures and functions can be radically altered under cellular conditions. We previously reported that tRNAphe secondary and tertiary structures unfold together in a cooperative two-state fashion under crowded in vivo-like ionic conditions, but in a noncooperative multistate fashion under dilute in vitro ionic conditions unless in nonphysiologically high concentrations of Mg2+. The mechanistic basis behind these effects remains unclear, however. To address the mechanism that drives RNA folding cooperativity, we probe effects of cellular conditions on structures and stabilities of individual secondary structure fragments comprising the full-length RNA. We elucidate effects of a diverse set of crowders on tRNA secondary structural fragments and full-length tRNA at three levels: at the nucleotide level by temperature-dependent in-line probing, at the tertiary structure level by small-angle X-ray scattering, and at the global level by thermal denaturation. We conclude that cooperative RNA folding is induced by two overlapping mechanisms: increased stability and compaction of tertiary structure through effects of Mg2+, and decreased stability of certain secondary structure elements through the effects of molecular crowders. These findings reveal that despite having very different chemical makeups RNA and protein can both have weak secondary structures in vivo leading to cooperative folding.
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Affiliation(s)
- Kathleen A Leamy
- Department of Chemistry, ‡Center for RNA Molecular Biology, §Huck Institutes of the Life Sciences, and ⊥Department of Biochemistry and Molecular Biology, Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Neela H Yennawar
- Department of Chemistry, ‡Center for RNA Molecular Biology, §Huck Institutes of the Life Sciences, and ⊥Department of Biochemistry and Molecular Biology, Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Philip C Bevilacqua
- Department of Chemistry, ‡Center for RNA Molecular Biology, §Huck Institutes of the Life Sciences, and ⊥Department of Biochemistry and Molecular Biology, Pennsylvania State University , University Park, Pennsylvania 16802, United States
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Nakano SI, Tanino Y, Hirayama H, Sugimoto N. Thermal Stability of RNA Structures with Bulky Cations in Mixed Aqueous Solutions. Biophys J 2017; 111:1350-1360. [PMID: 27705759 DOI: 10.1016/j.bpj.2016.08.031] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 08/25/2016] [Accepted: 08/29/2016] [Indexed: 11/16/2022] Open
Abstract
Bulky cations are used to develop nucleic-acid-based technologies for medical and technological applications in which nucleic acids function under nonaqueous conditions. In this study, the thermal stability of RNA structures was measured in the presence of various bulky cations in aqueous mixtures with organic solvents or polymer additives. The stability of oligonucleotide, transfer RNA, and polynucleotide structures was decreased in the presence of salts of tetrabutylammonium and tetrapentylammonium ions, and the stability and salt concentration dependences were dependent on cation sizes. The degree to which stability was dependent on salt concentration was correlated with reciprocals of the dielectric constants of mixed solutions, regardless of interactions between the cosolutes and RNA. Our results show that organic solvents affect the strength of electrostatic interactions between RNA and cations. Analysis of ion binding to RNA indicated greater enhancement of cation binding to RNA single strands than to duplexes in media with low dielectric constants. Furthermore, background bulky ions changed the dependence of RNA duplex stability on the concentration of metal ion salts. These unique properties of large tetraalkylammonium ions are useful for controlling the stability of RNA structures and its sensitivity to metal ion salts.
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Affiliation(s)
- Shu-Ichi Nakano
- Department of Nanobiochemistry, Faculty of Frontiers of Innovative Research in Science and Technology, Konan University, Kobe, Japan.
| | - Yuichi Tanino
- Department of Nanobiochemistry, Faculty of Frontiers of Innovative Research in Science and Technology, Konan University, Kobe, Japan
| | - Hidenobu Hirayama
- Department of Nanobiochemistry, Faculty of Frontiers of Innovative Research in Science and Technology, Konan University, Kobe, Japan
| | - Naoki Sugimoto
- Department of Nanobiochemistry, Faculty of Frontiers of Innovative Research in Science and Technology, Konan University, Kobe, Japan; Frontier Institute for Biomolecular Engineering Research, Konan University, Kobe, Japan
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Bingaman JL, Messina KJ, Bevilacqua PC. Probing fast ribozyme reactions under biological conditions with rapid quench-flow kinetics. Methods 2017; 120:125-134. [PMID: 28315484 DOI: 10.1016/j.ymeth.2017.03.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 02/28/2017] [Accepted: 03/10/2017] [Indexed: 11/24/2022] Open
Abstract
Reaction kinetics on the millisecond timescale pervade the protein and RNA fields. To study such reactions, investigators often perturb the system with abiological solution conditions or substrates in order to slow the rate to timescales accessible by hand mixing; however, such perturbations can change the rate-limiting step and obscure key folding and chemical steps that are found under biological conditions. Mechanical methods for collecting data on the millisecond timescale, which allow these perturbations to be avoided, have been developed over the last few decades. These methods are relatively simple and can be conducted on affordable and commercially available instruments. Here, we focus on using the rapid quench-flow technique to study the fast reaction kinetics of RNA enzymes, or ribozymes, which often react on the millisecond timescale under biological conditions. Rapid quench of ribozymes is completely parallel to the familiar hand-mixing approach, including the use of radiolabeled RNAs and fractionation of reactions on polyacrylamide gels. We provide tips on addressing and preventing common problems that can arise with the rapid-quench technique. Guidance is also offered on ensuring the ribozyme is properly folded and fast-reacting. We hope that this article will facilitate the broader use of rapid-quench instrumentation to study fast-reacting ribozymes under biological reaction conditions.
