1
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He YN, Han XR, Wang D, Hou JL, Hou XM. Dual mode of DDX3X as an ATP-dependent RNA helicase and ATP-independent nucleic acid chaperone. Biochem Biophys Res Commun 2024; 714:149964. [PMID: 38669753 DOI: 10.1016/j.bbrc.2024.149964] [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: 04/11/2024] [Accepted: 04/16/2024] [Indexed: 04/28/2024]
Abstract
Human DDX3X, an important member of the DEAD-box family RNA helicases, plays a crucial role in RNA metabolism and is involved in cancer development, viral infection, and neurodegenerative disease. Although there have been many studies on the physiological functions of human DDX3X, issues regarding its exact targets and mechanisms of action remain unclear. In this study, we systematically characterized the biochemical activities and substrate specificity of DDX3X. The results demonstrate that DDX3X is a bidirectional RNA helicase to unwind RNA duplex and RNA-DNA hybrid driven by ATP. DDX3X also has nucleic acid annealing activity, especially for DNA. More importantly, it can function as a typical nucleic acid chaperone which destabilizes highly structured DNA and RNA in an ATP-independent manner and promotes their annealing to form a more stable structure. Further truncation mutations confirmed that the highly disordered N-tail and C-tail are critical for the biochemical activities of DDX3X. They are functionally complementary, with the N-tail being crucial. These results will shed new light on our understanding of the molecular mechanism of DDX3X in RNA metabolism and DNA repair, and have potential significance for the development of antiviral/anticancer drugs targeting DDX3X.
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Affiliation(s)
- Yi-Ning He
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Xiao-Rui Han
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Dong Wang
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Jia-Li Hou
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Xi-Miao Hou
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China.
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2
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Toyama Y, Shimada I. NMR characterization of RNA binding property of the DEAD-box RNA helicase DDX3X and its implications for helicase activity. Nat Commun 2024; 15:3303. [PMID: 38664397 PMCID: PMC11045745 DOI: 10.1038/s41467-024-47659-w] [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: 10/17/2023] [Accepted: 04/05/2024] [Indexed: 04/28/2024] Open
Abstract
The DEAD-box RNA helicase (DDX) plays a central role in many aspects of RNA metabolism by remodeling the defined structure of RNA molecules. While a number of structural studies have revealed the atomistic details of the interaction between DDX and RNA ligands, the molecular mechanism of how this molecule unwinds a structured RNA into an unstructured single-stranded RNA (ssRNA) has largely remained elusive. This is due to challenges in structurally characterizing the unwinding intermediate state and the lack of thermodynamic details underlying this process. In this study, we use solution nuclear magnetic resonance (NMR) spectroscopy to characterize the interaction of human DDX3X, a member of the DDX family, with various RNA ligands. Our results show that the inherent binding affinity of DDX3X for ssRNA is significantly higher than that for structured RNA elements. This preferential binding, accompanied by the formation of a domain-closed conformation in complex with ssRNA, effectively stabilizes the denatured ssRNA state and thus underlies the unwinding activity of DDX3X. Our results provide a thermodynamic and structural basis for the DDX function, whereby DDX can recognize and remodel a distinct set of structured RNAs to participate in a wide range of physiological processes.
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Affiliation(s)
- Yuki Toyama
- RIKEN Center for Biosystems Dynamics Research (BDR), 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan.
| | - Ichio Shimada
- RIKEN Center for Biosystems Dynamics Research (BDR), 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan.
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8528, Japan.
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3
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Cruz VE, Weirich CS, Peddada N, Erzberger JP. The DEAD-box ATPase Dbp10/DDX54 initiates peptidyl transferase center formation during 60S ribosome biogenesis. Nat Commun 2024; 15:3296. [PMID: 38632236 PMCID: PMC11024185 DOI: 10.1038/s41467-024-47616-7] [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: 12/12/2023] [Accepted: 04/04/2024] [Indexed: 04/19/2024] Open
Abstract
DEAD-box ATPases play crucial roles in guiding rRNA restructuring events during the biogenesis of large (60S) ribosomal subunits, but their precise molecular functions are currently unknown. In this study, we present cryo-EM reconstructions of nucleolar pre-60S intermediates that reveal an unexpected, alternate secondary structure within the nascent peptidyl-transferase-center (PTC). Our analysis of three sequential nucleolar pre-60S intermediates reveals that the DEAD-box ATPase Dbp10/DDX54 remodels this alternate base pairing and enables the formation of the rRNA junction that anchors the mature form of the universally conserved PTC A-loop. Post-catalysis, Dbp10 captures rRNA helix H61, initiating the concerted exchange of biogenesis factors during late nucleolar 60S maturation. Our findings show that Dbp10 activity is essential for the formation of the ribosome active site and reveal how this function is integrated with subsequent assembly steps to drive the biogenesis of the large ribosomal subunit.
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Affiliation(s)
- Victor E Cruz
- Department of Biophysics, UT Southwestern Medical Center - ND10.124B, 5323 Harry Hines Blvd., Dallas, TX, 75390, USA
- O'Donnell Brain Institute/CAND, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, 75390, USA
| | - Christine S Weirich
- Department of Biophysics, UT Southwestern Medical Center - ND10.124B, 5323 Harry Hines Blvd., Dallas, TX, 75390, USA
| | - Nagesh Peddada
- Department of Biophysics, UT Southwestern Medical Center - ND10.124B, 5323 Harry Hines Blvd., Dallas, TX, 75390, USA
- Center for the Genetics of Host Defense, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, 75390, USA
| | - Jan P Erzberger
- Department of Biophysics, UT Southwestern Medical Center - ND10.124B, 5323 Harry Hines Blvd., Dallas, TX, 75390, USA.
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4
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Chen HH, Yu HI, Chang JJS, Li CW, Yang MH, Hung MC, Tarn WY. DDX3 regulates cancer immune surveillance via 3' UTR-mediated cell-surface expression of PD-L1. Cell Rep 2024; 43:113937. [PMID: 38489268 DOI: 10.1016/j.celrep.2024.113937] [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: 11/17/2023] [Revised: 02/06/2024] [Accepted: 02/23/2024] [Indexed: 03/17/2024] Open
Abstract
Programmed death-1 (PD-1)/PD ligand-1 (PD-L1)-mediated immune escape contributes to cancer development and has been targeted as an anti-cancer strategy. Here, we show that inhibition of the RNA helicase DDX3 increased CD8+ T cell infiltration in syngeneic oral squamous cell carcinoma tumors. DDX3 knockdown compromised interferon-γ-induced PD-L1 expression and, in particular, reduced the level of cell-surface PD-L1. DDX3 promoted surface PD-L1 expression by recruiting the adaptor protein 2 (AP2) complex to the 3' UTR of PD-L1 mRNA. DDX3 depletion or 3' UTR truncation increased the binding of the coatomer protein complexes to PD-L1, leading to its intracellular accumulation. Therefore, this 3' UTR-dependent mechanism may counteract cellular negative effects on surface trafficking of PD-L1. Finally, pharmaceutic disruption of DDX3's interaction with AP2 reduced surface PD-L1 expression, supporting that the DDX3-AP2 pathway routes PD-L1 to the cell surface. Targeting DDX3 to modulate surface trafficking of immune checkpoint proteins may provide a potential strategy for cancer immunotherapy.
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Affiliation(s)
- Hung-Hsi Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Hsin-I Yu
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | | | - Chia-Wei Li
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Muh-Hwa Yang
- Institute of Clinical Medicine, School of Medicine, National Yang-Ming Chao-Tung University, Taipei, Taiwan
| | - Mien-Chie Hung
- Graduate Institute of Biomedical Sciences, Research Center for Cancer Biology and Center for Molecular Medicine, China Medical University, Taichung, Taiwan
| | - Woan-Yuh Tarn
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
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5
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Patrick EM, Yadav R, Senanayake K, Cotter K, Putnam AA, Jankowsky E, Comstock MJ. High-resolution fleezers reveal duplex opening and stepwise assembly by an oligomer of the DEAD-box helicase Ded1p. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.29.582829. [PMID: 38496418 PMCID: PMC10942383 DOI: 10.1101/2024.02.29.582829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
DEAD-box RNA helicases are ubiquitous in all domains of life where they bind and remodel RNA and RNA-protein complexes. DEAD-box helicases unwind RNA duplexes by local opening of helical regions without directional movement through the duplexes and some of these enzymes, including Ded1p from Saccharomyces cerevisiae, oligomerize to effectively unwind RNA duplexes. Whether and how DEAD-box helicases coordinate oligomerization and unwinding is not known and it is unclear how many base pairs are actively opened. Using high-resolution optical tweezers and fluorescence, we reveal a highly dynamic and stochastic process of multiple Ded1p protomers assembling on and unwinding an RNA duplex. One Ded1p protomer binds to a duplex-adjacent ssRNA tail and promotes binding and subsequent unwinding of the duplex by additional Ded1p protomers in 4-6 bp steps. The data also reveal rapid duplex unwinding and rezipping linked with binding and dissociation of individual protomers and coordinated with the ATP hydrolysis cycle.
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6
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Owens MC, Shen H, Yanas A, Mendoza-Figueroa MS, Lavorando E, Wei X, Shweta H, Tang HY, Goldman YE, Liu KF. Mutant forms of DDX3X with diminished catalysis form hollow condensates that exhibit sex-specific regulation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.19.533240. [PMID: 38076929 PMCID: PMC10705264 DOI: 10.1101/2023.03.19.533240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Mutations in the RNA helicase DDX3X, implicated in various cancers and neurodevelopmental disorders, often impair RNA unwinding and translation. However, the mechanisms underlying this impairment and the differential interactions of DDX3X mutants with wild-type (WT) X-linked DDX3X and Y-linked homolog DDX3Y remain elusive. This study reveals that specific DDX3X mutants more frequently found in disease form distinct hollow condensates in cells. Using a combined structural, biochemical, and single-molecule microscopy study, we show that reduced ATPase and RNA release activities contribute to condensate formation and the catalytic deficits result from inhibiting the catalytic cycle at multiple steps. Proteomic investigations further demonstrate that these hollow condensates sequester WT DDX3X/DDX3Y and other proteins crucial for diverse signaling pathways. WT DDX3X enhances the dynamics of heterogeneous mutant/WT hollow condensates more effectively than DDX3Y. These findings offer valuable insights into the catalytic defects of specific DDX3X mutants and their differential interactions with wild-type DDX3X and DDX3Y, potentially explaining sex biases in disease.
