1
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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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2
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Alternative RNA Conformations: Companion or Combatant. Genes (Basel) 2022; 13:genes13111930. [DOI: 10.3390/genes13111930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 10/19/2022] [Accepted: 10/19/2022] [Indexed: 11/04/2022] Open
Abstract
RNA molecules, in one form or another, are involved in almost all aspects of cell physiology, as well as in disease development. The diversity of the functional roles of RNA comes from its intrinsic ability to adopt complex secondary and tertiary structures, rivaling the diversity of proteins. The RNA molecules form dynamic ensembles of many interconverting conformations at a timescale of seconds, which is a key for understanding how they execute their cellular functions. Given the crucial role of RNAs in various cellular processes, we need to understand the RNA molecules from a structural perspective. Central to this review are studies aimed at revealing the regulatory role of conformational equilibria in RNA in humans to understand genetic diseases such as cancer and neurodegenerative diseases, as well as in pathogens such as bacteria and viruses so as to understand the progression of infectious diseases. Furthermore, we also summarize the prior studies on the use of RNA structures as platforms for the rational design of small molecules for therapeutic applications.
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3
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Wang Y, Yuan J, Dong S, Hao J. Multilayer-Stabilized Water-in-Water Emulsions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:4713-4721. [PMID: 35384674 DOI: 10.1021/acs.langmuir.2c00271] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Water-in-water (W/W) emulsions are of interest for various applications due to their inherent biocompatibility, ultralow interfacial tensions, and large interface thickness. However, it is still challenging to prepare stable W/W emulsions with tailored phase architectures compared to oil-in-water (O/W) and water-in-oil (W/O) emulsions. Here, we report a multilayer-stabilized W/W emulsion composed of poly(ethylene glycol)/dextran in the presence of DNA strands. The W/W emulsions present onion-ring-like structures, which are interpreted by a nanofluid film model. Emulsion behavior, e.g., stability, interface tension, etc., can be controlled by the type of DNA (single or double strands), DNA concentration, and volume fraction of dispersed phase. Our findings could broaden the preparation of novel emulsions for potential applications in emulsion polymerization, new media of homogeneous catalysis, and DNA transportation of water-in-water media.
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Affiliation(s)
- Yitong Wang
- Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, Shandong University, Jinan 250100, China
| | - Jin Yuan
- Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, Shandong University, Jinan 250100, China
| | - Shuli Dong
- Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, Shandong University, Jinan 250100, China
| | - Jingcheng Hao
- Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, Shandong University, Jinan 250100, China
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4
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Peng H, Lelievre A, Landenfeld K, Müller S, Chen IA. Vesicle encapsulation stabilizes intermolecular association and structure formation of functional RNA and DNA. Curr Biol 2022; 32:86-96.e6. [PMID: 34762821 PMCID: PMC8752491 DOI: 10.1016/j.cub.2021.10.047] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 09/02/2021] [Accepted: 10/21/2021] [Indexed: 01/12/2023]
Abstract
During the origin of life, encapsulation of RNA inside vesicles is believed to have been a defining feature of the earliest cells (protocells). The confined biophysical environment provided by membrane encapsulation differs from that of bulk solution and has been shown to increase activity as well as evolutionary rate for functional RNA. However, the structural basis of the effect on RNA has not been clear. Here, we studied how encapsulation of the hairpin ribozyme inside model protocells affects ribozyme kinetics, ribozyme folding into the active conformation, and cleavage and ligation activities. We further examined the effect of encapsulation on the folding of a stem-loop RNA structure and on the formation of a triplex structure in a pH-sensitive DNA switch. The results indicate that encapsulation promotes RNA-RNA association, both intermolecular and intramolecular, and also stabilizes tertiary folding, including the docked conformation characteristic of the active hairpin ribozyme and the triplex structure. The effects of encapsulation were sufficient to rescue the activity of folding-deficient mutants of the hairpin ribozyme. Stabilization of multiple modes of nucleic acid folding and interaction thus enhanced the activity of encapsulated nucleic acids. Increased association between RNA molecules may facilitate the formation of more complex structures and cooperative interactions. These effects could promote the emergence of biological functions in an "RNA world" and may have utility in the construction of minimal synthetic cells.
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Affiliation(s)
- Huan Peng
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA 90095, USA
| | - Amandine Lelievre
- Institute of Biochemistry, University of Greifswald, 17487 Greifswald, Germany
| | | | - Sabine Müller
- Institute of Biochemistry, University of Greifswald, 17487 Greifswald, Germany
| | - Irene A. Chen
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA 90095, USA,Lead Contact:
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5
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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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6
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Zhang Y, Chen Y, Yang X, He X, Li M, Liu S, Wang K, Liu J, Mann S. Giant Coacervate Vesicles As an Integrated Approach to Cytomimetic Modeling. J Am Chem Soc 2021; 143:2866-2874. [PMID: 33566601 DOI: 10.1021/jacs.0c12494] [Citation(s) in RCA: 74] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Although giant unilamellar vesicles (GUVs) have been extensively studied as synthetic cell-like microcompartments, their applicability as cytomimetic models is severely compromised by low levels of membrane permeability, low encapsulation efficiencies, and high physicochemical instability. Here, we develop an integrated cytomimetic model comprising a macromolecularly crowded interior with high sequestration efficiency and enclosed within a phospholipid membrane that is permeable to molecules below a molecular weight cutoff of ca. 4 kDa. The protocells are readily prepared by spontaneous assembly of a phospholipid membrane on the surface of preformed polynucleotide/polysaccharide coacervate microdroplets and are designated as giant coacervate vesicles (GCVs). Partial anchoring of the GCV membrane to the underlying coacervate phase results in increased robustness, lower membrane fluidity, and increased permeability compared with GUV counterparts. As a consequence, enzyme and ribozyme catalysis can be triggered in the molecularly crowded interior of the GCV but not inside the GUVs when small molecule substrates or inducers are present in the external environment. By integrating processes of membrane-mediated compartmentalization and liquid-liquid microphase separation, GCVs could offer substantial advantages as cytomimetic models, synthetic protocells, and artificial biomolecular microreactors.
