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Solà Colom M, Fu Z, Gunkel P, Güttler T, Trakhanov S, Srinivasan V, Gregor K, Pleiner T, Görlich D. A checkpoint function for Nup98 in nuclear pore formation suggested by novel inhibitory nanobodies. EMBO J 2024; 43:2198-2232. [PMID: 38649536 PMCID: PMC11148069 DOI: 10.1038/s44318-024-00081-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 03/11/2024] [Accepted: 03/13/2024] [Indexed: 04/25/2024] Open
Abstract
Nuclear pore complex (NPC) biogenesis is a still enigmatic example of protein self-assembly. We now introduce several cross-reacting anti-Nup nanobodies for imaging intact nuclear pore complexes from frog to human. We also report a simplified assay that directly tracks postmitotic NPC assembly with added fluorophore-labeled anti-Nup nanobodies. During interphase, NPCs are inserted into a pre-existing nuclear envelope. Monitoring this process is challenging because newly assembled NPCs are indistinguishable from pre-existing ones. We overcame this problem by inserting Xenopus-derived NPCs into human nuclear envelopes and using frog-specific anti-Nup nanobodies for detection. We further asked whether anti-Nup nanobodies could serve as NPC assembly inhibitors. Using a selection strategy against conserved epitopes, we obtained anti-Nup93, Nup98, and Nup155 nanobodies that block Nup-Nup interfaces and arrest NPC assembly. We solved structures of nanobody-target complexes and identified roles for the Nup93 α-solenoid domain in recruiting Nup358 and the Nup214·88·62 complex, as well as for Nup155 and the Nup98 autoproteolytic domain in NPC scaffold assembly. The latter suggests a checkpoint linking pore formation to the assembly of the Nup98-dominated permeability barrier.
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Affiliation(s)
- Mireia Solà Colom
- Department of Cellular Logistics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- AI Proteins, 20 Overland St., Boston, MA, USA
| | - Zhenglin Fu
- Department of Cellular Logistics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Philip Gunkel
- Department of Cellular Logistics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Thomas Güttler
- Department of Cellular Logistics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Octapharma Biopharmaceuticals, Im Neuenheimer Feld 590, 69120, Heidelberg, Germany
| | - Sergei Trakhanov
- Department of Cellular Logistics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Vasundara Srinivasan
- Department of Cellular Logistics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Department of Chemistry, Institute of Biochemistry and Molecular Biology, Universität Hamburg, Hamburg, Germany
| | - Kathrin Gregor
- Department of Cellular Logistics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Tino Pleiner
- Department of Cellular Logistics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Dirk Görlich
- Department of Cellular Logistics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
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2
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Chatterjee S, Ganguly A, Bhattacharyya D. Reprogramming nucleolar size by genetic perturbation of the extranuclear Rab GTPases Ypt6 and Ypt32. FEBS Lett 2024; 598:283-301. [PMID: 37994551 DOI: 10.1002/1873-3468.14776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Revised: 10/05/2023] [Accepted: 10/09/2023] [Indexed: 11/24/2023]
Abstract
Reprogramming organelle size has been proposed as a potential therapeutic approach. However, there have been few reports of nucleolar size reprogramming. We addressed this question in Saccharomyces cerevisiae by studying mutants having opposite effects on the nucleolar size. Mutations in genes involved in nuclear functions (KAR3, CIN8, and PRP45) led to enlarged nuclei/nucleoli, whereas mutations in secretory pathway family genes, namely the Rab-GTPases YPT6 and YPT32, reduced nucleolar size. When combined with mutations leading to enlarged nuclei/nucleoli, the YPT6 or YPT32 mutants can effectively reprogram the nuclear/nucleolar size almost back to normal. Our results further indicate that null mutation of YPT6 causes secretory stress that indirectly influences nuclear localization of Maf1, the negative regulator of RNA Polymerase III, which might reduce the nucleolar size by inhibiting nucleolar transcript enrichment.
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Affiliation(s)
- Shreosi Chatterjee
- Department of Cell and Tumor Biology, Advanced Centre for Treatment Research & Education in Cancer (ACTREC), Tata Memorial Centre, Navi Mumbai, Maharashtra, India
- Homi Bhabha National Institute, Training School Complex, Mumbai, Maharashtra, India
| | - Abira Ganguly
- Department of Cell and Tumor Biology, Advanced Centre for Treatment Research & Education in Cancer (ACTREC), Tata Memorial Centre, Navi Mumbai, Maharashtra, India
- Homi Bhabha National Institute, Training School Complex, Mumbai, Maharashtra, India
| | - Dibyendu Bhattacharyya
- Department of Cell and Tumor Biology, Advanced Centre for Treatment Research & Education in Cancer (ACTREC), Tata Memorial Centre, Navi Mumbai, Maharashtra, India
- Homi Bhabha National Institute, Training School Complex, Mumbai, Maharashtra, India
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
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3
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Penzo A, Palancade B. Puzzling out nuclear pore complex assembly. FEBS Lett 2023; 597:2705-2727. [PMID: 37548888 DOI: 10.1002/1873-3468.14713] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 07/12/2023] [Accepted: 07/17/2023] [Indexed: 08/08/2023]
Abstract
Nuclear pore complexes (NPCs) are sophisticated multiprotein assemblies embedded within the nuclear envelope and controlling the exchanges of molecules between the cytoplasm and the nucleus. In this review, we summarize the mechanisms by which these elaborate complexes are built from their subunits, the nucleoporins, based on our ever-growing knowledge of NPC structural organization and on the recent identification of additional features of this process. We present the constraints faced during the production of nucleoporins, their gathering into oligomeric complexes, and the formation of NPCs within nuclear envelopes, and review the cellular strategies at play, from co-translational assembly to the enrolment of a panel of cofactors. Remarkably, the study of NPCs can inform our perception of the biogenesis of multiprotein complexes in general - and vice versa.
