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Yu X, Teng T, Duan Z, Wang J. AcMNPV-miR-2 affects Autographa californica nucleopolyhedrovirus infection by regulating the expression of ac28 and several other viral early genes. J Virol 2024:e0057024. [PMID: 39023251 DOI: 10.1128/jvi.00570-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2024] [Accepted: 06/21/2024] [Indexed: 07/20/2024] Open
Abstract
Virus-encoded microRNAs (miRNAs) exert diverse regulatory roles in the biological processes of both viruses and hosts. This study delves into the functions of AcMNPV-miR-2, an early miRNA encoded by Autographa californica multiple nucleopolyhedrovirus (AcMNPV). AcMNPV-miR-2 targets viral early genes ac28 (lef-6), ac37 (lef-11), ac49, and ac63. Overexpression of AcMNPV-miR-2 leads to reduced production of infectious budded virions (BVs) and diminished viral DNA replication. Delayed polyhedron formation was observed through light and transmission electron microscopy, and the larval lifespan extended in oral infection assays. Moreover, the mRNA expression levels of two Lepidoptera-specific immune-related proteins, Gloverin and Spod-11-tox, significantly decreased. These findings indicate that AcMNPV-miR-2 restrains viral load, reducing host immune sensitivity. This beneficial effect enables the virus to combat host defense mechanisms and reside within the host for an extended duration. IMPORTANCE Virus-encoded miRNAs have been extensively studied for their pivotal roles in finetuning viral infections. Baculoviruses, highly pathogenic in insects, remain underexplored concerning their encoded miRNAs. Previous reports outlined three AcMNPV-encoded miRNAs, AcMNPV-miR-1, -miR-3, and -miR-4. This study delves into the functions of another AcMNPV-encoded miRNA, AcMNPV-miR-2 (Ac-miR-2). Through a comprehensive analysis of target gene expression, the impact on larvae, and variations in host immune-related gene expression, we elucidate a functional pathway for Ac-miR-2. This miRNA suppresses viral load and infectivity and prolongs lifespans of infected larva by downregulating specific viral early genes and host immune-related genes. These mechanisms ultimately serve the virus's primary goal of enhanced propagation. Our study significantly contributes to understanding of the intricate regulatory mechanisms of virus-encoded miRNAs in baculovirus infections.
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Affiliation(s)
- Xinghua Yu
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Tingkai Teng
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Zhuowen Duan
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Jinwen Wang
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
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2
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Kehlenbach RH, Neumann P, Ficner R, Dickmanns A. Interaction of nucleoporins with nuclear transport receptors: a structural perspective. Biol Chem 2023; 404:791-805. [PMID: 37210735 DOI: 10.1515/hsz-2023-0155] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 05/04/2023] [Indexed: 05/23/2023]
Abstract
Soluble nuclear transport receptors and stationary nucleoporins are at the heart of the nucleocytoplasmic transport machinery. A subset of nucleoporins contains characteristic and repetitive FG (phenylalanine-glycine) motifs, which are the basis for the permeability barrier of the nuclear pore complex (NPC) that controls transport of macromolecules between the nucleus and the cytoplasm. FG-motifs can interact with each other and/or with transport receptors, mediating their translocation across the NPC. The molecular details of homotypic and heterotypic FG-interactions have been analyzed at the structural level. In this review, we focus on the interactions of nucleoporins with nuclear transport receptors. Besides the conventional FG-motifs as interaction spots, a thorough structural analysis led us to identify additional similar motifs at the binding interface between nucleoporins and transport receptors. A detailed analysis of all known human nucleoporins revealed a large number of such phenylalanine-containing motifs that are not buried in the predicted 3D-structure of the respective protein but constitute part of the solvent-accessible surface area. Only nucleoporins that are rich in conventional FG-repeats are also enriched for these motifs. This additional layer of potential low-affinity binding sites on nucleoporins for transport receptors may have a strong impact on the interaction of transport complexes with the nuclear pore and, thus, the efficiency of nucleocytoplasmic transport.
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Affiliation(s)
- Ralph H Kehlenbach
- Department of Molecular Biology, Faculty of Medicine, GZMB, Georg-August-University Göttingen, Humboldtallee 23, D-37073 Göttingen, Germany
| | - Piotr Neumann
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, GZMB, Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, D-37077 Göttingen, Germany
| | - Ralf Ficner
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, GZMB, Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, D-37077 Göttingen, Germany
| | - Achim Dickmanns
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, GZMB, Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, D-37077 Göttingen, Germany
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3
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Zhang B, Zhang Z, Yong S, Yu S, Feng H, Yin M, Ye W, Wang Y, Qiu M. An Oomycete-Specific Leucine-Rich Repeat-Containing Protein Is Involved in Zoospore Flagellum Development in Phytophthora sojae. PHYTOPATHOLOGY 2022; 112:2351-2359. [PMID: 35694885 DOI: 10.1094/phyto-12-21-0523-r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
A leucine-rich repeat (LRR) is a widespread structural motif of 20 to 30 amino acids with characteristic repetitive sequences rich in leucine. LRR-containing proteins are critical for ligand recognition and binding, participating in plant development and defense. Like plants, oomycetes also harbor genes encoding LRR-containing proteins, but their functions remain largely unknown. We identified a zoospore-upregulated gene from Phytophthora sojae with LRRs and an extra structural maintenance of chromosomes-like domain. We generated knockout and complemented knockout strains of this LRR protein and found that its deletion resulted in a pronounced reduction in zoospore mobility and chemotaxis, cyst germination, and virulence. Interestingly, micro-examination of zoospores under a scanning electron microscope revealed irregularly shaped zoospores without flagella in these deletion mutants. In addition, the reintroduction of this LRR protein into the knockout mutant reversed all the deficiencies. Our data demonstrate a critical role for the Phytophthora LRR protein in modulating zoospore development, which impairs migration to the host soybean and affects the spread of Phytophthora pathogens.
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Affiliation(s)
- Baiyu Zhang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
- Key Laboratory of Soybean Disease and Pest Control (Ministry of Agriculture and Rural Affairs), Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Zhichao Zhang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
- Key Laboratory of Soybean Disease and Pest Control (Ministry of Agriculture and Rural Affairs), Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Saijiang Yong
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
- Key Laboratory of Soybean Disease and Pest Control (Ministry of Agriculture and Rural Affairs), Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Shuyang Yu
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
- Key Laboratory of Soybean Disease and Pest Control (Ministry of Agriculture and Rural Affairs), Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Hui Feng
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
- Key Laboratory of Soybean Disease and Pest Control (Ministry of Agriculture and Rural Affairs), Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Maozhu Yin
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
- Key Laboratory of Soybean Disease and Pest Control (Ministry of Agriculture and Rural Affairs), Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Wenwu Ye
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
- Key Laboratory of Soybean Disease and Pest Control (Ministry of Agriculture and Rural Affairs), Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Yuanchao Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
- Key Laboratory of Soybean Disease and Pest Control (Ministry of Agriculture and Rural Affairs), Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Min Qiu
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
- Key Laboratory of Soybean Disease and Pest Control (Ministry of Agriculture and Rural Affairs), Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
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Sending the message: specialized RNA export mechanisms in trypanosomes. Trends Parasitol 2022; 38:854-867. [PMID: 36028415 PMCID: PMC9894534 DOI: 10.1016/j.pt.2022.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 07/25/2022] [Accepted: 07/25/2022] [Indexed: 02/04/2023]
Abstract
Export of RNA from the nucleus is essential for all eukaryotic cells and has emerged as a major step in the control of gene expression. mRNA molecules are required to complete a complex series of processing events and pass a quality control system to protect the cytoplasm from the translation of aberrant proteins. Many of these events are highly conserved across eukaryotes, reflecting their ancient origin, but significant deviation from a canonical pathway as described from animals and fungi has emerged in the trypanosomatids. With significant implications for the mechanisms that control gene expression and hence differentiation, responses to altered environments and fitness as a parasite, these deviations may also reveal additional, previously unsuspected, mRNA export pathways.
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5
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Dual contribution of the mTOR pathway and of the metabolism of amino acids in prostate cancer. Cell Oncol (Dordr) 2022; 45:831-859. [PMID: 36036882 DOI: 10.1007/s13402-022-00706-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2022] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Prostate cancer is the leading cause of cancer in men, and its incidence increases with age. Among other risk factors, pre-existing metabolic diseases have been recently linked with prostate cancer, and our current knowledge recognizes prostate cancer as a condition with important metabolic anomalies as well. In malignancies, metabolic disorders are commonly associated with aberrations in mTOR, which is the master regulator of protein synthesis and energetic homeostasis. Although there are reports demonstrating the high dependency of prostate cancer cells for lipid derivatives and even for carbohydrates, the understanding regarding amino acids, and the relationship with the mTOR pathway ultimately resulting in metabolic aberrations, is still scarce. CONCLUSIONS AND PERSPECTIVES In this review, we briefly provide evidence supporting prostate cancer as a metabolic disease, and discuss what is known about mTOR signaling and prostate cancer. Next, we emphasized on the amino acids glutamine, leucine, serine, glycine, sarcosine, proline and arginine, commonly related to prostate cancer, to explore the alterations in their regulatory pathways and to link them with the associated metabolic reprogramming events seen in prostate cancer. Finally, we display potential therapeutic strategies for targeting mTOR and the referred amino acids, as experimental approaches to selectively attack prostate cancer cells.