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Affiliation(s)
- Jamie L Bingaman
- Department of Chemistry and Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA 16802, United States.
| | - Kyle J Messina
- Department of Chemistry and Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA 16802, United States
| | - Philip C Bevilacqua
- Department of Chemistry and Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA 16802, United States; Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, United States.
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Miner JC, García AE. Equilibrium Denaturation and Preferential Interactions of an RNA Tetraloop with Urea. J Phys Chem B 2017; 121:3734-3746. [PMID: 28181434 DOI: 10.1021/acs.jpcb.6b10767] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Urea is an important organic cosolute with implications in maintaining osmotic stress in cells and differentially stabilizing ensembles of folded biomolecules. We report an equilibrium study of urea-induced denaturation of a hyperstable RNA tetraloop through unbiased replica exchange molecular dynamics. We find that, in addition to destabilizing the folded state, urea smooths the RNA free energy landscape by destabilizing specific configurations, and forming favorable interactions with RNA nucleobases. A linear concentration-dependence of the free energy (m-value) is observed, in agreement with the results of other RNA hairpins and proteins. Additionally, analysis of the hydrogen-bonding and stacking interactions within RNA primarily show temperature-dependence, while interactions between RNA and urea primarily show concentration-dependence. Our findings provide valuable insight into the effects of urea on RNA folding and describe the thermodynamics of a basic RNA hairpin as a function of solution chemistry.
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Affiliation(s)
- Jacob C Miner
- Theoretical Biology and Biophysics, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.,Center for Nonlinear Studies, CNLS, MS B258, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Angel E García
- Center for Nonlinear Studies, CNLS, MS B258, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
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Ferreira LA, Uversky VN, Zaslavsky BY. Role of solvent properties of water in crowding effects induced by macromolecular agents and osmolytes. MOLECULAR BIOSYSTEMS 2017; 13:2551-2563. [DOI: 10.1039/c7mb00436b] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Dipolarity/polarizability of water in polymer mixtures may be additive, reduced or enhanced depending on the composition of the mixture.
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Affiliation(s)
| | - V. N. Uversky
- Department of Molecular Medicine
- Morsant College of Medicine
- University of South Florida
- Tampa
- USA
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Thoring L, Wüstenhagen DA, Borowiak M, Stech M, Sonnabend A, Kubick S. Cell-Free Systems Based on CHO Cell Lysates: Optimization Strategies, Synthesis of "Difficult-to-Express" Proteins and Future Perspectives. PLoS One 2016; 11:e0163670. [PMID: 27684475 PMCID: PMC5042383 DOI: 10.1371/journal.pone.0163670] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 09/11/2016] [Indexed: 11/18/2022] Open
Abstract
Nowadays, biotechnological processes play a pivotal role in target protein production. In this context, Chinese Hamster Ovary (CHO) cells are one of the most prominent cell lines for the expression of recombinant proteins and revealed as a safe host for nearly 40 years. Nevertheless, the major bottleneck of common in vivo protein expression platforms becomes obvious when looking at the production of so called “difficult-to-express” proteins. This class of proteins comprises in particular several ion channels and multipass membrane proteins as well as cytotoxic proteins. To enhance the production of “difficult-to-express” proteins, alternative technologies were developed, mainly based on translationally active cell lysates. These so called “cell-free” protein synthesis systems enable an efficient production of different classes of proteins. Eukaryotic cell-free systems harboring endogenous microsomal structures for the synthesis of functional membrane proteins and posttranslationally modified proteins are of particular interest for future applications. Therefore, we present current developments in cell-free protein synthesis based on translationally active CHO cell extracts, underlining the high potential of this platform. We present novel results highlighting the optimization of protein yields, the synthesis of various “difficult-to-express” proteins and the cotranslational incorporation of non-standard amino acids, which was exemplarily demonstrated by residue specific labeling of the glycoprotein Erythropoietin and the multimeric membrane protein KCSA.
