1
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Liu L, Luo D, Zhang Y, Liu D, Yin K, Tang Q, Chou SH, He J. Characterization of the dual regulation by a c-di-GMP riboswitch Bc1 with a long expression platform from Bacillus thuringiensis. Microbiol Spectr 2024; 12:e0045024. [PMID: 38819160 DOI: 10.1128/spectrum.00450-24] [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: 02/19/2024] [Accepted: 04/29/2024] [Indexed: 06/01/2024] Open
Abstract
A riboswitch generally regulates the expression of its downstream genes through conformational change in its expression platform (EP) upon ligand binding. The cyclic diguanosine monophosphate (c-di-GMP) class I riboswitch Bc1 is widespread and conserved among Bacillus cereus group species. In this study, we revealed that Bc1 has a long EP with two typical ρ-independent terminator sequences 28 bp apart. The upstream terminator T1 is dominant in vitro, while downstream terminator T2 is more efficient in vivo. Through mutation analysis, we elucidated that Bc1 exerts a rare and incoherent "transcription-translation" dual regulation with T2 playing a crucial role. However, we found that Bc1 did not respond to c-di-GMP under in vitro transcription conditions, and the expressions of downstream genes did not change with fluctuation in intracellular c-di-GMP concentration. To explore this puzzle, we conducted SHAPE-MaP and confirmed the interaction of Bc1 with c-di-GMP. This shows that as c-di-GMP concentration increases, T1 unfolds but T2 remains almost intact and functional. The presence of T2 masks the effect of T1 unwinding, resulting in no response of Bc1 to c-di-GMP. The high Shannon entropy values of EP region imply the potential alternative structures of Bc1. We also found that zinc uptake regulator can specifically bind to the dual terminator coding sequence and slightly trigger the response of Bc1 to c-di-GMP. This work will shed light on the dual-regulation riboswitch and enrich our understanding of the RNA world.IMPORTANCEIn nature, riboswitches are involved in a variety of metabolic regulation, most of which preferentially regulate transcription termination or translation initiation of downstream genes in specific ways. Alternatively, the same or different riboswitches can exist in tandem to enhance regulatory effects or respond to multiple ligands. However, many putative conserved riboswitches have not yet been experimentally validated. Here, we found that the c-di-GMP riboswitch Bc1 with a long EP could form a dual terminator and exhibit non-canonical and incoherent "transcription-translation" dual regulation. Besides, zinc uptake regulator specifically bound to the coding sequence of the Bc1 EP and slightly mediated the action of Bc1. The application of SHAPE-MaP to the dual regulation mechanism of Bc1 may establish the foundation for future studies of such complex untranslated regions in other bacterial genomes.
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Affiliation(s)
- Lu Liu
- National Key Laboratory of Agricultural Microbiology & Hubei Hongshan Laboratory, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Dehua Luo
- National Key Laboratory of Agricultural Microbiology & Hubei Hongshan Laboratory, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Yongji Zhang
- National Key Laboratory of Agricultural Microbiology & Hubei Hongshan Laboratory, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Dingqi Liu
- National Key Laboratory of Agricultural Microbiology & Hubei Hongshan Laboratory, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Kang Yin
- National Key Laboratory of Agricultural Microbiology & Hubei Hongshan Laboratory, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Qing Tang
- National Key Laboratory of Agricultural Microbiology & Hubei Hongshan Laboratory, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Shan-Ho Chou
- National Key Laboratory of Agricultural Microbiology & Hubei Hongshan Laboratory, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Jin He
- National Key Laboratory of Agricultural Microbiology & Hubei Hongshan Laboratory, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
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2
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Li J, Zhou Y, Chen SJ. Embracing exascale computing in nucleic acid simulations. Curr Opin Struct Biol 2024; 87:102847. [PMID: 38815519 DOI: 10.1016/j.sbi.2024.102847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Revised: 04/18/2024] [Accepted: 05/09/2024] [Indexed: 06/01/2024]
Abstract
This mini-review reports the recent advances in biomolecular simulations, particularly for nucleic acids, and provides the potential effects of the emerging exascale computing on nucleic acid simulations, emphasizing the need for advanced computational strategies to fully exploit this technological frontier. Specifically, we introduce recent breakthroughs in computer architectures for large-scale biomolecular simulations and review the simulation protocols for nucleic acids regarding force fields, enhanced sampling methods, coarse-grained models, and interactions with ligands. We also explore the integration of machine learning methods into simulations, which promises to significantly enhance the predictive modeling of biomolecules and the analysis of complex data generated by the exascale simulations. Finally, we discuss the challenges and perspectives for biomolecular simulations as we enter the dawning exascale computing era.
