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Riedelbauch S, Masser S, Fasching S, Lin SY, Salgania HK, Aarup M, Ebert A, Jeske M, Levine MT, Stelzl U, Andersen P. Recurrent innovation of protein-protein interactions in the Drosophila piRNA pathway. EMBO J 2025:10.1038/s44318-025-00439-8. [PMID: 40275032 DOI: 10.1038/s44318-025-00439-8] [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: 10/22/2024] [Revised: 03/22/2025] [Accepted: 04/03/2025] [Indexed: 04/26/2025] Open
Abstract
Despite being essential for fertility, genome-defense-pathway genes often evolve rapidly. However, little is known about the molecular basis of this adaptation. Here, we characterized the evolution of a protein interaction network within the PIWI-interacting small RNA (piRNA) genome-defense pathway in Drosophila at unprecedented scale and evolutionary resolution. We uncovered the pervasive rapid evolution of a protein interaction network anchored at the heterochromatin protein 1 (HP1) paralog Rhino. Through cross-species high-throughput yeast-two-hybrid screening, we identified three distinct evolutionary protein interaction trajectories across ~40 million years of Drosophila evolution. While several protein interactions are fully conserved, indicating functional conservation despite rapid amino acid-sequence change, other interactions are preserved through coevolution and were detected only between proteins within or from closely related species. We also identified species-restricted protein interactions, revealing insight into the mechanistic diversity and ongoing molecular innovation in Drosophila piRNA production. In sum, our analyses reveal principles of interaction evolution in an adaptively evolving protein-protein interaction network, and support intermolecular interaction innovation as a central molecular mechanism of evolutionary adaptation in protein-coding genes.
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Affiliation(s)
- Sebastian Riedelbauch
- Department of Molecular Biology and Genetics, Aarhus University, 8000, Aarhus C, Denmark
| | - Sarah Masser
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
| | - Sandra Fasching
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
| | - Sung-Ya Lin
- Department of Biology, Epigenetics Institute, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Mie Aarup
- Department of Molecular Biology and Genetics, Aarhus University, 8000, Aarhus C, Denmark
| | - Anja Ebert
- Department of Molecular Biology and Genetics, Aarhus University, 8000, Aarhus C, Denmark
| | - Mandy Jeske
- Heidelberg University Biochemistry Center (BZH), 69120, Heidelberg, Germany
| | - Mia T Levine
- Department of Biology, Epigenetics Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Ulrich Stelzl
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
- Field of Excellence BioHealth-University of Graz, Graz, Austria
| | - Peter Andersen
- Department of Molecular Biology and Genetics, Aarhus University, 8000, Aarhus C, Denmark.
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2
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Yellamaty R, Sharma S. Critical Cellular Functions and Mechanisms of Action of the RNA Helicase UAP56. J Mol Biol 2024; 436:168604. [PMID: 38729260 PMCID: PMC11168752 DOI: 10.1016/j.jmb.2024.168604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 04/24/2024] [Accepted: 05/03/2024] [Indexed: 05/12/2024]
Abstract
Posttranscriptional maturation and export from the nucleus to the cytoplasm are essential steps in the normal processing of many cellular RNAs. The RNA helicase UAP56 (U2AF associated protein 56; also known as DDX39B) has emerged as a critical player in facilitating and co-transcriptionally linking these steps. Originally identified as a helicase involved in pre-mRNA splicing, UAP56 has been shown to facilitate formation of the A complex during spliceosome assembly. Additionally, it has been found to be critical for interactions between components of the exon junction and transcription and export complexes to promote the loading of export receptors. Although it appears to be structurally similar to other helicase superfamily 2 members, UAP56's ability to interact with multiple different protein partners allows it to perform its various cellular functions. Herein, we describe the structure-activity relationship studies that identified protein interactions of UAP56 and its human paralog URH49 (UAP56-related helicase 49; also known as DDX39A) and are beginning to reveal molecular mechanisms by which interacting proteins and substrate RNAs may regulate these helicases. We also provide an overview of reports that have demonstrated less well-characterized roles for UAP56, including R-loop resolution and telomere maintenance. Finally, we discuss studies that indicate a potential pathogenic effect of UAP56 in the development of autoimmune diseases and cancer, and identify the association of somatic and genetic mutations in UAP56 with neurodevelopmental disorders.
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Affiliation(s)
- Ryan Yellamaty
- Department of Basic Medical Sciences, College of Medicine-Phoenix, University of Arizona, Phoenix, AZ 85004, USA
| | - Shalini Sharma
- Department of Basic Medical Sciences, College of Medicine-Phoenix, University of Arizona, Phoenix, AZ 85004, USA.
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3
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TREX (transcription/export)-NP complex exerts a dual effect on regulating polymerase activity and replication of influenza A virus. PLoS Pathog 2022; 18:e1010835. [PMID: 36084138 PMCID: PMC9491529 DOI: 10.1371/journal.ppat.1010835] [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: 05/08/2022] [Revised: 09/21/2022] [Accepted: 08/29/2022] [Indexed: 11/30/2022] Open
Abstract
Influenza A viruses effectively hijack the intracellular "resources" to complete transcription and replication, which involve extensive interactions between the viral and host proteins. Herein, we screened the host factors, which belong to DExD/H-box protein family members, RNA-binding proteins or mitochondrial anchoring proteins, to investigate their effects on polymerase activity. We observed DDX39B and DDX39A, DEAD-box RNA-Helicases, exert a dual effect on regulating polymerase activity and replication of influenza A viruses. We further revealed that DDX39B and DDX39A interact with viral NP and NS1 proteins. Interestingly, the viral NP proteins could reverse the inhibitory effect of excess DDX39B or DDX39A on polymerase activity. Mechanistically, the TREX complex subunits, THOC1, THOC4 and CIP29, were recruited to DDX39B-DDX39A-NP complex in an ATP-dependent manner, via the interaction with DDX39B or DDX39A, followed by excess TREX-NP complexes interfere with the normal oligomerization state of NP depending on the ratio between the viral and host proteins. On the other hand, the TREX complex, an evolutionarily conserved protein complex, is responsible for the integration of several mRNA processing steps to export viral mRNA. Knockdown of TREX complex subunits significantly down-regulated viral titers and protein levels, accompanied by retention of viral mRNA in the nucleus. Taken together, screening the host factors that regulate the replication of influenza virus advances our understanding of viral pathogenesis and our findings point out a previously unclear mechanism of TREX complex function. In this study, we investigated the regulation of polymerase activity by host factors associated with vRNPs (PB2627E, PB2627K, PB2627 domain del, PB2627 CON) and provided novel insights into regulatory mechanisms of DDX39B and DDX39A during viral replication. Our results demonstrated that DDX39B and its paralog DDX39A inhibited polymerase activity via forming TREX-NP complex with concomitant effects on the oligomeric state of NP proteins. Moreover, TREX complex is necessary for expression of viral proteins. Our findings provided potential therapeutic targets for dealing with IAV infection.
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4
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Shi P, Guo Y, Su Y, Zhu M, Fu Y, Chi H, Wu J, Huang J. SUMOylation of DDX39A Alters Binding and Export of Antiviral Transcripts to Control Innate Immunity. THE JOURNAL OF IMMUNOLOGY 2020; 205:168-180. [DOI: 10.4049/jimmunol.2000053] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 04/21/2020] [Indexed: 12/22/2022]
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5
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Fujita KI, Yamazaki T, Harada K, Seno S, Matsuda H, Masuda S. URH49 exports mRNA by remodeling complex formation and mediating the NXF1-dependent pathway. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194480. [PMID: 31917363 DOI: 10.1016/j.bbagrm.2020.194480] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 12/19/2019] [Accepted: 01/03/2020] [Indexed: 12/27/2022]
Abstract
The TREX complex integrates information from nuclear mRNA processing events to ensure the timely export of mRNA to the cytoplasm. In humans, UAP56 and its paralog URH49 form distinct complexes, the TREX complex and the AREX complex, respectively, which cooperatively regulate the expression of a specific set of mRNA species on a genome wide scale. The difference in the complex formation between UAP56 and URH49 are thought to play a critical role in the regulation of target mRNAs. To date, the underlying mechanism remains poorly understood. Here we characterize the formation of the TREX complex and the AREX complex. In the ATP depleted condition, UAP56 formed an Apo-TREX complex containing the THO subcomplex but not ALYREF and CIP29. URH49 formed an Apo-AREX complex containing CIP29 but not ALYREF and the THO subcomplex. However, with the addition of ATP, both the Apo-TREX complex and the Apo-AREX complex were remodeled to highly similar ATP-TREX complex containing the THO subcomplex, ALYREF and CIP29. The knockdown of URH49 caused a reduction in its target mRNAs and a cytokinesis failure. Similarly, cytokinesis abnormality was observed in CIP29 knockdown cells, suggesting that CIP29 belongs to the URH49 regulated mRNA export pathway. Lastly, we confirmed that the export of mRNA in URH49-dependent pathway is achieved by NXF1, which is also observed in UAP56-dependent pathway. Our studies propose an mRNA export model that the mRNA selectivity depends on the Apo-form TREX/AREX complex, which is remodeled to the highly similar ATP-form complex upon ATP loading, and integrated to NXF1.