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7
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Ripin N, Parker R. Formation, function, and pathology of RNP granules. Cell 2023; 186:4737-4756. [PMID: 37890457 PMCID: PMC10617657 DOI: 10.1016/j.cell.2023.09.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 07/28/2023] [Accepted: 09/07/2023] [Indexed: 10/29/2023]
Abstract
Ribonucleoprotein (RNP) granules are diverse membrane-less organelles that form through multivalent RNA-RNA, RNA-protein, and protein-protein interactions between RNPs. RNP granules are implicated in many aspects of RNA physiology, but in most cases their functions are poorly understood. RNP granules can be described through four key principles. First, RNP granules often arise because of the large size, high localized concentrations, and multivalent interactions of RNPs. Second, cells regulate RNP granule formation by multiple mechanisms including posttranslational modifications, protein chaperones, and RNA chaperones. Third, RNP granules impact cell physiology in multiple manners. Finally, dysregulation of RNP granules contributes to human diseases. Outstanding issues in the field remain, including determining the scale and molecular mechanisms of RNP granule function and how granule dysfunction contributes to human disease.
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Affiliation(s)
- Nina Ripin
- Department of Biochemistry and Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Roy Parker
- Department of Biochemistry and Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80303, USA.
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8
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Bohnsack KE, Yi S, Venus S, Jankowsky E, Bohnsack MT. Cellular functions of eukaryotic RNA helicases and their links to human diseases. Nat Rev Mol Cell Biol 2023; 24:749-769. [PMID: 37474727 DOI: 10.1038/s41580-023-00628-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2023] [Indexed: 07/22/2023]
Abstract
RNA helicases are highly conserved proteins that use nucleoside triphosphates to bind or remodel RNA, RNA-protein complexes or both. RNA helicases are classified into the DEAD-box, DEAH/RHA, Ski2-like, Upf1-like and RIG-I families, and are the largest class of enzymes active in eukaryotic RNA metabolism - virtually all aspects of gene expression and its regulation involve RNA helicases. Mutation and dysregulation of these enzymes have been linked to a multitude of diseases, including cancer and neurological disorders. In this Review, we discuss the regulation and functional mechanisms of RNA helicases and their roles in eukaryotic RNA metabolism, including in transcription regulation, pre-mRNA splicing, ribosome assembly, translation and RNA decay. We highlight intriguing models that link helicase structure, mechanisms of function (such as local strand unwinding, translocation, winching, RNA clamping and displacing RNA-binding proteins) and biological roles, including emerging connections between RNA helicases and cellular condensates formed through liquid-liquid phase separation. We also discuss associations of RNA helicases with human diseases and recent efforts towards the design of small-molecule inhibitors of these pivotal regulators of eukaryotic gene expression.
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Affiliation(s)
- Katherine E Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany.
| | - Soon Yi
- Center for RNA Science and Therapeutics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
- Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Sarah Venus
- Center for RNA Science and Therapeutics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
- Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Eckhard Jankowsky
- Center for RNA Science and Therapeutics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
- Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
- Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
- Moderna, Cambridge, MA, USA.
| | - Markus T Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany.
- Göttingen Centre for Molecular Biosciences, University of Göttingen, Göttingen, Germany.
- Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
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9
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Wurm JP. Structural basis for RNA-duplex unwinding by the DEAD-box helicase DbpA. RNA (NEW YORK, N.Y.) 2023; 29:1339-1354. [PMID: 37221012 PMCID: PMC10573307 DOI: 10.1261/rna.079582.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Accepted: 04/29/2023] [Indexed: 05/25/2023]
Abstract
DEAD-box RNA helicases are implicated in most aspects of RNA biology, where these enzymes unwind short RNA duplexes in an ATP-dependent manner. During the central step of the unwinding cycle, the two domains of the helicase core form a distinct closed conformation that destabilizes the RNA duplex, which ultimately leads to duplex melting. Despite the importance of this step for the unwinding process no high-resolution structures of this state are available. Here, I used nuclear magnetic resonance spectroscopy and X-ray crystallography to determine structures of the DEAD-box helicase DbpA in the closed conformation, complexed with substrate duplexes and single-stranded unwinding product. These structures reveal that DbpA initiates duplex unwinding by interacting with up to three base-paired nucleotides and a 5' single-stranded RNA duplex overhang. These high-resolution snapshots, together with biochemical assays, rationalize the destabilization of the RNA duplex and are integrated into a conclusive model of the unwinding process.
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Affiliation(s)
- Jan Philip Wurm
- Institute of Biophysics and Physical Biochemistry, Regensburg Center for Biochemistry, University of Regensburg, 93053 Regensburg, Germany
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10
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Adashev VE, Kotov AA, Olenina LV. RNA Helicase Vasa as a Multifunctional Conservative Regulator of Gametogenesis in Eukaryotes. Curr Issues Mol Biol 2023; 45:5677-5705. [PMID: 37504274 PMCID: PMC10378496 DOI: 10.3390/cimb45070358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Revised: 06/30/2023] [Accepted: 07/03/2023] [Indexed: 07/29/2023] Open
Abstract
Being a conservative marker of germ cells across metazoan species, DEAD box RNA helicase Vasa (DDX4) remains the subject of worldwide investigations thanks to its multiple functional manifestations. Vasa takes part in the preformation of primordial germ cells in a group of organisms and contributes to the maintenance of germline stem cells. Vasa is an essential player in the piRNA-mediated silencing of harmful genomic elements and in the translational regulation of selected mRNAs. Vasa is the top hierarchical protein of germ granules, liquid droplet organelles that compartmentalize RNA processing factors. Here, we survey current advances and problems in the understanding of the multifaceted functions of Vasa proteins in the gametogenesis of different eukaryotic organisms, from nematodes to humans.
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Affiliation(s)
- Vladimir E Adashev
- Department of Molecular Mechanisms for Realization of Genetic Information, Laboratory of Biochemical Genetics of Animals, National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
| | - Alexei A Kotov
- Department of Molecular Mechanisms for Realization of Genetic Information, Laboratory of Biochemical Genetics of Animals, National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
| | - Ludmila V Olenina
- Department of Molecular Mechanisms for Realization of Genetic Information, Laboratory of Biochemical Genetics of Animals, National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
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11
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Cruz VE, Sekulski K, Peddada N, Sailer C, Balasubramanian S, Weirich CS, Stengel F, Erzberger JP. Sequence-specific remodeling of a topologically complex RNP substrate by Spb4. Nat Struct Mol Biol 2022; 29:1228-1238. [PMID: 36482249 PMCID: PMC10680166 DOI: 10.1038/s41594-022-00874-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 10/14/2022] [Indexed: 12/13/2022]
Abstract
DEAD-box ATPases are ubiquitous enzymes essential in all aspects of RNA biology. However, the limited in vitro catalytic activities described for these enzymes are at odds with their complex cellular roles, most notably in driving large-scale RNA remodeling steps during the assembly of ribonucleoproteins (RNPs). We describe cryo-EM structures of 60S ribosomal biogenesis intermediates that reveal how context-specific RNA unwinding by the DEAD-box ATPase Spb4 results in extensive, sequence-specific remodeling of rRNA secondary structure. Multiple cis and trans interactions stabilize Spb4 in a post-catalytic, high-energy intermediate that drives the organization of the three-way junction at the base of rRNA domain IV. This mechanism explains how limited strand separation by DEAD-box ATPases is leveraged to provide non-equilibrium directionality and ensure efficient and accurate RNP assembly.
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Affiliation(s)
- Victor Emmanuel Cruz
- Department of Biophysics, UT Southwestern Medical Center - ND10.124B, Dallas, TX, USA
| | - Kamil Sekulski
- Department of Biophysics, UT Southwestern Medical Center - ND10.124B, Dallas, TX, USA
| | - Nagesh Peddada
- Department of Biophysics, UT Southwestern Medical Center - ND10.124B, Dallas, TX, USA
| | - Carolin Sailer
- Department of Biology, University of Konstanz, Konstanz, Germany
- Konstanz Research School Chemical Biology, University of Konstanz, Konstanz, Germany
- Department of Biomedical Sciences, University of Copenhagen, København, Denmark
| | - Sahana Balasubramanian
- Department of Biophysics, UT Southwestern Medical Center - ND10.124B, Dallas, TX, USA
- Cell Biology & Molecular Physiology Department, University of Pittsburgh, Pittsburgh, PA, USA
| | - Christine S Weirich
- Department of Biophysics, UT Southwestern Medical Center - ND10.124B, Dallas, TX, USA
| | - Florian Stengel
- Department of Biology, University of Konstanz, Konstanz, Germany
- Konstanz Research School Chemical Biology, University of Konstanz, Konstanz, Germany
| | - Jan P Erzberger
- Department of Biophysics, UT Southwestern Medical Center - ND10.124B, Dallas, TX, USA.
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12
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Weinreb JT, Bowman TV. Clinical and mechanistic insights into the roles of DDX41 in haematological malignancies. FEBS Lett 2022; 596:2736-2745. [PMID: 36036093 PMCID: PMC9669125 DOI: 10.1002/1873-3468.14487] [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: 06/17/2022] [Revised: 07/17/2022] [Accepted: 07/20/2022] [Indexed: 11/10/2022]
Abstract
DEAD-box Helicase 41 (DDX41) is a member of the DExD/H-box helicase family that has a variety of cellular functions. Of note, germline and somatic mutations in the DDX41 gene are prevalently found in myeloid malignancies. Here, we present a comprehensive and analytic review covering relevant clinical, translational and basic science findings on DDX41. We first describe the initial characterisation of DDX41 mutations in patients affected by myelodysplastic syndromes, their associated clinical characteristics, and current treatment modalities. We then cover the known cellular functions of DDX41, spanning from its discovery in Drosophila as a neuroregulator through its more recently described roles in inflammatory signalling, R-loop metabolism and snoRNA processing. We end with a summary of the identified basic functions of DDX41 that when perturbed may contribute to the underlying pathology of haematologic neoplasms.
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Affiliation(s)
- Joshua T. Weinreb
- Albert Einstein College of Medicine, Department of Developmental and Molecular Biology, Bronx, NY, USA
- Albert Einstein College of Medicine, Gottesman Institute for Stem Cell Biology and Regenerative Medicine, Bronx, NY, USA
| | - Teresa V. Bowman
- Albert Einstein College of Medicine, Department of Developmental and Molecular Biology, Bronx, NY, USA
- Albert Einstein College of Medicine, Gottesman Institute for Stem Cell Biology and Regenerative Medicine, Bronx, NY, USA
- Albert Einstein College of Medicine and the Montefiore Medical Center, Department of Oncology, Bronx, NY, USA
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13
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Dai S, Tang X, Li L, Ishidate T, Ozturk AR, Chen H, Dude AL, Yan YH, Dong MQ, Shen EZ, Mello CC. A family of C. elegans VASA homologs control Argonaute pathway specificity and promote transgenerational silencing. Cell Rep 2022; 40:111265. [PMID: 36070689 PMCID: PMC9887883 DOI: 10.1016/j.celrep.2022.111265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 06/01/2022] [Accepted: 08/04/2022] [Indexed: 02/02/2023] Open
Abstract
Germline Argonautes direct transcriptome surveillance within perinuclear membraneless organelles called nuage. In C. elegans, a family of Vasa-related Germ Line Helicase (GLH) proteins localize in and promote the formation of nuage. Previous studies have implicated GLH proteins in inherited silencing, but direct roles in small-RNA production, Argonaute binding, or mRNA targeting have not been identified. Here we show that GLH proteins compete with each other to control Argonaute pathway specificity, bind directly to Argonaute target mRNAs, and promote the amplification of small RNAs required for transgenerational inheritance. We show that the ATPase cycle of GLH-1 regulates direct binding to the Argonaute WAGO-1, which engages amplified small RNAs. Our findings support a dynamic and direct role for GLH proteins in inherited silencing beyond their role as structural components of nuage.
