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Chauvier A, Dandpat SS, Romero R, Walter NG. A nascent riboswitch helix orchestrates robust transcriptional regulation through signal integration. Nat Commun 2024; 15:3955. [PMID: 38729929 PMCID: PMC11087558 DOI: 10.1038/s41467-024-48409-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 04/29/2024] [Indexed: 05/12/2024] Open
Abstract
Widespread manganese-sensing transcriptional riboswitches effect the dependable gene regulation needed for bacterial manganese homeostasis in changing environments. Riboswitches - like most structured RNAs - are believed to fold co-transcriptionally, subject to both ligand binding and transcription events; yet how these processes are orchestrated for robust regulation is poorly understood. Through a combination of single-molecule and bulk approaches, we discover how a single Mn2+ ion and the transcribing RNA polymerase (RNAP), paused immediately downstream by a DNA template sequence, are coordinated by the bridging switch helix P1.1 in the representative Lactococcus lactis riboswitch. This coordination achieves a heretofore-overlooked semi-docked global conformation of the nascent RNA, P1.1 base pair stabilization, transcription factor NusA ejection, and RNAP pause extension, thereby enforcing transcription readthrough. Our work demonstrates how a central, adaptable RNA helix functions analogous to a molecular fulcrum of a first-class lever system to integrate disparate signals for finely balanced gene expression control.
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Affiliation(s)
- Adrien Chauvier
- Single Molecule Analysis Group and Center for RNA Biomedicine, Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Shiba S Dandpat
- Single Molecule Analysis Group and Center for RNA Biomedicine, Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
- Intel Corporation, Hillsboro, OR, USA
| | - Rosa Romero
- Single Molecule Analysis Group and Center for RNA Biomedicine, Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Nils G Walter
- Single Molecule Analysis Group and Center for RNA Biomedicine, Department of Chemistry, University of Michigan, Ann Arbor, MI, USA.
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2
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Walter N, Chauvier A, Dandpat S, Romero R. A nascent riboswitch helix orchestrates robust transcriptional regulation through signal integration. RESEARCH SQUARE 2024:rs.3.rs-3849447. [PMID: 38352525 PMCID: PMC10862961 DOI: 10.21203/rs.3.rs-3849447/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/21/2024]
Abstract
Widespread manganese-sensing transcriptional riboswitches effect the dependable gene regulation needed for bacterial manganese homeostasis in changing environments. Riboswitches - like most structured RNAs - are believed to fold co-transcriptionally, subject to both ligand binding and transcription events; yet how these processes are orchestrated for robust regulation is poorly understood. Through a combination of single molecule and bulk approaches, we discovered how a single Mn 2+ ion and the transcribing RNA polymerase (RNAP), paused immediately downstream by a DNA template sequence, are coordinated by the bridging switch helix P1.1 in the paradigmatic Lactococcus lactis riboswitch. This coordination achieves a heretofore-overlooked semi-docked global conformation of the nascent RNA, P1.1 base pair stabilization, transcription factor NusA ejection, and RNAP pause extension, thereby enforcing transcription readthrough. Our work demonstrates how a central, adaptable RNA helix functions analogous to a molecular fulcrum of a first-class lever system to integrate disparate signals for finely balanced gene expression control.
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3
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Hartmann A, Sreenivasa K, Schenkel M, Chamachi N, Schake P, Krainer G, Schlierf M. An automated single-molecule FRET platform for high-content, multiwell plate screening of biomolecular conformations and dynamics. Nat Commun 2023; 14:6511. [PMID: 37845199 PMCID: PMC10579363 DOI: 10.1038/s41467-023-42232-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 10/03/2023] [Indexed: 10/18/2023] Open
Abstract
Single-molecule FRET (smFRET) has become a versatile tool for probing the structure and functional dynamics of biomolecular systems, and is extensively used to address questions ranging from biomolecular folding to drug discovery. Confocal smFRET measurements are amongst the widely used smFRET assays and are typically performed in a single-well format. Thus, sampling of many experimental parameters is laborious and time consuming. To address this challenge, we extend here the capabilities of confocal smFRET beyond single-well measurements by integrating a multiwell plate functionality to allow for continuous and automated smFRET measurements. We demonstrate the broad applicability of the multiwell plate assay towards DNA hairpin dynamics, protein folding, competitive and cooperative protein-DNA interactions, and drug-discovery, revealing insights that would be very difficult to achieve with conventional single-well format measurements. For the adaptation into existing instrumentations, we provide a detailed guide and open-source acquisition and analysis software.