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Affiliation(s)
- Yanwen Zhang
- College of Chemistry and Chemical Engineering, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082, P. R. China
| | - Yufeng Chen
- College of Chemistry and Chemical Engineering, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082, P. R. China
| | - Xiaohai Yang
- College of Chemistry and Chemical Engineering, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082, P. R. China
| | - Xiaoxiao He
- College of Biology, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082, P. R. China
| | | | - Songyang Liu
- College of Chemistry and Chemical Engineering, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082, P. R. China
| | - Kemin Wang
- College of Chemistry and Chemical Engineering, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082, P. R. China
| | - Jianbo Liu
- College of Chemistry and Chemical Engineering, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082, P. R. China
| | - Stephen Mann
- School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
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7
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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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8
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NMR analysis of nucleotide π-stacking in prebiotically relevant crowded environment. Commun Chem 2020; 3:51. [PMID: 36703483 PMCID: PMC9814533 DOI: 10.1038/s42004-020-0300-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Accepted: 04/07/2020] [Indexed: 01/29/2023] Open
Abstract
The prebiotic soup of a putative 'RNA World' would have been replete with a plethora of molecules resulting from complex chemical syntheses and exogeneous delivery. The presence of background molecules could lead to molecular crowding, potentially affecting the course of the reactions facilitated therein. Using NMR spectroscopy, we have analyzed the effect of crowding on the stacking ability of RNA monomers. Our findings corroborate that the purines stack more efficiently than the pyrimidine ribonucleotides. This competence is further enhanced in the presence of a crowding agent. This enhanced stacking could result in greater sequestration of the purine monomers, putting their ready availability for relevant nonenzymatic reactions into question. Thus, this study demonstrates the need for systematic characterization of molecular crowding in the context of prebiotically pertinent processes. Unraveling such phenomena is essential for our understanding of the transition from abiotic to biotic, during the origin of life.
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9
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Ganser LR, Kelly ML, Herschlag D, Al-Hashimi HM. The roles of structural dynamics in the cellular functions of RNAs. Nat Rev Mol Cell Biol 2020; 20:474-489. [PMID: 31182864 DOI: 10.1038/s41580-019-0136-0] [Citation(s) in RCA: 263] [Impact Index Per Article: 65.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
RNAs fold into 3D structures that range from simple helical elements to complex tertiary structures and quaternary ribonucleoprotein assemblies. The functions of many regulatory RNAs depend on how their 3D structure changes in response to a diverse array of cellular conditions. In this Review, we examine how the structural characterization of RNA as dynamic ensembles of conformations, which form with different probabilities and at different timescales, is improving our understanding of RNA function in cells. We discuss the mechanisms of gene regulation by microRNAs, riboswitches, ribozymes, post-transcriptional RNA modifications and RNA-binding proteins, and how the cellular environment and processes such as liquid-liquid phase separation may affect RNA folding and activity. The emerging RNA-ensemble-function paradigm is changing our perspective and understanding of RNA regulation, from in vitro to in vivo and from descriptive to predictive.
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Affiliation(s)
- Laura R Ganser
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Megan L Kelly
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Daniel Herschlag
- Department of Biochemistry, Stanford ChEM-H Chemistry, Engineering, and Medicine for Human Health, Stanford University, Stanford, CA, USA.,Department of Chemical Engineering, Stanford ChEM-H Chemistry, Engineering, and Medicine for Human Health, Stanford University, Stanford, CA, USA.,Department of Chemistry, Stanford ChEM-H Chemistry, Engineering, and Medicine for Human Health, Stanford University, Stanford, CA, USA
| | - Hashim M Al-Hashimi
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA. .,Department of Chemistry, Duke University, Durham, NC, USA.
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10
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Rahman MS, Gulshan MA, Matsumura S, Ikawa Y. Polyethylene glycol molecular crowders enhance the catalytic ability of bimolecular bacterial RNase P ribozymes. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2020; 39:715-729. [PMID: 32039645 DOI: 10.1080/15257770.2019.1687909] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The modular structure of bacterial ribonuclease P (RNase P) ribozymes, which recognize tertiary structures of precursor tRNAs (pre-tRNAs) to cleave their 5' leader sequence, can be dissected physically into the two structured domain RNAs (S-domain and C-domain). Separately prepared S-domain RNA and C-domain RNA assemble to form bimolecular forms of RNase P ribozymes. We analyzed the effects of polyethylene glycols (PEGs) on pre-tRNA cleavage catalyzed by bimolecular RNase P ribozymes to examine the effects of molecular crowding on the reaction. PEG molecular crowders significantly enhanced the activities of bimolecular RNase P ribozymes, some of which were hardly active without PEGs.