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6
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Wang DO. Epitranscriptomic regulation of cognitive development and decline. Semin Cell Dev Biol 2021; 129:3-13. [PMID: 34857470 DOI: 10.1016/j.semcdb.2021.11.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 11/16/2021] [Accepted: 11/19/2021] [Indexed: 11/24/2022]
Abstract
Functional genomics and systems biology have opened new doors to previously inaccessible genomic information and holistic approaches to study complex networks of genes and proteins in the central nervous system. The advances are revolutionizing our understanding of the genetic underpinning of cognitive development and decline by facilitating identifications of novel molecular regulators and physiological pathways underlying brain function, and by associating polymorphism and mutations to cognitive dysfunction and neurological diseases. However, our current understanding of these complex gene regulatory mechanisms has yet lacked sufficient mechanistic resolution for further translational breakthroughs. Here we review recent findings from the burgeoning field of epitranscriptomics in association of cognitive functions with a special focus on the epitranscritomic regulation in subcellular locations such as chromosome, synapse, and mitochondria. Although there are important gaps in knowledge, current evidence is suggesting that this layer of RNA regulation may be of particular interest for the spatiotemporally coordinated regulation of gene networks in developing and maintaining brain function that underlie cognitive changes.
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Affiliation(s)
- Dan Ohtan Wang
- Center for Biosystems Dynamics Research, RIKEN, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan; Graduate School of Biostudies, Kyoto University, Yoshida Hon-machi, Kyoto 606-8501, Japan.
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7
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De Magistris P. The Great Escape: mRNA Export through the Nuclear Pore Complex. Int J Mol Sci 2021; 22:ijms222111767. [PMID: 34769195 PMCID: PMC8583845 DOI: 10.3390/ijms222111767] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 10/18/2021] [Accepted: 10/21/2021] [Indexed: 12/30/2022] Open
Abstract
Nuclear export of messenger RNA (mRNA) through the nuclear pore complex (NPC) is an indispensable step to ensure protein translation in the cytoplasm of eukaryotic cells. mRNA is not translocated on its own, but it forms ribonuclear particles (mRNPs) in association with proteins that are crucial for its metabolism, some of which; like Mex67/MTR2-NXF1/NXT1; are key players for its translocation to the cytoplasm. In this review, I will summarize our current body of knowledge on the basic characteristics of mRNA export through the NPC. To be granted passage, the mRNP cargo needs to bind transport receptors, which facilitate the nuclear export. During NPC transport, mRNPs undergo compositional and conformational changes. The interactions between mRNP and the central channel of NPC are described; together with the multiple quality control steps that mRNPs undergo at the different rings of the NPC to ensure only proper export of mature transcripts to the cytoplasm. I conclude by mentioning new opportunities that arise from bottom up approaches for a mechanistic understanding of nuclear export.
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8
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Derrer CP, Mancini R, Vallotton P, Huet S, Weis K, Dultz E. The RNA export factor Mex67 functions as a mobile nucleoporin. J Cell Biol 2019; 218:3967-3976. [PMID: 31753862 PMCID: PMC6891080 DOI: 10.1083/jcb.201909028] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 11/01/2019] [Accepted: 11/04/2019] [Indexed: 01/09/2023] Open
Abstract
Derrer et al. show that the mRNA export factor Mex67 can perform its essential function when stably tethered to the nuclear pore complex. The RNA export factor Mex67 is essential for the transport of mRNA through the nuclear pore complex (NPC) in yeast, but the molecular mechanism of this export process remains poorly understood. Here, we use quantitative fluorescence microscopy techniques in live budding yeast cells to investigate how Mex67 facilitates mRNA export. We show that Mex67 exhibits little interaction with mRNA in the nucleus and localizes to the NPC independently of mRNA, occupying a set of binding sites offered by FG repeats in the NPC. The ATPase Dbp5, which is thought to remove Mex67 from transcripts, does not affect the interaction of Mex67 with the NPC. Strikingly, we find that the essential function of Mex67 is spatially restricted to the NPC since a fusion of Mex67 to the nucleoporin Nup116 rescues a deletion of MEX67. Thus, Mex67 functions as a mobile NPC component, which receives mRNA export substrates in the central channel of the NPC to facilitate their translocation to the cytoplasm.
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Affiliation(s)
| | | | | | - Sébastien Huet
- Université de Rennes, Centre National de la Recherche Scientifique, Institut de génétique et développement de Rennes - UMR 6290, Rennes, France
| | - Karsten Weis
- Institute of Biochemistry, ETH Zürich, Zurich, Switzerland
| | - Elisa Dultz
- Institute of Biochemistry, ETH Zürich, Zurich, Switzerland
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9
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Batki J, Schnabl J, Wang J, Handler D, Andreev VI, Stieger CE, Novatchkova M, Lampersberger L, Kauneckaite K, Xie W, Mechtler K, Patel DJ, Brennecke J. The nascent RNA binding complex SFiNX licenses piRNA-guided heterochromatin formation. Nat Struct Mol Biol 2019; 26:720-731. [PMID: 31384064 PMCID: PMC6828549 DOI: 10.1038/s41594-019-0270-6] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 06/17/2019] [Indexed: 12/21/2022]
Abstract
The PIWI-interacting RNA (piRNA) pathway protects genome integrity in part through establishing repressive heterochromatin at transposon loci. Silencing requires piRNA-guided targeting of nuclear PIWI proteins to nascent transposon transcripts, yet the subsequent molecular events are not understood. Here, we identify SFiNX (silencing factor interacting nuclear export variant), an interdependent protein complex required for Piwi-mediated cotranscriptional silencing in Drosophila. SFiNX consists of Nxf2-Nxt1, a gonad-specific variant of the heterodimeric messenger RNA export receptor Nxf1-Nxt1 and the Piwi-associated protein Panoramix. SFiNX mutant flies are sterile and exhibit transposon derepression because piRNA-loaded Piwi is unable to establish heterochromatin. Within SFiNX, Panoramix recruits heterochromatin effectors, while the RNA binding protein Nxf2 licenses cotranscriptional silencing. Our data reveal how Nxf2 might have evolved from an RNA transport receptor into a cotranscriptional silencing factor. Thus, NXF variants, which are abundant in metazoans, can have diverse molecular functions and might have been coopted for host genome defense more broadly.
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Affiliation(s)
- Julia Batki
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter, Vienna, Austria
| | - Jakob Schnabl
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter, Vienna, Austria
| | - Juncheng Wang
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Dominik Handler
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter, Vienna, Austria
| | - Veselin I Andreev
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter, Vienna, Austria
| | - Christian E Stieger
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter, Vienna, Austria
- Institute of Molecular Pathology (IMP), Vienna BioCenter, Vienna, Austria
| | - Maria Novatchkova
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter, Vienna, Austria
- Institute of Molecular Pathology (IMP), Vienna BioCenter, Vienna, Austria
| | - Lisa Lampersberger
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter, Vienna, Austria
| | - Kotryna Kauneckaite
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter, Vienna, Austria
| | - Wei Xie
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Karl Mechtler
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter, Vienna, Austria
- Institute of Molecular Pathology (IMP), Vienna BioCenter, Vienna, Austria
| | - Dinshaw J Patel
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Julius Brennecke
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter, Vienna, Austria.
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10
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Williams RJ, Karpuzoglu E, Connell H, Hurley DJ, Holladay SD, Gogal RM. Lead alters intracellular protein signaling and suppresses pro-inflammatory activation in TLR4 and IFNR-stimulated murine RAW 264.7 cells, in vitro. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2019; 82:279-298. [PMID: 30890031 DOI: 10.1080/15287394.2019.1591315] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Lead (Pb) is a persistent environmental pollutant that has a structure and charge similar to many ions, such as calcium, that are essential for normal cellular function. Pb may compete with calcium for protein binding sites and inhibit signaling pathways within the cell affecting many organ systems including the immune system. The aim of the current study was to assess whether the calcium/calmodulin pathway is a principal target of environmentally relevant Pb during pro-inflammatory activation in a RAW 264.7 macrophage cell line. RAW 264.7 cells were cultured with 5 μM Pb(NO3)2, LPS, rIFNγ, or LPS+rIFNγ for 12, 24, or 48 hr. Intracellular protein signaling and multiple functional endpoints were investigated to determine Pb-mediated effects on macrophage function. Western blot analysis revealed that Pb initially modulated nuclear localization of NFκB p65 and cytoplasmic phosphorylation of CaMKIV accompanied by increased phosphorylation of STAT1β at 24 hr. Macrophage proliferation was significantly decreased at 12 hr in the presence of Pb, while nitric oxide (NO) was significantly reduced at 12 and 24 hr. Cells cultured with Pb for 12, 24, or 48 hr exhibited altered cytokine levels after specific stimuli activation. Our findings are in agreement with previous reports suggesting that macrophage pro-inflammatory responses are significantly modulated by Pb. Further, Pb-induced phosphorylation of CaMKIV (pCaMKIV), observed in the present study, may be a contributing factor in metal-induced autophagy noted in our previous study with this same cell line.