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Affiliation(s)
- Arianna Penzo
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | - Benoit Palancade
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
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4
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Guo J, Zhu Y, Ma X, Shang G, Liu B, Zhang K. Virus Infection and mRNA Nuclear Export. Int J Mol Sci 2023; 24:12593. [PMID: 37628773 PMCID: PMC10454920 DOI: 10.3390/ijms241612593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 07/29/2023] [Accepted: 08/03/2023] [Indexed: 08/27/2023] Open
Abstract
Gene expression in eukaryotes begins with transcription in the nucleus, followed by the synthesis of messenger RNA (mRNA), which is then exported to the cytoplasm for its translation into proteins. Along with transcription and translation, mRNA export through the nuclear pore complex (NPC) is an essential regulatory step in eukaryotic gene expression. Multiple factors regulate mRNA export and hence gene expression. Interestingly, proteins from certain types of viruses interact with these factors in infected cells, and such an interaction interferes with the mRNA export of the host cell in favor of viral RNA export. Thus, these viruses hijack the host mRNA nuclear export mechanism, leading to a reduction in host gene expression and the downregulation of immune/antiviral responses. On the other hand, the viral mRNAs successfully evade the host surveillance system and are efficiently exported from the nucleus to the cytoplasm for translation, which enables the continuation of the virus life cycle. Here, we present this review to summarize the mechanisms by which viruses suppress host mRNA nuclear export during infection, as well as the key strategies that viruses use to facilitate their mRNA nuclear export. These studies have revealed new potential antivirals that may be used to inhibit viral mRNA transport and enhance host mRNA nuclear export, thereby promoting host gene expression and immune responses.
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Affiliation(s)
- Jiayin Guo
- University of Chinese Academy of Sciences, Beijing 100049, China; (J.G.); (Y.Z.); (X.M.)
| | - Yaru Zhu
- University of Chinese Academy of Sciences, Beijing 100049, China; (J.G.); (Y.Z.); (X.M.)
| | - Xiaoya Ma
- University of Chinese Academy of Sciences, Beijing 100049, China; (J.G.); (Y.Z.); (X.M.)
| | - Guijun Shang
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China;
| | - Bo Liu
- Key Laboratory of Molecular Virology and Immunology, Chinese Academy of Sciences, Shanghai 200031, China
- Shanghai Huashen Institute of Microbes and Infections, Shanghai 200052, China
| | - Ke Zhang
- Key Laboratory of Molecular Virology and Immunology, Chinese Academy of Sciences, Shanghai 200031, China
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5
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Li Z, Chen S, Zhao L, Huang G, Xu H, Yang X, Wang P, Gao N, Sui SF. Nuclear export of pre-60S particles through the nuclear pore complex. Nature 2023:10.1038/s41586-023-06128-y. [PMID: 37258668 DOI: 10.1038/s41586-023-06128-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 04/25/2023] [Indexed: 06/02/2023]
Abstract
The nuclear pore complex (NPC) is the bidirectional gate that mediates the exchange of macromolecules or their assemblies between nucleus and cytoplasm1-3. The assembly intermediates of the ribosomal subunits, pre-60S and pre-40S particles, are among the largest cargoes of the NPC and the export of these gigantic ribonucleoproteins requires numerous export factors4,5. Here we report the cryo-electron microscopy structure of native pre-60S particles trapped in the channel of yeast NPCs. In addition to known assembly factors, multiple factors with export functions are also included in the structure. These factors in general bind to either the flexible regions or subunit interface of the pre-60S particle, and virtually form many anchor sites for NPC binding. Through interactions with phenylalanine-glycine (FG) repeats from various nucleoporins of NPC, these factors collectively facilitate the passage of the pre-60S particle through the central FG repeat network of the NPC. Moreover, in silico analysis of the axial and radial distribution of pre-60S particles within the NPC shows that a single NPC can take up to four pre-60S particles simultaneously, and pre-60S particles are enriched in the inner ring regions close to the wall of the NPC with the solvent-exposed surface facing the centre of the nuclear pore. Our data suggest a translocation model for the export of pre-60S particles through the NPC.
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Affiliation(s)
- Zongqiang Li
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing, China
| | - Shuaijiabin Chen
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing, China
| | - Liang Zhao
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing, China
| | - Guoqiang Huang
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing, China
| | - Huiqin Xu
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Xiaoyun Yang
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Peiyi Wang
- Cryo-EM Center, Southern University of Science and Technology, Shenzhen, China
| | - Ning Gao
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Sen-Fang Sui
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, China.
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing, China.
- Cryo-EM Center, Southern University of Science and Technology, Shenzhen, China.
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Tingey M, Li Y, Yu W, Young A, Yang W. Spelling out the roles of individual nucleoporins in nuclear export of mRNA. Nucleus 2022; 13:170-193. [PMID: 35593254 PMCID: PMC9132428 DOI: 10.1080/19491034.2022.2076965] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 05/08/2022] [Accepted: 05/09/2022] [Indexed: 11/01/2022] Open
Abstract
The Nuclear Pore Complex (NPC) represents a critical passage through the nuclear envelope for nuclear import and export that impacts nearly every cellular process at some level. Recent technological advances in the form of Auxin Inducible Degron (AID) strategies and Single-Point Edge-Excitation sub-Diffraction (SPEED) microscopy have enabled us to provide new insight into the distinct functions and roles of nuclear basket nucleoporins (Nups) upon nuclear docking and export for mRNAs. In this paper, we provide a review of our recent findings as well as an assessment of new techniques, updated models, and future perspectives in the studies of mRNA's nuclear export.