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Affiliation(s)
- Ken-Ichi Fujita
- Division of Integrated Life Sciences, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Tomohiro Yamazaki
- Division of Integrated Life Sciences, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Kotaro Harada
- Division of Integrated Life Sciences, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Shigeto Seno
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, Osaka 565-0871, Japan
| | - Hideo Matsuda
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, Osaka 565-0871, Japan
| | - Seiji Masuda
- Division of Integrated Life Sciences, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
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6
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Awasthi S, Verma M, Mahesh A, K Khan MI, Govindaraju G, Rajavelu A, Chavali PL, Chavali S, Dhayalan A. DDX49 is an RNA helicase that affects translation by regulating mRNA export and the levels of pre-ribosomal RNA. Nucleic Acids Res 2019; 46:6304-6317. [PMID: 29618122 PMCID: PMC6158705 DOI: 10.1093/nar/gky231] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 03/28/2018] [Indexed: 12/19/2022] Open
Abstract
Among the proteins predicted to be a part of the DExD box RNA helicase family, the functions of DDX49 are unknown. Here, we characterize the enzymatic activities and functions of DDX49 by comparing its properties with the well-studied RNA helicase, DDX39B. We find that DDX49 exhibits a robust ATPase and RNA helicase activity, significantly higher than that of DDX39B. DDX49 is required for the efficient export of poly (A)+ RNA from nucleus in a splicing-independent manner. Furthermore, DDX49 is a resident protein of nucleolus and regulates the steady state levels of pre-ribosomal RNA by regulating its transcription and stability. These dual functions of regulating mRNA export and pre-ribosomal RNA levels enable DDX49 to modulate global translation. Phenotypically, DDX49 promotes proliferation and colony forming potential of cells. Strikingly, DDX49 is significantly elevated in diverse cancer types suggesting that the increased abundance of DDX49 has a role in oncogenic transformation of cells. Taken together, this study shows the physiological role of DDX49 in regulating distinct steps of mRNA and pre-ribosomal RNA metabolism and hence translation and potential pathological role of its dysregulation, especially in cancers.
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Affiliation(s)
- Sharad Awasthi
- Department of Biotechnology, Pondicherry University, Puducherry 605 014, India
| | - Mamta Verma
- Department of Biotechnology, Pondicherry University, Puducherry 605 014, India
| | - Arun Mahesh
- Department of Biotechnology, Pondicherry University, Puducherry 605 014, India
| | - Mohd Imran K Khan
- Department of Biotechnology, Pondicherry University, Puducherry 605 014, India
| | - Gayathri Govindaraju
- Bacterial and Parasite Disease Biology, Rajiv Gandhi Center for Biotechnology, Trivandrum 695 014, India
| | - Arumugam Rajavelu
- Bacterial and Parasite Disease Biology, Rajiv Gandhi Center for Biotechnology, Trivandrum 695 014, India
| | - Pavithra L Chavali
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Sreenivas Chavali
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Arunkumar Dhayalan
- Department of Biotechnology, Pondicherry University, Puducherry 605 014, India
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7
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Mechanism and Regulation of Co-transcriptional mRNP Assembly and Nuclear mRNA Export. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1203:1-31. [DOI: 10.1007/978-3-030-31434-7_1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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8
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Espinosa S, Zhang L, Li X, Zhao R. Understanding pre-mRNA splicing through crystallography. Methods 2017; 125:55-62. [PMID: 28506657 PMCID: PMC5546983 DOI: 10.1016/j.ymeth.2017.04.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 04/11/2017] [Accepted: 04/26/2017] [Indexed: 01/07/2023] Open
Abstract
Crystallography is a powerful tool to determine the atomic structures of proteins and RNAs. X-ray crystallography has been used to determine the structure of many splicing related proteins and RNAs, making major contributions to our understanding of the molecular mechanism and regulation of pre-mRNA splicing. Compared to other structural methods, crystallography has its own advantage in the high-resolution structural information it can provide and the unique biological questions it can answer. In addition, two new crystallographic methods - the serial femtosecond crystallography and 3D electron crystallography - were developed to overcome some of the limitations of traditional X-ray crystallography and broaden the range of biological problems that crystallography can solve. This review discusses the theoretical basis, instrument requirements, troubleshooting, and exciting potential of these crystallographic methods to further our understanding of pre-mRNA splicing, a critical event in gene expression of all eukaryotes.
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9
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Studying structure and function of spliceosomal helicases. Methods 2017; 125:63-69. [PMID: 28668587 DOI: 10.1016/j.ymeth.2017.06.028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 06/21/2017] [Accepted: 06/24/2017] [Indexed: 12/27/2022] Open
Abstract
The splicing of eukaryotic precursor mRNAs requires the activity of at least three DEAD-box helicases, one Ski2-like helicase and four DEAH-box helicases. High resolution structures for five of these spliceosomal helicases were obtained by means of X-ray crystallography. Additional low resolution structural information could be derived from single particle cryo electron microscopy and small angle X-ray scattering. The functional characterization includes biochemical methods to measure the ATPase and helicase activities. This review gives an overview on the techniques used to gain insights in to the structure and function of spliceosomal helicases.
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10
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Kumar S, Sharma G, Chakraborty C, Sharma AR, Kim J. Regulatory functional territory of PLK-1 and their substrates beyond mitosis. Oncotarget 2017; 8:37942-37962. [PMID: 28415805 PMCID: PMC5514964 DOI: 10.18632/oncotarget.16290] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 03/03/2017] [Indexed: 12/04/2022] Open
Abstract
Polo-like kinase 1 (PLK-1) is a well-known (Ser/Thr) mitotic protein kinase and is considered as a proto-oncogene. As hyper-activation of PLK-1 is broadly associated with poor prognosis and cancer progression, it is one of the most extensively studied mitotic kinases. During mitosis, PLK-1 regulates various cell cycle events, such as spindle pole maturation, chromosome segregation and cytokinesis. However, studies have demonstrated that the role of PLK-1 is not only restricted to mitosis, but PLK-1 can also regulate other vital events beyond mitosis, including transcription, translation, ciliogenesis, checkpoint adaptation and recovery, apoptosis, chromosomes dynamics etc. Recent reviews have tried to define the regulatory role of PLK-1 during mitosis progression and tumorigenesis, but its' functional role beyond mitosis is still largely unexplored. PLK-1 can regulate the activity of many proteins that work outside of its conventional territory. The dysregulation of these proteins can cause diseases such as Alzheimer's disease, tumorigenesis etc. and may also lead to drug resistance. Thus, in this review, we discussed the versatile role of PLK-1 and tried to collect data to validate its' functional role in cell cycle regulation apart from mitosis.
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Affiliation(s)
- Shiv Kumar
- Department of Biochemistry, Institute of Cell Differentiation and Aging, Hallym University, College of Medicine, Chucheonsi, Gangwondo, Republic of Korea
| | - Garima Sharma
- Institute For Skeletal Aging & Orthopedic Surgery, Hallym University, College of Medicine, Chucheonsi, Gangwondo, Republic of Korea
| | - Chiranjib Chakraborty
- Department of Bio-informatics, School of Computer and Information Sciences, Galgotias University, Greater Noida, Uttar Pradesh, India
| | - Ashish Ranjan Sharma
- Institute For Skeletal Aging & Orthopedic Surgery, Hallym University, College of Medicine, Chucheonsi, Gangwondo, Republic of Korea
| | - Jaebong Kim
- Department of Biochemistry, Institute of Cell Differentiation and Aging, Hallym University, College of Medicine, Chucheonsi, Gangwondo, Republic of Korea
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11
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Dehghani M, Lasko P. C-terminal residues specific to Vasa among DEAD-box helicases are required for its functions in piRNA biogenesis and embryonic patterning. Dev Genes Evol 2016; 226:401-412. [PMID: 27572922 DOI: 10.1007/s00427-016-0560-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 08/09/2016] [Indexed: 10/21/2022]
Abstract
The DEAD-box RNA helicase Vasa (Vas, also known as DDX4) is required for germ cell development. In Drosophila, analysis of hypomorphic mutations has implicated maternally expressed Vas in germ cell formation and posterior embryonic patterning. vas-null females, which rarely complete oogenesis, exhibit defects in mitotic progression of germline stem cells, Piwi-interacting RNA (piRNA)-mediated transposon silencing, and translation of Gurken (Grk), an EGFR ligand. The carboxy-terminal region of Vas orthologs throughout the animal kingdom consists of several acidic residues as well as an invariant tryptophan in the penultimate or ultimate position (Trp660 in Drosophila melanogaster). Using CRISPR/Cas9 gene editing, we made a substitution mutant in this residue. Replacing Trp660 by Glu (W660E) abolishes the ability of Vas to support germ cell formation and embryonic patterning and greatly reduces Vas activity in piRNA biogenesis, as measured by transposon silencing, and in activating Grk translation. A conservative substitution (W660F) has much milder phenotypic consequences. In addition, females expressing only a form of Vas in which the seven C-terminal amino acids were replaced with the corresponding residues from Belle (Bel, also known as DDX3) show defects in perinuclear nuage assembly and transposon silencing. Oogenesis in females expressing only the chimeric Vas arrests early; however, in a vas 1 background, in which early expression of endogenous Vas supports oogenesis, the chimeric protein supports posterior patterning and germ cell specification. These results indicate that the unique C-terminus of Vas is essential for its function in piRNA biogenesis and that the conserved Trp660 residue has an important functional role.
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Affiliation(s)
- Mehrnoush Dehghani
- Department of Biology, McGill University, 3649 Promenade Sir William Osler, Montréal, Québec, H3G 0B1, Canada
| | - Paul Lasko
- Department of Biology, McGill University, 3649 Promenade Sir William Osler, Montréal, Québec, H3G 0B1, Canada.
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12
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Schumann S, Jackson BR, Yule I, Whitehead SK, Revill C, Foster R, Whitehouse A. Targeting the ATP-dependent formation of herpesvirus ribonucleoprotein particle assembly as an antiviral approach. Nat Microbiol 2016; 2:16201. [PMID: 27798559 PMCID: PMC7617399 DOI: 10.1038/nmicrobiol.2016.201] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 09/01/2016] [Indexed: 12/16/2022]
Abstract
Human herpesviruses are responsible for a range of debilitating acute and recurrent diseases, including a number of malignancies. Current treatments are limited to targeting the herpesvirus DNA polymerases, but with emerging viral resistance and little efficacy against the oncogenic herpesviruses, there is an urgent need for new antiviral strategies. Here, we describe a mechanism to inhibit the replication of the oncogenic herpesvirus Kaposi's sarcoma-associated herpesvirus (KSHV), by targeting the ATP-dependent formation of viral ribonucleoprotein particles (vRNPs). We demonstrate that small-molecule inhibitors which selectively inhibit the ATPase activity of the cellular human transcription/export complex (hTREX) protein UAP56 result in effective inhibition of vRNP formation, viral lytic replication and infectious virion production. Strikingly, as all human herpesviruses use conserved mRNA processing pathways involving hTREX components, we demonstrate the feasibility of this approach for pan-herpesvirus inhibition.