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Affiliation(s)
- Siyuan Dai
- RNA Therapeutic Institute, UMass Chan Medical School, Worcester, MA 01605, USA; Morningside Graduate School of Biomedical Sciences, UMass Chan Medical School, Worcester, MA 01605, USA
| | - Xiaoyin Tang
- Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China
| | - Lili Li
- Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China
| | - Takao Ishidate
- RNA Therapeutic Institute, UMass Chan Medical School, Worcester, MA 01605, USA
| | - Ahmet R Ozturk
- RNA Therapeutic Institute, UMass Chan Medical School, Worcester, MA 01605, USA
| | - Hao Chen
- Program in Bioinformatics and Integrative Biology, UMass Chan Medical School, Worcester, MA 01605, USA; Bioinformatics Program, Boston University, Boston, MA 02215, USA
| | - Altair L Dude
- RNA Therapeutic Institute, UMass Chan Medical School, Worcester, MA 01605, USA
| | - Yong-Hong Yan
- National Institute of Biological Sciences, Beijing 102206, China
| | - Meng-Qiu Dong
- National Institute of Biological Sciences, Beijing 102206, China
| | - En-Zhi Shen
- Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China.
| | - Craig C Mello
- RNA Therapeutic Institute, UMass Chan Medical School, Worcester, MA 01605, USA; Howard Hughes Medical Institute, Worcester, MA 01605, USA.
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14
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Venus S, Jankowsky E. Measuring the impact of cofactors on RNA helicase activities. Methods 2022; 204:376-385. [PMID: 35429628 PMCID: PMC9306305 DOI: 10.1016/j.ymeth.2022.04.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 04/03/2022] [Accepted: 04/12/2022] [Indexed: 12/25/2022] Open
Abstract
RNA helicases are the largest class of enzymes in eukaryotic RNA metabolism. In cells, protein cofactors regulate RNA helicase functions and impact biochemical helicase activities. Understanding how cofactors affect enzymatic activities of RNA helicases is thus critical for delineating physical roles and regulation of RNA helicases in cells. Here, we discuss approaches and conceptual considerations for the design of experiments to interrogate cofactor effects on RNA helicase activities in vitro. We outline the mechanistic frame for helicase reactions, discuss optimization of experimental setup and reaction parameters for measuring cofactor effects on RNA helicase activities, and provide basic guides to data analysis and interpretation. The described approaches are also instructive for determining the impact of small molecule inhibitors of RNA helicases.
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15
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Hage A, Bharaj P, van Tol S, Giraldo MI, Gonzalez-Orozco M, Valerdi KM, Warren AN, Aguilera-Aguirre L, Xie X, Widen SG, Moulton HM, Lee B, Johnson JR, Krogan NJ, García-Sastre A, Shi PY, Freiberg AN, Rajsbaum R. The RNA helicase DHX16 recognizes specific viral RNA to trigger RIG-I-dependent innate antiviral immunity. Cell Rep 2022; 38:110434. [PMID: 35263596 PMCID: PMC8903195 DOI: 10.1016/j.celrep.2022.110434] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 11/02/2021] [Accepted: 02/02/2022] [Indexed: 12/13/2022] Open
Abstract
Type I interferons (IFN-I) are essential to establish antiviral innate immunity. Unanchored (or free) polyubiquitin (poly-Ub) has been shown to regulate IFN-I responses. However, few unanchored poly-Ub interactors are known. To identify factors regulated by unanchored poly-Ub in a physiological setting, we developed an approach to isolate unanchored poly-Ub from lung tissue. We identified the RNA helicase DHX16 as a potential pattern recognition receptor (PRR). Silencing of DHX16 in cells and in vivo diminished IFN-I responses against influenza virus. These effects extended to members of other virus families, including Zika and SARS-CoV-2. DHX16-dependent IFN-I production requires RIG-I and unanchored K48-poly-Ub synthesized by the E3-Ub ligase TRIM6. DHX16 recognizes a signal in influenza RNA segments that undergo splicing and requires its RNA helicase motif for direct, high-affinity interactions with specific viral RNAs. Our study establishes DHX16 as a PRR that partners with RIG-I for optimal activation of antiviral immunity requiring unanchored poly-Ub.
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Affiliation(s)
- Adam Hage
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Preeti Bharaj
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Sarah van Tol
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Maria I Giraldo
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Maria Gonzalez-Orozco
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Karl M Valerdi
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Abbey N Warren
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Leopoldo Aguilera-Aguirre
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Xuping Xie
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Steven G Widen
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Hong M Moulton
- Department of Biomedical Sciences, Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA
| | - Benhur Lee
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Jeffrey R Johnson
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Nevan J Krogan
- Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI) COVID-19 Research Group (QCRG), University of California at San Francisco, San Francisco, CA 94158, USA; Gladstone Institute of Data Science and Biotechnology, J. David Gladstone Institutes, San Francisco, CA 94158, USA
| | - Adolfo García-Sastre
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Department of Medicine, Division of Infectious Diseases, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Department of Pathology, Molecular and Cell-Based Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Pei-Yong Shi
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA; Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, TX 77555, USA; Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA; Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Alexander N Freiberg
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA; Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA; Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Ricardo Rajsbaum
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA; Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA.
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16
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Natural transformation protein ComFA exhibits single-stranded DNA translocase activity. J Bacteriol 2022; 204:e0051821. [PMID: 35041498 DOI: 10.1128/jb.00518-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Natural transformation is one of the major mechanisms of horizontal gene transfer in bacterial populations and has been demonstrated in numerous species of bacteria. Despite the prevalence of natural transformation, much of the molecular mechanism remains unexplored. One major outstanding question is how the cell powers DNA import, which is rapid and highly processive. ComFA is one of a handful of proteins required for natural transformation in gram-positive bacteria. Its structural resemblance to the DEAD-box helicase family has led to a long-held hypothesis that ComFA acts as a motor to help drive DNA import into the cytosol. Here, we explored the helicase and translocase activity of ComFA to address this hypothesis. We followed the DNA-dependent ATPase activity of ComFA and, combined with mathematical modeling, demonstrated that ComFA likely translocates on single-stranded DNA from 5' to 3'. However, this translocase activity does not lead to DNA unwinding in the conditions we tested. Further, we analyzed the ATPase cycle of ComFA and found that ATP hydrolysis stimulates the release of DNA, providing a potential mechanism for translocation. These findings help define the molecular contribution of ComFA to natural transformation and support the conclusion that ComFA plays a key role in powering DNA uptake. Importance Competence, or the ability of bacteria to take up and incorporate foreign DNA in a process called natural transformation, is common in the bacterial kingdom. Research in several bacterial species suggests that long, contiguous stretches of DNA are imported into cells in a processive manner, but how bacteria power transformation remains unclear. Our finding that ComFA, a DEAD-box helicase required for competence in gram-positive bacteria, translocates on single-stranded DNA from 5' to 3', supports the long held hypothesis that ComFA may be the motor powering DNA transport during natural transformation. Moreover, ComFA may be a previously unidentified type of DEAD-box helicase-one with the capability of extended translocation on single-stranded DNA.
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Jarmoskaite I, Helmers AE, Russell R. Measurement of ATP utilization in RNA unwinding and RNA chaperone activities by DEAD-box helicase proteins. Methods Enzymol 2022; 673:53-76. [PMID: 35965018 PMCID: PMC10040262 DOI: 10.1016/bs.mie.2022.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
RNA helicase proteins perform coupled reactions in which cycles of ATP binding and hydrolysis are used to drive local unwinding of double-stranded RNA (dsRNA). For some helicases in the ubiquitous DEAD-box family, these local unwinding events are integral to folding transitions in structured RNAs, and thus these helicases function as RNA chaperones. An important measure of the efficiency of the helicase-catalyzed reaction is the ATP utilization value, which represents the average number of ATP molecules hydrolyzed during RNA unwinding or a chaperone-assisted RNA structural rearrangement. Here we outline procedures that can be used to measure the ATP utilization value in RNA unwinding or folding transitions. As an example of an RNA folding transition, we focus on the refolding of the Tetrahymena thermophila group I intron ribozyme from a long-lived misfolded structure to its native structure, and we outline strategies for adapting this assay to other RNA folding transitions. For a simple dsRNA unwinding event, the ATP utilization value provides a measure of the coupling between the ATPase and RNA unwinding activities, and for a complex RNA structural transition it can give insight into the scope of the rearrangement and the efficiency with which the helicase uses the energy from ATPase cycles to promote the rearrangement.
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Affiliation(s)
- Inga Jarmoskaite
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, United States
| | - Anna E Helmers
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, United States
| | - Rick Russell
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, United States.
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18
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Ripin N, Parker R. Are stress granules the RNA analogs of misfolded protein aggregates? RNA (NEW YORK, N.Y.) 2022; 28:67-75. [PMID: 34670846 PMCID: PMC8675284 DOI: 10.1261/rna.079000.121] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Ribonucleoprotein granules are ubiquitous features of eukaryotic cells. Several observations argue that the formation of at least some RNP granules can be considered analogous to the formation of unfolded protein aggregates. First, unfolded protein aggregates form from the exposure of promiscuous protein interaction surfaces, while some mRNP granules form, at least in part, by promiscuous intermolecular RNA-RNA interactions due to exposed RNA surfaces when mRNAs are not engaged with ribosomes. Second, analogous to the role of protein chaperones in preventing misfolded protein aggregation, cells contain abundant "RNA chaperones" to limit inappropriate RNA-RNA interactions and prevent mRNP granule formation. Third, analogous to the role of protein aggregates in diseases, situations where RNA aggregation exceeds the capacity of RNA chaperones to disaggregate RNAs may contribute to human disease. Understanding that RNP granules can be considered as promiscuous, reversible RNA aggregation events allow insight into their composition and how cells have evolved functions for RNP granules.