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Affiliation(s)
- Jun Li
- Department of Physics, Department of Biochemistry and Institute for Data Science and Informatics, University of Missouri, 223 Physics Bldg., Columbia, 65211, MO, USA
| | - Yuanzhe Zhou
- Department of Physics, Department of Biochemistry and Institute for Data Science and Informatics, University of Missouri, 223 Physics Bldg., Columbia, 65211, MO, USA
| | - Shi-Jie Chen
- Department of Physics, Department of Biochemistry and Institute for Data Science and Informatics, University of Missouri, 223 Physics Bldg., Columbia, 65211, MO, USA.
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3
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Wang Y, Wu J, Zsolnay V, Pollard TD, Voth GA. Mechanism of Phosphate Release from Actin Filaments. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.08.03.551904. [PMID: 37577500 PMCID: PMC10418243 DOI: 10.1101/2023.08.03.551904] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
After ATP-actin monomers assemble filaments, the ATP's γ-phosphate is hydrolyzed within seconds and dissociates over minutes. We used all-atom molecular dynamics simulations to sample the release of phosphate from filaments and study residues that gate release. Dissociation of phosphate from Mg2+ is rate limiting and associated with an energy barrier of 20 kcal/mol, consistent with experimental rates of phosphate release. Phosphate then diffuses in an internal cavity toward a gate formed by R177 suggested in prior computational studies and cryo-EM structures. The gate is closed when R177 hydrogen bonds with N111 and is open when R177 forms a salt bridge with D179. Most of the time interactions of R177 with other residues occludes the phosphate release pathway. Machine learning analysis reveals that the occluding interactions fluctuate rapidly, underscoring the secondary role of backdoor gate opening in Pi release, in contrast with the previous hypothesis that gate opening is the primary event.
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Affiliation(s)
- Yihang Wang
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics and James Frank Institute, University of Chicago, Chicago, IL
| | - Jiangbo Wu
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics and James Frank Institute, University of Chicago, Chicago, IL
| | - Vilmos Zsolnay
- Graduate Program in Biophysical Sciences, University of Chicago, Chicago, IL
| | - Thomas D. Pollard
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT
- Department of Cell Biology, Yale University, New Haven, CT
| | - Gregory A. Voth
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics and James Frank Institute, University of Chicago, Chicago, IL
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4
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Parmar S, Bume DD, Conelly C, Boer R, Prestwood PR, Wang Z, Labuhn H, Sinnadurai K, Feri A, Ouellet J, Homan P, Numata T, Schneekloth JS. Mechanistic Analysis of Riboswitch Ligand Interactions Provides Insights into Pharmacological Control over Gene Expression. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.23.581746. [PMID: 38903087 PMCID: PMC11188086 DOI: 10.1101/2024.02.23.581746] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/22/2024]
Abstract
Riboswitches are structured RNA elements that regulate gene expression upon binding to small molecule ligands. Understanding the mechanisms by which small molecules impact riboswitch activity is key to developing potent, selective ligands for these and other RNA targets. We report the structure-informed design of chemically diverse synthetic ligands for PreQ1 riboswitches. Multiple X-ray co-crystal structures of synthetic ligands with the Thermoanaerobacter tengcongensis (Tte)-PreQ1 riboswitch confirm a common binding site with the cognate ligand, despite considerable chemical differences among the ligands. Structure probing assays demonstrate that one ligand causes conformational changes similar to PreQ1 in six structurally and mechanistically diverse PreQ1 riboswitch aptamers. Single-molecule force spectroscopy is used to demonstrate differential modes of riboswitch stabilization by the ligands. Binding of the natural ligand brings about the formation of a persistent, folded pseudoknot structure, whereas a synthetic ligand decreases the rate of unfolding through a kinetic mechanism. Single round transcription termination assays show the biochemical activity of the ligands, while a GFP reporter system reveals compound activity in regulating gene expression in live cells without toxicity. Taken together, this study reveals that diverse small molecules can impact gene expression in live cells by altering conformational changes in RNA structures through distinct mechanisms.