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Affiliation(s)
- Andreas Hartmann
- B CUBE Center for Molecular Bioengineering, TU Dresden, Tatzberg 41, 01307, Dresden, Germany.
| | - Koushik Sreenivasa
- B CUBE Center for Molecular Bioengineering, TU Dresden, Tatzberg 41, 01307, Dresden, Germany
- Department of Bionanoscience, Delft University of Technology, 2629HZ, Delft, Netherlands
| | - Mathias Schenkel
- B CUBE Center for Molecular Bioengineering, TU Dresden, Tatzberg 41, 01307, Dresden, Germany
| | - Neharika Chamachi
- B CUBE Center for Molecular Bioengineering, TU Dresden, Tatzberg 41, 01307, Dresden, Germany
| | - Philipp Schake
- B CUBE Center for Molecular Bioengineering, TU Dresden, Tatzberg 41, 01307, Dresden, Germany
| | - Georg Krainer
- B CUBE Center for Molecular Bioengineering, TU Dresden, Tatzberg 41, 01307, Dresden, Germany
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW, Cambridge, UK
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/III, 8010, Graz, Austria
| | - Michael Schlierf
- B CUBE Center for Molecular Bioengineering, TU Dresden, Tatzberg 41, 01307, Dresden, Germany.
- Physics of Life, DFG Cluster of Excellence, TU Dresden, 01062, Dresden, Germany.
- Faculty of Physics, TU Dresden, 01062, Dresden, Germany.
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4
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Haghizadeh A, Iftikhar M, Dandpat SS, Simpson T. Looking at Biomolecular Interactions through the Lens of Correlated Fluorescence Microscopy and Optical Tweezers. Int J Mol Sci 2023; 24:2668. [PMID: 36768987 PMCID: PMC9916863 DOI: 10.3390/ijms24032668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 12/19/2022] [Accepted: 01/26/2023] [Indexed: 02/01/2023] Open
Abstract
Understanding complex biological events at the molecular level paves the path to determine mechanistic processes across the timescale necessary for breakthrough discoveries. While various conventional biophysical methods provide some information for understanding biological systems, they often lack a complete picture of the molecular-level details of such dynamic processes. Studies at the single-molecule level have emerged to provide crucial missing links to understanding complex and dynamic pathways in biological systems, which are often superseded by bulk biophysical and biochemical studies. Latest developments in techniques combining single-molecule manipulation tools such as optical tweezers and visualization tools such as fluorescence or label-free microscopy have enabled the investigation of complex and dynamic biomolecular interactions at the single-molecule level. In this review, we present recent advances using correlated single-molecule manipulation and visualization-based approaches to obtain a more advanced understanding of the pathways for fundamental biological processes, and how this combination technique is facilitating research in the dynamic single-molecule (DSM), cell biology, and nanomaterials fields.