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Affiliation(s)
- Mark Tingey
- Department of Biology, Temple University, Philadelphia, Pennsylvania, USA
| | - Yichen Li
- Department of Genetics, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
| | - Wenlan Yu
- Department of Biology, Temple University, Philadelphia, Pennsylvania, USA
| | - Albert Young
- Department of Biology, Temple University, Philadelphia, Pennsylvania, USA
| | - Weidong Yang
- Department of Biology, Temple University, Philadelphia, Pennsylvania, USA
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7
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Petrovic S, Samanta D, Perriches T, Bley CJ, Thierbach K, Brown B, Nie S, Mobbs GW, Stevens TA, Liu X, Tomaleri GP, Schaus L, Hoelz A. Architecture of the linker-scaffold in the nuclear pore. Science 2022; 376:eabm9798. [PMID: 35679425 PMCID: PMC9867570 DOI: 10.1126/science.abm9798] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
INTRODUCTION In eukaryotic cells, the selective bidirectional transport of macromolecules between the nucleus and cytoplasm occurs through the nuclear pore complex (NPC). Embedded in nuclear envelope pores, the ~110-MDa human NPC is an ~1200-Å-wide and ~750-Å-tall assembly of ~1000 proteins, collectively termed nucleoporins. Because of the NPC's eightfold rotational symmetry along the nucleocytoplasmic axis, each of the ~34 different nucleoporins occurs in multiples of eight. Architecturally, the NPC's symmetric core is composed of an inner ring encircling the central transport channel and two outer rings anchored on both sides of the nuclear envelope. Because of its central role in the flow of genetic information from DNA to RNA to protein, the NPC is commonly targeted in viral infections and its nucleoporin constituents are associated with a plethora of diseases. RATIONALE Although the arrangement of most scaffold nucleoporins in the NPC's symmetric core was determined by quantitative docking of crystal structures into cryo-electron tomographic (cryo-ET) maps of intact NPCs, the topology and molecular details of their cohesion by multivalent linker nucleoporins have remained elusive. Recently, in situ cryo-ET reconstructions of NPCs from various species have indicated that the NPC's inner ring is capable of reversible constriction and dilation in response to variations in nuclear envelope membrane tension, thereby modulating the diameter of the central transport channel by ~200 Å. We combined biochemical reconstitution, high-resolution crystal and single-particle cryo-electron microscopy (cryo-EM) structure determination, docking into cryo-ET maps, and physiological validation to elucidate the molecular architecture of the linker-scaffold interaction network that not only is essential for the NPC's integrity but also confers the plasticity and robustness necessary to allow and withstand such large-scale conformational changes. RESULTS By biochemically mapping scaffold-binding regions of all fungal and human linker nucleoporins and determining crystal and single-particle cryo-EM structures of linker-scaffold complexes, we completed the characterization of the biochemically tractable linker-scaffold network and established its evolutionary conservation, despite considerable sequence divergence. We determined a series of crystal and single-particle cryo-EM structures of the intact Nup188 and Nup192 scaffold hubs bound to their Nic96, Nup145N, and Nup53 linker nucleoporin binding regions, revealing that both proteins form distinct question mark-shaped keystones of two evolutionarily conserved hetero‑octameric inner ring complexes. Linkers bind to scaffold surface pockets through short defined motifs, with flanking regions commonly forming additional disperse interactions that reinforce the binding. Using a structure‑guided functional analysis in Saccharomyces cerevisiae, we confirmed the robustness of linker‑scaffold interactions and established the physiological relevance of our biochemical and structural findings. The near-atomic composite structures resulting from quantitative docking of experimental structures into human and S. cerevisiae cryo-ET maps of constricted and dilated NPCs structurally disambiguated the positioning of the Nup188 and Nup192 hubs in the intact fungal and human NPC and revealed the topology of the linker-scaffold network. The linker-scaffold gives rise to eight relatively rigid inner ring spokes that are flexibly interconnected to allow for the formation of lateral channels. Unexpectedly, we uncovered that linker‑scaffold interactions play an opposing role in the outer rings by forming tight cross-link staples between the eight nuclear and cytoplasmic outer ring spokes, thereby limiting the dilatory movements to the inner ring. CONCLUSION We have substantially advanced the structural and biochemical characterization of the symmetric core of the S. cerevisiae and human NPCs and determined near-atomic composite structures. The composite structures uncover the molecular mechanism by which the evolutionarily conserved linker‑scaffold establishes the NPC's integrity while simultaneously allowing for the observed plasticity of the central transport channel. The composite structures are roadmaps for the mechanistic dissection of NPC assembly and disassembly, the etiology of NPC‑associated diseases, the role of NPC dilation in nucleocytoplasmic transport of soluble and integral membrane protein cargos, and the anchoring of asymmetric nucleoporins. [Figure: see text].
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Affiliation(s)
- Stefan Petrovic
- California Institute of Technology, Division of Chemistry and Chemical Engineering, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Dipanjan Samanta
- California Institute of Technology, Division of Chemistry and Chemical Engineering, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Thibaud Perriches
- California Institute of Technology, Division of Chemistry and Chemical Engineering, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Christopher J. Bley
- California Institute of Technology, Division of Chemistry and Chemical Engineering, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Karsten Thierbach
- California Institute of Technology, Division of Chemistry and Chemical Engineering, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Bonnie Brown
- California Institute of Technology, Division of Chemistry and Chemical Engineering, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Si Nie
- California Institute of Technology, Division of Chemistry and Chemical Engineering, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - George W. Mobbs
- California Institute of Technology, Division of Chemistry and Chemical Engineering, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Taylor A. Stevens
- California Institute of Technology, Division of Chemistry and Chemical Engineering, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Xiaoyu Liu
- California Institute of Technology, Division of Chemistry and Chemical Engineering, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Giovani Pinton Tomaleri
- California Institute of Technology, Division of Chemistry and Chemical Engineering, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Lucas Schaus
- California Institute of Technology, Division of Chemistry and Chemical Engineering, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - André Hoelz
- California Institute of Technology, Division of Chemistry and Chemical Engineering, 1200 East California Boulevard, Pasadena, CA 91125, USA,Corresponding author. (A.H.)