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Affiliation(s)
- Nina Ripin
- Department of Biochemistry and Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, Colorado 80303, USA
| | - Roy Parker
- Department of Biochemistry and Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, Colorado 80303, USA
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19
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De Colibus L, Stunnenberg M, Geijtenbeek TB. DDX3X structural analysis: Implications in the pharmacology and innate immunity. CURRENT RESEARCH IN IMMUNOLOGY 2022; 3:100-109. [PMID: 35647523 PMCID: PMC9133689 DOI: 10.1016/j.crimmu.2022.05.002] [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: 12/13/2021] [Revised: 05/01/2022] [Accepted: 05/04/2022] [Indexed: 11/13/2022] Open
Abstract
The human DEAD-Box Helicase 3 X-Linked (DDX3X) is an ATP-dependent RNA helicase involved in virtually every step of RNA metabolism, ranging from transcription regulation in the nucleus to translation initiation and stress granule (SG) formation, and plays crucial roles in innate immunity, as well as tumorigenesis and viral infections. This review discusses latest advances in DDX3X biology and structure-function relationship, including the implications of the recent DDX3X crystal structure in complex with double stranded RNA for RNA metabolism, DDX3X involvement in the cross-talk between innate immune responses and cell stress adaptation, and the roles of DDX3X in controlling cell fate. The human DDX3X, an ATP-dependent RNA helicase, plays a central role in a variety of cellular processes involving RNA. DDX3X is implicated in antiviral signalling pathways. DDX3X interacts with full-length NLRP3 and its NACHT domain. The recent crystal structure of DDX3X in complex with dsRNA offers a model for understanding its binding to the HIV-1 TAR hairpin sequence.
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20
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Puno MR, Lima CD. Methods to assess helicase and translocation activities of human nuclear RNA exosome and RNA adaptor complexes. Methods Enzymol 2022; 673:453-473. [PMID: 35965016 PMCID: PMC9382703 DOI: 10.1016/bs.mie.2022.03.060] [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] [Indexed: 11/02/2022]
Abstract
The nuclear RNA exosome collaborates with the MTR4 helicase and RNA adaptor complexes to process, surveil, and degrade RNA. Here we outline methods to characterize RNA translocation and strand displacement by exosome-associated helicases and adaptor complexes using fluorescence-based strand displacement assays. The design and preparation of substrates suitable for analysis of helicase and decay activities of reconstituted MTR4–exosome complexes are described. To aid structural and biophysical studies, we present strategies for engineering substrates that can stall helicases during translocation, providing a means to capture snapshots of interactions and molecular steps involved in substrate translocation and delivery to the exosome.
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21
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Karbstein K. Attacking a DEAD problem: The role of DEAD-box ATPases in ribosome assembly and beyond. Methods Enzymol 2022; 673:19-38. [PMID: 35965007 PMCID: PMC10154911 DOI: 10.1016/bs.mie.2022.03.033] [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: 11/30/2022]
Abstract
DEAD-box proteins are a subfamily of ATPases with similarity to RecA-type helicases that are involved in all aspects of RNA Biology. Despite their potential to regulate these processes via their RNA-dependent ATPase activity, their roles remain poorly characterized. Here I describe a roadmap to study these proteins in the context of ribosome assembly, the process that utilizes more than half of all DEAD-box proteins encoded in the yeast genome.
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Affiliation(s)
- Katrin Karbstein
- Department of Integrative Structural and Computational Biology, Scripps Florida, Jupiter, FL, United States; HHMI Faculty Scholar, Chevy Chase, MD, United States; The Skaggs Graduate School of Chemical and Biological Sciences, Scripps Florida, Jupiter, FL, United States.
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22
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Analysis of the conformational space and dynamics of RNA helicases by single-molecule FRET in solution and on surfaces. Methods Enzymol 2022; 673:251-310. [DOI: 10.1016/bs.mie.2022.03.043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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23
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Abstract
RNA viruses cause many routine illnesses, such as the common cold and the flu. Recently, more deadly diseases have emerged from this family of viruses. The hepatitis C virus has had a devastating impact worldwide. Despite the cures developed in the U.S. and Europe, economically disadvantaged countries remain afflicted by HCV infection due to the high cost of these medications. More recently, COVID-19 has swept across the world, killing millions and disrupting economies and lifestyles; the virus responsible for this pandemic is a coronavirus. Our understanding of HCV and SARS CoV-2 replication is still in its infancy. Helicases play a critical role in the replication, transcription and translation of viruses. These key enzymes need extensive study not only as an essential player in the viral lifecycle, but also as targets for antiviral therapeutics. In this review, we highlight the current knowledge for RNA helicases of high importance to human health.
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Affiliation(s)
- John C Marecki
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Binyam Belachew
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Jun Gao
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Kevin D Raney
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, United States.
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24
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Hudson L, Begg M, Wright B, Cheek T, Jahoda CAB, Reynolds NJ. Dominant effect of gap junction communication in wound-induced calcium-wave, NFAT activation and wound closure in keratinocytes. J Cell Physiol 2021; 236:8171-8183. [PMID: 34180060 DOI: 10.1002/jcp.30488] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 05/18/2021] [Accepted: 06/15/2021] [Indexed: 12/13/2022]
Abstract
Wounding induces a calcium wave and disrupts the calcium gradient across the epidermis but mechanisms mediating calcium and downstream signalling, and longer-term wound healing responses are incompletely understood. As expected, live-cell confocal imaging of Fluo-4-loaded normal human keratinocytes showed an immediate increase in [Ca2+ ]i at the wound edge that spread as a calcium wave (8.3 µm/s) away from the wound edge with gradually diminishing rate of rise and amplitude. The amplitude and area under the curve of [Ca2+ ]i flux was increased in high (1.2 mM) [Ca2+ ]o media. 18α-glycyrrhetinic acid (18αGA), a gap-junction inhibitor or hexokinase, an ATP scavenger, blocked the wound-induced calcium wave, dependent in part on [Ca2+ ]o . Wounding in a high [Ca2+ ]o increased nuclear factor of activated T-cells (NFAT) but not NFkB activation, assessed by dual-luciferase receptor assays compared to unwounded cells. Treatment with 18αGA or the store-operated channel blocker GSK-7975A inhibited wound-induced NFAT activation, whereas treatment with hexokinase did not. Real-time cell migration analysis, measuring wound closure rates over 24 h, revealed that 18αGA essentially blocked wound closure whereas hexokinase and GSK-7975A showed relatively minimal effects. Together these data indicate that while both gap-junction communication and ATP release from damaged cells are important in regulating the wound-induced calcium wave, long-term transcriptional and functional responses are dominantly regulated by gap-junction communication.
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Affiliation(s)
- Laura Hudson
- Institute of Translational and Clinical Medicine, Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Malcolm Begg
- Medicines Research Centre, GlaxoSmithKline, London, UK
| | - Blythe Wright
- Institute of Translational and Clinical Medicine, Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Tim Cheek
- Biosciences Institute, Medical School, Newcastle University, Newcastle upon Tyne, UK
| | | | - Nick J Reynolds
- Institute of Translational and Clinical Medicine, Medical School, Newcastle University, Newcastle upon Tyne, UK.,Department of Dermatology, Royal Victoria Infirmary and NIHR Newcastle Biomedical Research Centre, Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
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25
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Anders U, Gulotti-Georgieva M, Zelger-Paulus S, Hibti FE, Frydman C, Suckau D, Sigel RKO, Zenobi R. Screening for potential interaction partners with surface plasmon resonance imaging coupled to MALDI mass spectrometry. Anal Biochem 2021; 624:114195. [PMID: 33857502 DOI: 10.1016/j.ab.2021.114195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 03/14/2021] [Accepted: 04/02/2021] [Indexed: 11/29/2022]
Abstract
We coupled SPR imaging (SPRi) with matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) to identify new potential RNA binders. Here, we improve this powerful method, especially by optimizing the proteolytic digestion (type of reducing agent, its concentration, and incubation time), to work with complex mixtures, specifically a lysate of the rough mitochondrial fraction from yeast. The advantages of this hyphenated method compared to column-based or separate analyses are (i) rapid and direct visual readout from the SPRi array, (ii) possibility of high-throughput analysis of different interactions in parallel, (iii) high sensitivity, and (iv) no sample loss or contamination due to elution or micro-recovery procedures. The model system used is a catalytically active RNA (group IIB intron from Saccharomyces cerevisiae, Sc.ai5γ) and its cofactor Mss116. The protein supports the RNA folding process and thereby the subsequent excision of the intronic RNA from the coding part. Using the novel approach of coupling SPR with MALDI MS, we report the identification of potential RNA-binding proteins from a crude yeast mitochondrial lysate in a non-targeted approach. Our results show that proteins other than the well-known cofactor Mss116 interact with Sc.ai5γ (Dbp8, Prp8, Mrp13, and Cullin-3), suggesting that the intron folding and splicing are regulated by more than one cofactor in vivo.
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Affiliation(s)
- Ulrike Anders
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 3, CH-8093, Zurich, Switzerland
| | - Maya Gulotti-Georgieva
- Department of Chemistry, University of Zurich, Winterthurerstr. 190, CH-8057, Zurich, Switzerland
| | - Susann Zelger-Paulus
- Department of Chemistry, University of Zurich, Winterthurerstr. 190, CH-8057, Zurich, Switzerland
| | - Fatima-Ezzahra Hibti
- Horiba France S.A.S, Avenue de La Vauve, Passage Jobin Yvon, CS 45002 - F-91120 Palaiseau, France
| | - Chiraz Frydman
- Horiba France S.A.S, Avenue de La Vauve, Passage Jobin Yvon, CS 45002 - F-91120 Palaiseau, France
| | - Detlev Suckau
- Bruker Daltonics, Fahrenheitstr. 4, D-28359 Bremen, Germany
| | - Roland K O Sigel
- Department of Chemistry, University of Zurich, Winterthurerstr. 190, CH-8057, Zurich, Switzerland
| | - Renato Zenobi
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 3, CH-8093, Zurich, Switzerland.
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26
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Singh RK, Jonely M, Leslie E, Rejali NA, Noriega R, Bass BL. Transient kinetic studies of the antiviral Drosophila Dicer-2 reveal roles of ATP in self-nonself discrimination. eLife 2021; 10:65810. [PMID: 33787495 PMCID: PMC8079148 DOI: 10.7554/elife.65810] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 03/31/2021] [Indexed: 11/25/2022] Open
Abstract
Some RIG-I-like receptors (RLRs) discriminate viral and cellular dsRNA by their termini, and Drosophila melanogaster Dicer-2 (dmDcr-2) differentially processes dsRNA with blunt or 2 nucleotide 3’-overhanging termini. We investigated the transient kinetic mechanism of the dmDcr-2 reaction using a rapid reaction stopped-flow technique and time-resolved fluorescence spectroscopy. Indeed, we found that ATP binding to dmDcr-2’s helicase domain impacts association and dissociation kinetics of dsRNA in a termini-dependent manner, revealing termini-dependent discrimination of dsRNA on a biologically relevant time scale (seconds). ATP hydrolysis promotes transient unwinding of dsRNA termini followed by slow rewinding, and directional translocation of the enzyme to the cleavage site. Time-resolved fluorescence anisotropy reveals a nucleotide-dependent modulation in conformational fluctuations (nanoseconds) of the helicase and Platform–PAZ domains that is correlated with termini-dependent dsRNA cleavage. Our study offers a kinetic framework for comparison to other Dicers, as well as all members of the RLRs involved in innate immunity.