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Affiliation(s)
- R J Williams
- a Department of Veterinary Biosciences & Diagnostic Imaging, College of Veterinary Medicine , University of Georgia , Athens , GA , USA
| | - E Karpuzoglu
- a Department of Veterinary Biosciences & Diagnostic Imaging, College of Veterinary Medicine , University of Georgia , Athens , GA , USA
| | - H Connell
- b Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, Pharmacy South , University of Georgia , Athens , GA , USA
| | - D J Hurley
- c Department of Population Health, College of Veterinary Medicine , University of Georgia , Athens , GA , USA
| | - S D Holladay
- a Department of Veterinary Biosciences & Diagnostic Imaging, College of Veterinary Medicine , University of Georgia , Athens , GA , USA
| | - R M Gogal
- a Department of Veterinary Biosciences & Diagnostic Imaging, College of Veterinary Medicine , University of Georgia , Athens , GA , USA
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11
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Lesbirel S, Wilson SA. The m 6A‑methylase complex and mRNA export. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2019; 1862:319-328. [PMID: 30290229 PMCID: PMC6414750 DOI: 10.1016/j.bbagrm.2018.09.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 09/26/2018] [Accepted: 09/28/2018] [Indexed: 11/21/2022]
Abstract
During synthesis, mRNA undergoes a number of modifications such as capping, splicing and polyadenylation. These processes are coupled with the orderly deposition of the TREX complex on the mRNA and subsequent recruitment of the NXF1-P15 heterodimer which stimulates the nuclear export of mature mRNAs. mRNAs also undergo a number of internal modifications, the most common of which is the N6‑methyladenosine (m6A) modification. In this review we discuss the recent evidence of coupling between the m6A modification, RNA processing and export.
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Affiliation(s)
- Simon Lesbirel
- Sheffield Institute For Nucleic Acids (SInFoNiA), Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court Western Bank, Sheffield S10 2TN, UK
| | - Stuart A Wilson
- Sheffield Institute For Nucleic Acids (SInFoNiA), Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court Western Bank, Sheffield S10 2TN, UK.
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12
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Abstract
TRanscription and EXport (TREX) is a conserved multisubunit complex essential for embryogenesis, organogenesis and cellular differentiation throughout life. By linking transcription, mRNA processing and export together, it exerts a physiologically vital role in the gene expression pathway. In addition, this complex prevents DNA damage and regulates the cell cycle by ensuring optimal gene expression. As the extent of TREX activity in viral infections, amyotrophic lateral sclerosis and cancer emerges, the need for a greater understanding of TREX function becomes evident. A complete elucidation of the composition, function and interactions of the complex will provide the framework for understanding the molecular basis for a variety of diseases. This review details the known composition of TREX, how it is regulated and its cellular functions with an emphasis on mammalian systems.
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13
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Huang HC, Lee CP, Liu HK, Chang MF, Lai YH, Lee YC, Huang C. Cellular Nuclear Export Factors TAP and Aly Are Required for HDAg-L-mediated Assembly of Hepatitis Delta Virus. J Biol Chem 2016; 291:26226-26238. [PMID: 27807029 DOI: 10.1074/jbc.m116.754853] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 11/01/2016] [Indexed: 12/18/2022] Open
Abstract
Hepatitis delta virus (HDV) is a satellite virus of hepatitis B virus (HBV). HDV genome encodes two forms of hepatitis delta antigen (HDAg), small HDAg (HDAg-S), which is required for viral replication, and large HDAg (HDAg-L), which is essential for viral assembly. HDAg-L is identical to HDAg-S except that it bears a 19-amino acid extension at the C terminus. Both HDAgs contain a nuclear localization signal (NLS), but only HDAg-L contains a CRM1-independent nuclear export signal at its C terminus. The nuclear export activity of HDAg-L is important for HDV particle formation. However, the mechanisms of HDAg-L-mediated nuclear export of HDV ribonucleoprotein are not clear. In this study, the host cellular RNA export complex TAP-Aly was found to form a complex with HDAg-L, but not with an export-defective HDAg-L mutant, in which Pro205 was replaced by Ala. HDAg-L was found to colocalize with TAP and Aly in the nucleus. The C-terminal domain of HDAg-L was shown to directly interact with the N terminus of TAP, whereas an HDAg-L mutant lacking the NLS failed to interact with full-length TAP. In addition, small hairpin RNA-mediated down-regulation of TAP or Aly reduced nuclear export of HDAg-L and assembly of HDV virions. Furthermore, a peptide, TAT-HDAg-L(198-210), containing the 10-amino acid TAT peptide and HDAg-L(198-210), inhibited the interaction between HDAg-L and TAP and blocked HDV virion assembly and secretion. These data demonstrate that formation and release of HDV particles are mediated by TAP and Aly.
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Affiliation(s)
- Hsiu-Chen Huang
- From the Department of Applied Science, National Hsinchu University of Education, Hsinchu 30014
| | - Chung-Pei Lee
- the School of Nursing, National Taipei University of Nursing and Health Sciences, Taipei 11219
| | - Hui-Kang Liu
- the National Research Institute of Chinese Medicine, Ministry of Health and Welfare, Taipei 11221.,the Ph.D Program for Clinical Drug Discovery from Botanical Herbs, Taipei Medical University, Taipei 11031
| | - Ming-Fu Chang
- the Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Taipei 10051
| | - Yu-Heng Lai
- the Department of Chemistry, Chinese Culture University, Taipei 11114
| | - Yu-Ching Lee
- the Center of Translational Medicine, Taipei Medical University, Taipei 11031.,the Ph.D. Program for Medical Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei 11031, and
| | - Cheng Huang
- the National Research Institute of Chinese Medicine, Ministry of Health and Welfare, Taipei 11221, .,the Department of Earth and Life Sciences, University of Taipei, Taipei 10048, Taiwan
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14
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Testis-specific products of the Drosophila melanogaster sbr gene, encoding nuclear export factor 1, are necessary for male fertility. Gene 2015; 577:153-60. [PMID: 26621383 DOI: 10.1016/j.gene.2015.11.030] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 11/18/2015] [Accepted: 11/21/2015] [Indexed: 01/08/2023]
Abstract
The evolutionarily conserved nuclear export factor 1 (NXF1) provides mRNA export from the nucleus to the cytoplasm. We described several testis-specific transcripts of the Drosophila melanogaster nxf1 gene designated “sbr” in this species via different PCR approaches and CAGE-seq analysis. Characteristically, most of them have truncated 3′UTRs compared with those in other organs. In addition to regular transcripts, there are shorter transcripts that begin in intron 3 of the sbr gene. These short, 5′-truncated testis-specific transcripts vary in terms of transcription start site and their ability to exclude or retain the last 237 nucleotides of intron 3 in their 5′UTR. Using an anti-SBR antibody against the C-terminal portion of this protein, we detected the major SBR protein (74 kDa) in all analyzed organs of the fly as well as a new smaller protein (60 kDa) found only in the testes. This protein corresponds to the detected sbr transcripts that start in intron 3, based on its molecular mass. We investigated the sbr12 allele of the sbr gene, which is lethal in homozygous females and causes dominant sterility in heterozygous males. Sequencing of the sbr12 gene allele revealed a 30-bp deletion in exon 9 without a frame shift.Western blot analysiswith an SBR-specific antibody revealed two bands of the expected size in the testes of heterozygous males. Thus, a mutant protein along with the normal protein presents in the testes of lethal allele-bearing flies and the described shorter testis-specific variant of SBR may account for male sterility.
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15
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Delaleau M, Borden KLB. Multiple Export Mechanisms for mRNAs. Cells 2015; 4:452-73. [PMID: 26343730 PMCID: PMC4588045 DOI: 10.3390/cells4030452] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 08/20/2015] [Accepted: 08/21/2015] [Indexed: 12/20/2022] Open
Abstract
Nuclear mRNA export plays an important role in gene expression. We describe the mechanisms of mRNA export including the importance of mRNP assembly, docking with the nuclear basket of the nuclear pore complex (NPC), transit through the central channel of the NPC and cytoplasmic release. We describe multiple mechanisms of mRNA export including NXF1 and CRM1 mediated pathways. Selective groups of mRNAs can be preferentially transported in order to respond to cellular stimuli. RNAs can be selected based on the presence of specific cis-acting RNA elements and binding of specific adaptor proteins. The role that dysregulation of this process plays in human disease is also discussed.
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Affiliation(s)
- Mildred Delaleau
- Department of Pathology and Cell Biology, Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, H3C 3J7, Canada.
| | - Katherine L B Borden
- Department of Pathology and Cell Biology, Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, H3C 3J7, Canada.
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16
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Dickmanns A, Kehlenbach RH, Fahrenkrog B. Nuclear Pore Complexes and Nucleocytoplasmic Transport: From Structure to Function to Disease. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 320:171-233. [PMID: 26614874 DOI: 10.1016/bs.ircmb.2015.07.010] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Nucleocytoplasmic transport is an essential cellular activity and occurs via nuclear pore complexes (NPCs) that reside in the double membrane of the nuclear envelope. Significant progress has been made during the past few years in unravelling the ultrastructural organization of NPCs and their constituents, the nucleoporins, by cryo-electron tomography and X-ray crystallography. Mass spectrometry and genomic approaches have provided deeper insight into the specific regulation and fine tuning of individual nuclear transport pathways. Recent research has also focused on the roles nucleoporins play in health and disease, some of which go beyond nucleocytoplasmic transport. Here we review emerging results aimed at understanding NPC architecture and nucleocytoplasmic transport at the atomic level, elucidating the specific function individual nucleoporins play in nuclear trafficking, and finally lighting up the contribution of nucleoporins and nuclear transport receptors in human diseases, such as cancer and certain genetic disorders.