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Affiliation(s)
- Shaifaly Parmar
- Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Desta Doro Bume
- Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Colleen Conelly
- Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Robert Boer
- Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Peri R. Prestwood
- Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Zhen Wang
- Depixus SAS, 3-5 Impasse Reille, 75014 Paris, France
| | | | | | - Adeline Feri
- Depixus SAS, 3-5 Impasse Reille, 75014 Paris, France
| | - Jimmy Ouellet
- Depixus SAS, 3-5 Impasse Reille, 75014 Paris, France
| | - Philip Homan
- Center for Cancer Research Collaborative Bioinformatics Resource, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
- Advanced Biomedical Computational Science, Frederick National Laboratory for Cancer Research, Frederick, MD, 21702, USA
| | - Tomoyuki Numata
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka 819-0395, Japan
| | - John S. Schneekloth
- Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
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5
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Akhter S, Tang Z, Wang J, Haboro M, Holmstrom ED, Wang J, Miao Y. Mechanism of Ligand Binding to Theophylline RNA Aptamer. J Chem Inf Model 2024; 64:1017-1029. [PMID: 38226603 PMCID: PMC11058067 DOI: 10.1021/acs.jcim.3c01454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2024]
Abstract
Studying RNA-ligand interactions and quantifying their binding thermodynamics and kinetics are of particular relevance in the field of drug discovery. Here, we combined biochemical binding assays and accelerated molecular simulations to investigate ligand binding and dissociation in RNA using the theophylline-binding RNA as a model system. All-atom simulations using a Ligand Gaussian accelerated Molecular Dynamics method (LiGaMD) have captured repetitive binding and dissociation of theophylline and caffeine to RNA. Theophylline's binding free energy and kinetic rate constants align with our experimental data, while caffeine's binding affinity is over 10,000 times weaker, and its kinetics could not be determined. LiGaMD simulations allowed us to identify distinct low-energy conformations and multiple ligand binding pathways to RNA. Simulations revealed a "conformational selection" mechanism for ligand binding to the flexible RNA aptamer, which provides important mechanistic insights into ligand binding to the theophylline-binding model. Our findings suggest that compound docking using a structural ensemble of representative RNA conformations would be necessary for structure-based drug design of flexible RNA.
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Affiliation(s)
- Sana Akhter
- Computational Biology Program and Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66047, United States
| | - Zhichao Tang
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66047, United States
| | - Jinan Wang
- Computational Biology Program and Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66047, United States
| | - Mercy Haboro
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66047, United States
| | - Erik D Holmstrom
- Department of Molecular Biosciences and Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Jingxin Wang
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66047, United States
| | - Yinglong Miao
- Computational Biology Program and Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66047, United States
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6
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Kovachka S, Panosetti M, Grimaldi B, Azoulay S, Di Giorgio A, Duca M. Small molecule approaches to targeting RNA. Nat Rev Chem 2024; 8:120-135. [PMID: 38278932 DOI: 10.1038/s41570-023-00569-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/04/2023] [Indexed: 01/28/2024]
Abstract
The development of innovative methodologies to identify RNA binders has attracted enormous attention in chemical biology and drug discovery. Although antibiotics targeting bacterial ribosomal RNA have been on the market for decades, the renewed interest in RNA targeting reflects the need to better understand complex intracellular processes involving RNA. In this context, small molecules are privileged tools used to explore the biological functions of RNA and to validate RNAs as therapeutic targets, and they eventually are to become new drugs. Despite recent progress, the rational design of specific RNA binders requires a better understanding of the interactions which occur with the RNA target to reach the desired biological response. In this Review, we discuss the challenges to approaching this underexplored chemical space, together with recent strategies to bind, interact and affect biologically relevant RNAs.