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Affiliation(s)
- Raushan K Singh
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | - McKenzie Jonely
- Department of Chemistry, University of Utah, Salt Lake City, United States
| | - Evan Leslie
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | - Nick A Rejali
- Department of Pathology, University of Utah, Salt Lake City, United States
| | - Rodrigo Noriega
- Department of Chemistry, University of Utah, Salt Lake City, United States
| | - Brenda L Bass
- Department of Biochemistry, University of Utah, Salt Lake City, United States
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27
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Ali MAM. DEAD-box RNA helicases: The driving forces behind RNA metabolism at the crossroad of viral replication and antiviral innate immunity. Virus Res 2021; 296:198352. [PMID: 33640359 DOI: 10.1016/j.virusres.2021.198352] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 02/22/2021] [Accepted: 02/22/2021] [Indexed: 02/07/2023]
Abstract
DEAD-box RNA helicases, the largest family of superfamily 2 helicases, are a profoundly conserved family of RNA-binding proteins, containing a distinctive Asp-Glu-Ala-Asp (D-E-A-D) sequence motif, which is the origin of their name. Aside from the ATP-dependent unwinding of RNA duplexes, which set up these proteins as RNA helicases, DEAD-box proteins have been found to additionally stimulate RNA duplex fashioning and to uproot proteins from RNA, aiding the reformation of RNA and RNA-protein complexes. There is accumulating evidence that DEAD-box helicases play functions in the recognition of foreign nucleic acids and the modification of viral infection. As intracellular parasites, viruses must avoid identification by innate immune sensing mechanisms and disintegration by cellular machinery, whilst additionally exploiting host cell activities to assist replication. The capability of DEAD-box helicases to sense RNA in a sequence-independent way, as well as the broadness of cellular roles performed by members of this family, drive them to affect innate sensing and viral infections in numerous manners. Undoubtedly, DEAD-box helicases have been demonstrated to contribute to intracellular immune recognition, function as antiviral effectors, and even to be exploited by viruses to support their replication. Relying on the virus or the viral cycle phase, a DEAD-box helicase can function either in a proviral manner or as an antiviral factor. This review gives a comprehensive perspective on the various biochemical characteristics of DEAD-box helicases and their links to structural data. It additionally outlines the multiple functions that members of the DEAD-box helicase family play during viral infections.
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Affiliation(s)
- Mohamed A M Ali
- Department of Biochemistry, Faculty of Science, Ain Shams University, Abbassia, 11566, Cairo, Egypt.
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28
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Tobiasson V, Gahura O, Aibara S, Baradaran R, Zíková A, Amunts A. Interconnected assembly factors regulate the biogenesis of mitoribosomal large subunit. EMBO J 2021; 40:e106292. [PMID: 33576519 PMCID: PMC7957421 DOI: 10.15252/embj.2020106292] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 12/18/2020] [Accepted: 12/23/2020] [Indexed: 12/11/2022] Open
Abstract
Mitoribosomes consist of ribosomal RNA and protein components, coordinated assembly of which is critical for function. We used mitoribosomes from Trypanosoma brucei with reduced RNA and increased protein mass to provide insights into the biogenesis of the mitoribosomal large subunit. Structural characterization of a stable assembly intermediate revealed 22 assembly factors, some of which have orthologues/counterparts/homologues in mammalian genomes. These assembly factors form a protein network that spans a distance of 180 Å, shielding the ribosomal RNA surface. The central protuberance and L7/L12 stalk are not assembled entirely and require removal of assembly factors and remodeling of the mitoribosomal proteins to become functional. The conserved proteins GTPBP7 and mt‐EngA are bound together at the subunit interface in proximity to the peptidyl transferase center. A mitochondrial acyl‐carrier protein plays a role in docking the L1 stalk, which needs to be repositioned during maturation. Additional enzymatically deactivated factors scaffold the assembly while the exit tunnel is blocked. Together, this extensive network of accessory factors stabilizes the immature sites and connects the functionally important regions of the mitoribosomal large subunit.
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Affiliation(s)
- Victor Tobiasson
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden
| | - Ondřej Gahura
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Ceske Budejovice, Czech Republic
| | - Shintaro Aibara
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden
| | - Rozbeh Baradaran
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden
| | - Alena Zíková
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Ceske Budejovice, Czech Republic.,Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
| | - Alexey Amunts
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden
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29
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Human DDX3X Unwinds Japanese Encephalitis and Zika Viral 5' Terminal Regions. Int J Mol Sci 2021; 22:ijms22010413. [PMID: 33401776 PMCID: PMC7795613 DOI: 10.3390/ijms22010413] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/26/2020] [Accepted: 12/29/2020] [Indexed: 12/27/2022] Open
Abstract
Flavivirus genus includes many deadly viruses such as the Japanese encephalitis virus (JEV) and Zika virus (ZIKV). The 5' terminal regions (TR) of flaviviruses interact with human proteins and such interactions are critical for viral replication. One of the human proteins identified to interact with the 5' TR of JEV is the DEAD-box helicase, DDX3X. In this study, we in vitro transcribed the 5' TR of JEV and demonstrated its direct interaction with recombinant DDX3X (Kd of 1.66 ± 0.21 µM) using microscale thermophoresis (MST). Due to the proposed structural similarities of 5' and 3' TRs of flaviviruses, we investigated if the ZIKV 5' TR could also interact with human DDX3X. Our MST studies suggested that DDX3X recognizes ZIKV 5' TR with a Kd of 7.05 ± 0.75 µM. Next, we performed helicase assays that suggested that the binding of DDX3X leads to the unwinding of JEV and ZIKV 5' TRs. Overall, our data indicate, for the first time, that DDX3X can directly bind and unwind in vitro transcribed flaviviral TRs. In summary, our work indicates that DDX3X could be further explored as a therapeutic target to inhibit Flaviviral replication.
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30
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Brown NP, Vergara AM, Whelan AB, Guerra P, Bolger TA. Medulloblastoma-associated mutations in the DEAD-box RNA helicase DDX3X/DED1 cause specific defects in translation. J Biol Chem 2021; 296:100296. [PMID: 33460649 PMCID: PMC7949108 DOI: 10.1016/j.jbc.2021.100296] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 01/05/2021] [Accepted: 01/12/2021] [Indexed: 01/22/2023] Open
Abstract
Medulloblastoma is the most common pediatric brain cancer, and sequencing studies identified frequent mutations in DDX3X, a DEAD-box RNA helicase primarily implicated in translation. Forty-two different sites were identified, suggesting that the functional effects of the mutations are complex. To investigate how these mutations are affecting DDX3X cellular function, we constructed a full set of equivalent mutant alleles in DED1, the Saccharomyces cerevisiae ortholog of DDX3X, and characterized their effects in vivo and in vitro. Most of the medulloblastoma-associated mutants in DDX3X/DED1 (ded1-mam) showed substantial growth defects, indicating that functional effects are conserved in yeast. Further, while translation was affected in some mutants, translation defects affecting bulk mRNA were neither consistent nor correlated with the growth phenotypes. Likewise, increased formation of stress granules in ded1-mam mutants was common but did not correspond to the severity of the mutants' growth defects. In contrast, defects in translating mRNAs containing secondary structure in their 5' untranslated regions (UTRs) were found in almost all ded1-mam mutants and correlated well with growth phenotypes. We thus conclude that these specific translation defects, rather than generalized effects on translation, are responsible for the observed cellular phenotypes and likely contribute to DDX3X-mutant medulloblastoma. Examination of ATPase activity and RNA binding of recombinant mutant proteins also did not reveal a consistent defect, indicating that the translation defects are derived from multiple enzymatic deficiencies. This work suggests that future studies into medulloblastoma pathology should focus on this specific translation defect, while taking into account the wide spectrum of DDX3X mutations.
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Affiliation(s)
- Nicolette P Brown
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, USA
| | - Ashley M Vergara
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, USA
| | - Alisha B Whelan
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, USA
| | - Paolo Guerra
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, USA
| | - Timothy A Bolger
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, USA.
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31
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Abstract
RNA helicases are ubiquitous, highly conserved RNA-binding enzymes that use the energy derived from the hydrolysis of nucleoside triphosphate to modify the structure of RNA molecules and/or the functionality of ribonucleoprotein complexes. Ultimately, the action of RNA helicases results in changes in gene expression that allow the cell to perform crucial functions. In this chapter, we review established and emerging concepts for DEAD-box and DExH-box RNA helicases. We mention examples from both eukaryotic and prokaryotic systems, in order to highlight common themes and specific actions.
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Affiliation(s)
- Martina Valentini
- Faculty of Medicine, Department of Microbiology and Molecular Medicine, University of Geneva, Genève, Switzerland
| | - Patrick Linder
- Faculty of Medicine, Department of Microbiology and Molecular Medicine, University of Geneva, Genève, Switzerland.
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32
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Marcaida MJ, Kauzlaric A, Duperrex A, Sülzle J, Moncrieffe MC, Adebajo D, Manley S, Trono D, Dal Peraro M. The Human RNA Helicase DDX21 Presents a Dimerization Interface Necessary for Helicase Activity. iScience 2020; 23:101811. [PMID: 33313488 PMCID: PMC7721647 DOI: 10.1016/j.isci.2020.101811] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 09/02/2020] [Accepted: 11/11/2020] [Indexed: 02/07/2023] Open
Abstract
Members of the DEAD-box helicase family are involved in all fundamental processes of RNA metabolism, and as such, their malfunction is associated with various diseases. Currently, whether and how oligomerization impacts their biochemical and biological functions is not well understood. In this work, we show that DDX21, a human DEAD-box helicase with RNA G-quadruplex resolving activity, is dimeric and that its oligomerization state influences its helicase activity. Solution small-angle X-ray scattering (SAXS) analysis uncovers a flexible multi-domain protein with a central dimerization domain. While the Arg/Gly rich C termini, rather than dimerization, are key to maintaining high affinity for RNA substrates, in vitro helicase assays indicate that an intact dimer is essential for both DDX21 ATP-dependent double-stranded RNA unwinding and ATP-independent G-quadruplex remodeling activities. Our results suggest that oligomerization plays a key role in regulating RNA DEAD-box helicase activity. The human RNA DEAD-box helicase DDX21 is dimeric DDX21 dimerization is mediated by a hydrophobic central core domain SAXS-based modeling reveals that DDX21 is intrinsically flexible Dimerization and C-terminal domains mediate G-quadruplex and dsRNA unwinding
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Affiliation(s)
- Maria J Marcaida
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, 1015 Switzerland
| | - Annamaria Kauzlaric
- Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, 1015 Switzerland
| | - Alice Duperrex
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, 1015 Switzerland
| | - Jenny Sülzle
- Laboratory for Experimental Biophysics, Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, 1015 Switzerland
| | - Martin C Moncrieffe
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK
| | - Damilola Adebajo
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, 1015 Switzerland
| | - Suliana Manley
- Laboratory for Experimental Biophysics, Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, 1015 Switzerland
| | - Didier Trono
- Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, 1015 Switzerland
| | - Matteo Dal Peraro
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, 1015 Switzerland
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33
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Chang-Gu B, Bradburn D, Yangyuoru PM, Russell R. The DHX36-specific-motif (DSM) enhances specificity by accelerating recruitment of DNA G-quadruplex structures. Biol Chem 2020; 402:593-604. [PMID: 33857359 DOI: 10.1515/hsz-2020-0302] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Accepted: 12/07/2020] [Indexed: 01/15/2023]
Abstract
DHX36 is a eukaryotic DEAH/RHA family helicase that disrupts G-quadruplex structures (G4s) with high specificity, contributing to regulatory roles of G4s. Here we used a DHX36 truncation to examine the roles of the 13-amino acid DHX36-specific motif (DSM) in DNA G4 recognition and disruption. We found that the DSM promotes G4 recognition and specificity by increasing the G4 binding rate of DHX36 without affecting the dissociation rate. Further, for most of the G4s measured, the DSM has little or no effect on the G4 disruption step by DHX36, implying that contacts with the G4 are maintained through the transition state for G4 disruption. This result suggests that partial disruption of the G4 from the 3' end is sufficient to reach the overall transition state for G4 disruption, while the DSM remains unperturbed at the 5' end. Interestingly, the DSM does not contribute to G4 binding kinetics or thermodynamics at low temperature, indicating a highly modular function. Together, our results animate recent DHX36 crystal structures, suggesting a model in which the DSM recruits G4s in a modular and flexible manner by contacting the 5' face early in binding, prior to rate-limiting capture and disruption of the G4 by the helicase core.