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8
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Bley CJ, Nie S, Mobbs GW, Petrovic S, Gres AT, Liu X, Mukherjee S, Harvey S, Huber FM, Lin DH, Brown B, Tang AW, Rundlet EJ, Correia AR, Chen S, Regmi SG, Stevens TA, Jette CA, Dasso M, Patke A, Palazzo AF, Kossiakoff AA, Hoelz A. Architecture of the cytoplasmic face of the nuclear pore. Science 2022; 376:eabm9129. [PMID: 35679405 DOI: 10.1126/science.abm9129] [Citation(s) in RCA: 58] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
INTRODUCTION The subcellular compartmentalization of eukaryotic cells requires selective transport of folded proteins and protein-nucleic acid complexes. Embedded in nuclear envelope pores, which are generated by the circumscribed fusion of the inner and outer nuclear membranes, nuclear pore complexes (NPCs) are the sole bidirectional gateways for nucleocytoplasmic transport. The ~110-MDa human NPC is an ~1000-protein assembly that comprises multiple copies of ~34 different proteins, collectively termed nucleoporins. The symmetric core of the NPC is composed of an inner ring encircling the central transport channel and outer rings formed by Y‑shaped coat nucleoporin complexes (CNCs) anchored atop both sides of the nuclear envelope. The outer rings are decorated with compartment‑specific asymmetric nuclear basket and cytoplasmic filament nucleoporins, which establish transport directionality and provide docking sites for transport factors and the small guanosine triphosphatase Ran. The cytoplasmic filament nucleoporins also play an essential role in the irreversible remodeling of messenger ribonucleoprotein particles (mRNPs) as they exit the central transport channel. Unsurprisingly, the NPC's cytoplasmic face represents a hotspot for disease‑associated mutations and is commonly targeted by viral virulence factors. RATIONALE Previous studies established a near-atomic composite structure of the human NPC's symmetric core by combining (i) biochemical reconstitution to elucidate the interaction network between symmetric nucleoporins, (ii) crystal and single-particle cryo-electron microscopy structure determination of nucleoporins and nucleoporin complexes to reveal their three-dimensional shape and the molecular details of their interactions, (iii) quantitative docking in cryo-electron tomography (cryo-ET) maps of the intact human NPC to uncover nucleoporin stoichiometry and positioning, and (iv) cell‑based assays to validate the physiological relevance of the biochemical and structural findings. In this work, we extended our approach to the cytoplasmic filament nucleoporins to reveal the near-atomic architecture of the cytoplasmic face of the human NPC. RESULTS Using biochemical reconstitution, we elucidated the protein-protein and protein-RNA interaction networks of the human and Chaetomium thermophilum cytoplasmic filament nucleoporins, establishing an evolutionarily conserved heterohexameric cytoplasmic filament nucleoporin complex (CFNC) held together by a central heterotrimeric coiled‑coil hub that tethers two separate mRNP‑remodeling complexes. Further biochemical analysis and determination of a series of crystal structures revealed that the metazoan‑specific cytoplasmic filament nucleoporin NUP358 is composed of 16 distinct domains, including an N‑terminal S‑shaped α‑helical solenoid followed by a coiled‑coil oligomerization element, numerous Ran‑interacting domains, an E3 ligase domain, and a C‑terminal prolyl‑isomerase domain. Physiologically validated quantitative docking into cryo-ET maps of the intact human NPC revealed that pentameric NUP358 bundles, conjoined by the oligomerization element, are anchored through their N‑terminal domains to the central stalk regions of the CNC, projecting flexibly attached domains as far as ~600 Å into the cytoplasm. Using cell‑based assays, we demonstrated that NUP358 is dispensable for the architectural integrity of the assembled interphase NPC and RNA export but is required for efficient translation. After NUP358 assignment, the remaining 4-shaped cryo‑ET density matched the dimensions of the CFNC coiled‑coil hub, in close proximity to an outer-ring NUP93. Whereas the N-terminal NUP93 assembly sensor motif anchors the properly assembled related coiled‑coil channel nucleoporin heterotrimer to the inner ring, biochemical reconstitution confirmed that the NUP93 assembly sensor is reused in anchoring the CFNC to the cytoplasmic face of the human NPC. By contrast, two C. thermophilum CFNCs are anchored by a divergent mechanism that involves assembly sensors located in unstructured portions of two CNC nucleoporins. Whereas unassigned cryo‑ET density occupies the NUP358 and CFNC binding sites on the nuclear face, docking of the nuclear basket component ELYS established that the equivalent position on the cytoplasmic face is unoccupied, suggesting that mechanisms other than steric competition promote asymmetric distribution of nucleoporins. CONCLUSION We have substantially advanced the biochemical and structural characterization of the asymmetric nucleoporins' architecture and attachment at the cytoplasmic and nuclear faces of the NPC. Our near‑atomic composite structure of the human NPC's cytoplasmic face provides a biochemical and structural framework for elucidating the molecular basis of mRNP remodeling, viral virulence factor interference with NPC function, and the underlying mechanisms of nucleoporin diseases at the cytoplasmic face of the NPC. [Figure: see text].
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Affiliation(s)
- Christopher J Bley
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Si Nie
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - George W Mobbs
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Stefan Petrovic
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Anna T Gres
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Xiaoyu Liu
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Somnath Mukherjee
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Sho Harvey
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Ferdinand M Huber
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Daniel H Lin
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Bonnie Brown
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Aaron W Tang
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Emily J Rundlet
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Ana R Correia
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Shane Chen
- Division of Molecular and Cellular Biology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Saroj G Regmi
- Division of Molecular and Cellular Biology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Taylor A Stevens
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Claudia A Jette
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Mary Dasso
- Division of Molecular and Cellular Biology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Alina Patke
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Alexander F Palazzo
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Anthony A Kossiakoff
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - André Hoelz
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
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9
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Silva PMA, Bousbaa H. BUB3, beyond the Simple Role of Partner. Pharmaceutics 2022; 14:pharmaceutics14051084. [PMID: 35631670 PMCID: PMC9147866 DOI: 10.3390/pharmaceutics14051084] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 05/12/2022] [Accepted: 05/16/2022] [Indexed: 12/07/2022] Open
Abstract
The BUB3 protein plays a key role in the activation of the spindle assembly checkpoint (SAC), a ubiquitous surveillance mechanism that ensures the fidelity of chromosome segregation in mitosis and, consequently, prevents chromosome mis-segregation and aneuploidy. Besides its role in SAC signaling, BUB3 regulates chromosome attachment to the spindle microtubules. It is also involved in telomere replication and maintenance. Deficiency of the BUB3 gene has been closely linked to premature aging. Upregulation of the BUB3 gene has been found in a variety of human cancers and is associated with poor prognoses. Here, we review the structure and functions of BUB3 in mitosis, its expression in cancer and association with survival prognoses, and its potential as an anticancer target.