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5
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Probing Transient Riboswitch Structures via Single Molecule Accessibility Analysis. Methods Mol Biol 2023; 2568:37-51. [PMID: 36227561 PMCID: PMC10078578 DOI: 10.1007/978-1-0716-2687-0_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Riboswitches are a class of RNA motifs in the untranslated regions of bacterial messenger RNAs (mRNAs) that can adopt different conformations to regulate gene expression. The binding of specific small molecule or ion ligands, or other RNAs, influences the conformation the riboswitch adopts. Single Molecule Kinetic Analysis of RNA Transient Structure (SiM-KARTS) offers an approach for probing this structural isomerization, or conformational switching, at the level of single mRNA molecules. SiM-KARTS utilizes fluorescently labeled, short, sequence-complementary DNA or RNA oligonucleotide probes that transiently access a specific RNA conformation over another. Binding and dissociation to a surface-immobilized target RNA of arbitrary length are monitored by Total Internal Reflection Fluorescence Microscopy (TIRFM) and quantitatively analyzed, via spike train and burst detection, to elucidate the rate constants of isomerization, revealing mechanistic insights into riboswitching.
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6
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Yang W, Lyu Y, Xiang R, Yang J. Long Noncoding RNAs in the Pathogenesis of Insulin Resistance. Int J Mol Sci 2022; 23:ijms232416054. [PMID: 36555704 PMCID: PMC9785789 DOI: 10.3390/ijms232416054] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/10/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022] Open
Abstract
Insulin resistance (IR), designated as the blunted response of insulin target tissues to physiological level of insulin, plays crucial roles in the development and progression of diabetes, nonalcoholic fatty liver disease (NAFLD) and other diseases. So far, the distinct mechanism(s) of IR still needs further exploration. Long non-coding RNA (lncRNA) is a class of non-protein coding RNA molecules with a length greater than 200 nucleotides. LncRNAs are widely involved in many biological processes including cell differentiation, proliferation, apoptosis and metabolism. More recently, there has been increasing evidence that lncRNAs participated in the pathogenesis of IR, and the dysregulated lncRNA profile played important roles in the pathogenesis of metabolic diseases including obesity, diabetes and NAFLD. For example, the lncRNAs MEG3, H19, MALAT1, GAS5, lncSHGL and several other lncRNAs have been shown to regulate insulin signaling and glucose/lipid metabolism in various tissues. In this review, we briefly introduced the general features of lncRNA and the methods for lncRNA research, and then summarized and discussed the recent advances on the roles and mechanisms of lncRNAs in IR, particularly focused on liver, skeletal muscle and adipose tissues.
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Affiliation(s)
- Weili Yang
- Beijing Key Laboratory of Diabetes Research and Care, Beijing Diabetes Institute, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China
| | - Yixiang Lyu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
- Key Laboratory of Cardiovascular Science of the Ministry of Education, Center for Non-Coding RNA Medicine, Beijing 100191, China
| | - Rui Xiang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
- Key Laboratory of Cardiovascular Science of the Ministry of Education, Center for Non-Coding RNA Medicine, Beijing 100191, China
| | - Jichun Yang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
- Key Laboratory of Cardiovascular Science of the Ministry of Education, Center for Non-Coding RNA Medicine, Beijing 100191, China
- Correspondence:
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7
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Bushhouse DZ, Choi EK, Hertz LM, Lucks JB. How does RNA fold dynamically? J Mol Biol 2022; 434:167665. [PMID: 35659535 DOI: 10.1016/j.jmb.2022.167665] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 05/26/2022] [Accepted: 05/27/2022] [Indexed: 10/18/2022]
Abstract
Recent advances in interrogating RNA folding dynamics have shown the classical model of RNA folding to be incomplete. Here, we pose three prominent questions for the field that are at the forefront of our understanding of the importance of RNA folding dynamics for RNA function. The first centers on the most appropriate biophysical framework to describe changes to the RNA folding energy landscape that a growing RNA chain encounters during transcriptional elongation. The second focuses on the potential ubiquity of strand displacement - a process by which RNA can rapidly change conformations - and how this process may be generally present in broad classes of seemingly different RNAs. The third raises questions about the potential importance and roles of cellular protein factors in RNA conformational switching. Answers to these questions will greatly improve our fundamental knowledge of RNA folding and function, drive biotechnological advances that utilize engineered RNAs, and potentially point to new areas of biology yet to be discovered.