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Affiliation(s)
- Achim Dickmanns
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Ralph H Kehlenbach
- Department of Molecular Biology, Faculty of Medicine, Georg-August-University of Göttingen, Göttingen, Germany
| | - Birthe Fahrenkrog
- Institute of Molecular Biology and Medicine, Université Libre de Bruxelles, Charleroi, Belgium
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17
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Aibara S, Valkov E, Lamers MH, Dimitrova L, Hurt E, Stewart M. Structural characterization of the principal mRNA-export factor Mex67-Mtr2 from Chaetomium thermophilum. Acta Crystallogr F Struct Biol Commun 2015; 71:876-88. [PMID: 26144233 PMCID: PMC4498709 DOI: 10.1107/s2053230x15008766] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 05/05/2015] [Indexed: 12/11/2022] Open
Abstract
Members of the Mex67-Mtr2/NXF-NXT1 family are the principal mediators of the nuclear export of mRNA. Mex67/NXF1 has a modular structure based on four domains (RRM, LRR, NTF2-like and UBA) that are thought to be present across species, although the level of sequence conservation between organisms, especially in lower eukaryotes, is low. Here, the crystal structures of these domains from the thermophilic fungus Chaetomium thermophilum are presented together with small-angle X-ray scattering (SAXS) and in vitro RNA-binding data that indicate that, not withstanding the limited sequence conservation between different NXF family members, the molecules retain similar structural and RNA-binding properties. Moreover, the resolution of crystal structures obtained with the C. thermophilum domains was often higher than that obtained previously and, when combined with solution and biochemical studies, provided insight into the structural organization, self-association and RNA-binding properties of Mex67-Mtr2 that facilitate mRNA nuclear export.
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Affiliation(s)
- Shintaro Aibara
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, England
| | - Eugene Valkov
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, England
| | - Meindert H. Lamers
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, England
| | - Lyudmila Dimitrova
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Ed Hurt
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Murray Stewart
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, England
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18
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Structural Characterization of the Chaetomium thermophilum TREX-2 Complex and its Interaction with the mRNA Nuclear Export Factor Mex67:Mtr2. Structure 2015; 23:1246-57. [PMID: 26051714 PMCID: PMC4509546 DOI: 10.1016/j.str.2015.05.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 04/09/2015] [Accepted: 05/05/2015] [Indexed: 01/17/2023]
Abstract
The TREX-2 complex integrates mRNA nuclear export into the gene expression pathway and is based on a Sac3 scaffold to which Thp1, Sem1, Sus1, and Cdc31 bind. TREX-2 also binds the mRNA nuclear export factor, Mex67:Mtr2, through the Sac3 N-terminal region (Sac3N). Here, we characterize Chaetomium thermophilum TREX-2, show that the in vitro reconstituted complex has an annular structure, and define the structural basis for interactions between Sac3, Sus1, Cdc31, and Mex67:Mtr2. Crystal structures show that the binding of C. thermophilum Sac3N to the Mex67 NTF2-like domain (Mex67NTF2L) is mediated primarily through phenylalanine residues present in a series of repeating sequence motifs that resemble those seen in many nucleoporins, and Mlp1 also binds Mex67:Mtr2 using a similar motif. Deletion of Sac3N generated growth and mRNA export defects in Saccharomyces cerevisiae, and we propose TREX-2 and Mlp1 function to facilitate export by concentrating mature messenger ribonucleoparticles at the nuclear pore entrance. Chaetomium thermophilum TREX-2 has an annular structure resembling the letter Q Structure of interfaces between TREX-2 components Sac3, Sus1, and Cdc31 defined Sac3N phenylalanines dominate C. thermophilum TREX-2 binding to Mex67 NTF2L domain TREX-2 facilitates mRNA export by concentrating mature mRNPs at nuclear pores
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19
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Nuclear export of messenger RNA. Genes (Basel) 2015; 6:163-84. [PMID: 25836925 PMCID: PMC4488659 DOI: 10.3390/genes6020163] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 03/23/2015] [Accepted: 03/24/2015] [Indexed: 11/29/2022] Open
Abstract
Transport of messenger RNA (mRNA) from the nucleus to the cytoplasm is an essential step of eukaryotic gene expression. In the cell nucleus, a precursor mRNA undergoes a series of processing steps, including capping at the 5' ends, splicing and cleavage/polyadenylation at the 3' ends. During this process, the mRNA associates with a wide variety of proteins, forming a messenger ribonucleoprotein (mRNP) particle. Association with factors involved in nuclear export also occurs during transcription and processing, and thus nuclear export is fully integrated into mRNA maturation. The coupling between mRNA maturation and nuclear export is an important mechanism for providing only fully functional and competent mRNA to the cytoplasmic translational machinery, thereby ensuring accuracy and swiftness of gene expression. This review describes the molecular mechanism of nuclear mRNA export mediated by the principal transport factors, including Tap-p15 and the TREX complex.
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20
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RNA Export through the NPC in Eukaryotes. Genes (Basel) 2015; 6:124-49. [PMID: 25802992 PMCID: PMC4377836 DOI: 10.3390/genes6010124] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 02/27/2015] [Accepted: 03/10/2015] [Indexed: 02/08/2023] Open
Abstract
In eukaryotic cells, RNAs are transcribed in the nucleus and exported to the cytoplasm through the nuclear pore complex. The RNA molecules that are exported from the nucleus into the cytoplasm include messenger RNAs (mRNAs), ribosomal RNAs (rRNAs), transfer RNAs (tRNAs), small nuclear RNAs (snRNAs), micro RNAs (miRNAs), and viral mRNAs. Each RNA is transported by a specific nuclear export receptor. It is believed that most of the mRNAs are exported by Nxf1 (Mex67 in yeast), whereas rRNAs, snRNAs, and a certain subset of mRNAs are exported in a Crm1/Xpo1-dependent manner. tRNAs and miRNAs are exported by Xpot and Xpo5. However, multiple export receptors are involved in the export of some RNAs, such as 60S ribosomal subunit. In addition to these export receptors, some adapter proteins are required to export RNAs. The RNA export system of eukaryotic cells is also used by several types of RNA virus that depend on the machineries of the host cell in the nucleus for replication of their genome, therefore this review describes the RNA export system of two representative viruses. We also discuss the NPC anchoring-dependent mRNA export factors that directly recruit specific genes to the NPC.
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21
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Aibara S, Katahira J, Valkov E, Stewart M. The principal mRNA nuclear export factor NXF1:NXT1 forms a symmetric binding platform that facilitates export of retroviral CTE-RNA. Nucleic Acids Res 2015; 43:1883-93. [PMID: 25628361 PMCID: PMC4330390 DOI: 10.1093/nar/gkv032] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The NXF1:NXT1 complex (also known as TAP:p15) is a general mRNA nuclear export factor that is conserved from yeast to humans. NXF1 is a modular protein constructed from four domains (RRM, LRR, NTF2-like and UBA domains). It is currently unclear how NXF1:NXT1 binds transcripts and whether there is higher organization of the NXF1 domains. We report here the 3.4 Å resolution crystal structure of the first three domains of human NXF1 together with NXT1 that has two copies of the complex in the asymmetric unit arranged to form an intimate domain-swapped dimer. In this dimer, the linkers between the NXF1 LRR and NTF2-like domains interact with NXT1, generating a 2-fold symmetric platform in which the RNA-binding RRM, LRR and NTF2-like domains are arranged on one face. In addition to bulk transcripts, NXF1:NXT1 also facilitates the export of unspliced retroviral genomic RNA from simple type-D retroviruses such as SRV-1 that contain a constitutive transport element (CTE), a cis-acting 2-fold symmetric RNA stem–loop motif. Complementary structural, biochemical and cellular techniques indicated that the formation of a symmetric RNA binding platform generated by dimerization of NXF1:NXT1 facilitates the recognition of CTE-RNA and promotes its nuclear export.
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Affiliation(s)
- Shintaro Aibara
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Jun Katahira
- Biomolecular Networks Laboratories, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadoka, Suita, Osaka 565-0871, Japan Department of Biochemistry, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka Suita, Osaka 565-0871, Japan
| | - Eugene Valkov
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Murray Stewart
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
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22
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Katahira J, Dimitrova L, Imai Y, Hurt E. NTF2-like domain of Tap plays a critical role in cargo mRNA recognition and export. Nucleic Acids Res 2015; 43:1894-904. [PMID: 25628355 PMCID: PMC4330393 DOI: 10.1093/nar/gkv039] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Metazoan Tap-p15 (also called Nxf1-Nxt1) and yeast Mex67-Mtr2 heterodimers are the general mRNA export receptors. The RNA binding activity of Tap-p15, which is essential for mRNA nuclear export, has been attributed to the amino-terminal RNA binding module of Tap consists of RNA recognition motif (RRM) and leucine-rich repeat. In this study, we identified a novel RNA interaction surface in the NTF2-like (NTF2L) domain of Tap, which is analogous to the rRNA binding platform of Mex67-Mtr2. Tap-p15 uses the three domains to tightly bind the retroviral constitutive transport element. The RNA binding through the NTF2L domain is functionally relevant as introduction of mutations in this region reduced CTE-containing mRNA export activity. In contrast, only when the RRM and NTF2L domains were mutated simultaneously, bulk poly (A)(+) RNA export and in vivo poly (A)(+) RNA binding activities of Tap-p15 were significantly attenuated. Moreover, an engineered human cell line harboring the NTF2L domain mutation in the NXF1 gene showed a synthetic growth phenotype and severe mRNA export defect under Aly/REF and Thoc5 depleted condition. These data suggest that Tap-p15 recognizes bulk mRNAs through combinatorial use of the distinct RNA binding domains.