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Affiliation(s)
- Sophie Schumann
- School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, United Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Brian R. Jackson
- School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, United Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Ian Yule
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | | | - Charlotte Revill
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Richard Foster
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, United Kingdom
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Adrian Whitehouse
- School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, United Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, United Kingdom
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13
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Jacewicz A, Chico L, Smith P, Schwer B, Shuman S. Structural basis for recognition of intron branchpoint RNA by yeast Msl5 and selective effects of interfacial mutations on splicing of yeast pre-mRNAs. RNA (NEW YORK, N.Y.) 2015; 21:401-14. [PMID: 25587180 PMCID: PMC4338336 DOI: 10.1261/rna.048942.114] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Saccharomyces cerevisiae Msl5 orchestrates spliceosome assembly by binding the intron branchpoint sequence 5'-UACUAAC and, with its heterodimer partner protein Mud2, establishing cross intron-bridging interactions with the U1 snRNP at the 5' splice site. Here we define the central Msl5 KH-QUA2 domain as sufficient for branchpoint RNA recognition. The 1.8 Å crystal structure of Msl5-(KH-QUA2) bound to the branchpoint highlights an extensive network of direct and water-mediated protein-RNA and intra-RNA atomic contacts at the interface that illuminate how Msl5 recognizes each nucleobase of the UACUAAC element. The Msl5 structure rationalizes a large body of mutational data and inspires new functional studies herein, which reveal how perturbations of the Msl5·RNA interface impede the splicing of specific yeast pre-mRNAs. We also identify interfacial mutations in Msl5 that bypass the essentiality of Sub2, a DExD-box ATPase implicated in displacing Msl5 from the branchpoint in exchange for the U2 snRNP. These studies establish an atomic resolution framework for understanding splice site selection and early spliceosome dynamics.
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Affiliation(s)
- Agata Jacewicz
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065, USA
| | - Lidia Chico
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065, USA Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York 10065, USA
| | - Paul Smith
- Department of Chemistry, Fordham University, Bronx, New York 10458, USA
| | - Beate Schwer
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065, USA
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14
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Jacewicz A, Schwer B, Smith P, Shuman S. Crystal structure, mutational analysis and RNA-dependent ATPase activity of the yeast DEAD-box pre-mRNA splicing factor Prp28. Nucleic Acids Res 2014; 42:12885-98. [PMID: 25303995 PMCID: PMC4227776 DOI: 10.1093/nar/gku930] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Yeast Prp28 is a DEAD-box pre-mRNA splicing factor implicated in displacing U1 snRNP from the 5′ splice site. Here we report that the 588-aa Prp28 protein consists of a trypsin-sensitive 126-aa N-terminal segment (of which aa 1–89 are dispensable for Prp28 function in vivo) fused to a trypsin-resistant C-terminal catalytic domain. Purified recombinant Prp28 and Prp28-(127–588) have an intrinsic RNA-dependent ATPase activity, albeit with a low turnover number. The crystal structure of Prp28-(127–588) comprises two RecA-like domains splayed widely apart. AMPPNP•Mg2+ is engaged by the proximal domain, with proper and specific contacts from Phe194 and Gln201 (Q motif) to the adenine nucleobase. The triphosphate moiety of AMPPNP•Mg2+ is not poised for catalysis in the open domain conformation. Guided by the Prp28•AMPPNP structure, and that of the Drosophila Vasa•AMPPNP•Mg2+•RNA complex, we targeted 20 positions in Prp28 for alanine scanning. ATP-site components Asp341 and Glu342 (motif II) and Arg527 and Arg530 (motif VI) and RNA-site constituent Arg476 (motif Va) are essential for Prp28 activity in vivo. Synthetic lethality of double-alanine mutations highlighted functionally redundant contacts in the ATP-binding (Phe194-Gln201, Gln201-Asp502) and RNA-binding (Arg264-Arg320) sites. Overexpression of defective ATP-site mutants, but not defective RNA-site mutants, elicited severe dominant-negative growth defects.
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Affiliation(s)
- Agata Jacewicz
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Beate Schwer
- Microbiology and Immunology Department, Weill Cornell Medical College, New York, NY 10065, USA
| | - Paul Smith
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
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15
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Ostareck DH, Naarmann-de Vries IS, Ostareck-Lederer A. DDX6 and its orthologs as modulators of cellular and viral RNA expression. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 5:659-78. [PMID: 24788243 DOI: 10.1002/wrna.1237] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 03/19/2014] [Accepted: 03/21/2014] [Indexed: 12/21/2022]
Abstract
DDX6 (Rck/p54), a member of the DEAD-box family of helicases, is highly conserved from unicellular eukaryotes to vertebrates. Functions of DDX6 and its orthologs in dynamic ribonucleoproteins contribute to global and transcript-specific messenger RNA (mRNA) storage, translational repression, and decay during development and differentiation in the germline and somatic cells. Its role in pathways that promote mRNA-specific alternative translation initiation has been shown to be linked to cellular homeostasis, deregulated tissue development, and the control of gene expression in RNA viruses. Recently, DDX6 was found to participate in mRNA regulation mediated by miRNA-mediated silencing. DDX6 and its orthologs have versatile functions in mRNA metabolism, which characterize them as important post-transcriptional regulators of gene expression.
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Affiliation(s)
- Dirk H Ostareck
- Experimental Research Unit, Department of Intensive Care and Intermediate Care, University Hospital, RWTH Aachen University, Aachen, Germany
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16
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Liu F, Putnam AA, Jankowsky E. DEAD-box helicases form nucleotide-dependent, long-lived complexes with RNA. Biochemistry 2014; 53:423-33. [PMID: 24367975 DOI: 10.1021/bi401540q] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
DEAD-box RNA helicases bind and remodel RNA and RNA-protein complexes in an ATP-dependent fashion. Several lines of evidence suggest that DEAD-box RNA helicases can also form stable, persistent complexes with RNA in a process referred to as RNA clamping. The molecular basis of RNA clamping is not well understood. Here we show that the yeast DEAD-box helicase Ded1p forms exceptionally long-lived complexes with RNA and the nonhydrolyzable ATP ground-state analogue ADP-BeFx or the nonhydrolyzable ATP transition state analogue ADP-AlFx. The complexes have lifetimes of several hours, and neither nucleotide nor Mg(2+) is released during this period. Mutation of arginine 489, which stabilizes the transition state, prevents formation of long-lived complexes with the ATP transition state analogue, but not with the ground state analogue. We also show that two other yeast DEAD-box helicases, Mss116p and Sub2p, form comparably long-lived complexes with RNA and ADP-BeFx. Like Ded1p, Mss116p forms long-lived complexes with ADP-AlFx, but Sub2p does not. These data suggest that the ATP transition state might vary for distinct DEAD-box helicases, or that the transition state triggers differing RNA binding properties in these proteins. In the ATP ground state, however, all tested DEAD-box helicases establish a persistent grip on RNA, revealing an inherent capacity of the enzymes to function as potent, ATP-dependent RNA clamps.
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Affiliation(s)
- Fei Liu
- College of Veterinary Medicine, Nanjing Agricultural University , Nanjing, Jiangsu, 210095, China
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17
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Zhang L, Li X, Zhao R. Structural analyses of the pre-mRNA splicing machinery. Protein Sci 2013; 22:677-92. [PMID: 23592432 DOI: 10.1002/pro.2266] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 04/03/2013] [Accepted: 04/08/2013] [Indexed: 01/03/2023]
Abstract
Pre-mRNA splicing is a critical event in the gene expression pathway of all eukaryotes. The splicing reaction is catalyzed by the spliceosome, a huge protein-RNA complex that contains five snRNAs and hundreds of different protein factors. Understanding the structure of this large molecular machinery is critical for understanding its function. Although the highly dynamic nature of the spliceosome, in both composition and conformation, posed daunting challenges to structural studies, there has been significant recent progress on structural analyses of the splicing machinery, using electron microscopy, crystallography, and nuclear magnetic resonance. This review discusses key recent findings in the structural analyses of the spliceosome and its components and how these findings advance our understanding of the function of the splicing machinery.
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Affiliation(s)
- Lingdi Zhang
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
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18
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Zhang F, Wang J, Xu J, Zhang Z, Koppetsch BS, Schultz N, Vreven T, Meignin C, Davis I, Zamore PD, Weng Z, Theurkauf WE. UAP56 couples piRNA clusters to the perinuclear transposon silencing machinery. Cell 2013; 151:871-884. [PMID: 23141543 DOI: 10.1016/j.cell.2012.09.040] [Citation(s) in RCA: 169] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 03/09/2012] [Accepted: 09/20/2012] [Indexed: 11/18/2022]
Abstract
piRNAs silence transposons during germline development. In Drosophila, transcripts from heterochromatic clusters are processed into primary piRNAs in the perinuclear nuage. The nuclear DEAD box protein UAP56 has been previously implicated in mRNA splicing and export, whereas the DEAD box protein Vasa has an established role in piRNA production and localizes to nuage with the piRNA binding PIWI proteins Ago3 and Aub. We show that UAP56 colocalizes with the cluster-associated HP1 variant Rhino, that nuage granules containing Vasa localize directly across the nuclear envelope from cluster foci containing UAP56 and Rhino, and that cluster transcripts immunoprecipitate with both Vasa and UAP56. Significantly, a charge-substitution mutation that alters a conserved surface residue in UAP56 disrupts colocalization with Rhino, germline piRNA production, transposon silencing, and perinuclear localization of Vasa. We therefore propose that UAP56 and Vasa function in a piRNA-processing compartment that spans the nuclear envelope.