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Affiliation(s)
- Bruce Chang-Gu
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX78712, USA
| | - Devin Bradburn
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX78712, USA.,Department of Biology, Stanford University, Stanford, CA94305, USA
| | - Philip M Yangyuoru
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX78712, USA.,Department of Chemistry, Northern Michigan University, Marquette, MI49855, USA
| | - Rick Russell
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX78712, USA
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34
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Jarmoskaite I, Tijerina P, Russell R. ATP utilization by a DEAD-box protein during refolding of a misfolded group I intron ribozyme. J Biol Chem 2020; 296:100132. [PMID: 33262215 PMCID: PMC7948464 DOI: 10.1074/jbc.ra120.015029] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 11/17/2020] [Accepted: 12/01/2020] [Indexed: 12/31/2022] Open
Abstract
DEAD-box helicase proteins perform ATP-dependent rearrangements of structured RNAs throughout RNA biology. Short RNA helices are unwound in a single ATPase cycle, but the ATP requirement for more complex RNA structural rearrangements is unknown. Here we measure the amount of ATP used for native refolding of a misfolded group I intron ribozyme by CYT-19, a Neurospora crassa DEAD-box protein that functions as a general chaperone for mitochondrial group I introns. By comparing the rates of ATP hydrolysis and ribozyme refolding, we find that several hundred ATP molecules are hydrolyzed during refolding of each ribozyme molecule. After subtracting nonproductive ATP hydrolysis that occurs in the absence of ribozyme refolding, we find that approximately 100 ATPs are hydrolyzed per refolded RNA as a consequence of interactions specific to the misfolded ribozyme. This value is insensitive to changes in ATP and CYT-19 concentration and decreases with decreasing ribozyme stability. Because of earlier findings that ∼90% of global ribozyme unfolding cycles lead back to the kinetically preferred misfolded conformation and are not observed, we estimate that each global unfolding cycle consumes ∼10 ATPs. Our results indicate that CYT-19 functions as a general RNA chaperone by using a stochastic, energy-intensive mechanism to promote RNA unfolding and refolding, suggesting an evolutionary convergence with protein chaperones.
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Affiliation(s)
- Inga Jarmoskaite
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, USA
| | - Pilar Tijerina
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, USA
| | - Rick Russell
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, USA.
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35
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Key Points to Consider When Studying RNA Remodeling by Proteins. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2020; 2209:1-16. [PMID: 33201459 DOI: 10.1007/978-1-0716-0935-4_1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Cellular RNAs depend on proteins for efficient folding to specific functional structures and for transitions between functional structures. This dependence arises from intrinsic properties of RNA structure. Specifically, RNAs possess stable local structure, largely in the form of helices, and there are abundant opportunities for RNAs to form alternative helices and tertiary contacts and therefore to populate alternative structures. Proteins with RNA chaperone activity, either ATP-dependent or ATP-independent, can promote structural transitions by interacting with single-stranded RNA (ssRNA) to compete away partner interactions and then release ssRNA so that it can form new interactions. In this chapter we review the basic properties of RNA and the proteins that function as chaperones and remodelers. We then use these properties as a foundation to explore key points for the design and interpretation of experiments that probe RNA rearrangements and their acceleration by proteins.
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36
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Emerging molecular functions and novel roles for the DEAD-box protein Dbp5/DDX19 in gene expression. Cell Mol Life Sci 2020; 78:2019-2030. [PMID: 33205304 DOI: 10.1007/s00018-020-03680-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 09/21/2020] [Accepted: 10/06/2020] [Indexed: 12/23/2022]
Abstract
The DEAD-box protein (DBP) Dbp5, a member of the superfamily II (SFII) helicases, has multiple reported roles in gene expression. First identified as an essential regulator of mRNA export in Saccharomyces cerevisiae, the enzyme now has reported functions in non-coding RNA export, translation, transcription, and DNA metabolism. Localization of the protein to various cellular compartments (nucleoplasm, nuclear envelope, and cytoplasm) highlights the ability of Dbp5 to modulate different stages of the RNA lifecycle. While Dbp5 has been well studied for > 20 years, several critical questions remain regarding the mechanistic principles that govern Dbp5 localization, substrate selection, and functions in gene expression. This review aims to take a holistic view of the proposed functions of Dbp5 and evaluate models that accommodate current published data.
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37
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General and Target-Specific DExD/H RNA Helicases in Eukaryotic Translation Initiation. Int J Mol Sci 2020; 21:ijms21124402. [PMID: 32575790 PMCID: PMC7352612 DOI: 10.3390/ijms21124402] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 06/17/2020] [Accepted: 06/18/2020] [Indexed: 12/19/2022] Open
Abstract
DExD (DDX)- and DExH (DHX)-box RNA helicases, named after their Asp-Glu-x-Asp/His motifs, are integral to almost all RNA metabolic processes in eukaryotic cells. They play myriad roles in processes ranging from transcription and mRNA-protein complex remodeling, to RNA decay and translation. This last facet, translation, is an intricate process that involves DDX/DHX helicases and presents a regulatory node that is highly targetable. Studies aimed at better understanding this family of conserved proteins have revealed insights into their structures, catalytic mechanisms, and biological roles. They have also led to the development of chemical modulators that seek to exploit their essential roles in diseases. Herein, we review the most recent insights on several general and target-specific DDX/DHX helicases in eukaryotic translation initiation.
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38
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DEAD-box RNA Helicase DDX3: Functional Properties and Development of DDX3 Inhibitors as Antiviral and Anticancer Drugs. Molecules 2020; 25:molecules25041015. [PMID: 32102413 PMCID: PMC7070539 DOI: 10.3390/molecules25041015] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 02/05/2020] [Accepted: 02/21/2020] [Indexed: 12/11/2022] Open
Abstract
This short review is focused on enzymatic properties of human ATP-dependent RNA helicase DDX3 and the development of antiviral and anticancer drugs targeting cellular helicases. DDX3 belongs to the DEAD-box proteins, a large family of RNA helicases that participate in all aspects of cellular processes, such as cell cycle progression, apoptosis, innate immune response, viral replication, and tumorigenesis. DDX3 has a variety of functions in the life cycle of different viruses. DDX3 helicase is required to facilitate both the Rev-mediated export of unspliced/partially spliced human immunodeficiency virus (HIV) RNA from nucleus and Tat-dependent translation of viral genes. DDX3 silencing blocks the replication of HIV, HCV, and some other viruses. On the other hand, DDX displays antiviral effect against Dengue virus and hepatitis B virus through the stimulation of interferon beta production. The role of DDX3 in different types of cancer is rather controversial. DDX3 acts as an oncogene in one type of cancer, but demonstrates tumor suppressor properties in other types. The human DDX3 helicase is now considered as a new attractive target for the development of novel pharmaceutical drugs. The most interesting inhibitors of DDX3 helicase and the mechanisms of their actions as antiviral or anticancer drugs are discussed in this short review.
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39
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Nakao S, Nogami M, Iwatani M, Imaeda T, Ito M, Tanaka T, Tawada M, Endo S, Cary DR, Ohori M, Imaeda Y, Kawamoto T, Aparicio S, Nakanishi A, Araki S. Identification of a selective DDX3X inhibitor with newly developed quantitative high-throughput RNA helicase assays. Biochem Biophys Res Commun 2020; 523:795-801. [PMID: 31954521 DOI: 10.1016/j.bbrc.2019.12.094] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 12/17/2019] [Indexed: 12/28/2022]
Abstract
The DEAD-box family of RNA helicases plays essential roles in both transcriptional and translational mRNA degradation; they unwind short double-stranded RNA by breaking the RNA-RNA interactions. Two DEAD-box RNA helicases, eukaryotic translation initiation factor 4A3 (eIF4A3) and DEAD-box helicase 3 (DDX3X), show high homology in the ATP-binding region and are considered key molecules for cancer progression. Several small molecules that target eIF4A3 and DDX3X have been reported to inhibit cancer cell growth; however, more potent compounds are required for cancer therapeutics, and there is a critical need for high-throughput assays to screen for RNA helicase inhibitors. In this study, we developed novel fluorescence resonance energy transfer-based high-throughput RNA helicase assays for eIF4A3 and DDX3X. Using these assays, we identified several eIF4A3 allosteric inhibitors whose inhibitory effect on eIF4A3 ATPase showed a strong correlation with inhibitory effect on helicase activity. From 102 compounds that exhibited eIF4A3 ATPase inhibition, we identified a selective DDX3X inhibitor, C1, which showed stronger inhibition of DDX3X than of eIF4A3. Small-molecule helicase inhibitors can be valuable for clarifying the molecular machinery of DEAD-box RNA helicases. The high-throughput quantitative assays established here should facilitate the evaluation of the helicase inhibitory activity of compounds.
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Affiliation(s)
- Shoichi Nakao
- Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Masahiro Nogami
- Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Misa Iwatani
- Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Toshihiro Imaeda
- Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Masahiro Ito
- Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Toshio Tanaka
- Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Michiko Tawada
- Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Satoshi Endo
- Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Douglas R Cary
- Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Momoko Ohori
- Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Yasuhiro Imaeda
- Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Tomohiro Kawamoto
- Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Samuel Aparicio
- Department of Molecular Oncology, BC Cancer Agency, Vancouver, BC, V5Z 1L3, Canada; Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, V6T 2B5, Canada
| | - Atsushi Nakanishi
- Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa, 251-8555, Japan
| | - Shinsuke Araki
- Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa, 251-8555, Japan.