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Affiliation(s)
- David Z Bushhouse
- Interdisciplinary Biological Sciences Graduate Program, Northwestern University, Evanston, Illinois 60208, USA; Center for Synthetic Biology, Northwestern University, Evanston, Illinois 60208, USA
| | - Edric K Choi
- Interdisciplinary Biological Sciences Graduate Program, Northwestern University, Evanston, Illinois 60208, USA; Center for Synthetic Biology, Northwestern University, Evanston, Illinois 60208, USA
| | - Laura M Hertz
- Interdisciplinary Biological Sciences Graduate Program, Northwestern University, Evanston, Illinois 60208, USA; Center for Synthetic Biology, Northwestern University, Evanston, Illinois 60208, USA
| | - Julius B Lucks
- Interdisciplinary Biological Sciences Graduate Program, Northwestern University, Evanston, Illinois 60208, USA; Center for Synthetic Biology, Northwestern University, Evanston, Illinois 60208, USA; Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, USA; Center for Water Research, Northwestern University, Evanston, Illinois 60208, USA; Center for Engineering Sustainability and Resilience, Northwestern University, Evanston, Illinois 60208, USA.
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8
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Du Y, Zhang P, Liu W, Tian J. Optical Imaging of Epigenetic Modifications in Cancer: A Systematic Review. PHENOMICS (CHAM, SWITZERLAND) 2022; 2:88-101. [PMID: 36939779 PMCID: PMC9590553 DOI: 10.1007/s43657-021-00041-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 12/10/2021] [Accepted: 12/17/2021] [Indexed: 02/07/2023]
Abstract
Increasing evidence has demonstrated that abnormal epigenetic modifications are strongly related to cancer initiation. Thus, sensitive and specific detection of epigenetic modifications could markedly improve biological investigations and cancer precision medicine. A rapid development of molecular imaging approaches for the diagnosis and prognosis of cancer has been observed during the past few years. Various biomarkers unique to epigenetic modifications and targeted imaging probes have been characterized and used to discriminate cancer from healthy tissues, as well as evaluate therapeutic responses. In this study, we summarize the latest studies associated with optical molecular imaging of epigenetic modification targets, such as those involving DNA methylation, histone modification, noncoding RNA regulation, and chromosome remodeling, and further review their clinical application on cancer diagnosis and treatment. Lastly, we further propose the future directions for precision imaging of epigenetic modification in cancer. Supported by promising clinical and preclinical studies associated with optical molecular imaging technology and epigenetic drugs, the central role of epigenetics in cancer should be increasingly recognized and accepted.
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Affiliation(s)
- Yang Du
- grid.9227.e0000000119573309CAS Key Laboratory of Molecular Imaging, Beijing Key Laboratory of Molecular Imaging, the State Key Laboratory of Management and Control for Complex Systems, Institute of Automation, Chinese Academy of Sciences, Beijing, 100190 China
- grid.410726.60000 0004 1797 8419The University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Pei Zhang
- grid.9227.e0000000119573309CAS Key Laboratory of Molecular Imaging, Beijing Key Laboratory of Molecular Imaging, the State Key Laboratory of Management and Control for Complex Systems, Institute of Automation, Chinese Academy of Sciences, Beijing, 100190 China
- grid.412474.00000 0001 0027 0586Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Supportive Care Center and Day Oncology Unit, Peking University Cancer Hospital and Institute, Beijing, 100142 China
| | - Wei Liu
- grid.412474.00000 0001 0027 0586Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Supportive Care Center and Day Oncology Unit, Peking University Cancer Hospital and Institute, Beijing, 100142 China
| | - Jie Tian
- grid.9227.e0000000119573309CAS Key Laboratory of Molecular Imaging, Beijing Key Laboratory of Molecular Imaging, the State Key Laboratory of Management and Control for Complex Systems, Institute of Automation, Chinese Academy of Sciences, Beijing, 100190 China
- grid.64939.310000 0000 9999 1211Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, School of Medicine, Beihang University, Beijing, 100191 China
- grid.440736.20000 0001 0707 115XSchool of Life Science and Technology, Xidian University, Xi’an, 710071 Shaanxi China
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9
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Małecka EM, Hua B, Woodson SA. Single-Molecule FRET Studies of RNA Structural Rearrangements and RNA-RNA Interactions. Methods Mol Biol 2022; 2518:271-289. [PMID: 35666451 PMCID: PMC10052914 DOI: 10.1007/978-1-0716-2421-0_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
RNA-guided regulation of gene expression is found in all cell types. In this mode of regulation, antisense interactions between the regulatory RNA and its target are typically facilitated by a protein partner. Single-molecule fluorescence microscopy is a powerful tool for dissecting the conformational states and intermediates that contribute to target recognition. This chapter describes protocols for studying target recognition by bacterial small RNAs and their chaperone Hfq on the single-molecule level, using a total internal reflection fluorescence microscope. The sections cover the design of suitable RNA substrates for sRNA-mRNA annealing reactions, preparation of internally labeled mRNA for detecting conformational changes in the target, and key steps of the data analysis. These protocols can be adapted to other RNA-binding proteins that chaperone RNA interactions.