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Affiliation(s)
- Jun Katahira
- Biomolecular Networks Laboratories, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan Department of Biochemistry, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Lyudmila Dimitrova
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, Heidelberg D-69120, Germany
| | - Yumiko Imai
- Department of Biological Informatics and Experimental Therapeutics, Graduate School of Medicine, Akita University, Akita 010-8543, Japan
| | - Ed Hurt
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, Heidelberg D-69120, Germany
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23
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Aibara S, Valkov E, Lamers M, Stewart M. Domain organization within the nuclear export factor Mex67:Mtr2 generates an extended mRNA binding surface. Nucleic Acids Res 2015; 43:1927-36. [PMID: 25618852 PMCID: PMC4330389 DOI: 10.1093/nar/gkv030] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The Mex67:Mtr2 complex is the principal yeast nuclear export factor for bulk mRNA and also contributes to ribosomal subunit export. Mex67 is a modular protein constructed from four domains (RRM, LRR, NTF2-like and UBA) that have been thought to be joined by flexible linkers like beads on a string, with the RRM and LRR domains binding RNAs and the NTF2-like and UBA domains binding FG-nucleoporins to facilitate movement through nuclear pores. Here, we show that the NTF2-like domain from Saccharomyces cerevisiae Mex67:Mtr2 also contributes to RNA binding. Moreover, the 3.3 Å resolution crystal structure of the Mex67ΔUBA:Mtr2 complex, supplemented with small angle X-ray scattering data, indicated that the LRR domain has a defined spatial relationship to the Mex67NTF2L:Mtr2 region. Conversely, the RRM domain and especially the UBA domain are more mobile. The conformation assumed by the LRR and NTF2-like domains results in clusters of positively-charged residues on each becoming arranged to form a continuous interface for binding RNA on the opposite side of the complex to the region that interacts with FG-nucleoporins to facilitate passage through nuclear pores.
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Affiliation(s)
- Shintaro Aibara
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Eugene Valkov
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Meindert Lamers
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Murray Stewart
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
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24
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Role of omega-3 PUFA-derived mediators, the protectins, in influenza virus infection. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:496-502. [PMID: 25617737 DOI: 10.1016/j.bbalip.2015.01.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 01/11/2015] [Accepted: 01/12/2015] [Indexed: 12/31/2022]
Abstract
Influenza A viruses are the causative agents of seasonal and pandemic infections. Influenza strains have recently emerged that show resistance to anti-viral drugs. Moreover, therapies in critically ill patients with severe influenza are limited, with the current anti-viral drugs showing disappointing results even in the absence of obvious viral resistance. Given the high mortality associated with avian H5N1 or H7N9 infections and the risk of pandemic potentials, effective drugs are needed for the treatment of severe influenza. A virus-host interaction is a multidimensional host response, in which not only genes and protein but also metabolites are up- or down-regulated, and cellular pathways and networks implicated in the viral pathogenesis are perturbed. Thus, it seems an attractive strategy to overcome influenza by targeting host metabolites and/or metabolic pathways involved in viral pathogenesis. Using lipidomics and lipid libraries screening, potectin D1 isomer (PDX) derived from the 15-lipoxygenase product 17S-H(p)DHA and/or 17HDHA precursor, has recently been identified, which suppresses influenza virus replication by inhibiting the nuclear export of viral mRNA rather than regulating resolution of inflammation. Contribution of the protectins to control influenza virus replication and their therapeutic potentials are reviewed here. This article is part of a Special Issue entitled "Oxygenated metabolism of PUFA: analysis and biological relevance".
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25
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Murine leukemia virus uses TREX components for efficient nuclear export of unspliced viral transcripts. Viruses 2014; 6:1135-48. [PMID: 24618812 PMCID: PMC3970143 DOI: 10.3390/v6031135] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 02/21/2014] [Accepted: 02/25/2014] [Indexed: 11/17/2022] Open
Abstract
Previously we reported that nuclear export of both unspliced and spliced murine leukemia virus (MLV) transcripts depends on the nuclear export factor (NXF1) pathway. Although the mRNA export complex TREX, which contains Aly/REF, UAP56, and the THO complex, is involved in the NXF1-mediated nuclear export of cellular mRNAs, its contribution to the export of MLV mRNA transcripts remains poorly understood. Here, we studied the involvement of TREX components in the export of MLV transcripts. Depletion of UAP56, but not Aly/REF, reduced the level of both unspliced and spliced viral transcripts in the cytoplasm. Interestingly, depletion of THO components, including THOC5 and THOC7, affected only unspliced viral transcripts in the cytoplasm. Moreover, the RNA immunoprecipitation assay showed that only the unspliced viral transcript interacted with THOC5. These results imply that MLV requires UAP56, THOC5 and THOC7, in addition to NXF1, for nuclear export of viral transcripts. Given that naturally intronless mRNAs, but not bulk mRNAs, require THOC5 for nuclear export, it is plausible that THOC5 plays a key role in the export of unspliced MLV transcripts.
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26
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Kelly SE, Meisl G, Rowling PJE, McLaughlin SH, Knowles T, Itzhaki LS. Diffuse transition state structure for the unfolding of a leucine-rich repeat protein. Phys Chem Chem Phys 2014; 16:6448-59. [PMID: 24535093 DOI: 10.1039/c3cp54818j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Tandem-repeat proteins, such as leucine-rich repeats, comprise arrays of small structural motifs that pack in a linear fashion to produce elongated architectures. They lack contacts between residues that are distant in primary sequence, a feature that distinguishes them from the complex topologies of globular proteins. Here we have investigated the unfolding pathway of the leucine-rich repeat domain of the mRNA export protein TAP (TAPLRR) using Φ-value analysis. Whereas most of the tandem-repeat proteins studied to date have been found to unfold via a polarised mechanism in which only a small, localised number of repeats are structured in the transition state, the unfolding mechanism of TAPLRR is more diffuse in nature. In the transition state for unfolding of TAPLRR, three of the four LRRs are highly structured and non-native interactions are formed within the N-terminal α-helical cap and the first LRR. Thus, the α-helical cap plays an important role in which non-native interactions are required to provide a scaffold for the LRRs to pack against in the folding reaction.
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Affiliation(s)
- Sadie E Kelly
- MRC Cancer Cell Unit, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 0XZ, UK
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27
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Jeon J, Nim S, Teyra J, Datti A, Wrana JL, Sidhu SS, Moffat J, Kim PM. A systematic approach to identify novel cancer drug targets using machine learning, inhibitor design and high-throughput screening. Genome Med 2014; 6:57. [PMID: 25165489 PMCID: PMC4143549 DOI: 10.1186/s13073-014-0057-7] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 07/18/2014] [Indexed: 12/14/2022] Open
Abstract
We present an integrated approach that predicts and validates novel anti-cancer drug targets. We first built a classifier that integrates a variety of genomic and systematic datasets to prioritize drug targets specific for breast, pancreatic and ovarian cancer. We then devised strategies to inhibit these anti-cancer drug targets and selected a set of targets that are amenable to inhibition by small molecules, antibodies and synthetic peptides. We validated the predicted drug targets by showing strong anti-proliferative effects of both synthetic peptide and small molecule inhibitors against our predicted targets.
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Affiliation(s)
- Jouhyun Jeon
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1 Canada
| | - Satra Nim
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1 Canada
| | - Joan Teyra
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1 Canada
| | - Alessandro Datti
- Center for Systems Biology, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, ON M5S 3E1 Canada
- Department of Agricultural, Food and Environmental Sciences, University of Perugia, Perugia, 06100 Italy
| | - Jeffrey L Wrana
- Center for Systems Biology, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, ON M5S 3E1 Canada
| | - Sachdev S Sidhu
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1 Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 3E1 Canada
| | - Jason Moffat
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1 Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 3E1 Canada
| | - Philip M Kim
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1 Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 3E1 Canada
- Department of Computer Science, University of Toronto, Toronto, ON M5S 3E1 Canada
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28
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Zhang W, Zeng F, Liu Y, Zhao Y, Lv H, Niu L, Teng M, Li X. Crystal structures and RNA-binding properties of the RNA recognition motifs of heterogeneous nuclear ribonucleoprotein L: insights into its roles in alternative splicing regulation. J Biol Chem 2013; 288:22636-49. [PMID: 23782695 DOI: 10.1074/jbc.m113.463901] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Heterogeneous nuclear ribonucleoprotein L (hnRNP L) is an abundant RNA-binding protein implicated in many bioprocesses, including pre-mRNA processing, mRNA export of intronless genes, internal ribosomal entry site-mediated translation, and chromatin modification. It contains four RNA recognition motifs (RRMs) that bind with CA repeats or CA-rich elements. In this study, surface plasmon resonance spectroscopy assays revealed that all four RRM domains contribute to RNA binding. Furthermore, we elucidated the crystal structures of hnRNP L RRM1 and RRM34 at 2.0 and 1.8 Å, respectively. These RRMs all adopt the typical β1α1β2β3α2β4 topology, except for an unusual fifth β-strand in RRM3. RRM3 and RRM4 interact intimately with each other mainly through helical surfaces, leading the two β-sheets to face opposite directions. Structure-based mutations and surface plasmon resonance assay results suggested that the β-sheets of RRM1 and RRM34 are accessible for RNA binding. FRET-based gel shift assays (FRET-EMSA) and steady-state FRET assays, together with cross-linking and dynamic light scattering assays, demonstrated that hnRNP L RRM34 facilitates RNA looping when binding to two appropriately separated binding sites within the same target pre-mRNA. EMSA and isothermal titration calorimetry binding studies with in vivo target RNA suggested that hnRNP L-mediated RNA looping may occur in vivo. Our study provides a mechanistic explanation for the dual functions of hnRNP L in alternative splicing regulation as an activator or repressor.