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Affiliation(s)
- Sandra Kovachka
- Université Côte d'Azur, CNRS, Institute of Chemistry of Nice, Nice, France
| | - Marc Panosetti
- Université Côte d'Azur, CNRS, Institute of Chemistry of Nice, Nice, France
- Molecular Medicine Research Line, Istituto Italiano di Tecnologia (IIT), Genoa, Italy
| | - Benedetto Grimaldi
- Molecular Medicine Research Line, Istituto Italiano di Tecnologia (IIT), Genoa, Italy
| | - Stéphane Azoulay
- Université Côte d'Azur, CNRS, Institute of Chemistry of Nice, Nice, France
| | - Audrey Di Giorgio
- Université Côte d'Azur, CNRS, Institute of Chemistry of Nice, Nice, France
| | - Maria Duca
- Université Côte d'Azur, CNRS, Institute of Chemistry of Nice, Nice, France.
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7
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Arunkumar G. LncRNAs: the good, the bad, and the unknown. Biochem Cell Biol 2024; 102:9-27. [PMID: 37579511 DOI: 10.1139/bcb-2023-0155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2023] Open
Abstract
Long non-coding RNAs (lncRNAs) are significant contributors in maintaining genomic integrity through epigenetic regulation. LncRNAs can interact with chromatin-modifying complexes in both cis and trans pathways, drawing them to specific genomic loci and influencing gene expression via DNA methylation, histone modifications, and chromatin remodeling. They can also operate as building blocks to assemble different chromatin-modifying components, facilitating their interactions and gene regulatory functions. Deregulation of these molecules has been associated with various human diseases, including cancer, cardiovascular disease, and neurological disorders. Thus, lncRNAs are implicated as potential diagnostic indicators and therapeutic targets. This review discusses the current understanding of how lncRNAs mediate epigenetic control, genomic integrity, and their putative functions in disease pathogenesis.
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Affiliation(s)
- Ganesan Arunkumar
- The LncRNA, Epigenetics, and Genome Organization Laboratory, Department of Cell Biology and Physiology, School of Medicine, University of New Mexico, Albuquerque, NM, USA
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8
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Chan KH, Wang Y, Zheng BX, Long W, Feng X, Wong WL. RNA-Selective Small-Molecule Ligands: Recent Advances in Live-Cell Imaging and Drug Discovery. ChemMedChem 2023; 18:e202300271. [PMID: 37649155 DOI: 10.1002/cmdc.202300271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Revised: 08/13/2023] [Accepted: 08/24/2023] [Indexed: 09/01/2023]
Abstract
RNA structures, including those formed from coding and noncoding RNAs, alternative to protein-based drug targets, could be a promising target of small molecules for drug discovery against various human diseases, particularly in anticancer, antibacterial and antivirus development. The normal cellular activity of cells is critically dependent on the function of various RNA molecules generated from DNA transcription. Moreover, many studies support that mRNA-targeting small molecules may regulate the synthesis of disease-related proteins via the non-covalent mRNA-ligand interactions that do not involve gene modification. RNA-ligand interaction is thus an attractive approach to address the challenge of "undruggable" proteins in drug discovery because the intracellular activity of these proteins is hard to be suppressed with small molecule ligands. We selectively surveyed a specific area of RNA structure-selective small molecule ligands in fluorescence live cell imaging and drug discovery because the area was currently underexplored. This state-of-the-art review thus mainly focuses on the research published within the past three years and aims to provide the most recent information on this research area; hopefully, it could be complementary to the previously reported reviews and give new insights into the future development on RNA-specific small molecule ligands for live cell imaging and drug discovery.