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Affiliation(s)
- Md Sohanur Rahman
- Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Gofuku 3190, Toyama, Japan.,Graduate School of Innovative Life Science, University of Toyama, Gofuku 3190, Toyama, Japan
| | - Mst Ara Gulshan
- Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Gofuku 3190, Toyama, Japan.,Graduate School of Innovative Life Science, University of Toyama, Gofuku 3190, Toyama, Japan
| | - Shigeyoshi Matsumura
- Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Gofuku 3190, Toyama, Japan.,Graduate School of Innovative Life Science, University of Toyama, Gofuku 3190, Toyama, Japan
| | - Yoshiya Ikawa
- Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Gofuku 3190, Toyama, Japan.,Graduate School of Innovative Life Science, University of Toyama, Gofuku 3190, Toyama, Japan
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11
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Ward FR, Watson ZL, Ad O, Schepartz A, Cate JHD. Defects in the Assembly of Ribosomes Selected for β-Amino Acid Incorporation. Biochemistry 2019; 58:4494-4504. [PMID: 31607123 PMCID: PMC8435211 DOI: 10.1021/acs.biochem.9b00746] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Ribosome engineering has emerged as a promising field in synthetic biology, particularly concerning the production of new sequence-defined polymers. Mutant ribosomes have been developed that improve the incorporation of several nonstandard monomers including d-amino acids, dipeptides, and β-amino acids into polypeptide chains. However, there remains little mechanistic understanding of how these ribosomes catalyze incorporation of these new substrates. Here, we probed the properties of a mutant ribosome-P7A7-evolved for better in vivo β-amino acid incorporation through in vitro biochemistry and cryo-electron microscopy. Although P7A7 is a functional ribosome in vivo, it is inactive in vitro, and assembles poorly into 70S ribosome complexes. Structural characterization revealed large regions of disorder in the peptidyltransferase center and nearby features, suggesting a defect in assembly. Comparison of RNA helix and ribosomal protein occupancy with other assembly intermediates revealed that P7A7 is stalled at a late stage in ribosome assembly, explaining its weak activity. These results highlight the importance of ensuring efficient ribosome assembly during ribosome engineering toward new catalytic abilities.
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Affiliation(s)
- Fred R. Ward
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, CA
| | - Zoe L. Watson
- Department of Chemistry, University of California-Berkeley, Berkeley, CA
| | - Omer Ad
- Department of Chemistry, Yale University, New Haven, CT
| | - Alanna Schepartz
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, CA
- Department of Chemistry, University of California-Berkeley, Berkeley, CA
- Department of Chemistry, Yale University, New Haven, CT
| | - Jamie H. D. Cate
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, CA
- Department of Chemistry, University of California-Berkeley, Berkeley, CA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA
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12
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Rahman MM, Matsumura S, Ikawa Y. Effects of molecular crowding on a bimolecular group I ribozyme and its derivative that self-assembles to form ribozyme oligomers. Biochem Biophys Res Commun 2018; 507:136-141. [DOI: 10.1016/j.bbrc.2018.10.188] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 10/29/2018] [Indexed: 01/04/2023]
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13
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Paudel BP, Fiorini E, Börner R, Sigel RKO, Rueda DS. Optimal molecular crowding accelerates group II intron folding and maximizes catalysis. Proc Natl Acad Sci U S A 2018; 115:11917-11922. [PMID: 30397128 PMCID: PMC6255197 DOI: 10.1073/pnas.1806685115] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Unlike in vivo conditions, group II intron ribozymes are known to require high magnesium(II) concentrations ([Mg2+]) and high temperatures (42 °C) for folding and catalysis in vitro. A possible explanation for this difference is the highly crowded cellular environment, which can be mimicked in vitro by macromolecular crowding agents. Here, we combined bulk activity assays and single-molecule Förster Resonance Energy Transfer (smFRET) to study the influence of polyethylene glycol (PEG) on catalysis and folding of the ribozyme. Our activity studies reveal that PEG reduces the [Mg2+] required, and we found an "optimum" [PEG] that yields maximum activity. smFRET experiments show that the most compact state population, the putative active state, increases with increasing [PEG]. Dynamic transitions between folded states also increase. Therefore, this study shows that optimal molecular crowding concentrations help the ribozyme not only to reach the native fold but also to increase its in vitro activity to approach that in physiological conditions.