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Affiliation(s)
- Fan Zhang
- Program in Cell and Developmental Dynamics, University of Massachusetts Medical School, Worcester, MA 01655, USA; Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Jie Wang
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Jia Xu
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Zhao Zhang
- Program in Cell and Developmental Dynamics, University of Massachusetts Medical School, Worcester, MA 01655, USA; Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Birgit S Koppetsch
- Program in Cell and Developmental Dynamics, University of Massachusetts Medical School, Worcester, MA 01655, USA; Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Nadine Schultz
- Program in Cell and Developmental Dynamics, University of Massachusetts Medical School, Worcester, MA 01655, USA; Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Thom Vreven
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Carine Meignin
- Centre National de la Recherche Scientifique, Unité Propre de Recherche 9022, Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, 67 084 Strasbourg Cedex, France
| | - Ilan Davis
- Department of Biochemistry, The University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Phillip D Zamore
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01655, USA; Howard Hughes Medical Institute
| | - Zhiping Weng
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
| | - William E Theurkauf
- Program in Cell and Developmental Dynamics, University of Massachusetts Medical School, Worcester, MA 01655, USA; Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01655, USA.
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19
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Wisskirchen C, Ludersdorfer TH, Müller DA, Moritz E, Pavlovic J. Interferon-induced antiviral protein MxA interacts with the cellular RNA helicases UAP56 and URH49. J Biol Chem 2011; 286:34743-51. [PMID: 21859714 DOI: 10.1074/jbc.m111.251843] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Mx proteins are a family of large GTPases that are induced exclusively by interferon-α/β and have a broad antiviral activity against several viruses, including influenza A virus (IAV). Although the antiviral activities of mouse Mx1 and human MxA have been studied extensively, the molecular mechanism of action remains largely unsolved. Because no direct interaction between Mx proteins and IAV proteins or RNA had been demonstrated so far, we addressed the question of whether Mx protein would interact with cellular proteins required for efficient replication of IAV. Immunoprecipitation of MxA revealed its association with two closely related RNA helicases, UAP56 and URH49. UAP56 and its paralog URH49 play an important role in IAV replication and are involved in nuclear export of IAV mRNAs and prevention of dsRNA accumulation in infected cells. In vitro binding assays with purified recombinant proteins revealed that MxA formed a direct complex with the RNA helicases. In addition, recombinant mouse Mx1 was also able to bind to UAP56 or URH49. Furthermore, the complex formation between cytoplasmic MxA and UAP56 or URH49 occurred in the perinuclear region, whereas nuclear Mx1 interacted with UAP56 or URH49 in distinct dots in the nucleus. Taken together, our data reveal that Mx proteins exerting antiviral activity can directly bind to the two cellular DExD/H box RNA helicases UAP56 and URH49. Moreover, the observed subcellular localization of the Mx-RNA helicase complexes coincides with the subcellular localization, where human MxA and mouse Mx1 proteins act antivirally. On the basis of these data, we propose that Mx proteins exert their antiviral activity against IAV by interfering with the function of the RNA helicases UAP56 and URH49.
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20
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Dutta A, Zheng S, Jain D, Cameron CE, Reese JC. Intermolecular interactions within the abundant DEAD-box protein Dhh1 regulate its activity in vivo. J Biol Chem 2011; 286:27454-70. [PMID: 21642421 PMCID: PMC3149339 DOI: 10.1074/jbc.m111.220251] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Revised: 06/01/2011] [Indexed: 12/17/2022] Open
Abstract
Dhh1 is a highly conserved DEAD-box protein that has been implicated in many processes involved in mRNA regulation. At least some functions of Dhh1 may be carried out in cytoplasmic foci called processing bodies (P-bodies). Dhh1 was identified initially as a putative RNA helicase based solely on the presence of conserved helicase motifs found in the superfamily 2 (Sf2) of DEXD/H-box proteins. Although initial mutagenesis studies revealed that the signature DEAD-box motif is required for Dhh1 function in vivo, enzymatic (ATPase or helicase) or ATP binding activities of Dhh1 or those of any its many higher eukaryotic orthologues have not been described. Here we provide the first characterization of the biochemical activities of Dhh1. Dhh1 has weaker RNA-dependent ATPase activity than other well characterized DEAD-box helicases. We provide evidence that intermolecular interactions between the N- and C-terminal RecA-like helicase domains restrict its ATPase activity; mutation of residues mediating these interactions enhanced ATP hydrolysis. Interestingly, the interdomain interaction mutant displayed enhanced mRNA turnover, RNA binding, and recruitment into cytoplasmic foci in vivo compared with wild type Dhh1. Also, we demonstrate that the ATPase activity of Dhh1 is not required for it to be recruited into cytoplasmic foci, but it regulates its association with RNA in vivo. We hypothesize that the activity of Dhh1 is restricted by interdomain interactions, which can be regulated by cellular factors to impart stringent control over this very abundant RNA helicase.
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Affiliation(s)
- Arnob Dutta
- From the Center for Eukaryotic Gene Regulation and
- Department of Biochemistry and Molecular Biology, Penn State University, University Park, Pennsylvania 16802
| | - Suting Zheng
- From the Center for Eukaryotic Gene Regulation and
- Department of Biochemistry and Molecular Biology, Penn State University, University Park, Pennsylvania 16802
| | - Deepti Jain
- From the Center for Eukaryotic Gene Regulation and
- Department of Biochemistry and Molecular Biology, Penn State University, University Park, Pennsylvania 16802
| | - Craig E. Cameron
- Department of Biochemistry and Molecular Biology, Penn State University, University Park, Pennsylvania 16802
| | - Joseph C. Reese
- From the Center for Eukaryotic Gene Regulation and
- Department of Biochemistry and Molecular Biology, Penn State University, University Park, Pennsylvania 16802
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21
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Yoo HH, Chung IK. Requirement of DDX39 DEAD box RNA helicase for genome integrity and telomere protection. Aging Cell 2011; 10:557-71. [PMID: 21388492 DOI: 10.1111/j.1474-9726.2011.00696.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Human chromosome ends associate with shelterin, a six-protein complex that protects telomeric DNA from being recognized as sites of DNA damage. The shelterin subunit TRF2 has been implicated in the protection of chromosome ends by facilitating their organization into the protective capping structure and by associating with several accessory proteins involved in various DNA transactions. Here we describe the characterization of DDX39 DEAD-box RNA helicase as a novel TRF2-interacting protein. DDX39 directly interacts with the telomeric repeat binding factor homology domain of TRF2 via the FXLXP motif (where X is any amino acid). DDX39 is also found in association with catalytically competent telomerase in cell lysates through an interaction with hTERT but has no effect on telomerase activity. Whereas overexpression of DDX39 in telomerase-positive human cancer cells led to progressive telomere elongation, depletion of endogenous DDX39 by small hairpin RNA (shRNA) resulted in telomere shortening. Furthermore, depletion of DDX39 induced DNA-damage response foci at internal genome as well as telomeres as evidenced by telomere dysfunction-induced foci. Some of the metaphase chromosomes showed no telomeric signal at chromatid ends, suggesting an aberrant telomere structure. Our findings suggest that DDX39, in addition to its role in mRNA splicing and nuclear export, is required for global genome integrity as well as telomere protection and represents a new pathway for telomere maintenance by modulating telomere length homeostasis.
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Affiliation(s)
- Hyun Hee Yoo
- Departments of Biology and Integrated Omics for Biomedical Science, WCU program of Graduate School, Yonsei University, 134 Shinchon-dong, Seoul, Korea
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22
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Thomas M, Lischka P, Müller R, Stamminger T. The cellular DExD/H-box RNA-helicases UAP56 and URH49 exhibit a CRM1-independent nucleocytoplasmic shuttling activity. PLoS One 2011; 6:e22671. [PMID: 21799930 PMCID: PMC3142171 DOI: 10.1371/journal.pone.0022671] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Accepted: 07/03/2011] [Indexed: 01/26/2023] Open
Abstract
Cellular DExD/H-box RNA-helicases perform essential functions during mRNA biogenesis. The closely related human proteins UAP56 and URH49 are members of this protein family and play an essential role for cellular mRNA export by recruiting the adaptor protein REF to spliced and unspliced mRNAs. In order to gain insight into their mode of action, we aimed to characterize these RNA-helicases in more detail. Here, we demonstrate that UAP56 and URH49 exhibit an intrinsic CRM1-independent nucleocytoplasmic shuttling activity. Extensive mapping studies identified distinct regions within UAP56 or URH49 required for (i) intranuclear localization (UAP56 aa81-381) and (ii) interaction with REF (UAP56 aa51-428). Moreover, the region conferring nucleocytoplasmic shuttling activity was mapped to the C-terminus of UAP56, comprising the amino acids 195-428. Interestingly, this region coincides with a domain within Uap56p of S. pombe that has been reported to be required for both Rae1p-interaction and nucleocytoplasmic shuttling. However, in contrast to this finding we report that human UAP56 shuttles independently from Rae1. In summary, our results reveal nucleocytoplasmic shuttling as a conserved feature of yeast and human UAP56, while their export receptor seems to have diverged during evolution.