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Affiliation(s)
- Wenjuan Zhang
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
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29
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Affiliation(s)
- C A Niño
- Institut Jacques Monod, Paris Diderot University , Sorbonne Paris Cité, CNRS UMR7592, Equipe labellisée Ligue contre le cancer, 15 rue Hélène Brion, 75205 Paris Cedex 13, France
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30
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Morita M, Kuba K, Ichikawa A, Nakayama M, Katahira J, Iwamoto R, Watanebe T, Sakabe S, Daidoji T, Nakamura S, Kadowaki A, Ohto T, Nakanishi H, Taguchi R, Nakaya T, Murakami M, Yoneda Y, Arai H, Kawaoka Y, Penninger JM, Arita M, Imai Y. The lipid mediator protectin D1 inhibits influenza virus replication and improves severe influenza. Cell 2013; 153:112-25. [PMID: 23477864 DOI: 10.1016/j.cell.2013.02.027] [Citation(s) in RCA: 344] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 12/08/2012] [Accepted: 02/13/2013] [Indexed: 12/23/2022]
Abstract
Influenza A viruses are a major cause of mortality. Given the potential for future lethal pandemics, effective drugs are needed for the treatment of severe influenza such as that caused by H5N1 viruses. Using mediator lipidomics and bioactive lipid screen, we report that the omega-3 polyunsaturated fatty acid (PUFA)-derived lipid mediator protectin D1 (PD1) markedly attenuated influenza virus replication via RNA export machinery. Production of PD1 was suppressed during severe influenza and PD1 levels inversely correlated with the pathogenicity of H5N1 viruses. Suppression of PD1 was genetically mapped to 12/15-lipoxygenase activity. Importantly, PD1 treatment improved the survival and pathology of severe influenza in mice, even under conditions where known antiviral drugs fail to protect from death. These results identify the endogenous lipid mediator PD1 as an innate suppressor of influenza virus replication that protects against lethal influenza virus infection.
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Affiliation(s)
- Masayuki Morita
- Department of Biological Informatics and Experimental Therapeutics, Graduate School of Medicine, Akita University, Akita 010-8543, Japan
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31
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TREX exposes the RNA-binding domain of Nxf1 to enable mRNA export. Nat Commun 2013; 3:1006. [PMID: 22893130 PMCID: PMC3654228 DOI: 10.1038/ncomms2005] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 07/11/2012] [Indexed: 12/03/2022] Open
Abstract
The metazoan TREX complex is recruited to mRNA during nuclear RNA processing and functions in exporting mRNA to the cytoplasm. Nxf1 is an mRNA export receptor, which binds processed mRNA and transports it through the nuclear pore complex. At present, the relationship between TREX and Nxf1 is not understood. Here we show that Nxf1 uses an intramolecular interaction to inhibit its own RNA binding activity. When the TREX subunits Aly and Thoc5 make contact with Nxf1, Nxf1 is driven into an open conformation, exposing its RNA binding domain, allowing RNA binding. Moreover, the combined knockdown of Aly and Thoc5 drastically reduces the amount of Nxf1 bound to mRNA in vivo and also causes a severe mRNA export block. Together, our data indicate that TREX provides a license for mRNA export by driving Nxf1 into a conformation capable of binding mRNA.
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32
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Mamon LA, Kliver SF, Golubkova EV. Evolutionarily conserved features of the retained intron in alternative transcripts of the <i>nxf1</i> (nuclear export factor) genes in different organisms. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/ojgen.2013.33018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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33
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Ihalainen TO, Willman SF, Niskanen EA, Paloheimo O, Smolander H, Laurila JP, Kaikkonen MU, Vihinen-Ranta M. Distribution and dynamics of transcription-associated proteins during parvovirus infection. J Virol 2012; 86:13779-84. [PMID: 23035221 PMCID: PMC3503060 DOI: 10.1128/jvi.01625-12] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 09/24/2012] [Indexed: 12/23/2022] Open
Abstract
Canine parvovirus (CPV) infection leads to reorganization of nuclear proteinaceous subcompartments. Our studies showed that virus infection causes a time-dependent increase in the amount of viral nonstructural protein NS1 mRNA. Fluorescence recovery after photobleaching showed that the recovery kinetics of nuclear transcription-associated proteins, TATA binding protein (TBP), transcription factor IIB (TFIIB), and poly(A) binding protein nuclear 1 (PABPN1) were different in infected and noninfected cells, pointing to virus-induced alterations in binding dynamics of these proteins.
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Affiliation(s)
- Teemu O. Ihalainen
- Nanoscience Center, Department of Biological and Environmental Science, University of Jyväskylä, Finland
- Department of Health Sciences and Technology, Laboratory for Biologically Oriented Materials, ETH Zurich, Zurich, Switzerland
| | - Sami F. Willman
- Nanoscience Center, Department of Biological and Environmental Science, University of Jyväskylä, Finland
| | - Einari A. Niskanen
- Nanoscience Center, Department of Biological and Environmental Science, University of Jyväskylä, Finland
- Department of Biochemistry, Medical Genetics Cluster, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Outi Paloheimo
- Nanoscience Center, Department of Biological and Environmental Science, University of Jyväskylä, Finland
| | - Hanna Smolander
- Nanoscience Center, Department of Biological and Environmental Science, University of Jyväskylä, Finland
- Department of Virology, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - Juha P. Laurila
- Nanoscience Center, Department of Biological and Environmental Science, University of Jyväskylä, Finland
- University of Turku, Turku, Finland
| | - Minna U. Kaikkonen
- AI Virtanen Institute, Department of Biotechnology and Molecular Medicine, University of Eastern Finland, Kuopio, Finland
| | - Maija Vihinen-Ranta
- Nanoscience Center, Department of Biological and Environmental Science, University of Jyväskylä, Finland
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34
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Abstract
Exchange of macromolecules between the nucleus and cytoplasm is a key regulatory event in the expression of a cell's genome. This exchange requires a dedicated transport system: (1) nuclear pore complexes (NPCs), embedded in the nuclear envelope and composed of proteins termed nucleoporins (or "Nups"), and (2) nuclear transport factors that recognize the cargoes to be transported and ferry them across the NPCs. This transport is regulated at multiple levels, and the NPC itself also plays a key regulatory role in gene expression by influencing nuclear architecture and acting as a point of control for various nuclear processes. Here we summarize how the yeast Saccharomyces has been used extensively as a model system to understand the fundamental and highly conserved features of this transport system, revealing the structure and function of the NPC; the NPC's role in the regulation of gene expression; and the interactions of transport factors with their cargoes, regulatory factors, and specific nucleoporins.
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35
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Mackereth CD, Sattler M. Dynamics in multi-domain protein recognition of RNA. Curr Opin Struct Biol 2012; 22:287-96. [DOI: 10.1016/j.sbi.2012.03.013] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 03/25/2012] [Indexed: 12/28/2022]
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36
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The structure of the ASAP core complex reveals the existence of a Pinin-containing PSAP complex. Nat Struct Mol Biol 2012; 19:378-86. [PMID: 22388736 DOI: 10.1038/nsmb.2242] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Accepted: 01/03/2012] [Indexed: 12/31/2022]
Abstract
The ASAP complex interacts with the exon-junction complex (EJC), a messenger ribonucleoprotein complex involved in post-transcriptional regulation. The three ASAP subunits (Acinus, RNPS1 and SAP18) have been individually implicated in transcriptional regulation, pre-mRNA splicing and mRNA quality control. To shed light on the basis for and consequences of ASAP's interaction with the EJC, we have determined the 1.9-Å resolution structure of a eukaryotic ASAP core complex. The RNA-recognition motif of RNPS1 binds to a conserved motif of Acinus with a recognition mode similar to that observed in splicing U2AF proteins. The Acinus-RNPS1 platform recruits the ubiquitin-like domain of SAP18, forming a ternary complex that has both RNA- and protein-binding properties. Unexpectedly, our structural analysis identified an Acinus-like motif in Pinin, another EJC-associated splicing factor. We show that Pinin physically interacts with RNPS1 and SAP18, forming an alternative ternary complex, PSAP.
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37
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Valkov E, Dean JC, Jani D, Kuhlmann SI, Stewart M. Structural basis for the assembly and disassembly of mRNA nuclear export complexes. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1819:578-92. [PMID: 22406340 DOI: 10.1016/j.bbagrm.2012.02.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 01/26/2012] [Accepted: 02/17/2012] [Indexed: 12/17/2022]
Abstract
Most of the individual components of the nuclear elements of the gene expression pathway have been identified and high-resolution structural information is becoming available for many of them. Information is also starting to become available on the larger complexes they form and is beginning to give clues about how the dynamics of their interactions generate function. Although the translocation of export-competent messenger ribonucleoprotein particles (mRNPs) through the nuclear pore transport channel that is mediated by interactions with nuclear pore proteins (nucleoporins) is relatively well understood, the precise molecular mechanisms underlying the assembly of export-competent mRNPs in the nucleus and their Dbp5-mediated disassembly in the cytoplasm is less well defined. Considerable information has been obtained on the structure of Dbp5 in its different nucleotide-bound states and in complex with Gle1 or Nup159/NUP214. Although the precise manner by which the Dbp5 ATPase cycle is coupled to mRNP remodelling remains to be established, current models capture many key details of this process. The formation of export-competent mRNPs in the nucleus remains an elusive component of this pathway and the precise nature of the remodelling that generates these mRNPs as well as detailed understanding of the molecular mechanisms by which this step is integrated with the transcriptional, splicing and polyadenylation machinery by the TREX and TREX-2 complexes remain obscure. This article is part of a Special Issue entitled: Nuclear Transport and RNA Processing.