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Affiliation(s)
- Bishnu P Paudel
- Molecular Virology, Department of Medicine, Imperial College London, London W12 0NN, United Kingdom
- Single Molecule Imaging, Medical Research Council London Institute of Medical Sciences, London W12 0NN, United Kingdom
| | - Erica Fiorini
- Department of Chemistry, University of Zurich, 8057 Zurich, Switzerland
| | - Richard Börner
- Department of Chemistry, University of Zurich, 8057 Zurich, Switzerland
| | - Roland K O Sigel
- Department of Chemistry, University of Zurich, 8057 Zurich, Switzerland
| | - David S Rueda
- Molecular Virology, Department of Medicine, Imperial College London, London W12 0NN, United Kingdom;
- Single Molecule Imaging, Medical Research Council London Institute of Medical Sciences, London W12 0NN, United Kingdom
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14
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Saha R, Verbanic S, Chen IA. Lipid vesicles chaperone an encapsulated RNA aptamer. Nat Commun 2018; 9:2313. [PMID: 29899431 PMCID: PMC5998061 DOI: 10.1038/s41467-018-04783-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Accepted: 05/22/2018] [Indexed: 01/08/2023] Open
Abstract
The organization of molecules into cells is believed to have been critical for the emergence of living systems. Early protocells likely consisted of RNA functioning inside vesicles made of simple lipids. However, little is known about how encapsulation would affect the activity and folding of RNA. Here we find that confinement of the malachite green RNA aptamer inside fatty acid vesicles increases binding affinity and locally stabilizes the bound conformation of the RNA. The vesicle effectively ‘chaperones’ the aptamer, consistent with an excluded volume mechanism due to confinement. Protocellular organization thereby leads to a direct benefit for the RNA. Coupled with previously described mechanisms by which encapsulated RNA aids membrane growth, this effect illustrates how the membrane and RNA might cooperate for mutual benefit. Encapsulation could thus increase RNA fitness and the likelihood that functional sequences would emerge during the origin of life. So far little is known about how encapsulation affects the activity and folding of RNA, which is of interest for understanding the origin of cellular life. Here the authors show that encapsulation of functional RNA in vesicles increases RNA activity and improves RNA folding through a biophysical confinement effect.
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Affiliation(s)
- Ranajay Saha
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, 93106, USA
| | - Samuel Verbanic
- Program in Biomolecular Sciences and Engineering, University of California, Santa Barbara, CA, 93106, USA
| | - Irene A Chen
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, 93106, USA. .,Program in Biomolecular Sciences and Engineering, University of California, Santa Barbara, CA, 93106, USA.
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15
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Chen G, Xu W, Lu D, Wu J, Liu Z. Markov-state model for CO 2 binding with carbonic anhydrase under confinement. J Chem Phys 2018; 148:035101. [PMID: 29352785 DOI: 10.1063/1.5003298] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Enzyme immobilization with a nanostructure material can enhance its stability and facilitate reusability. However, the apparent activity is often compromised due to additional diffusion barriers and complex interactions with the substrates and solvent molecules. The present study elucidates the effects of the surface hydrophobicity of nano-confinement on CO2 diffusion to the active site of human carbonic anhydrase II (CA), an enzyme that is able to catalyze CO2 hydration at extremely high turnover rates. Using the Markov-state model in combination with coarse-grained molecular dynamics simulations, we demonstrate that a hydrophobic cage increases CO2 local density but hinders its diffusion towards the active site of CA under confinement. By contrast, a hydrophilic cage hinders CO2 adsorption but promotes its binding with CA. An optimal surface hydrophobicity can be identified to maximize both the CO2 occupation probability and the diffusion rate. The simulation results offer insight into understanding enzyme performance under nano-confinement and help us to advance broader applications of CA for CO2 absorption and recovery.
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Affiliation(s)
- Gong Chen
- Ministry of Education Key Laboratory of Industrial Biocatalysis, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Weina Xu
- Ministry of Education Key Laboratory of Industrial Biocatalysis, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Diannan Lu
- Ministry of Education Key Laboratory of Industrial Biocatalysis, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Jianzhong Wu
- Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, USA
| | - Zheng Liu
- Ministry of Education Key Laboratory of Industrial Biocatalysis, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
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16
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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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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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18
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Marianelli AM, Miller BM, Keating CD. Impact of macromolecular crowding on RNA/spermine complex coacervation and oligonucleotide compartmentalization. SOFT MATTER 2018; 14:368-378. [PMID: 29265152 DOI: 10.1039/c7sm02146a] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report the effect of neutral macromolecular crowders poly(ethylene glycol) (PEG) (8 kDa) and Ficoll (70 kDa) on liquid-liquid phase separation in a polyuridylic acid (polyU)/spermine complex coacervate system. The addition of PEG decreased both the amount of spermine required for phase separation and the coacervation temperature (TC). We interpret these effects on phase behavior as arising due to excluded volume and preferential interactions on both the secondary structure/condensation of spermine-associated polyU molecules and on the association of soluble polyU/spermine polyelectrolyte complexes to form coacervate droplets. Examination of coacervates formed in the presence of fluorescently-labeled PEG or Ficoll crowders indicated that Ficoll is accumulated while PEG is excluded from the coacervate phase, which provides further insight into the differences in phase behavior. Crowding agents impact distribution of a biomolecular solute: partitioning of a fluorescently-labeled U15 RNA oligomer into the polyU/spermine coacervates was increased approximately two-fold by 20 wt% Ficoll 70 kDa and by more than two orders of magnitude by 20 wt% PEG 8 kDa. The volume of the coacervate phase decreased in the presence of crowder relative to a dilute buffer solution. These findings indicate that potential impacts of macromolecular crowding on phase behavior and solute partitioning should be considered in model systems for intracellular membraneless organelles.