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Affiliation(s)
- Marco Thomas
- Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Peter Lischka
- Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Regina Müller
- Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Thomas Stamminger
- Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, Erlangen, Germany
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23
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Brinkmeyer-Langford CL, Murphy WJ, Childers CP, Skow LC. A conserved segmental duplication within ELA. Anim Genet 2010; 41 Suppl 2:186-95. [DOI: 10.1111/j.1365-2052.2010.02137.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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24
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Charette JM, Baserga SJ. The DEAD-box RNA helicase-like Utp25 is an SSU processome component. RNA (NEW YORK, N.Y.) 2010; 16:2156-69. [PMID: 20884785 PMCID: PMC2957055 DOI: 10.1261/rna.2359810] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The SSU processome is a large ribonucleoprotein complex consisting of the U3 snoRNA and at least 43 proteins. A database search, initiated in an effort to discover additional SSU processome components, identified the uncharacterized, conserved and essential yeast nucleolar protein YIL091C/UTP25 as one such candidate. The C-terminal DUF1253 motif, a domain of unknown function, displays limited sequence similarity to DEAD-box RNA helicases. In the absence of the conserved DEAD-box sequence, motif Ia is the only clearly identifiable helicase element. Since the yeast homolog is nucleolar and interacts with components of the SSU processome, we examined its role in pre-rRNA processing. Genetic depletion of Utp25 resulted in slowed growth. Northern analysis of pre-rRNA revealed an 18S rRNA maturation defect at sites A₀, A₁, and A₂. Coimmunoprecipitation confirmed association with U3 snoRNA and with Mpp10, and with components of the t-Utp/UtpA, UtpB, and U3 snoRNP subcomplexes. Mutation of the conserved motif Ia residues resulted in no discernable temperature-sensitive or cold-sensitive growth defects, implying that this motif is dispensable for Utp25 function. A yeast two-hybrid screen of Utp25 against other SSU processome components revealed several interacting proteins, including Mpp10, Utp3, and Utp21, thereby identifying the first interactions among the different subcomplexes of the SSU processome. Furthermore, the DUF1253 domain is required and sufficient for the interaction of Utp25 with Utp3. Thus, Utp25 is a novel SSU processome component that, along with Utp3, forms the first identified interactions among the different SSU processome subcomplexes.
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Affiliation(s)
- J Michael Charette
- Department of Molecular Biophysics & Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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25
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Abstract
mRNA decay is critical for the regulation of gene expression and the quality control of mRNA. RNA helicases play a key role in eukaryotic mRNA decay. In general, RNA helicases utilize the energy of ATP hydrolysis to remodel RNA or RNA-protein complexes, resulting in the separation of RNA duplex strand and/or displacement of proteins from the RNA molecule in RNP (ribonucleoprotein) complexes. Recently, high-resolution crystal structures of RNA helicases in mRNA decay have contributed a great deal to our understanding of these key molecules. In the present review, we focus on the structural and mechanistic aspects of three RNA helicases, Dhh1, Upf1 and eIF4AIII, that are involved in eukaryotic mRNA decay.
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26
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Zhang L, Xu T, Maeder C, Bud LO, Shanks J, Nix J, Guthrie C, Pleiss JA, Zhao R. Structural evidence for consecutive Hel308-like modules in the spliceosomal ATPase Brr2. Nat Struct Mol Biol 2009; 16:731-9. [PMID: 19525970 PMCID: PMC2743687 DOI: 10.1038/nsmb.1625] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 05/22/2009] [Indexed: 11/29/2022]
Abstract
Brr2 is a DExD/H-box helicase responsible for U4/U6 unwinding during spliceosomal activation. Brr2 contains two helicase-like domains, each of which is followed by a Sec63 domain with unknown function. We determined the crystal structure of the second Sec63 domain, which unexpectedly resembles domains 4 and 5 of DNA helicase Hel308. This, together with sequence similarities between Brr2's helicase-like domains and domains 1-3 of Hel308, led us to hypothesize that Brr2 contains two consecutive Hel308-like modules (Hel308-I and Hel308-II). Our structural model and mutagenesis data suggest that Brr2 shares a similar helicase mechanism with Hel308. We demonstrate that Hel308-II interacts with Prp8 and Snu114 in vitro and in vivo. We further find that the C-terminal region of Prp8 (Prp8-CTR) facilitates the binding of the Brr2-Prp8-CTR complex to U4/U6. Our results have important implications for the mechanism and regulation of Brr2's activity in splicing.
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Affiliation(s)
- Lingdi Zhang
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver, Aurora, CO 80045
| | - Tao Xu
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver, Aurora, CO 80045
| | - Corina Maeder
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143
| | - Laura-Oana Bud
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
| | - James Shanks
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver, Aurora, CO 80045
| | - Jay Nix
- Molecular Biology Consortium, Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Christine Guthrie
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143
| | - Jeffrey A. Pleiss
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
| | - Rui Zhao
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver, Aurora, CO 80045
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27
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Shen H. UAP56- a key player with surprisingly diverse roles in pre-mRNA splicing and nuclear export. BMB Rep 2009; 42:185-8. [PMID: 19403039 DOI: 10.5483/bmbrep.2009.42.4.185] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Transcripts contain introns that are usually removed from premessenger RNA (MRNA) in the process of pre-mRNA splicing. After splicing, the mature RNA is exported from the nucleus to the cytoplasm. The splicing and export processes are coupled. UAP56 protein, which is ubiquitously present in organisms from yeasts to humans, is a DExD/H-box family RNA helicase that is an essential splicing factor with various functions in the prespliceosome assembly and mature spliceosome assembly. Collective evidence indicates that UAP56 has an essential role in mRNA nuclear export. This mini-review summarizes recent evidence for the role of UAP56 in pre-mRNA splicing and nuclear export.
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Affiliation(s)
- Haihong Shen
- Department of Life Science, Gwangju Institute of Science and Technology, Gwangju, Korea.
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28
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Tritschler F, Braun JE, Eulalio A, Truffault V, Izaurralde E, Weichenrieder O. Structural basis for the mutually exclusive anchoring of P body components EDC3 and Tral to the DEAD box protein DDX6/Me31B. Mol Cell 2009; 33:661-8. [PMID: 19285948 DOI: 10.1016/j.molcel.2009.02.014] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Revised: 12/24/2008] [Accepted: 02/18/2009] [Indexed: 11/17/2022]
Abstract
The DEAD box helicase DDX6/Me31B functions in translational repression and mRNA decapping. How particular RNA helicases are recruited specifically to distinct functional complexes is poorly understood. We present the crystal structure of the DDX6 C-terminal RecA-like domain bound to a highly conserved FDF sequence motif in the decapping activator EDC3. The FDF peptide adopts an alpha-helical conformation upon binding to DDX6, occupying a shallow groove opposite to the DDX6 surface involved in RNA binding and ATP hydrolysis. Mutagenesis of Me31B shows the relevance of the FDF interaction surface both for Me31B's accumulation in P bodies and for its ability to repress the expression of bound mRNAs. The translational repressor Tral contains a similar FDF motif. Together with mutational and competition studies, the structure reveals why the interactions of Me31B with EDC3 and Tral are mutually exclusive and how the respective decapping and translational repressor complexes might hook onto an mRNA substrate.
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Affiliation(s)
- Felix Tritschler
- Max Planck Institute for Developmental Biology, Tübingen, Germany
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29
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Fan JS, Cheng Z, Zhang J, Noble C, Zhou Z, Song H, Yang D. Solution and crystal structures of mRNA exporter Dbp5p and its interaction with nucleotides. J Mol Biol 2009; 388:1-10. [PMID: 19281819 DOI: 10.1016/j.jmb.2009.03.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Revised: 02/28/2009] [Accepted: 03/03/2009] [Indexed: 11/19/2022]
Abstract
DEAD-box protein 5 (Dbp5p) plays very important roles in RNA metabolism from transcription, to translation, to RNA decay. It is an RNA helicase and functions as an essential RNA export factor from nucleus. Here, we report the solution NMR structures of the N- and C-terminal domains (NTD and CTD, respectively) of Dbp5p from Saccharomyces cerevisiae (ScDbp5p) and X-ray crystal structure of Dbp5p from Schizosaccharomyces pombe (SpDbp5p) in the absence of nucleotides and RNA. The crystal structure clearly shows that SpDbp5p comprises two RecA-like domains that do not interact with each other. NMR results show that the N-terminal flanking region of ScDpbp5 (M1-E70) is intrinsically unstructured and the region Y71-R121 including the Q motif is highly dynamic on millisecond-microsecond timescales in solution. The C-terminal flanking region of ScDbp5p forms a short beta-strand and a long helix. This helix is unique for ScDbp5p and has not been observed in other DEAD-box proteins. Compared with other DEAD-box proteins, Dbp5p has an extra insert with six residues in the CTD. NMR structure reveals that the insert is located in a solvent-exposed loop capable of interacting with other proteins. ATP and ADP titration experiments show that both ADP and ATP bind to the consensus binding site in the NTD of ScDbp5p but do not interact with the CTD at all. Binding of ATP or ADP to NTD induces significant conformational rearrangement too.
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Affiliation(s)
- Jing-Song Fan
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
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30
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Ohnishi S, Pääkkönen K, Koshiba S, Tochio N, Sato M, Kobayashi N, Harada T, Watanabe S, Muto Y, Güntert P, Tanaka A, Kigawa T, Yokoyama S. Solution structure of the GUCT domain from human RNA helicase II/Guβ reveals the RRM fold, but implausible RNA interactions. Proteins 2009; 74:133-44. [DOI: 10.1002/prot.22138] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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31
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Klostermeier D, Rudolph MG. A novel dimerization motif in the C-terminal domain of the Thermus thermophilus DEAD box helicase Hera confers substantial flexibility. Nucleic Acids Res 2008; 37:421-30. [PMID: 19050012 PMCID: PMC2632915 DOI: 10.1093/nar/gkn947] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
DEAD box helicases are involved in nearly all aspects of RNA metabolism. They share a common helicase core, and may comprise additional domains that contribute to RNA binding. The Thermus thermophilus helicase Hera is the first dimeric DEAD box helicase. Crystal structures of Hera fragments reveal a bipartite C-terminal domain with a novel dimerization motif and an RNA-binding module. We provide a first glimpse on the additional RNA-binding module outside the Hera helicase core. The dimerization and RNA-binding domains are connected to the C-terminal RecA domain by a hinge region that confers exceptional flexibility onto the helicase, allowing for different juxtapositions of the RecA-domains in the dimer. Combination of the previously determined N-terminal Hera structure with the C-terminal Hera structures allows generation of a model for the entire Hera dimer, where two helicase cores can work in conjunction on large RNA substrates.