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Affiliation(s)
- Ewelina M Małecka
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
| | - Boyang Hua
- Department of Molecular Biology and Genetics, Johns Hopkins Medical School, Baltimore, MD, USA
| | - Sarah A Woodson
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA.
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Chandler M, Johnson B, Khisamutdinov E, Dobrovolskaia MA, Sztuba-Solinska J, Salem AK, Breyne K, Chammas R, Walter NG, Contreras LM, Guo P, Afonin KA. The International Society of RNA Nanotechnology and Nanomedicine (ISRNN): The Present and Future of the Burgeoning Field. ACS NANO 2021; 15:16957-16973. [PMID: 34677049 PMCID: PMC9023608 DOI: 10.1021/acsnano.0c10240] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The International Society of RNA Nanotechnology and Nanomedicine (ISRNN) hosts an annual meeting series focused on presenting the latest research achievements involving RNA-based therapeutics and strategies, aiming to expand their current biomedical applications while overcoming the remaining challenges of the burgeoning field of RNA nanotechnology. The most recent online meeting hosted a series of engaging talks and discussions from an international cohort of leading nanotechnologists that focused on RNA modifications and modulation, dynamic RNA structures, overcoming delivery limitations using a variety of innovative platforms and approaches, and addressing the newly explored potential for immunomodulation with programmable nucleic acid nanoparticles. In this Nano Focus, we summarize the main discussion points, conclusions, and future directions identified during this two-day webinar as well as more recent advances to highlight and to accelerate this exciting field.
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Affiliation(s)
- Morgan Chandler
- Nanoscale Science Program, Department of Chemistry, University of North Carolina at Charlotte, Charlotte, North Carolina 28223, United States
| | - Brittany Johnson
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, North Carolina 28223, United States
| | - Emil Khisamutdinov
- Department of Chemistry, Ball State University, Muncie, Indiana 47304, United States
| | - Marina A Dobrovolskaia
- Nanotechnology Characterization Lab, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland 21702, United States
| | - Joanna Sztuba-Solinska
- Department of Biological Sciences, Auburn University, 120 W. Samford Avenue, Rouse Life Sciences Building, Auburn, Alabama 36849, United States
| | - Aliasger K Salem
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, University of Iowa, Iowa City, Iowa 52242, United States
| | - Koen Breyne
- Molecular Neurogenetics Unit, Department of Neurology and Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachussets 02114, United States
| | - Roger Chammas
- Nanoscale Science Program, Department of Chemistry, University of North Carolina at Charlotte, Charlotte, North Carolina 28223, United States
- Centro de Investigação Translacional em Oncologia, Departamento de Radiologia e Oncologia, Instituto do Cancer do Estado de São Paulo - ICESP, Faculdade de Medicina da Universidade de São Paulo - FMUSP, Avenida Dr. Arnaldo 251, Cerqueira César, São Paulo 01246-000, São Paulo, Brazil
| | - Nils G Walter
- Single Molecule Analysis Group, Department of Chemistry and Center for RNA Biomedicine, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Lydia M Contreras
- McKetta Department of Chemical Engineering and Department of Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78714, United States
| | - Peixuan Guo
- Center for RNA Nanobiotechnology and Nanomedicine, College of Pharmacy, Division of Pharmaceutics and Pharmaceutical Chemistry, College of Medicine, Dorothy M. Davis Heart and Lung Research Institute, James Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio 43210, United States
| | - Kirill A Afonin
- Nanoscale Science Program, Department of Chemistry, University of North Carolina at Charlotte, Charlotte, North Carolina 28223, United States
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11