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Affiliation(s)
- Eugene Valkov
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge, UK
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38
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Zhang ZC, Satterly N, Fontoura BMA, Chook YM. Evolutionary development of redundant nuclear localization signals in the mRNA export factor NXF1. Mol Biol Cell 2011; 22:4657-68. [PMID: 21965294 PMCID: PMC3226482 DOI: 10.1091/mbc.e11-03-0222] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Unexpected redundancy in the nuclear import pathways used by the essential mRNA export factor NXF1 increases progressively from fungi to nematodes and insects to chordates, potentially paralleling the increasing complexity in mRNA export regulation and the evolution of new nuclear functions for NXF1. In human cells, the mRNA export factor NXF1 resides in the nucleoplasm and at nuclear pore complexes. Karyopherin β2 or transportin recognizes a proline–tyrosine nuclear localization signal (PY-NLS) in the N-terminal tail of NXF1 and imports it into the nucleus. Here biochemical and cellular studies to understand the energetic organization of the NXF1 PY-NLS reveal unexpected redundancy in the nuclear import pathways used by NXF1. Human NXF1 can be imported via importin β, karyopherin β2, importin 4, importin 11, and importin α. Two NLS epitopes within the N-terminal tail, an N-terminal basic segment and a C-terminal R-X2-5-P-Y motif, provide the majority of binding energy for all five karyopherins. Mutation of both NLS epitopes abolishes binding to the karyopherins, mislocalized NXF1 to the cytoplasm, and significantly compromised its mRNA export function. The understanding of how different karyopherins recognize human NXF1, the examination of NXF1 sequences from divergent eukaryotes, and the interactions of NXF1 homologues with various karyopherins reveals the evolutionary development of redundant NLSs in NXF1 of higher eukaryotes. Redundancy of nuclear import pathways for NXF1 increases progressively from fungi to nematodes and insects to chordates, potentially paralleling the increasing complexity in mRNA export regulation and the evolution of new nuclear functions for NXF1.
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Affiliation(s)
- Zi Chao Zhang
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9041, USA
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39
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Teplova M, Wohlbold L, Khin NW, Izaurralde E, Patel DJ. Structure-function studies of nucleocytoplasmic transport of retroviral genomic RNA by mRNA export factor TAP. Nat Struct Mol Biol 2011; 18:990-8. [PMID: 21822283 PMCID: PMC3167930 DOI: 10.1038/nsmb.2094] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Accepted: 06/01/2011] [Indexed: 11/09/2022]
Abstract
Messenger RNA export is mediated by the TAP-p15 heterodimer, which belongs to the family of NTF2-like export receptors. TAP-p15 heterodimers also bind to the constitutive transport element (CTE) present in simian type D retroviral RNAs, and mediate export of viral unspliced RNAs to the host cytoplasm. We have solved the crystal structure of the RNA recognition and leucine-rich repeat motifs of TAP bound to one symmetrical-half of CTE RNA. L-shaped conformations of protein and RNA are involved in a mutual molecular embrace on complex formation. We have monitored the impact of structure-guided mutations on binding affinities in vitro and transport assays in vivo. Our studies define the principles by which CTE RNA subverts the mRNA export receptor TAP, thereby facilitating nuclear export of viral genomic RNAs, and more generally, provide insights on cargo RNA recognition by mRNA export receptors.
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Affiliation(s)
- Marianna Teplova
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, USA
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40
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Zhao H, Yang Y, Zhou Y. Structure-based prediction of RNA-binding domains and RNA-binding sites and application to structural genomics targets. Nucleic Acids Res 2010; 39:3017-25. [PMID: 21183467 PMCID: PMC3082898 DOI: 10.1093/nar/gkq1266] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Mechanistic understanding of many key cellular processes often involves identification of RNA binding proteins (RBPs) and RNA binding sites in two separate steps. Here, they are predicted simultaneously by structural alignment to known protein-RNA complex structures followed by binding assessment with a DFIRE-based statistical energy function. This method achieves 98% accuracy and 91% precision for predicting RBPs and 93% accuracy and 78% precision for predicting RNA-binding amino-acid residues for a large benchmark of 212 RNA binding and 6761 non-RNA binding domains (leave-one-out cross-validation). Additional tests revealed that the method makes no false positive prediction from 311 DNA binding domains but correctly detects six domains binding with both DNA and RNA. In addition, it correctly identified 31 of 75 unbound RNA-binding domains with 92% accuracy and 65% precision for predicted binding residues and achieved 86% success rate in its application to SCOP RNA binding domain superfamily (Structural Classification Of Proteins). It further predicts 25 targets as RBPs in 2076 structural genomics targets: 20 of 25 predicted ones (80%) are putatively RNA binding. The superior performance over existing methods indicates the importance of dividing structures into domains, using a Z-score to measure relative structural similarity, and a statistical energy function to measure protein-RNA binding affinity.
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Affiliation(s)
- Huiying Zhao
- School of Informatics, Indiana University Purdue University and Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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41
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Nuclear export of mRNA. Trends Biochem Sci 2010; 35:609-17. [PMID: 20719516 DOI: 10.1016/j.tibs.2010.07.001] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 07/05/2010] [Accepted: 07/07/2010] [Indexed: 01/19/2023]
Abstract
The nuclear export of mRNA, in which Mex67-Mtr2 mediates movement of mature transcripts through nuclear pores, represents the culmination of the nuclear portion of the gene expression pathway. Nuclear export is closely integrated with transcription and processing, and is based on forming a messenger ribonucleoprotein (mRNP) export complex in the nucleus that is able to diffuse back and forth through the pores. Directionality is imposed by remodelling of the mRNP in the cytoplasm, thereby removing key transport-related proteins and preventing its return to the nucleus. The nuclear and cytoplasmic steps of this pathway, in which Mex67-Mtr2 and Nab2 are added and removed, are crucial, and both involve remodelling of the mRNP, which is mediated by DEAD-box helicases together with adaptor and accessory proteins. Recent structural and cell biology results provide key information that should enable development of a detailed understanding of this central cellular process at a molecular level.
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42
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Leeper TC, Qu X, Lu C, Moore C, Varani G. Novel protein-protein contacts facilitate mRNA 3'-processing signal recognition by Rna15 and Hrp1. J Mol Biol 2010; 401:334-49. [PMID: 20600122 DOI: 10.1016/j.jmb.2010.06.032] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Revised: 06/10/2010] [Accepted: 06/10/2010] [Indexed: 12/22/2022]
Abstract
Precise 3'-end processing of mRNA is essential for correct gene expression, yet in yeast, 3'-processing signals consist of multiple ambiguous sequence elements. Two neighboring elements upstream of the cleavage site are particularly important for the accuracy (positioning element) and efficiency (efficiency element) of 3'-processing and are recognized by the RNA-binding proteins Rna15 and Hrp1, respectively. In vivo, these interactions are strengthened by the scaffolding protein Rna14 that stabilizes their association. The NMR structure of the 34 -kDa ternary complex of the RNA recognition motif (RRM) domains of Hrp1 and Rna15 bound to this pair of RNA elements was determined by residual dipolar coupling and paramagnetic relaxation experiments. It reveals how each of the proteins binds to RNA and introduces a novel class of protein-protein contact in regions of previously unknown function. These interdomain contacts had previously been overlooked in other multi-RRM structures, although a careful analysis suggests that they may be frequently present. Mutations in the regions of these contacts disrupt 3'-end processing, suggesting that they may structurally organize the ribonucleoprotein complexes responsible for RNA processing.
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Affiliation(s)
- Thomas C Leeper
- Department of Chemistry, University of Washington, Seattle, WA 98195-1700, USA.
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43
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Doolittle JM, Gomez SM. Structural similarity-based predictions of protein interactions between HIV-1 and Homo sapiens. Virol J 2010; 7:82. [PMID: 20426868 PMCID: PMC2877021 DOI: 10.1186/1743-422x-7-82] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Accepted: 04/28/2010] [Indexed: 01/05/2023] Open
Abstract
Background In the course of infection, viruses such as HIV-1 must enter a cell, travel to sites where they can hijack host machinery to transcribe their genes and translate their proteins, assemble, and then leave the cell again, all while evading the host immune system. Thus, successful infection depends on the pathogen's ability to manipulate the biological pathways and processes of the organism it infects. Interactions between HIV-encoded and human proteins provide one means by which HIV-1 can connect into cellular pathways to carry out these survival processes. Results We developed and applied a computational approach to predict interactions between HIV and human proteins based on structural similarity of 9 HIV-1 proteins to human proteins having known interactions. Using functional data from RNAi studies as a filter, we generated over 2000 interaction predictions between HIV proteins and 406 unique human proteins. Additional filtering based on Gene Ontology cellular component annotation reduced the number of predictions to 502 interactions involving 137 human proteins. We find numerous known interactions as well as novel interactions showing significant functional relevance based on supporting Gene Ontology and literature evidence. Conclusions Understanding the interplay between HIV-1 and its human host will help in understanding the viral lifecycle and the ways in which this virus is able to manipulate its host. The results shown here provide a potential set of interactions that are amenable to further experimental manipulation as well as potential targets for therapeutic intervention.