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Affiliation(s)
- Patrícia M. A. Silva
- UNIPRO—Oral Pathology and Rehabilitation Research Unit, University Institute of Health Sciences (IUCS), University Polytechnic Higher Education Cooperative (CESPU), Rua Central de Gandra, 4585-116 Gandra, Portugal;
- TOXRUN—Toxicology Research Unit, University Institute of Health Sciences (IUCS), University Polytechnic Higher Education Cooperative (CESPU), Rua Central de Gandra, 4585-116 Gandra, Portugal
| | - Hassan Bousbaa
- UNIPRO—Oral Pathology and Rehabilitation Research Unit, University Institute of Health Sciences (IUCS), University Polytechnic Higher Education Cooperative (CESPU), Rua Central de Gandra, 4585-116 Gandra, Portugal;
- Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR), Universidade do Porto, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208 Matosinhos, Portugal
- Correspondence:
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10
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The Nuclear Pore Complex: Birth, Life, and Death of a Cellular Behemoth. Cells 2022; 11:cells11091456. [PMID: 35563762 PMCID: PMC9100368 DOI: 10.3390/cells11091456] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/22/2022] [Accepted: 04/23/2022] [Indexed: 02/01/2023] Open
Abstract
Nuclear pore complexes (NPCs) are the only transport channels that cross the nuclear envelope. Constructed from ~500–1000 nucleoporin proteins each, they are among the largest macromolecular assemblies in eukaryotic cells. Thanks to advances in structural analysis approaches, the construction principles and architecture of the NPC have recently been revealed at submolecular resolution. Although the overall structure and inventory of nucleoporins are conserved, NPCs exhibit significant compositional and functional plasticity even within single cells and surprising variability in their assembly pathways. Once assembled, NPCs remain seemingly unexchangeable in post-mitotic cells. There are a number of as yet unresolved questions about how the versatility of NPC assembly and composition is established, how cells monitor the functional state of NPCs or how they could be renewed. Here, we review current progress in our understanding of the key aspects of NPC architecture and lifecycle.
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11
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Najbauer EE, Ng SC, Griesinger C, Görlich D, Andreas LB. Atomic resolution dynamics of cohesive interactions in phase-separated Nup98 FG domains. Nat Commun 2022; 13:1494. [PMID: 35314668 PMCID: PMC8938434 DOI: 10.1038/s41467-022-28821-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 02/09/2022] [Indexed: 01/02/2023] Open
Abstract
Cohesive FG domains assemble into a condensed phase forming the selective permeability barrier of nuclear pore complexes. Nanoscopic insight into fundamental cohesive interactions has long been hampered by the sequence heterogeneity of native FG domains. We overcome this challenge by utilizing an engineered perfectly repetitive sequence and a combination of solution and magic angle spinning NMR spectroscopy. We map the dynamics of cohesive interactions in both phase-separated and soluble states at atomic resolution using TROSY for rotational correlation time (TRACT) measurements. We find that FG repeats exhibit nanosecond-range rotational correlation times and remain disordered in both states, although FRAP measurements show slow translation of phase-separated FG domains. NOESY measurements enable the direct detection of contacts involved in cohesive interactions. Finally, increasing salt concentration and temperature enhance phase separation and decrease local mobility of FG repeats. This lower critical solution temperature (LCST) behaviour indicates that cohesive interactions are driven by entropy. The permeability barrier of nuclear pores is formed by disordered and yet self-interacting FG repeat domains, whose sequence heterogeneity is a challenge for mechanistic insights. Here the authors overcome this challenge and characterize the protein’s dynamics by applying NMR techniques to an FG phase system that has been simplified to its essentials.
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12
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Seidel M, Becker A, Pereira F, Landry JJM, de Azevedo NTD, Fusco CM, Kaindl E, Romanov N, Baumbach J, Langer JD, Schuman EM, Patil KR, Hummer G, Benes V, Beck M. Co-translational assembly orchestrates competing biogenesis pathways. Nat Commun 2022; 13:1224. [PMID: 35264577 PMCID: PMC8907234 DOI: 10.1038/s41467-022-28878-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 02/11/2022] [Indexed: 12/27/2022] Open
Abstract
During the co-translational assembly of protein complexes, a fully synthesized subunit engages with the nascent chain of a newly synthesized interaction partner. Such events are thought to contribute to productive assembly, but their exact physiological relevance remains underexplored. Here, we examine structural motifs contained in nucleoporins for their potential to facilitate co-translational assembly. We experimentally test candidate structural motifs and identify several previously unknown co-translational interactions. We demonstrate by selective ribosome profiling that domain invasion motifs of beta-propellers, coiled-coils, and short linear motifs may act as co-translational assembly domains. Such motifs are often contained in proteins that are members of multiple complexes (moonlighters) and engage with closely related paralogs. Surprisingly, moonlighters and paralogs assemble co-translationally in only some but not all of the relevant biogenesis pathways. Our results highlight the regulatory complexity of assembly pathways.
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Affiliation(s)
- Maximilian Seidel
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Frankfurt, Germany
- Faculty of Bioscience, Heidelberg University, Heidelberg, Germany
| | - Anja Becker
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Filipa Pereira
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Jonathan J M Landry
- Genomics Core Facility, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | | | - Claudia M Fusco
- Department of Synaptic Plasticity, Max Planck Institute for Brain Research, Frankfurt, Germany
| | - Eva Kaindl
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Natalie Romanov
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Janina Baumbach
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Frankfurt, Germany
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Julian D Langer
- Department of Synaptic Plasticity, Max Planck Institute for Brain Research, Frankfurt, Germany
- Membrane Proteomics and Mass Spectrometry, Max Planck Institute of Biophysics, Frankfurt, Germany
- Mass Spectrometry, Max Planck Institute for Brain Research, Frankfurt, Germany
| | - Erin M Schuman
- Department of Synaptic Plasticity, Max Planck Institute for Brain Research, Frankfurt, Germany
| | - Kiran Raosaheb Patil
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
- Medical Research Council Toxicology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt, Germany
- Institute of Biophysics, Goethe University Frankfurt, Frankfurt, Germany
| | - Vladimir Benes
- Genomics Core Facility, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Martin Beck
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Frankfurt, Germany.
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany.
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13
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van Leeuwen J, Pons C, Tan G, Wang JZ, Hou J, Weile J, Gebbia M, Liang W, Shuteriqi E, Li Z, Lopes M, Ušaj M, Dos Santos Lopes A, van Lieshout N, Myers CL, Roth FP, Aloy P, Andrews BJ, Boone C. Systematic analysis of bypass suppression of essential genes. Mol Syst Biol 2021; 16:e9828. [PMID: 32939983 PMCID: PMC7507402 DOI: 10.15252/msb.20209828] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 08/11/2020] [Accepted: 08/13/2020] [Indexed: 12/15/2022] Open
Abstract
Essential genes tend to be highly conserved across eukaryotes, but, in some cases, their critical roles can be bypassed through genetic rewiring. From a systematic analysis of 728 different essential yeast genes, we discovered that 124 (17%) were dispensable essential genes. Through whole-genome sequencing and detailed genetic analysis, we investigated the genetic interactions and genome alterations underlying bypass suppression. Dispensable essential genes often had paralogs, were enriched for genes encoding membrane-associated proteins, and were depleted for members of protein complexes. Functionally related genes frequently drove the bypass suppression interactions. These gene properties were predictive of essential gene dispensability and of specific suppressors among hundreds of genes on aneuploid chromosomes. Our findings identify yeast's core essential gene set and reveal that the properties of dispensable essential genes are conserved from yeast to human cells, correlating with human genes that display cell line-specific essentiality in the Cancer Dependency Map (DepMap) project.