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Affiliation(s)
- A M Marianelli
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
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19
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Phromsiri P, Gerling RR, Blose JM. The effects of a neutral cosolute on the B to Z transition for DNA duplexes incorporating both CG and CA steps. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2017; 36:690-703. [PMID: 29185909 DOI: 10.1080/15257770.2017.1388395] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In the cell, nearly 40% of the volume is occupied by macromolecular crowding agents and smaller osmolytes accumulate in response to environmental stresses. Of particular interest is the influence of osmolytes on the transition of the right-handed B-DNA to the left-handed Z-DNA. Due to the correlation between Z-DNA formation potential and regions of active transcription, Z-DNA is believed to serve a vital role in the transcription process, and changes in osmolyte concentration may influence transcription as a part of the stress response. We utilized circular dichroism spectroscopy to monitor changes in conformation of DNA duplexes containing a full-turn of Z-DNA in the presence and absence of PEG 200. We used PEG 200 as a model neutral cosolute. Sodium ion titrations revealed that PEG 200 influenced the folding of Z-DNA compared to dilute solution conditions by decreasing the free energy of folding, increasing folding cooperativity, and decreasing the in vitro [Na+] and Δn required for folding for all sequences tested, even those that included 40% CA steps instead of the classic CG repeats. Moreover, the presence of 40% PEG 200 induced the Z-form conformation in sequences that would not fully adopt the Z-form structure even in 5 M NaCl. These results suggest that osmolytes may play a significant role in supporting the transient formation of Z-DNA in vivo, and that sequences containing a significant amounts of CA instead of CG repeats may more favorably adopt the Z-conformation as a part of binding and regulatory processes than had been previously considered.
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Affiliation(s)
- Pakinee Phromsiri
- a The College at Brockport , State University of New York, Department of Chemistry and Biochemistry , Brockport , NY
| | - Rebecca R Gerling
- a The College at Brockport , State University of New York, Department of Chemistry and Biochemistry , Brockport , NY
| | - Joshua M Blose
- a The College at Brockport , State University of New York, Department of Chemistry and Biochemistry , Brockport , NY
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20
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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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21
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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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22
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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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23
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Eggert F, Kulikov K, Domnick C, Leifels P, Kath-Schorr S. Iluminated by foreign letters - Strategies for site-specific cyclopropene modification of large functional RNAs via in vitro transcription. Methods 2017; 120:17-27. [PMID: 28454775 DOI: 10.1016/j.ymeth.2017.04.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 04/18/2017] [Accepted: 04/23/2017] [Indexed: 10/19/2022] Open
Abstract
The synthesis of sequence-specifically modified long RNA molecules, which cannot entirely be prepared via solid phase synthesis methods is experimentally challenging. We are using a new approach based on an expanded genetic alphabet preparing site-specifically modified RNA molecules via standard in vitro transcription. In this report, the site-specific labeling of functional RNAs, in particular ribozymes and a long non-coding RNA with cyclopropene moieties, is presented. We provide detailed instructions for RNA labeling via in vitro transcription and include required analytical methods to verify production and identity of the transcript. We further present post-transcriptional inverse electron demand Diels-Alder cycloaddition reactions on the cyclopropene-modified sequences and discuss applications of the genetic alphabet expansion transcription for in vitro preparation of labeled functional RNAs with complex foldings. In detail, the glmS and CPEB3 ribozymes were site-specifically decorated with methyl cyclopropene moieties using the unnatural TPT3CP triphosphate and were proven to be still functional. In addition, the structurally complex A region of the Xist lncRNA (401nt) was site-specifically modified with methyl cyclopropene and detected by fluorescence after cycloaddition reaction with a tetrazine-BODIPY conjugate.
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Affiliation(s)
- Frank Eggert
- LIMES Institute, Chemical Biology & Medicinal Chemistry Unit, University of Bonn, Gerhard-Domagk-Straße 1, 53121 Bonn, Germany
| | - Katharina Kulikov
- LIMES Institute, Chemical Biology & Medicinal Chemistry Unit, University of Bonn, Gerhard-Domagk-Straße 1, 53121 Bonn, Germany
| | - Christof Domnick
- LIMES Institute, Chemical Biology & Medicinal Chemistry Unit, University of Bonn, Gerhard-Domagk-Straße 1, 53121 Bonn, Germany
| | - Philipp Leifels
- LIMES Institute, Chemical Biology & Medicinal Chemistry Unit, University of Bonn, Gerhard-Domagk-Straße 1, 53121 Bonn, Germany
| | - Stephanie Kath-Schorr
- LIMES Institute, Chemical Biology & Medicinal Chemistry Unit, University of Bonn, Gerhard-Domagk-Straße 1, 53121 Bonn, Germany.
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24
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Prebiotic Factors Influencing the Activity of a Ligase Ribozyme. Life (Basel) 2017; 7:life7020017. [PMID: 28383486 PMCID: PMC5492139 DOI: 10.3390/life7020017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 03/28/2017] [Accepted: 04/01/2017] [Indexed: 12/29/2022] Open
Abstract
An RNA-lipid origin of life scenario provides a plausible route for compartmentalized replication of an informational polymer and subsequent division of the container. However, a full narrative to form such RNA protocells implies that catalytic RNA molecules, called ribozymes, can operate in the presence of self-assembled vesicles composed of prebiotically relevant constituents, such as fatty acids. Hereby, we subjected a newly engineered truncated variant of the L1 ligase ribozyme, named tL1, to various environmental conditions that may have prevailed on the early Earth with the objective to find a set of control parameters enabling both tL1-catalyzed ligation and formation of stable myristoleic acid (MA) vesicles. The separate and concurrent effects of temperature, concentrations of Mg2+, MA, polyethylene glycol and various solutes were investigated. The most favorable condition tested consists of 100 mM NaCl, 1 mM Mg2+, 5 mM MA, and 4 °C temperature, whereas the addition of Mg2+-chelating solutes, such as citrate, tRNAs, aspartic acid, and nucleoside triphosphates severely inhibits the reaction. These results further solidify the RNA-lipid world hypothesis and stress the importance of using a systems chemistry approach whereby a wide range of prebiotic factors interfacing with ribozymes are considered.