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Affiliation(s)
- Ka Hin Chan
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, SAR 999077, P. R. China
| | - Yakun Wang
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, 518057, P. R. China
| | - Bo-Xin Zheng
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, SAR 999077, P. R. China
| | - Wei Long
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, SAR 999077, P. R. China
| | - Xinxin Feng
- State Key Laboratory of Chem-/Bio-Sensing and Chemometrics, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology and School of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan, 410082, P. R. China
| | - Wing-Leung Wong
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, SAR 999077, P. R. China
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, 518057, P. R. China
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9
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Lennon SR, Wierzba AJ, Siwik SH, Gryko D, Palmer AE, Batey RT. Targeting Riboswitches with Beta-Axial-Substituted Cobalamins. ACS Chem Biol 2023; 18:1136-1147. [PMID: 37094176 PMCID: PMC10395008 DOI: 10.1021/acschembio.2c00939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023]
Abstract
RNA-targeting small-molecule therapeutics is an emerging field hindered by an incomplete understanding of the basic principles governing RNA-ligand interactions. One way to advance our knowledge in this area is to study model systems where these interactions are better understood, such as riboswitches. Riboswitches bind a wide array of small molecules with high affinity and selectivity, providing a wealth of information on how RNA recognizes ligands through diverse structures. The cobalamin-sensing riboswitch is a particularly useful model system, as similar sequences show highly specialized binding preferences for different biological forms of cobalamin. This riboswitch is also widely dispersed across bacteria and therefore holds strong potential as an antibiotic target. Many synthetic cobalamin forms have been developed for various purposes including therapeutics, but their interaction with cobalamin riboswitches is yet to be explored. In this study, we characterize the interactions of 11 cobalamin derivatives with three representative cobalamin riboswitches using in vitro binding experiments (both chemical footprinting and a fluorescence-based assay) and a cell-based reporter assay. The derivatives show productive interactions with two of the three riboswitches, demonstrating simultaneous plasticity and selectivity within these RNAs. The observed plasticity is partially achieved through a novel structural rearrangement within the ligand binding pocket, providing insight into how similar RNA structures can be targeted. As the derivatives also show in vivo functionality, they serve as several potential lead compounds for further drug development.
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Affiliation(s)
- Shelby R. Lennon
- Department of Biochemistry, University of Colorado, Boulder, CO 80309-0596, USA
| | - Aleksandra J. Wierzba
- Department of Biochemistry, University of Colorado, Boulder, CO 80309-0596, USA
- BioFrontiers Institute, University of Colorado, Boulder, CO 80303 – 0596, USA
| | - Shea H. Siwik
- Department of Biochemistry, University of Colorado, Boulder, CO 80309-0596, USA
| | - Dorota Gryko
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Amy E. Palmer
- Department of Biochemistry, University of Colorado, Boulder, CO 80309-0596, USA
- BioFrontiers Institute, University of Colorado, Boulder, CO 80303 – 0596, USA
| | - Robert T. Batey
- Department of Biochemistry, University of Colorado, Boulder, CO 80309-0596, USA
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10
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Motta S, Siani P, Donadoni E, Frigerio G, Bonati L, Di Valentin C. Metadynamics simulations for the investigation of drug loading on functionalized inorganic nanoparticles. NANOSCALE 2023; 15:7909-7919. [PMID: 37066796 DOI: 10.1039/d3nr00397c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Inorganic nanoparticles show promising properties that allow them to be efficiently used as drug carriers. The main limitation in this type of application is currently the drug loading capacity, which can be overcome with a proper functionalization of the nanoparticle surface. In this study, we present, for the first time, a computational approach based on metadynamics to estimate the binding free energy of the doxorubicin drug (DOX) to a functionalized TiO2 nanoparticle under different pH conditions. On a thermodynamic basis, we demonstrate the robustness of our approach to capture the overall mechanism behind the pH-triggered release of DOX due to environmental pH changes. Notably, binding free energy estimations align well with what is expected for a pH-sensitive drug delivery system. Based on our results, we envision the use of metadynamics as a promising computational tool for the rational design and in silico optimization of organic ligands with improved drug carrier properties.