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Affiliation(s)
- Jolanda van Leeuwen
- Center for Integrative Genomics, Bâtiment Génopode, University of Lausanne, Lausanne, Switzerland.,Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada
| | - Carles Pons
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute for Science and Technology, Barcelona, Spain
| | - Guihong Tan
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada
| | - Jason Zi Wang
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Jing Hou
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada
| | - Jochen Weile
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.,Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON, Canada
| | - Marinella Gebbia
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada.,Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON, Canada
| | - Wendy Liang
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada
| | - Ermira Shuteriqi
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada
| | - Zhijian Li
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada
| | - Maykel Lopes
- Center for Integrative Genomics, Bâtiment Génopode, University of Lausanne, Lausanne, Switzerland
| | - Matej Ušaj
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada
| | - Andreia Dos Santos Lopes
- Center for Integrative Genomics, Bâtiment Génopode, University of Lausanne, Lausanne, Switzerland
| | - Natascha van Lieshout
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada.,Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON, Canada
| | - Chad L Myers
- Department of Computer Science and Engineering, University of Minnesota-Twin Cities, Minneapolis, MN, USA
| | - Frederick P Roth
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.,Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON, Canada.,Department of Computer Science, University of Toronto, Toronto, ON, Canada
| | - Patrick Aloy
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute for Science and Technology, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
| | - Brenda J Andrews
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Charles Boone
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
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14
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Ng SC, Güttler T, Görlich D. Recapitulation of selective nuclear import and export with a perfectly repeated 12mer GLFG peptide. Nat Commun 2021; 12:4047. [PMID: 34193851 PMCID: PMC8245513 DOI: 10.1038/s41467-021-24292-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 06/11/2021] [Indexed: 12/04/2022] Open
Abstract
The permeability barrier of nuclear pore complexes (NPCs) controls nucleocytoplasmic transport. It retains inert macromolecules while allowing facilitated passage of importins and exportins, which in turn shuttle cargo into or out of cell nuclei. The barrier can be described as a condensed phase assembled from cohesive FG repeat domains. NPCs contain several distinct FG domains, each comprising variable repeats. Nevertheless, we now found that sequence heterogeneity is no fundamental requirement for barrier function. Instead, we succeeded in engineering a perfectly repeated 12mer GLFG peptide that self-assembles into a barrier of exquisite transport selectivity and fast transport kinetics. This barrier recapitulates RanGTPase-controlled importin- and exportin-mediated cargo transport and thus represents an ultimately simplified experimental model system. An alternative proline-free sequence forms an amyloid FG phase. Finally, we discovered that FG phases stain bright with ‘DNA-specific’ DAPI/ Hoechst probes, and that such dyes allow for a photo-induced block of nuclear transport. The permeability barrier of nuclear pore complexes blocks passage of inert macromolecules but allows rapid, receptor-mediated, and RanGTPase-driven transport of cargoes up to ribosome size. The authors now show that such a barrier can be faithfully recapitulated by an ultimately simplified FG phase assembled solely from a tandemly repeated 12mer GLFG peptide.
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Affiliation(s)
- Sheung Chun Ng
- Department of Cellular Logistics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Thomas Güttler
- Department of Cellular Logistics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Dirk Görlich
- Department of Cellular Logistics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
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15
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Pardamean CI, Wu TT. Inhibition of Host Gene Expression by KSHV: Sabotaging mRNA Stability and Nuclear Export. Front Cell Infect Microbiol 2021; 11:648055. [PMID: 33898329 PMCID: PMC8062738 DOI: 10.3389/fcimb.2021.648055] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 03/19/2021] [Indexed: 12/25/2022] Open
Abstract
Viruses are known for their ability to alter host gene expression. Kaposi sarcoma-associated herpesvirus has two proteins that obstruct host gene expression. KSHV SOX, encoded by the open reading frame 37 (ORF37), induces a widespread cytoplasmic mRNA degradation and a block on mRNA nuclear export. The other KSHV protein, encoded by the open reading frame 10 (ORF10), was recently identified to inhibit host gene expression through its direct function on the cellular mRNA export pathway. In this review, we summarize the studies on both SOX and ORF10 in efforts to elucidate their mechanisms. We also discuss how the findings based on a closely related rodent virus, murine gammaherpesvirus-68 (MHV-68), complement the KSHV findings to decipher the role of these two proteins in viral pathogenesis.
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Affiliation(s)
- Carissa Ikka Pardamean
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, United States
| | - Ting-Ting Wu
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, United States
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16
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Lautier O, Penzo A, Rouvière JO, Chevreux G, Collet L, Loïodice I, Taddei A, Devaux F, Collart MA, Palancade B. Co-translational assembly and localized translation of nucleoporins in nuclear pore complex biogenesis. Mol Cell 2021; 81:2417-2427.e5. [PMID: 33838103 DOI: 10.1016/j.molcel.2021.03.030] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 02/24/2021] [Accepted: 03/18/2021] [Indexed: 01/03/2023]
Abstract
mRNA translation is coupled to multiprotein complex assembly in the cytoplasm or to protein delivery into intracellular compartments. Here, by combining systematic RNA immunoprecipitation and single-molecule RNA imaging in yeast, we have provided a complete depiction of the co-translational events involved in the biogenesis of a large multiprotein assembly, the nuclear pore complex (NPC). We report that binary interactions between NPC subunits can be established during translation, in the cytoplasm. Strikingly, the nucleoporins Nup1/Nup2, together with a number of nuclear proteins, are instead translated at nuclear pores, through a mechanism involving interactions between their nascent N-termini and nuclear transport receptors. Uncoupling this co-translational recruitment further triggers the formation of cytoplasmic foci of unassembled polypeptides. Altogether, our data reveal that distinct, spatially segregated modes of co-translational interactions foster the ordered assembly of NPC subunits and that localized translation can ensure the proper delivery of proteins to the pore and the nucleus.