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Affiliation(s)
- Dagmar Klostermeier
- Division of Biophysical Chemistry, Biozentrum, University of Basel, CH-4056 Basel, Switzerland.
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32
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Sperling J, Azubel M, Sperling R. Structure and function of the Pre-mRNA splicing machine. Structure 2008; 16:1605-15. [PMID: 19000813 DOI: 10.1016/j.str.2008.08.011] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Revised: 08/22/2008] [Accepted: 08/27/2008] [Indexed: 12/14/2022]
Abstract
Most eukaryotic pre-mRNAs contain non-coding sequences (introns) that must be removed in order to accurately place the coding sequences (exons) in the correct reading frame. This critical regulatory pre-mRNA splicing event is fundamental in development and cancer. It occurs within a mega-Dalton multicomponent machine composed of RNA and proteins, which undergoes dynamic changes in RNA-RNA, RNA-protein, and protein-protein interactions during the splicing reaction. Recent years have seen progress in functional and structural analyses of the splicing machine and its subcomponents, and this review is focused on structural aspects of the pre-mRNA splicing machine and their mechanistic implications on the splicing of multi-intronic pre-mRNAs. It brings together, in a comparative manner, structural information on spliceosomes and their intermediates in the stepwise assembly process in vitro, and on the preformed supraspliceosomes, which are isolated from living cell nuclei, with a view of portraying a consistent picture.
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Affiliation(s)
- Joseph Sperling
- Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel
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33
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Abstract
PDBsum (http://www.ebi.ac.uk/pdbsum) provides summary information about each experimentally determined structural model in the Protein Data Bank (PDB). Here we describe some of its most recent features, including figures from the structure's key reference, citation data, Pfam domain diagrams, topology diagrams and protein-protein interactions. Furthermore, it now accepts users' own PDB format files and generates a private set of analyses for each uploaded structure.
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Affiliation(s)
- Roman A Laskowski
- European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK.
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34
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Abstract
In eukaryotes, copying the genetic information from a DNA template into RNA is not sufficient itself to confer functional competence to the DNA-encoded message. mRNAs have to be processed by enzymes and packaged with proteins within nuclei to generate mRNP (messenger ribonucleoprotein) particles, before these can be exported to the cytoplasm. Processing and packaging factors are believed to interact with the nascent mRNA co-transcriptionally, which protects the highly reactive RNA molecule from a presumably aggressive nuclear environment while providing early commitment to its functional fate. In this review, we will describe the factors that are believed to provide the appropriate 'dress code' to the mRNA and the mechanisms underlying the proofreading events that guarantee its quality, focusing on yeast as a model system.
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35
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Kota KP, Wagner SR, Huerta E, Underwood JM, Nickerson JA. Binding of ATP to UAP56 is necessary for mRNA export. J Cell Sci 2008; 121:1526-37. [PMID: 18411249 DOI: 10.1242/jcs.021055] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The major-histocompatibility-complex protein UAP56 (BAT1) is a DEAD-box helicase that is deposited on mRNA during splicing. UAP56 is retained on spliced mRNA in an exon junction complex (EJC) or, alternatively, with the TREX complex at the 5' end, where it might facilitate the export of the spliced mRNA to the cytoplasm. Using confocal microscopy, UAP56 was found to be concentrated in RNA-splicing speckled domains of nuclei but was also enriched in adjacent nuclear regions, sites at which most mRNA transcription and splicing occur. At speckled domains, UAP56 was in complexes with the RNA-splicing and -export protein SRm160, and, as measured by FRAP, was in a dynamic binding equilibrium. The application of an in vitro FRAP assay, in which fluorescent nuclear proteins are photobleached in digitonin-extracted cells, revealed that the equilibrium binding of UAP56 in complexes at speckled domains was directly regulated by ATP binding. This was confirmed using a point mutant of UAP56 that did not bind ATP. Point mutation of UAP56 to eliminate ATP binding did not affect RNA splicing, but strongly inhibited the export of mRNA to the cytoplasm.
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Affiliation(s)
- Krishna P Kota
- Department of Cell Biology S7-214, University of Massachusetts Medical School, Worcester, MA 01655, USA
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36
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Meignin C, Davis I. UAP56 RNA helicase is required for axis specification and cytoplasmic mRNA localization in Drosophila. Dev Biol 2008; 315:89-98. [PMID: 18237727 DOI: 10.1016/j.ydbio.2007.12.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Revised: 11/30/2007] [Accepted: 12/05/2007] [Indexed: 10/22/2022]
Abstract
mRNA export from the nucleus requires the RNA helicase UAP56 and involves remodeling of ribonucleo-protein complexes in the nucleus. Here, we show that UAP56 is required for bulk mRNA export from the nurse cell nuclei that supply most of the material to the growing Drosophila oocyte and for the organization of chromatin in the oocyte nucleus. Loss of UAP56 function leads to patterning defects that identify uap56 as a spindle-class gene similar to the RNA helicase Vasa. UAP56 is required for the localization of gurken, bicoid and oskar mRNA as well as post-translational modification of Osk protein. By injecting grk RNA into the oocyte cytoplasm, we show that UAP56 plays a role in cytoplasmic mRNA localization. We propose that UAP56 has two independent functions in the remodeling of ribonucleo-protein complexes. The first is in the nucleus for mRNA export of most transcripts from the nucleus. The second is in the cytoplasm for remodeling the transacting factors that decorate mRNA and dictate its cytoplasmic destination.
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Affiliation(s)
- Carine Meignin
- Department of Biochemistry, The University of Oxford, South Parks Road, Oxford OX1 3QU, UK
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37
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Obarska-Kosinska A, Taylor JEN, Callow P, Orlowski J, Bujnicki JM, Kneale GG. HsdR subunit of the type I restriction-modification enzyme EcoR124I: biophysical characterisation and structural modelling. J Mol Biol 2008; 376:438-452. [PMID: 18164032 PMCID: PMC2878639 DOI: 10.1016/j.jmb.2007.11.024] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2007] [Revised: 11/08/2007] [Accepted: 11/09/2007] [Indexed: 01/19/2023]
Abstract
Type I restriction-modification (RM) systems are large, multifunctional enzymes composed of three different subunits. HsdS and HsdM form a complex in which HsdS recognizes the target DNA sequence, and HsdM carries out methylation of adenosine residues. The HsdR subunit, when associated with the HsdS-HsdM complex, translocates DNA in an ATP-dependent process and cleaves unmethylated DNA at a distance of several thousand base-pairs from the recognition site. The molecular mechanism by which these enzymes translocate the DNA is not fully understood, in part because of the absence of crystal structures. To date, crystal structures have been determined for the individual HsdS and HsdM subunits and models have been built for the HsdM-HsdS complex with the DNA. However, no structure is available for the HsdR subunit. In this work, the gene coding for the HsdR subunit of EcoR124I was re-sequenced, which showed that there was an error in the published sequence. This changed the position of the stop codon and altered the last 17 amino acid residues of the protein sequence. An improved purification procedure was developed to enable HsdR to be purified efficiently for biophysical and structural analysis. Analytical ultracentrifugation shows that HsdR is monomeric in solution, and the frictional ratio of 1.21 indicates that the subunit is globular and fairly compact. Small angle neutron-scattering of the HsdR subunit indicates a radius of gyration of 3.4 nm and a maximum dimension of 10 nm. We constructed a model of the HsdR using protein fold-recognition and homology modelling to model individual domains, and small-angle neutron scattering data as restraints to combine them into a single molecule. The model reveals an ellipsoidal shape of the enzymatic core comprising the N-terminal and central domains, and suggests conformational heterogeneity of the C-terminal region implicated in binding of HsdR to the HsdS-HsdM complex.
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Affiliation(s)
- Agnieszka Obarska-Kosinska
- Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, Trojdena 4, 02-109 Warsaw, Poland
| | - James E N Taylor
- Biophysics Laboratories, Institute of Biomedical and Biomolecular Sciences, University of Portsmouth, PO1 2DT, UK
| | - Philip Callow
- EPSAM and ISTM Research Institutes, Keele University, Staffordshire ST5 5BG, UK; ILL-EMBL Deuteration Laboratory, Partnership for Structural Biology, Institut Laue Langevin, 38042 Grenoble Cedex 9, Grenoble, France
| | - Jerzy Orlowski
- Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, Trojdena 4, 02-109 Warsaw, Poland
| | - Janusz M Bujnicki
- Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, Trojdena 4, 02-109 Warsaw, Poland.
| | - G Geoff Kneale
- Biophysics Laboratories, Institute of Biomedical and Biomolecular Sciences, University of Portsmouth, PO1 2DT, UK.
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Bernstein J, Patterson DN, Wilson GM, Toth EA. Characterization of the essential activities of Saccharomyces cerevisiae Mtr4p, a 3'->5' helicase partner of the nuclear exosome. J Biol Chem 2007; 283:4930-42. [PMID: 18096702 DOI: 10.1074/jbc.m706677200] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mtr4p belongs to the Ski2p family of DEVH-box containing proteins and is required for processing and degradation of a variety of RNA substrates in the nucleus. In particular, Mtr4p is required for creating the 5.8 S ribosomal RNA from its 7 S precursor, proper 3'-end processing of the U4 small nuclear RNA and some small nucleolar RNAs, and degradation of aberrant mRNAs and tRNAs. In these studies we have shown that Mtr4p has RNA-dependent ATPase (or dATPase) activity that is stimulated effectively by likely substrates (e.g. tRNA) but surprisingly weakly by poly(A). Using an RNA strand-displacement assay, we have demonstrated that Mtr4p can, in the presence of ATP or dATP, unwind the duplex region of a partial duplex RNA substrate in the 3'-->5' direction. We have examined the ability of Mtr4p to bind model RNA substrates in the presence of nucleotides that mimic the stages (i.e. ATP-bound, ADP-bound, and nucleotide-free) of the unwinding reaction. Our results demonstrate that the presence of a non-hydrolyzable ATP analog allows Mtr4p to discriminate between partial duplex RNA substrates, binding a 3'-tailed substrate with 5-fold higher affinity than a 5'-tailed substrate. In addition, Mtr4p displays a marked preference for binding to poly(A) RNA relative to an oligoribonucleotide of the same length and a random sequence. This binding exhibits apparent cooperativity and different dynamic behavior from binding to the random single-stranded RNA. This unique binding mode might be employed primarily for degradation.