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Dynamic competition between a ligand and transcription factor NusA governs riboswitch-mediated transcription regulation. Proc Natl Acad Sci U S A 2021; 118:2109026118. [PMID: 34782462 DOI: 10.1073/pnas.2109026118] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/11/2021] [Indexed: 11/18/2022] Open
Abstract
Cotranscriptional RNA folding is widely assumed to influence the timely control of gene expression, but our understanding remains limited. In bacteria, the fluoride (F-)-sensing riboswitch is a transcriptional control element essential to defend against toxic F- levels. Using this model riboswitch, we find that its ligand F- and essential bacterial transcription factor NusA compete to bind the cotranscriptionally folding RNA, opposing each other's modulation of downstream pausing and termination by RNA polymerase. Single-molecule fluorescence assays probing active transcription elongation complexes discover that NusA unexpectedly binds highly reversibly, frequently interrogating the complex for emerging, cotranscriptionally folding RNA duplexes. NusA thus fine-tunes the transcription rate in dependence of the ligand-responsive higher-order structure of the riboswitch. At the high NusA concentrations found intracellularly, this dynamic modulation is expected to lead to adaptive bacterial transcription regulation with fast response times.
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12
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A translational riboswitch coordinates nascent transcription-translation coupling. Proc Natl Acad Sci U S A 2021; 118:2023426118. [PMID: 33850018 DOI: 10.1073/pnas.2023426118] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Bacterial messenger RNA (mRNA) synthesis by RNA polymerase (RNAP) and first-round translation by the ribosome are often coupled to regulate gene expression, yet how coupling is established and maintained is ill understood. Here, we develop biochemical and single-molecule fluorescence approaches to probe the dynamics of RNAP-ribosome interactions on an mRNA with a translational preQ1-sensing riboswitch in its 5' untranslated region. Binding of preQ1 leads to the occlusion of the ribosome binding site (RBS), inhibiting translation initiation. We demonstrate that RNAP poised within the mRNA leader region promotes ribosomal 30S subunit binding, antagonizing preQ1-induced RBS occlusion, and that the RNAP-30S bridging transcription factors NusG and RfaH distinctly enhance 30S recruitment and retention, respectively. We further find that, while 30S-mRNA interaction significantly impedes RNAP in the absence of translation, an actively translating ribosome promotes productive transcription. A model emerges wherein mRNA structure and transcription factors coordinate to dynamically modulate the efficiency of transcription-translation coupling.
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13
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Scull CE, Dandpat SS, Romero RA, Walter NG. Transcriptional Riboswitches Integrate Timescales for Bacterial Gene Expression Control. Front Mol Biosci 2021; 7:607158. [PMID: 33521053 PMCID: PMC7838592 DOI: 10.3389/fmolb.2020.607158] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 12/11/2020] [Indexed: 12/16/2022] Open
Abstract
Transcriptional riboswitches involve RNA aptamers that are typically found in the 5' untranslated regions (UTRs) of bacterial mRNAs and form alternative secondary structures upon binding to cognate ligands. Alteration of the riboswitch's secondary structure results in perturbations of an adjacent expression platform that controls transcription elongation and termination, thus turning downstream gene expression "on" or "off." Riboswitch ligands are typically small metabolites, divalent cations, anions, signaling molecules, or other RNAs, and can be part of larger signaling cascades. The interconnectedness of ligand binding, RNA folding, RNA transcription, and gene expression empowers riboswitches to integrate cellular processes and environmental conditions across multiple timescales. For a successful response to an environmental cue that may determine a bacterium's chance of survival, a coordinated coupling of timescales from microseconds to minutes must be achieved. This review focuses on recent advances in our understanding of how riboswitches affect such critical gene expression control across time.