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Affiliation(s)
- Ophélie Lautier
- Université de Paris, CNRS, Institut Jacques Monod, 75006 Paris, France
| | - Arianna Penzo
- Université de Paris, CNRS, Institut Jacques Monod, 75006 Paris, France
| | - Jérôme O Rouvière
- Université de Paris, CNRS, Institut Jacques Monod, 75006 Paris, France
| | - Guillaume Chevreux
- ProteoSeine@IJM, Université de Paris, CNRS, Institut Jacques Monod, 75006 Paris, France
| | - Louis Collet
- Université de Paris, CNRS, Institut Jacques Monod, 75006 Paris, France
| | - Isabelle Loïodice
- Institut Curie, PSL Research University, CNRS, Sorbonne Université, UMR3664 Nuclear Dynamics, Paris, France
| | - Angela Taddei
- Institut Curie, PSL Research University, CNRS, Sorbonne Université, UMR3664 Nuclear Dynamics, Paris, France
| | - Frédéric Devaux
- Sorbonne Université, CNRS, Institut de biologie Paris-Seine (IBPS), UMR 7238, Laboratoire de biologie computationnelle et quantitative, LCQB, 4 place Jussieu, 75005 Paris, France
| | - Martine A Collart
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Benoit Palancade
- Université de Paris, CNRS, Institut Jacques Monod, 75006 Paris, France.
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17
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Maturation Kinetics of a Multiprotein Complex Revealed by Metabolic Labeling. Cell 2020; 183:1785-1800.e26. [DOI: 10.1016/j.cell.2020.11.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Revised: 09/21/2020] [Accepted: 10/30/2020] [Indexed: 12/12/2022]
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18
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Guha S, Bhaumik SR. Viral regulation of mRNA export with potentials for targeted therapy. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1864:194655. [PMID: 33246183 DOI: 10.1016/j.bbagrm.2020.194655] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 10/15/2020] [Accepted: 11/05/2020] [Indexed: 12/12/2022]
Abstract
Eukaryotic gene expression begins with transcription in the nucleus to synthesize mRNA (messenger RNA), which is subsequently exported to the cytoplasm for translation to protein. Like transcription and translation, mRNA export is an important regulatory step of eukaryotic gene expression. Various factors are involved in regulating mRNA export, and thus gene expression. Intriguingly, some of these factors interact with viral proteins, and such interactions interfere with mRNA export of the host cell, favoring viral RNA export. Hence, viruses hijack host mRNA export machinery for export of their own RNAs from nucleus to cytoplasm for translation to proteins for viral life cycle, suppressing host mRNA export (and thus host gene expression and immune/antiviral response). Therefore, the molecules that can impair the interactions of these mRNA export factors with viral proteins could emerge as antiviral therapeutic agents to suppress viral RNA transport and enhance host mRNA export, thereby promoting host gene expression and immune response. Thus, there has been a number of studies to understand how virus hijacks mRNA export machinery in suppressing host gene expression and promoting its own RNA export to the cytoplasm for translation to proteins required for viral replication/assembly/life cycle towards developing targeted antiviral therapies, as concisely described here.
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Affiliation(s)
- Shalini Guha
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
| | - Sukesh R Bhaumik
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA.
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19
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Shirnekhi HK, Herman JA, Paddison PJ, DeLuca JG. BuGZ facilitates loading of spindle assembly checkpoint proteins to kinetochores in early mitosis. J Biol Chem 2020; 295:14666-14677. [PMID: 32820050 DOI: 10.1074/jbc.ra120.013598] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 08/07/2020] [Indexed: 11/06/2022] Open
Abstract
BuGZ is a kinetochore component that binds to and stabilizes Bub3, a key player in mitotic spindle assembly checkpoint signaling. Bub3 is required for kinetochore recruitment of Bub1 and BubR1, two proteins that have essential and distinct roles in the checkpoint. Both Bub1 and BubR1 localize to kinetochores through interactions with Bub3, which are mediated through conserved GLEBS domains in both Bub1 and BubR1. BuGZ also has a GLEBS domain, which is required for its kinetochore localization as well, presumably mediated through Bub3 binding. Although much is understood about the requirements for Bub1 and BubR1 interaction with Bub3 and kinetochores, much less is known regarding BuGZ's requirements. Here, we used a series of mutants to demonstrate that BuGZ kinetochore localization requires only its core GLEBS domain, which is distinct from the requirements for both Bub1 and BubR1. Furthermore, we found that the kinetics of Bub1, BubR1, and BuGZ loading to kinetochores differ, with BuGZ localizing prior to BubR1 and Bub1. To better understand how complexes containing Bub3 and its binding partners are loaded to kinetochores, we carried out size-exclusion chromatography and analyzed Bub3-containing complexes from cells under different spindle assembly checkpoint signaling conditions. We found that prior to kinetochore formation, Bub3 is complexed with BuGZ but not Bub1 or BubR1. Our results point to a model in which BuGZ stabilizes Bub3 and promotes Bub3 loading onto kinetochores in early mitosis, which, in turn, facilitates Bub1 and BubR1 kinetochore recruitment and spindle assembly checkpoint signaling.
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Affiliation(s)
- Hazheen K Shirnekhi
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA
| | - Jacob A Herman
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Patrick J Paddison
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Jennifer G DeLuca
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA.
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20
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Molecular mechanism underlying selective inhibition of mRNA nuclear export by herpesvirus protein ORF10. Proc Natl Acad Sci U S A 2020; 117:26719-26727. [PMID: 33033226 PMCID: PMC7604486 DOI: 10.1073/pnas.2007774117] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Nuclear export of host mRNAs is critical for proper cellular functions and survival. To mitigate this effort, viruses have evolved multiple strategies to inhibit this process. Distinct to the generally nonselective inhibition mechanisms, ORF10 from gammaherpesviruses blocks nuclear export of selective mRNAs by forming a complex with Rae1 (RNA export 1) and Nup98 (nucleoporin 98). Here we determine the structure of the ORF10–Rae1–Nup98 ternary complex and demonstrate that the intermolecular interactions are critical for both complex assembly and mRNA export inhibition. Moreover, we find that the ORF10-RNA direct interaction is important for ORF10-mediated mRNA export inhibition. This work is essential to understand the diversity of viral-mediated mRNA export inhibition and to design potential antiviral therapies. Viruses employ multiple strategies to inhibit host mRNA nuclear export. Distinct to the generally nonselective inhibition mechanisms, ORF10 from gammaherpesviruses inhibits mRNA export in a transcript-selective manner by interacting with Rae1 (RNA export 1) and Nup98 (nucleoporin 98). We now report the structure of ORF10 from MHV-68 (murine gammaherpesvirus 68) bound to the Rae1–Nup98 heterodimer, thereby revealing detailed intermolecular interactions. Structural and functional assays highlight that two highly conserved residues of ORF10, L60 and M413, play critical roles in both complex assembly and mRNA export inhibition. Interestingly, although ORF10 occupies the RNA-binding groove of Rae1–Nup98, the ORF10–Rae1–Nup98 ternary complex still maintains a comparable RNA-binding ability due to the ORF10–RNA direct interaction. Moreover, mutations on the RNA-binding surface of ORF10 disrupt its function of mRNA export inhibition. Our work demonstrates the molecular mechanism of ORF10-mediated selective inhibition and provides insights into the functions of Rae1–Nup98 in regulating host mRNA export.