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Affiliation(s)
- Stefano Motta
- Dipartimento di Scienze dell'Ambiente e del Territorio, Università di Milano Bicocca, Piazza della Scienza 1, 20126 Milano, Italy
| | - Paulo Siani
- Dipartimento di Scienza dei Materiali, Università di Milano Bicocca, via R. Cozzi 55, 20125 Milano, Italy.
| | - Edoardo Donadoni
- Dipartimento di Scienza dei Materiali, Università di Milano Bicocca, via R. Cozzi 55, 20125 Milano, Italy.
| | - Giulia Frigerio
- Dipartimento di Scienza dei Materiali, Università di Milano Bicocca, via R. Cozzi 55, 20125 Milano, Italy.
| | - Laura Bonati
- Dipartimento di Scienze dell'Ambiente e del Territorio, Università di Milano Bicocca, Piazza della Scienza 1, 20126 Milano, Italy
| | - Cristiana Di Valentin
- Dipartimento di Scienza dei Materiali, Università di Milano Bicocca, via R. Cozzi 55, 20125 Milano, Italy.
- BioNanoMedicine Center NANOMIB, University of Milano-Bicocca, Italy
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11
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Sabei A, Caldas Baia TG, Saffar R, Martin J, Frezza E. Internal Normal Mode Analysis Applied to RNA Flexibility and Conformational Changes. J Chem Inf Model 2023; 63:2554-2572. [PMID: 36972178 DOI: 10.1021/acs.jcim.2c01509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
Abstract
We investigated the capability of internal normal modes to reproduce RNA flexibility and predict observed RNA conformational changes and, notably, those induced by the formation of RNA-protein and RNA-ligand complexes. Here, we extended our iNMA approach developed for proteins to study RNA molecules using a simplified representation of the RNA structure and its potential energy. Three data sets were also created to investigate different aspects. Despite all the approximations, our study shows that iNMA is a suitable method to take into account RNA flexibility and describe its conformational changes opening the route to its applicability in any integrative approach where these properties are crucial.
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12
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Schroeder GM, Akinyemi O, Malik J, Focht CM, Pritchett E, Baker C, McSally JP, Jenkins JL, Mathews D, Wedekind J. A riboswitch separated from its ribosome-binding site still regulates translation. Nucleic Acids Res 2023; 51:2464-2484. [PMID: 36762498 PMCID: PMC10018353 DOI: 10.1093/nar/gkad056] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/14/2023] [Accepted: 02/07/2023] [Indexed: 02/11/2023] Open
Abstract
Riboswitches regulate downstream gene expression by binding cellular metabolites. Regulation of translation initiation by riboswitches is posited to occur by metabolite-mediated sequestration of the Shine-Dalgarno sequence (SDS), causing bypass by the ribosome. Recently, we solved a co-crystal structure of a prequeuosine1-sensing riboswitch from Carnobacterium antarcticum that binds two metabolites in a single pocket. The structure revealed that the second nucleotide within the gene-regulatory SDS, G34, engages in a crystal contact, obscuring the molecular basis of gene regulation. Here, we report a co-crystal structure wherein C10 pairs with G34. However, molecular dynamics simulations reveal quick dissolution of the pair, which fails to reform. Functional and chemical probing assays inside live bacterial cells corroborate the dispensability of the C10-G34 pair in gene regulation, leading to the hypothesis that the compact pseudoknot fold is sufficient for translation attenuation. Remarkably, the C. antarcticum aptamer retained significant gene-regulatory activity when uncoupled from the SDS using unstructured spacers up to 10 nucleotides away from the riboswitch-akin to steric-blocking employed by sRNAs. Accordingly, our work reveals that the RNA fold regulates translation without SDS sequestration, expanding known riboswitch-mediated gene-regulatory mechanisms. The results infer that riboswitches exist wherein the SDS is not embedded inside a stable fold.
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Affiliation(s)
- Griffin M Schroeder
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
- Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Olayinka Akinyemi
- Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
- Department of Physics, University of Rochester, Rochester, NY 14642, USA
| | - Jeffrey Malik
- Genomics Research Center, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Caroline M Focht
- Department of Molecular Biophysics and Biochemistry and the Institute of Biomolecular Design and Discovery, Yale University, New Haven, CT 06516, USA
| | - Elizabeth M Pritchett
- Genomics Research Center, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Cameron D Baker
- Genomics Research Center, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - James P McSally
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
- Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Jermaine L Jenkins
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
- Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - David H Mathews
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
- Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Joseph E Wedekind
- To whom correspondence should be addressed. Tel: +1 585 273 4516; Fax: +1 585 275 6007;
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