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25
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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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26
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Abstract
Understanding how life arose is a fundamental problem of biology. Much progress has been made by adopting a synthetic and mechanistic perspective on originating life. We present a current view of the biochemistry of the origin of life, focusing on issues surrounding the emergence of an RNA World in which RNA dominated informational and functional roles. There is cause for optimism on this difficult problem: the prebiotic chemical inventory may not have been as nightmarishly complex as previously thought; the catalytic repertoire of ribozymes continues to expand, approaching the goal of self-replicating RNA; encapsulation in protocells provides evolutionary and biophysical advantages. Nevertheless, major issues remain unsolved, such as the origin of a genetic code. Attention to this field is particularly timely given the accelerating discovery and characterization of exoplanets.
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27
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Kilburn D, Behrouzi R, Lee HT, Sarkar K, Briber RM, Woodson SA. Entropic stabilization of folded RNA in crowded solutions measured by SAXS. Nucleic Acids Res 2016; 44:9452-9461. [PMID: 27378777 PMCID: PMC5100557 DOI: 10.1093/nar/gkw597] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 06/21/2016] [Indexed: 01/29/2023] Open
Abstract
Non-coding RNAs must fold into specific structures that are stabilized by metal ions and other co-solutes in the cell's interior. Large crowder molecules such as PEG stabilize a bacterial group I ribozyme so that the RNA folds in low Mg2+ concentrations typical of the cell's interior. To understand the thermodynamic origins of stabilization by crowder molecules, small angle X-ray scattering was used to measure the folding and helix assembly of a bacterial group I ribozyme at different temperatures and in different MgCl2 and polyethylene glycol (PEG) concentrations. The resulting phase diagrams show that perturbations to folding by each variable do not overlap. A favorable enthalpy change drives the formation of compact, native-like structures, but requires Mg2+ ions at all temperatures studied (5–55°C). PEG reduces the entropic cost of helix assembly and increases correlations between RNA segments at all temperatures. The phase diagrams also revealed a semi-compact intermediate between the unfolded and folded ensemble that is locally more flexible than the unfolded state, as judged by SHAPE modification. These results suggest that environmental variables such as temperature and solute density will favor different types of RNA structures.
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Affiliation(s)
- Duncan Kilburn
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Reza Behrouzi
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Hui-Ting Lee
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Krishnarjun Sarkar
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Robert M Briber
- Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742, USA
| | - Sarah A Woodson
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
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28
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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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29
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Skilandat M, Rowinska-Zyrek M, Sigel RKO. Secondary structure confirmation and localization of Mg2+ ions in the mammalian CPEB3 ribozyme. RNA (NEW YORK, N.Y.) 2016; 22:750-763. [PMID: 26966151 PMCID: PMC4836649 DOI: 10.1261/rna.053843.115] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Accepted: 01/04/2016] [Indexed: 06/05/2023]
Abstract
Most of today's knowledge of the CPEB3 ribozyme, one of the few small self-cleaving ribozymes known to occur in humans, is based on comparative studies with the hepatitis delta virus (HDV) ribozyme, which is highly similar in cleavage mechanism and probably also in structure. Here we present detailed NMR studies of the CPEB3 ribozyme in order to verify the formation of the predicted nested double pseudoknot in solution. In particular, the influence of Mg(2+), the ribozyme's crucial cofactor, on the CPEB3 structure is investigated. NMR titrations, Tb(3+)-induced cleavage, as well as stoichiometry determination by hydroxyquinoline sulfonic acid fluorescence and equilibrium dialysis, are used to evaluate the number, location, and binding mode of Mg(2+)ions. Up to eight Mg(2+)ions interact site-specifically with the ribozyme, four of which are bound with high affinity. The global fold of the CPEB3 ribozyme, encompassing 80%-90% of the predicted base pairs, is formed in the presence of monovalent ions alone. Low millimolar concentrations of Mg(2+)promote a more compact fold and lead to the formation of additional structures in the core of the ribozyme, which contains the inner small pseudoknot and the active site. Several Mg(2+)binding sites, which are important for the functional fold, appear to be located in corresponding locations in the HDV and CPEB3 ribozyme, demonstrating the particular relevance of Mg(2+)for the nested double pseudoknot structure.