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Affiliation(s)
- Lena Thoring
- Department of Cell-free and Cell-based Bioproduction, Branch Bioanalysis and Bioprocesses, Fraunhofer-Institute for Cell Therapy and Immunology (IZI-BB), Potsdam-Golm, Germany
- Institute for Biotechnology, Technical University of Berlin (TUB), Gustav-Meyer-Allee 25, 13355, Berlin
| | - Doreen A. Wüstenhagen
- Department of Cell-free and Cell-based Bioproduction, Branch Bioanalysis and Bioprocesses, Fraunhofer-Institute for Cell Therapy and Immunology (IZI-BB), Potsdam-Golm, Germany
| | - Maria Borowiak
- Department of Cell-free and Cell-based Bioproduction, Branch Bioanalysis and Bioprocesses, Fraunhofer-Institute for Cell Therapy and Immunology (IZI-BB), Potsdam-Golm, Germany
| | - Marlitt Stech
- Department of Cell-free and Cell-based Bioproduction, Branch Bioanalysis and Bioprocesses, Fraunhofer-Institute for Cell Therapy and Immunology (IZI-BB), Potsdam-Golm, Germany
| | - Andrei Sonnabend
- Department of Cell-free and Cell-based Bioproduction, Branch Bioanalysis and Bioprocesses, Fraunhofer-Institute for Cell Therapy and Immunology (IZI-BB), Potsdam-Golm, Germany
- Institute for Biotechnology, Technical University of Berlin (TUB), Gustav-Meyer-Allee 25, 13355, Berlin
| | - Stefan Kubick
- Department of Cell-free and Cell-based Bioproduction, Branch Bioanalysis and Bioprocesses, Fraunhofer-Institute for Cell Therapy and Immunology (IZI-BB), Potsdam-Golm, Germany
- * E-mail:
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Abstract
Deciphering the folding pathways and predicting the structures of complex three-dimensional biomolecules is central to elucidating biological function. RNA is single-stranded, which gives it the freedom to fold into complex secondary and tertiary structures. These structures endow RNA with the ability to perform complex chemistries and functions ranging from enzymatic activity to gene regulation. Given that RNA is involved in many essential cellular processes, it is critical to understand how it folds and functions in vivo. Within the last few years, methods have been developed to probe RNA structures in vivo and genome-wide. These studies reveal that RNA often adopts very different structures in vivo and in vitro, and provide profound insights into RNA biology. Nonetheless, both in vitro and in vivo approaches have limitations: studies in the complex and uncontrolled cellular environment make it difficult to obtain insight into RNA folding pathways and thermodynamics, and studies in vitro often lack direct cellular relevance, leaving a gap in our knowledge of RNA folding in vivo. This gap is being bridged by biophysical and mechanistic studies of RNA structure and function under conditions that mimic the cellular environment. To date, most artificial cytoplasms have used various polymers as molecular crowding agents and a series of small molecules as cosolutes. Studies under such in vivo-like conditions are yielding fresh insights, such as cooperative folding of functional RNAs and increased activity of ribozymes. These observations are accounted for in part by molecular crowding effects and interactions with other molecules. In this review, we report milestones in RNA folding in vitro and in vivo and discuss ongoing experimental and computational efforts to bridge the gap between these two conditions in order to understand how RNA folds in the cell.
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The structural stability and catalytic activity of DNA and RNA oligonucleotides in the presence of organic solvents. Biophys Rev 2016; 8:11-23. [PMID: 28510143 DOI: 10.1007/s12551-015-0188-0] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 12/03/2015] [Indexed: 01/02/2023] Open
Abstract
Organic solvents and apolar media are used in the studies of nucleic acids to modify the conformation and function of nucleic acids, to improve solubility of hydrophobic ligands, to construct molecular scaffolds for organic synthesis, and to study molecular crowding effects. Understanding how organic solvents affect nucleic acid interactions and identifying the factors that dominate solvent effects are important for the creation of oligonucleotide-based technologies. This review describes the structural and catalytic properties of DNA and RNA oligonucleotides in organic solutions and in aqueous solutions with organic cosolvents. There are several possible mechanisms underlying the effects of organic solvents on nucleic acid interactions. The reported results emphasize the significance of the osmotic pressure effect and the dielectric constant effect in addition to specific interactions with nucleic acid strands. This review will serve as a guide for the selection of solvent systems based on the purpose of the nucleic acid-based experiments.
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