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Affiliation(s)
- Janet M Doolittle
- Department of Computer Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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44
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Colwell LJ, Brenner MP, Ribbeck K. Charge as a selection criterion for translocation through the nuclear pore complex. PLoS Comput Biol 2010; 6:e1000747. [PMID: 20421988 PMCID: PMC2858669 DOI: 10.1371/journal.pcbi.1000747] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Accepted: 03/18/2010] [Indexed: 01/17/2023] Open
Abstract
Nuclear pore complexes (NPCs) are highly selective filters that control the exchange of material between nucleus and cytoplasm. The principles that govern selective filtering by NPCs are not fully understood. Previous studies find that cellular proteins capable of fast translocation through NPCs (transport receptors) are characterized by a high proportion of hydrophobic surface regions. Our analysis finds that transport receptors and their complexes are also highly negatively charged. Moreover, NPC components that constitute the permeability barrier are positively charged. We estimate that electrostatic interactions between a transport receptor and the NPC result in an energy gain of several kBT, which would enable significantly increased translocation rates of transport receptors relative to other cellular proteins. We suggest that negative charge is an essential criterion for selective passage through the NPC. All proteins that move between the cytoplasm and the nucleus must pass through nuclear pore complexes, large aqueous channels around 40nm in diameter. In some cases the nuclear envelope is perforated with several thousand nuclear pore complexes, while in other cases they are few and far between. Macromolecular transport through nuclear pores is highly regulated; an elaborate system, involving the binding and unbinding of accessory proteins (transport receptors), allows regulation of which proteins can pass through the pores. The basic principles that govern this selective filtering are not fully understood. Some proteins pass through the pore without binding to transport receptors, while others require the binding of multiple transport receptors for efficient translocation. How does the pore select which proteins can pass through, and which cannot? This paper carries out a biophysical analysis of the properties of proteins that can translocate through the nuclear pore. We find that proteins capable of fast translocation are highly negatively charged, whereas proteins that cannot pass through the pore are positively charged. Moreover, proteins that constitute the interior of the pore channel itself are net positively charged. This suggests that electrostatic interactions between translocating proteins and the pore are an essential part of the selective filtering mechanism.
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Affiliation(s)
- Lucy J. Colwell
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States of America
| | - Michael P. Brenner
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States of America
- * E-mail: (MPB); (KR)
| | - Katharina Ribbeck
- FAS Center for Systems Biology, Harvard University, Cambridge, Massachusetts, United States of America
- * E-mail: (MPB); (KR)
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45
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Abstract
The mRNA export adaptors provide an important link between multiple nuclear mRNA processing events and the mRNA export receptor TAP/NXF1/Mex67p. They are recruited to mRNA through transcriptional and post-transcriptional events, integrating this information to licence mRNA for export. Subsequently they hand mRNA over to TAP and switch TAP to a higher-affinity RNA-binding state, ensuring its stable association with mRNA destined for export. Here we discuss the structure and function of adaptors and how they are recruited to mRNA.
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46
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Abstract
AbstractThe centrosome functions as the microtubule-organizing center and plays a vital role in organizing spindle poles during mitosis. Recently, we identified a centrosomal protein called CLERC (Centrosomal leucine-rich repeat and coiled-coil containing protein) which is a human ortholog of Chlamydomonas Vfl1 protein. The bibliography as well as database searches provided evidence that the human proteome contains at least seven centrosomal leucine-rich repeat proteins including CLERC. CLERC and four other centrosomal leucine-rich repeat proteins contain the SDS22-like leucine-rich repeat motifs, whereas the remaining two proteins contain the RI-like and the cysteine-containing leucine-rich repeat motifs. Individual leucine-rich repeat motifs are highly conserved and present in evolutionarily diverse organisms. Here, we provide an overview of CLERC and other centrosomal leucine-rich repeat proteins, their structures, their evolutionary relationships, and their functional properties.
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47
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Hindle KL, Bella J, Lovell SC. Quantitative analysis and prediction of curvature in leucine-rich repeat proteins. Proteins 2009; 77:342-58. [PMID: 19452560 DOI: 10.1002/prot.22440] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Leucine-rich repeat (LRR) proteins form a large and diverse family. They have a wide range of functions most of which involve the formation of protein-protein interactions. All known LRR structures form curved solenoids, although there is large variation in their curvature. It is this curvature that determines the shape and dimensions of the inner space available for ligand binding. Unfortunately, large-scale parameters such as the overall curvature of a protein domain are extremely difficult to predict. Here, we present a quantitative analysis of determinants of curvature of this family. Individual repeats typically range in length between 20 and 30 residues and have a variety of secondary structures on their convex side. The observed curvature of the LRR domains correlates poorly with the lengths of their individual repeats. We have, therefore, developed a scoring function based on the secondary structure of the convex side of the protein that allows prediction of the overall curvature with a high degree of accuracy. We also demonstrate the effectiveness of this method in selecting a suitable template for comparative modeling. We have developed an automated, quantitative protocol that can be used to predict accurately the curvature of leucine-rich repeat proteins of unknown structure from sequence alone. This protocol is available as an online resource at http://www.bioinf.manchester.ac.uk/curlrr/.
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Affiliation(s)
- K Lauren Hindle
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
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48
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Adaptor Aly and co-adaptor Thoc5 function in the Tap-p15-mediated nuclear export of HSP70 mRNA. EMBO J 2009; 28:556-67. [PMID: 19165146 DOI: 10.1038/emboj.2009.5] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Accepted: 01/05/2009] [Indexed: 11/08/2022] Open
Abstract
In metazoans, nuclear export of bulk mRNA is mediated by Tap-p15, a conserved heterodimeric export receptor that cooperates with adaptor RNA-binding proteins. In this article, we show that Thoc5, a subunit of the mammalian TREX complex, binds to a distinct surface on the middle (Ntf2-like) domain of Tap. Notably, adaptor protein Aly and Thoc5 can simultaneously bind to non-overlapping binding sites on Tap-p15. In vivo, Thoc5 was not required for bulk mRNA export. However, nuclear export of HSP70 mRNA depends on both Thoc5 and Aly. Consistent with a function as a specific export adaptor, Thoc5 exhibits in vitro RNA-binding activity and is associated with HSP70 mRNPs in vivo as a component of the stable THO complex. Thus, through the combinatorial use of an adaptor (e.g., Aly) and co-adapter (e.g., Thoc5), Tap-p15 could function as an export receptor for different classes of mRNAs.
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49
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Interactions of human cytomegalovirus proteins with the nuclear transport machinery. Curr Top Microbiol Immunol 2008; 325:167-85. [PMID: 18637506 DOI: 10.1007/978-3-540-77349-8_10] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Accurate cellular localization is crucial for the effective function of most viral macromolecules and nuclear translocation is central to the function of herpesviral proteins that are involved in processes such as transcription and DNA replication. The passage of large molecules between the cytoplasm and nucleus, however, is restricted, and this restriction affords specific mechanisms that control nucleocytoplasmic exchange. In this review, we focus on two cytomegalovirus-encoded proteins, pUL69 and pUL84, that are able to shuttle between the nucleus and the cytoplasm. Both viral proteins use unconventional interactions with components of the cellular transport machinery: pUL69 binds to the mRNA export factor UAP56, and this interaction is crucial for pUL69-mediated nuclear export of unspliced RNA; pUL84 docks to importin-alpha proteins via an unusually large protein domain that contains functional leucine-rich nuclear export signals, thus serving as a complex bidirectional transport domain. Selective interference with these unconventional interactions, which disturbs the intracellular trafficking of important viral regulatory proteins, may constitute a novel and attractive principle for antiviral therapy.
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Gabel F, Simon B, Nilges M, Petoukhov M, Svergun D, Sattler M. A structure refinement protocol combining NMR residual dipolar couplings and small angle scattering restraints. JOURNAL OF BIOMOLECULAR NMR 2008; 41:199-208. [PMID: 18670889 DOI: 10.1007/s10858-008-9258-y] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Accepted: 05/16/2008] [Indexed: 05/26/2023]
Abstract
We present the implementation of a target function based on Small Angle Scattering data (Gabel et al. Eur Biophys J 35(4):313-327, 2006) into the Crystallography and NMR Systems (CNS) and demonstrate its utility in NMR structure calculations by simultaneous application of small angle scattering (SAS) and residual dipolar coupling (RDC) restraints. The efficiency and stability of the approach are demonstrated by reconstructing the structure of a two domain region of the 31 kDa nuclear export factor TAP (TIP-associated protein). Starting with the high resolution X-ray structures of the two individual TAP domains, the translational and orientational domain arrangement is refined simultaneously. We tested the stability of the protocol against variations of the SAS target parameters and the number of RDCs and their uncertainties. The activation of SAS restraints results in an improved translational clustering of the domain positions and lifts part of the fourfold degeneracy of their orientations (associated with a single alignment tensor). The resulting ensemble of structures reflects the conformational space that is consistent with the experimental SAS and RDC data. The SAS target function is computationally very efficient. SAS restraints can be activated at different levels of precision and only a limited SAS angular range is required. When combined with additional data from chemical shift perturbation, paramagnetic relaxation enhancement or mutational analysis the SAS refinement is an efficient approach for defining the topology of multi-domain and/or multimeric biomolecular complexes in solution based on available high resolution structures (NMR or X-ray) of the individual domains.
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Affiliation(s)
- F Gabel
- Structural and Computational Biology Unit, EMBL, Meyerhofstrasse 1, Heidelberg, Germany
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