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Affiliation(s)
- Miriam Skilandat
- Department of Chemistry, University of Zurich, CH-8057 Zurich, Switzerland
| | | | - Roland K O Sigel
- Department of Chemistry, University of Zurich, CH-8057 Zurich, Switzerland
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30
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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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31
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Tyrrell J, Weeks KM, Pielak GJ. Challenge of mimicking the influences of the cellular environment on RNA structure by PEG-induced macromolecular crowding. Biochemistry 2015; 54:6447-53. [PMID: 26430778 DOI: 10.1021/acs.biochem.5b00767] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
There are large differences between the cellular environment and the conditions widely used to study RNA in vitro. SHAPE RNA structure probing in Escherichia coli cells has shown that the cellular environment stabilizes both long-range and local tertiary interactions in the adenine riboswitch aptamer domain. Synthetic crowding agents are widely used to understand the forces that stabilize RNA structure and in efforts to recapitulate the cellular environment under simplified experimental conditions. Here, we studied the structure and ligand binding ability of the adenine riboswitch in the presence of the macromolecular crowding agent, polyethylene glycol (PEG). Ethylene glycol and low-molecular mass PEGs destabilized RNA structure and caused the riboswitch to sample secondary structures different from those observed in simple buffered solutions or in cells. In the presence of larger PEGs, longer-range loop-loop interactions were more similar to those in cells than in buffer alone, consistent with prior work showing that larger PEGs stabilize compact RNA states. Ligand affinity was weakened by low-molecular mass PEGs but increased with high-molecular mass PEGs, indicating that PEG cosolvents exert complex chemical and steric effects on RNA structure. Regardless of polymer size, however, nucleotide-resolution structural characteristics observed in cells were not recapitulated in PEG solutions. Our results reveal that the cellular environment is difficult to recapitulate in vitro; mimicking the cellular state will likely require a combination of crowding agents and other chemical species.
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Affiliation(s)
- Jillian Tyrrell
- Department of Chemistry, ‡Department of Biochemistry and Biophysics, and §Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States
| | - Kevin M Weeks
- Department of Chemistry, ‡Department of Biochemistry and Biophysics, and §Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States
| | - Gary J Pielak
- Department of Chemistry, ‡Department of Biochemistry and Biophysics, and §Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States
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Effect of Co-solutes on Template-Directed Nonenzymatic Replication of Nucleic Acids. J Mol Evol 2015; 81:72-80. [DOI: 10.1007/s00239-015-9700-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 09/23/2015] [Indexed: 12/14/2022]
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Nakano SI, Kitagawa Y, Yamashita H, Miyoshi D, Sugimoto N. Effects of Cosolvents on the Folding and Catalytic Activities of the Hammerhead Ribozyme. Chembiochem 2015; 16:1803-10. [DOI: 10.1002/cbic.201500139] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Indexed: 11/09/2022]
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Lee HT, Kilburn D, Behrouzi R, Briber RM, Woodson SA. Molecular crowding overcomes the destabilizing effects of mutations in a bacterial ribozyme. Nucleic Acids Res 2015; 43:1170-6. [PMID: 25541198 PMCID: PMC4333387 DOI: 10.1093/nar/gku1335] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 12/01/2014] [Accepted: 12/05/2014] [Indexed: 11/13/2022] Open
Abstract
The native structure of the Azoarcus group I ribozyme is stabilized by the cooperative formation of tertiary interactions between double helical domains. Thus, even single mutations that break this network of tertiary interactions reduce ribozyme activity in physiological Mg(2+) concentrations. Here, we report that molecular crowding comparable to that in the cell compensates for destabilizing mutations in the Azoarcus ribozyme. Small angle X-ray scattering, native polyacrylamide gel electrophoresis and activity assays were used to compare folding free energies in dilute and crowded solutions containing 18% PEG1000. Crowder molecules allowed the wild-type and mutant ribozymes to fold at similarly low Mg(2+) concentrations and stabilized the active structure of the mutant ribozymes under physiological conditions. This compensation helps explains why ribozyme mutations are often less deleterious in the cell than in the test tube. Nevertheless, crowding did not rescue the high fraction of folded but less active structures formed by double and triple mutants. We conclude that crowding broadens the fitness landscape by stabilizing compact RNA structures without improving the specificity of self-assembly.
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Affiliation(s)
- Hui-Ting Lee
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Duncan Kilburn
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA Center for Neutron Scattering Research, National Institute of Standards and Technology, 100 Bureau Dr., Gaithersburg, MD 20899, USA
| | - Reza Behrouzi
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Robert M Briber
- Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742, USA
| | - Sarah A Woodson
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
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Marcano-Velázquez JG, Batey RT. Structure-guided mutational analysis of gene regulation by the Bacillus subtilis pbuE adenine-responsive riboswitch in a cellular context. J Biol Chem 2014; 290:4464-75. [PMID: 25550163 DOI: 10.1074/jbc.m114.613497] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Riboswitches are a broadly distributed form of RNA-based gene regulation in Bacteria and, more rarely, Archaea and Eukarya. Most often found in the 5'-leader sequence of bacterial mRNAs, they are generally composed of two functional domains: a receptor (aptamer) domain that binds an effector molecule and a regulatory domain (or expression platform) that instructs the expression machinery. One of the most studied riboswitches is the Bacillus subtilis adenine-responsive pbuE riboswitch, which regulates gene expression at the transcriptional level, up-regulating expression in response to increased intracellular effector concentrations. In this work, we analyzed sequence and structural elements that contribute to efficient ligand-dependent regulatory activity in a co-transcriptional and cellular context. Unexpectedly, we found that the P1 helix, which acts as the antitermination element of the switch in this RNA, supported ligand-dependent activation of a reporter gene over a broad spectrum of lengths from 3 to 10 bp. This same trend was also observed using a minimal in vitro single-turnover transcription assay, revealing that this behavior is intrinsic to the RNA sequence. We also found that the sequences at the distal tip of the terminator not directly involved in alternative secondary structure formation are highly important for efficient regulation. These data strongly support a model in which the switch is highly localized to the P1 helix adjacent to the ligand-binding pocket that likely presents a local kinetic block to invasion of the aptamer by the terminator.