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40
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Tauber D, Tauber G, Khong A, Van Treeck B, Pelletier J, Parker R. Modulation of RNA Condensation by the DEAD-Box Protein eIF4A. Cell 2020; 180:411-426.e16. [PMID: 31928844 DOI: 10.1016/j.cell.2019.12.031] [Citation(s) in RCA: 153] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 11/04/2019] [Accepted: 12/20/2019] [Indexed: 01/12/2023]
Abstract
Stress granules are condensates of non-translating mRNAs and proteins involved in the stress response and neurodegenerative diseases. Stress granules form in part through intermolecular RNA-RNA interactions, and to better understand how RNA-based condensation occurs, we demonstrate that RNA is effectively recruited to the surfaces of RNA or RNP condensates in vitro. We demonstrate that, through ATP-dependent RNA binding, the DEAD-box protein eIF4A reduces RNA condensation in vitro and limits stress granule formation in cells. This defines a function for eIF4A to limit intermolecular RNA-RNA interactions in cells. These results establish an important role for eIF4A, and potentially other DEAD-box proteins, as ATP-dependent RNA chaperones that limit the condensation of RNA, analogous to the function of proteins like HSP70 in combatting protein aggregates.
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Affiliation(s)
- Devin Tauber
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Gabriel Tauber
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Anthony Khong
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA; Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Briana Van Treeck
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Jerry Pelletier
- Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada; The Rosalind and Morris Goodman Cancer Research Center and the Department of Oncology, McGill University, Montreal, QC, Canada
| | - Roy Parker
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA; Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80309, USA.
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41
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Ren R, Ghassabi Kondalaji S, Bowman GD. The Chd1 chromatin remodeler forms long-lived complexes with nucleosomes in the presence of ADP·BeF 3 - and transition state analogs. J Biol Chem 2019; 294:18181-18191. [PMID: 31636125 DOI: 10.1074/jbc.ra119.009782] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 10/17/2019] [Indexed: 01/03/2023] Open
Abstract
Chromatin remodelers use helicase-like ATPase domains to reorganize histone-DNA contacts within the nucleosome. Like other remodelers, the chromodomain helicase DNA-binding protein 1 (Chd1) remodeler repositions nucleosomes by altering DNA topology at its internal binding site on the nucleosome, coupling different degrees of DNA twist and DNA movement to distinct nucleotide-bound states of the ATPase motor. In this work, we used a competition assay to study how variations in the bound nucleotide, Chd1, and the nucleosome substrate affect stability of Chd1-nucleosome complexes. We found that Chd1-nucleosome complexes formed in nucleotide-free or ADP conditions were relatively unstable and dissociated within 30 s, whereas those with the nonhydrolyzable ATP analog AMP-PNP had a mean lifetime of 4.8 ± 0.7 min. Chd1-nucleosome complexes were remarkably stable with ADP·BeF3 - and the transition state analogs ADP·AlFX and ADP·MgFX, being resistant to competitor nucleosome over a 24-h period. For the tight ADP·BeF3 --stabilized complex, Mg2+ was a critical component that did not freely exchange, and formation of these long-lived complexes had a slow, concentration-dependent step. The ADP·BeF3 --stabilized complex did not require the Chd1 DNA-binding domain nor the histone H4 tail and appeared relatively insensitive to sequence differences on either side of the Widom 601 sequence. Interestingly, the complex remained stable in ADP·BeF3 - even when nucleosomes contained single-stranded gaps that disrupted most DNA contacts with the guide strand. This finding suggests that binding via the tracking strand alone is sufficient for stabilizing the complex in a hydrolysis-competent state.
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Affiliation(s)
- Ren Ren
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218
| | | | - Gregory D Bowman
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218.
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42
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Raj S, Bagchi D, Orero JV, Banroques J, Tanner NK, Croquette V. Mechanistic characterization of the DEAD-box RNA helicase Ded1 from yeast as revealed by a novel technique using single-molecule magnetic tweezers. Nucleic Acids Res 2019; 47:3699-3710. [PMID: 30993346 PMCID: PMC6468243 DOI: 10.1093/nar/gkz057] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 01/21/2019] [Accepted: 02/01/2019] [Indexed: 12/11/2022] Open
Abstract
DEAD-box helicases are involved in all steps of RNA metabolism. They are ATP-dependent RNA binding proteins and RNA-dependent ATPases. They can displace short duplexes, but they lack processivity. Their mechanism and functioning are not clearly understood; classical or bulk biochemical assays are not sufficient to answer these questions. Single-molecule techniques provide useful tools, but they are limited in cases where the proteins are nonprocessive and give weak signals. We present here a new, magnetic-tweezers-based, single-molecule assay that is simple and that can sensitively measure the displacement time of a small, hybridized, RNA oligonucleotide. Tens of molecules can be analyzed at the same time. Comparing the displacement times with and without a helicase gives insights into the enzymatic activity of the protein. We used this assay to study yeast Ded1, which is orthologous to human DDX3. Although Ded1 acts on a variety of substrates, we find that Ded1 requires an RNA substrate for its ATP-dependent unwinding activity and that ATP hydrolysis is needed to see this activity. Further, we find that only intramolecular single-stranded RNA extensions enhance this activity. We propose a model where ATP-bound Ded1 stabilizes partially unwound duplexes and where multiple binding events may be needed to see displacement.
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Affiliation(s)
- Saurabh Raj
- Laboratoire de Physique de l'Ecole normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France.,IBENS, Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University, 75005 Paris, France
| | - Debjani Bagchi
- Laboratoire de Physique de l'Ecole normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France.,IBENS, Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University, 75005 Paris, France
| | - Jessica Valle Orero
- Laboratoire de Physique de l'Ecole normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France.,IBENS, Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University, 75005 Paris, France
| | - Josette Banroques
- Laboratoire d'Expression Génétique Microbienne, CNRS UMR8261/Université Paris 7-Diderot, Sorbonne Paris Cité Universités, 13 rue Pierre et Marie Curie, Paris, France.,Institut de Biologie Physico-Chimique, PSL Research University, 75005 Paris, France
| | - N Kyle Tanner
- Laboratoire d'Expression Génétique Microbienne, CNRS UMR8261/Université Paris 7-Diderot, Sorbonne Paris Cité Universités, 13 rue Pierre et Marie Curie, Paris, France.,Institut de Biologie Physico-Chimique, PSL Research University, 75005 Paris, France
| | - Vincent Croquette
- Laboratoire de Physique de l'Ecole normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France.,IBENS, Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University, 75005 Paris, France.,ESPCI Paris, PSL University, 10 rue Vauquelin, 75005 Paris, France
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43
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DDX5 helicase resolves G-quadruplex and is involved in MYC gene transcriptional activation. Proc Natl Acad Sci U S A 2019; 116:20453-20461. [PMID: 31548374 DOI: 10.1073/pnas.1909047116] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
G-quadruplexes (G4) are noncanonical secondary structures formed in guanine-rich DNA and RNA sequences. MYC, one of the most critical oncogenes, forms a DNA G4 in its proximal promoter region (MycG4) that functions as a transcriptional silencer. However, MycG4 is highly stable in vitro and its regulatory role would require active unfolding. Here we report that DDX5, one of the founding members of the DEAD-box RNA helicase family, is extremely proficient at unfolding MycG4-DNA. Our results show that DDX5 is a highly active G4-resolvase that does not require a single-stranded overhang and that ATP hydrolysis is not directly coupled to G4-unfolding of DDX5. The chromatin binding sites of DDX5 are G-rich sequences. In cancer cells, DDX5 is enriched at the MYC promoter and activates MYC transcription. The DDX5 interaction with the MYC promoter and DDX5-mediated MYC activation is inhibited by G4-interactive small molecules. Our results uncover a function of DDX5 in resolving DNA and RNA G4s and suggest a molecular target to suppress MYC for cancer intervention.
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44
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Song H, Ji X. The mechanism of RNA duplex recognition and unwinding by DEAD-box helicase DDX3X. Nat Commun 2019; 10:3085. [PMID: 31300642 PMCID: PMC6626043 DOI: 10.1038/s41467-019-11083-2] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 06/16/2019] [Indexed: 12/02/2022] Open
Abstract
DEAD-box helicases (DDXs) regulate RNA processing and metabolism by unwinding short double-stranded (ds) RNAs. Sharing a helicase core composed of two RecA-like domains (D1D2), DDXs function in an ATP-dependent, non-processive manner. As an attractive target for cancer and AIDS treatment, DDX3X and its orthologs are extensively studied, yielding a wealth of biochemical and biophysical data, including structures of apo-D1D2 and post-unwound D1D2:single-stranded RNA complex, and the structure of a D2:dsRNA complex that is thought to represent a pre-unwound state. However, the structure of a pre-unwound D1D2:dsRNA complex remains elusive, and thus, the mechanism of DDX action is not fully understood. Here, we describe the structure of a D1D2 core in complex with a 23-base pair dsRNA at pre-unwound state, revealing that two DDXs recognize a 2-turn dsRNA, each DDX mainly recognizes a single RNA strand, and conformational changes induced by ATP binding unwinds the RNA duplex in a cooperative manner.
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Affiliation(s)
- He Song
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD, 21702, USA
| | - Xinhua Ji
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD, 21702, USA.
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45
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Liao SE, Kandasamy SK, Zhu L, Fukunaga R. DEAD-box RNA helicase Belle posttranscriptionally promotes gene expression in an ATPase activity-dependent manner. RNA (NEW YORK, N.Y.) 2019; 25:825-839. [PMID: 30979781 PMCID: PMC6573787 DOI: 10.1261/rna.070268.118] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/01/2019] [Accepted: 04/12/2019] [Indexed: 06/09/2023]
Abstract
Drosophila Belle (human ortholog DDX3) is a conserved DEAD-box RNA helicase implicated in regulating gene expression. However, the molecular mechanisms by which Belle/DDX3 regulates gene expression are poorly understood. Here we performed systematic mutational analysis to determine the contributions of conserved motifs within Belle to its in vivo function. We found that Belle RNA-binding and RNA-unwinding activities and intrinsically disordered regions (IDRs) are required for Belle in vivo function. Expression of Belle ATPase mutants that cannot bind, hydrolyze, or release ATP resulted in dominant toxic phenotypes. Mechanistically, we discovered that Belle up-regulates reporter protein level when tethered to reporter mRNA, without corresponding changes at the mRNA level, indicating that Belle promotes translation of mRNA that it binds. Belle ATPase activity and amino-terminal IDR were required for this translational promotion activity. We also found that ectopic ovary expression of dominant Belle ATPase mutants decreases levels of cyclin proteins, including Cyclin B, without corresponding changes in their mRNA levels. Finally, we found that Belle binds endogenous cyclin B mRNA. We propose that Belle promotes translation of specific target mRNAs, including cyclin B mRNA, in an ATPase activity-dependent manner.