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Affiliation(s)
- Jade Bernstein
- Department of Biochemistry and Molecular Biology, and Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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39
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Elles LMS, Uhlenbeck OC. Mutation of the arginine finger in the active site of Escherichia coli DbpA abolishes ATPase and helicase activity and confers a dominant slow growth phenotype. Nucleic Acids Res 2007; 36:41-50. [PMID: 17986459 PMCID: PMC2248767 DOI: 10.1093/nar/gkm926] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Escherichia coli DEAD-box protein A (DbpA) is an ATP-dependent RNA helicase with specificity for 23S ribosomal RNA. Although DbpA has been extensively characterized biochemically, its biological function remains unknown. Previous work has shown that a DbpA deletion strain is viable with little or no effect on growth rate. In attempt to elucidate a phenotype for DbpA, point mutations were made at eleven conserved residues in the ATPase active site, which have exhibited dominant-negative phenotypes in other DExD/H proteins. Biochemical analysis of these DbpA mutants shows the expected decrease in RNA-dependent ATPase activity and helix unwinding activity. Only the least biochemically active mutation, R331A, produces small colony phenotype and a reduced growth rate. This dominant slow growth mutant will be valuable to determine the cellular function of DbpA.
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Affiliation(s)
- Lisa M Sharpe Elles
- Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, IL 60208, USA
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40
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Pradhan A, Tuteja R. Bipolar, Dual Plasmodium falciparum helicase 45 expressed in the intraerythrocytic developmental cycle is required for parasite growth. J Mol Biol 2007; 373:268-81. [PMID: 17822710 DOI: 10.1016/j.jmb.2007.07.056] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2007] [Revised: 07/12/2007] [Accepted: 07/16/2007] [Indexed: 11/21/2022]
Abstract
Helicases are ubiquitous molecular motor proteins that have an important role in the metabolism of nucleic acids. The gene encoding a helicase was cloned from the human malaria parasite Plasmodium falciparum. The polypeptide of 398 amino acid residues has a molecular mass of 45 kDa, contains striking homology to eukaryotic translation initiation factor 4A (eIF4A) and all the conserved domains of the DEAD-box family. The recombinantly expressed and homogeneous P. falciparum protein PfH45 is an ATP-dependent DNA and RNA helicase, with ATPase and ATP-binding activities. PfH45 is a unique bipolar helicase that contains both the 3' to 5' and 5' to 3' directional helicase activities and anti-PfH45 antibodies curtail all its activities. PfH45 is expressed in all the intraerythrocytic developmental stages of the parasite and has a role in translation. Parasite cultures treated with PfH45 double-stranded RNA or purified immunoglobulins against PfH45 exhibited approximately 60% and approximately 55% growth inhibition, respectively. This inhibitory effect was due to interference with expression of the cognate messenger and down-regulation of synthesis of PfH45 protein in the parasite culture and was associated with morphologic deformation of the parasite. These studies indicate that PfH45 is an indispensable enzyme that is essential for growth, and probably survival, of P. falciparum.
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Affiliation(s)
- Arun Pradhan
- Malaria Group, International Centre for Genetic Engineering and Biotechnology, PO Box 10504, Aruna Asaf Ali Marg, New Delhi-110067, India
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41
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Högbom M, Collins R, van den Berg S, Jenvert RM, Karlberg T, Kotenyova T, Flores A, Karlsson Hedestam GB, Schiavone LH. Crystal structure of conserved domains 1 and 2 of the human DEAD-box helicase DDX3X in complex with the mononucleotide AMP. J Mol Biol 2007; 372:150-9. [PMID: 17631897 DOI: 10.1016/j.jmb.2007.06.050] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2007] [Revised: 06/12/2007] [Accepted: 06/14/2007] [Indexed: 11/24/2022]
Abstract
DExD-box helicases are involved in all aspects of cellular RNA metabolism. Conserved domains 1 and 2 contain nine signature motifs that are responsible for nucleotide binding, RNA binding and ATP hydrolysis. The human DEAD-box helicase DDX3X has been associated with several different cellular processes, such as cell-growth control, mRNA transport and translation, and is suggested to be essential for the export of unspliced/partially spliced HIV mRNAs from the nucleus to the cytoplasm. Here, the crystal structure of conserved domains 1 and 2 of DDX3X, including a DDX3-specific insertion that is not generally found in human DExD-box helicases, is presented. The N-terminal domain 1 and the C-terminal domain 2 both display RecA-like folds comprising a central beta-sheet flanked by alpha-helices. Interestingly, the DDX3X-specific insertion forms a helical element that extends a highly positively charged sequence in a loop, thus increasing the RNA-binding surface of the protein. Surprisingly, although DDX3X was crystallized in the presence of a large excess of ADP or the slowly hydrolyzable ATP analogue ATPgammaS the contaminant AMP was seen in the structure. A fluorescent-based stability assay showed that the thermal stability of DDX3X was increased by the mononucleotide AMP but not by ADP or ATPgammaS, suggesting that DDX3X is stabilized by AMP and elucidating why AMP was found in the nucleotide-binding pocket.
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Affiliation(s)
- Martin Högbom
- Structural Genomics Consortium, Department of Medical Biochemistry and Biophysics, Karolinska Institute, SE-171 77 Stockholm, Sweden
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42
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Shen J, Zhang L, Zhao R. Biochemical characterization of the ATPase and helicase activity of UAP56, an essential pre-mRNA splicing and mRNA export factor. J Biol Chem 2007; 282:22544-50. [PMID: 17562711 DOI: 10.1074/jbc.m702304200] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DEXD/H-box protein UAP56 is an essential pre-mRNA splicing factor required for the first ATP-dependent spliceosome assembly step. UAP56 is also essential for the export of the majority of mRNAs from the nucleus to the cytoplasm. We performed biochemical characterization of UAP56's ATPase and helicase activity, which is important for further understanding the role of these activities in UAP56's function. We showed that UAP56 is an RNA-stimulated ATPase that can only hydrolyze ATP. We demonstrated that UAP56 is an ATP-dependent RNA helicase that can unwind substrates with 5' or 3' overhangs or blunt ends in vitro. We showed that U2AF(65) and Aly, two proteins known to interact with UAP56, do not influence UAP56's ATPase or helicase activity. We also demonstrated that several mutants in the conserved helicase motifs I, II, and III abolish UAP56's ATPase and/or helicase activity, providing tools for future investigation of the role of UAP56's ATPase and helicase activity in spliceosome assembly and mRNA export.
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Affiliation(s)
- Jingping Shen
- Department of Biochemistry and Molecular Genetics, University of Colorado at Denver and Health Sciences Center, Aurora, Colorado 80045, USA
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43
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Franca R, Belfiore A, Spadari S, Maga G. Human DEAD-box ATPase DDX3 shows a relaxed nucleoside substrate specificity. Proteins 2007; 67:1128-37. [PMID: 17357160 DOI: 10.1002/prot.21433] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Human DDX3 (hDDX3) is a DEAD-box protein shown to possess RNA-unwinding and adenosine triphosphatase (ATPase) activities. The hDDX3 protein has been implicated in nuclear mRNA export, cell growth control, and cancer progression. In addition, a role of this protein in the replication of human immunodeficiency virus Type 1 and in the pathogenesis of hepatitis C virus has been recently proposed. Its enzymological properties, however, are largely unknown. In this work, we characterized its ATPase activity. We show that hDDX3 ATPase activity is stimulated by various ribo- and deoxynucleic acids. Comparative analysis with different nucleoside triphosphate analogs showed that the hDDX3 ATPase couples high catalytic efficiency to a rather relaxed substrate specificity, both in terms of base selection and sugar selection. In addition, its ability to recognize the L-stereoisomers of both 3' deoxy- and 2',3' dideoxy-ribose, points to a relaxed stereoselectivity. On the basis of these results, we hypothesize the presence of structural determinants on both the base and the sugar moieties, critical for nucleoside binding to the enzyme. Our results expand the knowledge about the DEAD-box RNA helicases in general and can be used for rational design of selective inhibitors of hDDX3, to be tested as potential antitumor and antiviral agents.
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Affiliation(s)
- Raffaella Franca
- DNA Enzymology and Molecular Virology Unit, Istituto di Genetica Molecolare IGM-CNR, via Abbiategrasso 207, 27100 Pavia, Italy
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44
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Karow AR, Theissen B, Klostermeier D. Authentic interdomain communication in an RNA helicase reconstituted by expressed protein ligation of two helicase domains. FEBS J 2007; 274:463-73. [PMID: 17229151 DOI: 10.1111/j.1742-4658.2006.05593.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
RNA helicases mediate structural rearrangements of RNA or RNA-protein complexes at the expense of ATP hydrolysis. Members of the DEAD box helicase family consist of two flexibly connected helicase domains. They share nine conserved sequence motifs that are involved in nucleotide binding and hydrolysis, RNA binding, and helicase activity. Most of these motifs line the cleft between the two helicase domains, and extensive communication between them is required for RNA unwinding. The two helicase domains of the Bacillus subtilis RNA helicase YxiN were produced separately as intein fusions, and a functional RNA helicase was generated by expressed protein ligation. The ligated helicase binds adenine nucleotides with very similar affinities to the wild-type protein. Importantly, its intrinsically low ATPase activity is stimulated by RNA, and the Michaelis-Menten parameters are similar to those of the wild-type. Finally, ligated YxiN unwinds a minimal RNA substrate to an extent comparable to that of the wild-type helicase, confirming authentic interdomain communication.