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Affiliation(s)
- Joan G Marcano-Velázquez
- From the Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0596
| | - Robert T Batey
- From the Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0596
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36
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Saha R, Pohorille A, Chen IA. Molecular crowding and early evolution. ORIGINS LIFE EVOL B 2014; 44:319-24. [PMID: 25585804 DOI: 10.1007/s11084-014-9392-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 10/31/2014] [Indexed: 10/24/2022]
Abstract
The environment of protocells might have been crowded with small molecules and functional and non-specific polymers. In addition to altering conformational equilibria, affecting reaction rates and changing the structure and activity of water, crowding might have enhanced the capabilities of protocells for evolutionary innovation through the creation of extended neutral networks in the fitness landscape.
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Affiliation(s)
- Ranajay Saha
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
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Abstract
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All biological processes take place
in highly crowded cellular
environments. However, the effect that molecular crowding agents have
on the folding and catalytic properties of RNA molecules remains largely
unknown. Here, we have combined single-molecule fluorescence resonance
energy transfer (smFRET) and bulk cleavage assays to determine the
effect of a molecular crowding agents on the folding and catalysis
of a model RNA enzyme, the hairpin ribozyme. Our single-molecule data
reveal that PEG favors the formation of the docked (active) structure
by increasing the docking rate constant with increasing PEG concentrations.
Furthermore, Mg2+ ion-induced folding in the presence of
PEG occurs at concentrations ∼7-fold lower than in the absence
of PEG, near the physiological range (∼1 mM). Lastly, bulk
cleavage assays in the presence of the crowding agent show that the
ribozyme’s activity increases while the heterogeneity decreases.
Our data is consistent with the idea that molecular crowding plays
an important role in the stabilization of ribozyme active conformations in vivo.
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Affiliation(s)
- Bishnu P Paudel
- Department of Medicine, Section of Virology, and Single Molecule Imaging Group, MRC-Clinical Sciences Centre, Imperial College London , Du Cane Road, London W12 0NN, U.K
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Dewey DC, Strulson CA, Cacace DN, Bevilacqua PC, Keating CD. Bioreactor droplets from liposome-stabilized all-aqueous emulsions. Nat Commun 2014; 5:4670. [DOI: 10.1038/ncomms5670] [Citation(s) in RCA: 173] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 07/11/2014] [Indexed: 12/21/2022] Open
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Strulson CA, Boyer JA, Whitman EE, Bevilacqua PC. Molecular crowders and cosolutes promote folding cooperativity of RNA under physiological ionic conditions. RNA (NEW YORK, N.Y.) 2014; 20:331-47. [PMID: 24442612 PMCID: PMC3923128 DOI: 10.1261/rna.042747.113] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Accepted: 11/22/2013] [Indexed: 05/21/2023]
Abstract
Folding mechanisms of functional RNAs under idealized in vitro conditions of dilute solution and high ionic strength have been well studied. Comparatively little is known, however, about mechanisms for folding of RNA in vivo where Mg(2+) ion concentrations are low, K(+) concentrations are modest, and concentrations of macromolecular crowders and low-molecular-weight cosolutes are high. Herein, we apply a combination of biophysical and structure mapping techniques to tRNA to elucidate thermodynamic and functional principles that govern RNA folding under in vivo-like conditions. We show by thermal denaturation and SHAPE studies that tRNA folding cooperativity increases in physiologically low concentrations of Mg(2+) (0.5-2 mM) and K(+) (140 mM) if the solution is supplemented with physiological amounts (∼ 20%) of a water-soluble neutral macromolecular crowding agent such as PEG or dextran. Low-molecular-weight cosolutes show varying effects on tRNA folding cooperativity, increasing or decreasing it based on the identity of the cosolute. For those additives that increase folding cooperativity, the gain is manifested in sharpened two-state-like folding transitions for full-length tRNA over its secondary structural elements. Temperature-dependent SHAPE experiments in the absence and presence of crowders and cosolutes reveal extent of cooperative folding of tRNA on a nucleotide basis and are consistent with the melting studies. Mechanistically, crowding agents appear to promote cooperativity by stabilizing tertiary structure, while those low molecular cosolutes that promote cooperativity stabilize tertiary structure and/or destabilize secondary structure. Cooperative folding of functional RNA under physiological-like conditions parallels the behavior of many proteins and has implications for cellular RNA folding kinetics and evolution.
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Affiliation(s)
- Christopher A. Strulson
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Joshua A. Boyer
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Elisabeth E. Whitman
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Philip C. Bevilacqua
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Corresponding authorE-mail
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Methods for Using New Conceptual Tools and Parameters to Assess RNA Structure by Small-Angle X-Ray Scattering. Methods Enzymol 2014; 549:235-63. [DOI: 10.1016/b978-0-12-801122-5.00011-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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