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Affiliation(s)
| | | | | | - Nils G. Walter
- Department of Chemistry, Single Molecule Analysis Group and Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI, United States
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14
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Huang Q, Li N, Zhang H, Che C, Sun F, Xiong Y, Canady TD, Cunningham BT. Critical Review: digital resolution biomolecular sensing for diagnostics and life science research. LAB ON A CHIP 2020; 20:2816-2840. [PMID: 32700698 PMCID: PMC7485136 DOI: 10.1039/d0lc00506a] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
One of the frontiers in the field of biosensors is the ability to quantify specific target molecules with enough precision to count individual units in a test sample, and to observe the characteristics of individual biomolecular interactions. Technologies that enable observation of molecules with "digital precision" have applications for in vitro diagnostics with ultra-sensitive limits of detection, characterization of biomolecular binding kinetics with a greater degree of precision, and gaining deeper insights into biological processes through quantification of molecules in complex specimens that would otherwise be unobservable. In this review, we seek to capture the current state-of-the-art in the field of digital resolution biosensing. We describe the capabilities of commercially available technology platforms, as well as capabilities that have been described in published literature. We highlight approaches that utilize enzymatic amplification, nanoparticle tags, chemical tags, as well as label-free biosensing methods.
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Affiliation(s)
- Qinglan Huang
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 208 North Wright Street, Urbana, IL 61801
- Holonyak Micro and Nanotechnology Laboratory, University of Illinois at Urbana–Champaign, Urbana, IL 61801
| | - Nantao Li
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 208 North Wright Street, Urbana, IL 61801
- Holonyak Micro and Nanotechnology Laboratory, University of Illinois at Urbana–Champaign, Urbana, IL 61801
| | - Hanyuan Zhang
- Holonyak Micro and Nanotechnology Laboratory, University of Illinois at Urbana–Champaign, Urbana, IL 61801
| | - Congnyu Che
- Holonyak Micro and Nanotechnology Laboratory, University of Illinois at Urbana–Champaign, Urbana, IL 61801
- Department of Bioengineering, University of Illinois at Urbana–Champaign, Urbana, IL 61801
| | - Fu Sun
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 208 North Wright Street, Urbana, IL 61801
- Holonyak Micro and Nanotechnology Laboratory, University of Illinois at Urbana–Champaign, Urbana, IL 61801
| | - Yanyu Xiong
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 208 North Wright Street, Urbana, IL 61801
- Holonyak Micro and Nanotechnology Laboratory, University of Illinois at Urbana–Champaign, Urbana, IL 61801
| | - Taylor D. Canady
- Holonyak Micro and Nanotechnology Laboratory, University of Illinois at Urbana–Champaign, Urbana, IL 61801
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana–Champaign, Urbana, IL 61801
| | - Brian T. Cunningham
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 208 North Wright Street, Urbana, IL 61801
- Holonyak Micro and Nanotechnology Laboratory, University of Illinois at Urbana–Champaign, Urbana, IL 61801
- Department of Bioengineering, University of Illinois at Urbana–Champaign, Urbana, IL 61801
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana–Champaign, Urbana, IL 61801
- Illinois Cancer Center, University of Illinois at Urbana-Champaign Urbana, IL 61801
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Ermolenko DN, Whitford PC. Experimental and computational techniques for studying structural dynamics and function of RNA. Methods 2019; 162-163:1-2. [DOI: 10.1016/j.ymeth.2019.06.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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