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Affiliation(s)
- Anne R Karow
- Department of Biophysical Chemistry, University of Basel, Switzerland
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45
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Sugiura T, Sakurai K, Nagano Y. Intracellular characterization of DDX39, a novel growth-associated RNA helicase. Exp Cell Res 2007; 313:782-90. [DOI: 10.1016/j.yexcr.2006.11.014] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2006] [Revised: 11/08/2006] [Accepted: 11/23/2006] [Indexed: 11/26/2022]
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46
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Kim OTP, Yura K, Go N. Amino acid residue doublet propensity in the protein-RNA interface and its application to RNA interface prediction. Nucleic Acids Res 2006; 34:6450-60. [PMID: 17130160 PMCID: PMC1761430 DOI: 10.1093/nar/gkl819] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Protein-RNA interactions play essential roles in a number of regulatory mechanisms for gene expression such as RNA splicing, transport, translation and post-transcriptional control. As the number of available protein-RNA complex 3D structures has increased, it is now possible to statistically examine protein-RNA interactions based on 3D structures. We performed computational analyses of 86 representative protein-RNA complexes retrieved from the Protein Data Bank. Interface residue propensity, a measure of the relative importance of different amino acid residues in the RNA interface, was calculated for each amino acid residue type (residue singlet interface propensity). In addition to the residue singlet propensity, we introduce a new residue-based propensity, which gives a measure of residue pairing preferences in the RNA interface of a protein (residue doublet interface propensity). The residue doublet interface propensity contains much more information than the sum of two singlet propensities alone. The prediction of the RNA interface using the two types of propensities plus a position-specific multiple sequence profile can achieve a specificity of about 80%. The prediction method was then applied to the 3D structure of two mRNA export factors, TAP (Mex67) and UAP56 (Sub2). The prediction enables us to point out candidate RNA interfaces, part of which are consistent with previous experimental studies and may contribute to elucidation of atomic mechanisms of mRNA export.
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Affiliation(s)
- Oanh T. P. Kim
- Quantum Bioinformatics Team, Center for Computational Science and Engineering, Japan Atomic Energy AgencyKizu-cho, Souraku-gun, Kyoto 619-0215, Japan
| | - Kei Yura
- Quantum Bioinformatics Team, Center for Computational Science and Engineering, Japan Atomic Energy AgencyKizu-cho, Souraku-gun, Kyoto 619-0215, Japan
- Research Unit for Quantum Beam Life Science Initiative, Quantum Beam Science Directorate, Japan Atomic Energy AgencyKizu-cho, Souraku-gun, Kyoto 619-0215, Japan
- CREST, JST, Japan Atomic Energy AgencyKizu-cho, Souraku-gun, Kyoto 619-0215, Japan
- To whom correspondence should be addressed. Tel: +81 774 71 3462; Fax: +81 774 71 3460;
| | - Nobuhiro Go
- Research Unit for Quantum Beam Life Science Initiative, Quantum Beam Science Directorate, Japan Atomic Energy AgencyKizu-cho, Souraku-gun, Kyoto 619-0215, Japan
- Computational Biology Group, Quantum Beam Science Directorate, Japan Atomic Energy AgencyKizu-cho, Souraku-gun, Kyoto 619-0215, Japan
- Bioinformatics Unit, Nara Institute of Science and TechnologyTakayama-cho, Ikoma-shi, Nara 630-0196, Japan
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47
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Naito T, Momose F, Kawaguchi A, Nagata K. Involvement of Hsp90 in assembly and nuclear import of influenza virus RNA polymerase subunits. J Virol 2006; 81:1339-49. [PMID: 17121807 PMCID: PMC1797515 DOI: 10.1128/jvi.01917-06] [Citation(s) in RCA: 197] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Transcription and replication of the influenza virus RNA genome occur in the nuclei of infected cells through the viral RNA-dependent RNA polymerase consisting of PB1, PB2, and PA. We previously identified a host factor designated RAF-1 (RNA polymerase activating factor 1) that stimulates viral RNA synthesis. RAF-1 is found to be identical to Hsp90. Here, we examined the intracellular localization of Hsp90 and viral RNA polymerase subunits and their molecular interaction. Hsp90 was found to interact with PB2 and PB1, and it was relocalized to the nucleus upon viral infection. We found that the nuclear transport of Hsp90 occurs in cells expressing PB2 alone. The nuclear transport of Hsp90 was in parallel with that of the viral RNA polymerase binary complexes, either PB1 and PB2 or PB1 and PA, as well as with that of PB2 alone. Hsp90 also interacted with the binary RNA polymerase complex PB1-PB2, and it was dissociated from the PB1-PB2 complex upon its association with PA. Furthermore, Hsp90 could form a stable PB1-PB2-Hsp90 complex prior to the formation of a ternary polymerase complex by the assembly of PA in the infected cells. These results suggest that Hsp90 is involved in the assembly and nuclear transport of viral RNA polymerase subunits, possibly as a molecular chaperone for the polymerase subunits prior to the formation of a mature ternary polymerase complex.
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Affiliation(s)
- Tadasuke Naito
- Department of Infection Biology, Graduate School of Comprehensive Human Sciences and Institute of Basic Medical Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan
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48
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Rudolph MG, Heissmann R, Wittmann JG, Klostermeier D. Crystal structure and nucleotide binding of the Thermus thermophilus RNA helicase Hera N-terminal domain. J Mol Biol 2006; 361:731-43. [PMID: 16890241 DOI: 10.1016/j.jmb.2006.06.065] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Revised: 06/20/2006] [Accepted: 06/26/2006] [Indexed: 02/06/2023]
Abstract
DEAD box RNA helicases use the energy of ATP hydrolysis to unwind double-stranded RNA regions or to disrupt RNA/protein complexes. A minimal RNA helicase comprises nine conserved motifs distributed over two RecA-like domains. The N-terminal domain contains all motifs involved in nucleotide binding, namely the Q-motif, the DEAD box, and the P-loop, as well as the SAT motif, which has been implicated in the coordination of ATP hydrolysis and RNA unwinding. We present here the crystal structure of the N-terminal domain of the Thermus thermophilus RNA helicase Hera in complex with adenosine monophosphate (AMP). Upon binding of AMP the P-loop adopts a partially collapsed or half-open conformation that is still connected to the DEAD box motif, and the DEAD box in turn is linked to the SAT motif via hydrogen bonds. This network of interactions communicates changes in the P-loop conformation to distant parts of the helicase. The affinity of AMP is comparable to that of ADP and ATP, substantiating that the binding energy from additional phosphate moieties is directly converted into conformational changes of the entire helicase. Importantly, the N-terminal Hera domain forms a dimer in the crystal similar to that seen in another thermophilic prokaryote. It is possible that this mode of dimerization represents the prototypic architecture in RNA helicases of thermophilic origin.
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Affiliation(s)
- Markus G Rudolph
- Department of Molecular Structural Biology, University of Göttingen, D-37077 Göttingen, Germany
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Keramisanou D, Biris N, Gelis I, Sianidis G, Karamanou S, Economou A, Kalodimos CG. Disorder-order folding transitions underlie catalysis in the helicase motor of SecA. Nat Struct Mol Biol 2006; 13:594-602. [PMID: 16783375 DOI: 10.1038/nsmb1108] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2005] [Accepted: 05/12/2006] [Indexed: 01/01/2023]
Abstract
SecA is a helicase-like motor that couples ATP hydrolysis with the translocation of extracytoplasmic protein substrates. As in most helicases, this process is thought to occur through nucleotide-regulated rigid-body movement of the motor domains. NMR, thermodynamic and biochemical data show that SecA uses a novel mechanism wherein conserved regions lining the nucleotide cleft undergo cycles of disorder-order transitions while switching among functional catalytic states. The transitions are regulated by interdomain interactions mediated by crucial 'arginine finger' residues located on helicase motifs. Furthermore, we show that the nucleotide cleft allosterically communicates with the preprotein substrate-binding domain and the regulatory, membrane-inserting C domain, thereby allowing for the coupling of the ATPase cycle to the translocation activity. The intrinsic plasticity and functional disorder-order folding transitions coupled to ligand binding seem to provide a precise control of the catalytic activation process and simple regulation of allosteric mechanisms.
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Sengoku T, Nureki O, Nakamura A, Kobayashi S, Yokoyama S. Structural basis for RNA unwinding by the DEAD-box protein Drosophila Vasa. Cell 2006; 125:287-300. [PMID: 16630817 DOI: 10.1016/j.cell.2006.01.054] [Citation(s) in RCA: 459] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2005] [Revised: 12/15/2005] [Accepted: 01/27/2006] [Indexed: 11/26/2022]
Abstract
DEAD-box RNA helicases, which regulate various processes involving RNA, have two RecA-like domains as a catalytic core to alter higher-order RNA structures. We determined the 2.2 A resolution structure of the core of the Drosophila DEAD-box protein Vasa in complex with a single-stranded RNA and an ATP analog. The ATP analog intensively interacts with both of the domains, thereby bringing them into the closed form, with many interdomain interactions of conserved residues. The bound RNA is sharply bent, avoiding a clash with a conserved alpha helix in the N-terminal domain. This "wedge" helix should disrupt base pairs by bending one of the strands when a duplex is bound. Mutational analyses indicated that the interdomain interactions couple ATP hydrolysis to RNA unwinding, probably through fine positioning of the duplex relative to the wedge helix. This mechanism, which differs from those for canonical translocating helicases, may enable the targeted modulation of intricate RNA structures.
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Affiliation(s)
- Toru Sengoku
- Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan
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