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Affiliation(s)
- Susan E Liao
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| | - Suresh K Kandasamy
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| | - Li Zhu
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| | - Ryuya Fukunaga
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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46
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Chen ZS, Cheng XW, Wang X, Hou DH, Huang GH. Proteomic analysis of the Heliothis virescens ascovirus 3i (HvAV-3i) virion. J Gen Virol 2018; 100:301-307. [PMID: 30540243 DOI: 10.1099/jgv.0.001197] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Ascoviruses are enveloped, circular, double-stranded DNA viruses that can effectively control the appetite of lepidopteran larvae, thereby reducing the consequent damage and economic losses to crops. In this study, the virion of a sequenced Heliothis virescens ascovirus 3i (HvAV-3i) strain was used to perform proteomic analysis using both in-gel and in-solution digestion. A total of 81 viral proteins, of which 67 were associated with the virions, were identified in the proteome of HvAV-3i virions. Among these proteins, 23 with annotated functions were associated with DNA/RNA metabolism/transcription, virion assembly, sugar and lipid metabolism, signalling, cellular homoeostasis and cell lysis. Twenty-one viral membrane proteins were also identified. Some of the minor 'virion' proteins identified may be non-virion contaminants of viral proteins synthesized during replication, identified by more recent and highly sensitive methods. The extensive identification of the ascoviral proteome will establish a foundation for further investigation of ascoviral replication and infection.
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Affiliation(s)
- Zi-Shu Chen
- 1Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, Hunan Agricultural University, Changsha, Hunan 410128, PR China.,2Institute of Virology, College of Plant Protection, Hunan Agricultural University, Changsha, Hunan 410128, PR China
| | - Xiao-Wen Cheng
- 3Department of Microbiology, 212 Pearson Hall, Miami University, Oxford, OH 45056, USA
| | - Xing Wang
- 1Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, Hunan Agricultural University, Changsha, Hunan 410128, PR China.,2Institute of Virology, College of Plant Protection, Hunan Agricultural University, Changsha, Hunan 410128, PR China
| | - Dian-Hai Hou
- 4School of Bioscience and Technology, Weifang Medical University, Weifang, Shandong 261053, PR China
| | - Guo-Hua Huang
- 2Institute of Virology, College of Plant Protection, Hunan Agricultural University, Changsha, Hunan 410128, PR China.,1Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, Hunan Agricultural University, Changsha, Hunan 410128, PR China
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47
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Xing Z, Ma WK, Tran EJ. The DDX5/Dbp2 subfamily of DEAD-box RNA helicases. WILEY INTERDISCIPLINARY REVIEWS-RNA 2018; 10:e1519. [PMID: 30506978 DOI: 10.1002/wrna.1519] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 10/26/2018] [Accepted: 11/01/2018] [Indexed: 01/05/2023]
Abstract
The mammalian DEAD-box RNA helicase DDX5, its paralog DDX17, and their orthologs in Saccharomyces cerevisiae and Drosophila melanogaster, namely Dbp2 and Rm62, define a subfamily of DEAD-box proteins. Members from this subfamily share highly conserved protein sequences and cellular functions. They are involved in multiple steps of RNA metabolism including mRNA processing, microRNA processing, ribosome biogenesis, RNA decay, and regulation of long noncoding RNA activities. The DDX5/Dbp2 subfamily is also implicated in transcription regulation, cellular signaling pathways, and energy metabolism. One emerging theme underlying the diverse cellular functions is that the DDX5/Dbp2 subfamily of DEAD-box helicases act as chaperones for complexes formed by RNA molecules and proteins (RNP) in vivo. This RNP chaperone activity governs the functions of various RNA species through their lifetime. Importantly, mammalian DDX5 and DDX17 are involved in cancer progression when overexpressed through alteration of transcription and signaling pathways, meaning that they are possible targets for cancer therapy. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes.
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Affiliation(s)
- Zheng Xing
- Department of Biochemistry, Purdue University, West Lafayette, Indiana.,Purdue Center for Cancer Research, Purdue University, West Lafayette, Indiana
| | - Wai Kit Ma
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York
| | - Elizabeth J Tran
- Department of Biochemistry, Purdue University, West Lafayette, Indiana.,Purdue Center for Cancer Research, Purdue University, West Lafayette, Indiana
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48
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Chen X, Wang C, Zhang X, Tian T, Zang J. Crystal structures of the N-terminal domain of the Staphylococcus aureus DEAD-box RNA helicase CshA and its complex with AMP. Acta Crystallogr F Struct Biol Commun 2018; 74:704-709. [PMID: 30387775 PMCID: PMC6213976 DOI: 10.1107/s2053230x1801292x] [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: 08/24/2018] [Accepted: 09/12/2018] [Indexed: 11/10/2022] Open
Abstract
CshA is a DEAD-box RNA helicase that belongs to the DExD/H-box family of proteins, which generally have an RNA-dependent ATPase activity. In Staphylococcus aureus, CshA was identified as a component of the RNA degradosome and plays important roles in RNA turnover. In this study, the crystal structures of the N-terminal RecA-like domain 1 of S. aureus CshA (SaCshAR1) and of its complex with AMP (SaCshAR1-AMP) are reported at resolutions of 1.5 and 1.8 Å, respectively. SaCshAR1 adopts a conserved α/β RecA-like structure with seven parallel strands surrounded by nine α-helices. The Q motif and motif I are responsible for the binding of the adenine group and phosphate group of AMP, respectively. Structure comparison of SaCshAR1-AMP and SaCshAR1 reveals that motif I undergoes a conformational change upon AMP binding. Isothermal titration calorimetry assays further conformed the essential roles of Phe22 in the Q motif and Lys52 in motif I for binding ATP, indicating a conserved substrate-binding mechanism in SaCshA compared with other DEAD-box RNA helicases.
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Affiliation(s)
- Xiaobao Chen
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, Collaborative Innovation Center of Chemistry for Life Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People’s Republic of China
- Key Laboratory of Structural Biology, Chinese Academy of Sciences, Hefei, Anhui 230027, People’s Republic of China
| | - Chengliang Wang
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, Collaborative Innovation Center of Chemistry for Life Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People’s Republic of China
- Key Laboratory of Structural Biology, Chinese Academy of Sciences, Hefei, Anhui 230027, People’s Republic of China
| | - Xuan Zhang
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, Collaborative Innovation Center of Chemistry for Life Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People’s Republic of China
- Key Laboratory of Structural Biology, Chinese Academy of Sciences, Hefei, Anhui 230027, People’s Republic of China
| | - Tian Tian
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, Collaborative Innovation Center of Chemistry for Life Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People’s Republic of China
- Key Laboratory of Structural Biology, Chinese Academy of Sciences, Hefei, Anhui 230027, People’s Republic of China
| | - Jianye Zang
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, Collaborative Innovation Center of Chemistry for Life Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People’s Republic of China
- Key Laboratory of Structural Biology, Chinese Academy of Sciences, Hefei, Anhui 230027, People’s Republic of China
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49
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Han KR, Lee JH, Kotiguda GG, Jung KH, Chung MS, Kang S, Hwang S, Kim KH. Nucleotide triphosphatase and RNA chaperone activities of murine norovirus NS3. J Gen Virol 2018; 99:1482-1493. [PMID: 30265237 DOI: 10.1099/jgv.0.001151] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Modulation of RNA structure is essential in the life cycle of RNA viruses. Immediate replication upon infection requires RNA unwinding to ensure that RNA templates are not in intra- or intermolecular duplex forms. The calicivirus NS3, one of the highly conserved nonstructural (NS) proteins, has conserved motifs common to helicase superfamily 3 among six genogroups. However, its biological functions are not fully understood. In this study we report the oligomeric state and the nucleotide triphosphatase (NTPase) and RNA chaperone activities of the recombinant full-length NS3 derived from murine norovirus (MNV). The MNV NS3 has an Mg2+-dependent NTPase activity, and site-directed mutagenesis of the conserved NTPase motifs blocked enzyme activity and viral replication in cells. Further, the NS3 was found via fluorescence resonance energy transfer (FRET)-based assays to destabilize double-stranded RNA in the presence of Mg2+ or Mn2+ in an NTP-independent manner. However, the RNA destabilization activity was not affected by mutagenesis of the conserved motifs of NTPase. These results reveal that the MNV NS3 has an NTPase-independent RNA chaperone-like activity, and that a FRET-based RNA destabilization assay has the potential to identify new antiviral drugs targeting NS3.
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Affiliation(s)
- Kang Rok Han
- 1Department of Biotechnology and Bioinformatics, Korea University, Sejong 339-700, Republic of Korea.,†Present address: Konkuk University, Seoul, Republic of Korea
| | - Ji-Hye Lee
- 1Department of Biotechnology and Bioinformatics, Korea University, Sejong 339-700, Republic of Korea
| | - Giri Gowda Kotiguda
- 1Department of Biotechnology and Bioinformatics, Korea University, Sejong 339-700, Republic of Korea.,‡Present address: Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Kyoung Ho Jung
- 1Department of Biotechnology and Bioinformatics, Korea University, Sejong 339-700, Republic of Korea
| | - Mi Sook Chung
- 2Department of Food and Nutrition, Duksung Women's University, Seoul 132-714, Republic of Korea
| | - Soowon Kang
- 3Department of Pathology, The University of Chicago, Chicago, IL 60637, USA
| | - Seungmin Hwang
- 3Department of Pathology, The University of Chicago, Chicago, IL 60637, USA
| | - Kyung Hyun Kim
- 1Department of Biotechnology and Bioinformatics, Korea University, Sejong 339-700, Republic of Korea
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50
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Barkovich KJ, Moore MK, Hu Q, Shokat KM. Chemical genetic inhibition of DEAD-box proteins using covalent complementarity. Nucleic Acids Res 2018; 46:8689-8699. [PMID: 30102385 PMCID: PMC6158709 DOI: 10.1093/nar/gky706] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 07/07/2018] [Accepted: 08/06/2018] [Indexed: 12/17/2022] Open
Abstract
DEAD-box proteins are an essential class of enzymes involved in all stages of RNA metabolism. The study of DEAD-box proteins is challenging in a native setting since they are structurally similar, often essential and display dosage sensitivity. Pharmacological inhibition would be an ideal tool to probe the function of these enzymes. In this work, we describe a chemical genetic strategy for the specific inactivation of individual DEAD-box proteins with small molecule inhibitors using covalent complementarity. We identify a residue of low conservation within the P-loop of the nucleotide-binding site of DEAD-box proteins and show that it can be mutated to cysteine without a substantial loss of enzyme function to generate electrophile-sensitive mutants. We then present a series of small molecules that rapidly and specifically bind and inhibit electrophile-sensitive DEAD-box proteins with high selectivity over the wild-type enzyme. Thus, this approach can be used to systematically generate small molecule-sensitive alleles of DEAD-box proteins, allowing for pharmacological inhibition and functional characterization of members of this enzyme family.
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Affiliation(s)
- Krister J Barkovich
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA
| | - Megan K Moore
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA
| | - Qi Hu
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA
| | - Kevan M Shokat
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA
- Howard Hughes Medical Institute, University of California, San Francisco, CA 94158, USA
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
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