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21
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Hurtig JE, Kim M, Orlando-Coronel LJ, Ewan J, Foreman M, Notice LA, Steiger MA, van Hoof A. Origin, conservation, and loss of alternative splicing events that diversify the proteome in Saccharomycotina budding yeasts. RNA (NEW YORK, N.Y.) 2020; 26:1464-1480. [PMID: 32631843 PMCID: PMC7491326 DOI: 10.1261/rna.075655.120] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 07/02/2020] [Indexed: 05/03/2023]
Abstract
Many eukaryotes use RNA processing, including alternative splicing, to express multiple gene products from the same gene. The budding yeast Saccharomyces cerevisiae has been successfully used to study the mechanism of splicing and the splicing machinery, but alternative splicing in yeast is relatively rare and has not been extensively studied. Alternative splicing of SKI7/HBS1 is widely conserved, but yeast and a few other eukaryotes have replaced this one alternatively spliced gene with a pair of duplicated, unspliced genes as part of a whole genome doubling (WGD). We show that other examples of alternative splicing known to have functional consequences are widely conserved within Saccharomycotina. A common mechanism by which alternative splicing has disappeared is by replacement of an alternatively spliced gene with duplicate unspliced genes. This loss of alternative splicing does not always take place soon after duplication, but can take place after sufficient time has elapsed for speciation. Saccharomycetaceae that diverged before WGD use alternative splicing more frequently than S. cerevisiae, suggesting that WGD is a major reason for infrequent alternative splicing in yeast. We anticipate that WGDs in other lineages may have had the same effect. Having observed that two functionally distinct splice-isoforms are often replaced by duplicated genes allowed us to reverse the reasoning. We thereby identify several splice isoforms that are likely to produce two functionally distinct proteins because we find them replaced by duplicated genes in related species. We also identify some alternative splicing events that are not conserved in closely related species and unlikely to produce functionally distinct proteins.
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Affiliation(s)
- Jennifer E Hurtig
- Microbiology and Molecular Genetics Department, University of Texas Health Science Center-Houston, Houston, Texas 77030, USA
| | - Minseon Kim
- Microbiology and Molecular Genetics Department, University of Texas Health Science Center-Houston, Houston, Texas 77030, USA
| | - Luisa J Orlando-Coronel
- Microbiology and Molecular Genetics Department, University of Texas Health Science Center-Houston, Houston, Texas 77030, USA
| | - Jellisa Ewan
- Microbiology and Molecular Genetics Department, University of Texas Health Science Center-Houston, Houston, Texas 77030, USA
| | - Michelle Foreman
- Microbiology and Molecular Genetics Department, University of Texas Health Science Center-Houston, Houston, Texas 77030, USA
| | - Lee-Ann Notice
- Microbiology and Molecular Genetics Department, University of Texas Health Science Center-Houston, Houston, Texas 77030, USA
| | - Michelle A Steiger
- Department of Chemistry and Biochemistry, University of St. Thomas, Houston, Texas 77006, USA
| | - Ambro van Hoof
- Microbiology and Molecular Genetics Department, University of Texas Health Science Center-Houston, Houston, Texas 77030, USA
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22
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Xie Y, Ren Y. Mechanisms of nuclear mRNA export: A structural perspective. Traffic 2019; 20:829-840. [PMID: 31513326 DOI: 10.1111/tra.12691] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 08/26/2019] [Indexed: 12/28/2022]
Abstract
Export of mRNA from the nucleus to the cytoplasm is a critical process for all eukaryotic gene expression. As mRNA is synthesized, it is packaged with a myriad of RNA-binding proteins to form ribonucleoprotein particles (mRNPs). For each step in the processes of maturation and export, mRNPs must have the correct complement of proteins. Much of the mRNA export pathway revolves around the heterodimeric export receptor yeast Mex67•Mtr2/human NXF1•NXT1, which is recruited to signal the completion of nuclear mRNP assembly, mediates mRNP targeting/translocation through the nuclear pore complex (NPC), and is displaced at the cytoplasmic side of the NPC to release the mRNP into the cytoplasm. Directionality of the transport is governed by at least two DEAD-box ATPases, yeast Sub2/human UAP56 in the nucleus and yeast Dbp5/human DDX19 at the cytoplasmic side of the NPC, which respectively mediate the association and dissociation of Mex67•Mtr2/NXF1•NXT1 onto the mRNP. Here we review recent progress from structural studies of key constituents in different steps of nuclear mRNA export. These findings have laid the foundation for further studies to obtain a comprehensive mechanistic view of the mRNA export pathway.
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Affiliation(s)
- Yihu Xie
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Yi Ren
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee
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23
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Zheng L, Nagar M, Maurais AJ, Slade DJ, Parelkar SS, Coonrod SA, Weerapana E, Thompson PR. Calcium Regulates the Nuclear Localization of Protein Arginine Deiminase 2. Biochemistry 2019; 58:3042-3056. [PMID: 31243954 DOI: 10.1021/acs.biochem.9b00225] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Protein arginine deiminases (PADs) are calcium-dependent enzymes that mediate the post-translational conversion of arginine into citrulline. Dysregulated PAD activity is associated with numerous autoimmune disorders and cancers. In breast cancer, PAD2 citrullinates histone H3R26 and activates the transcription of estrogen receptor target genes. However, PAD2 lacks a canonical nuclear localization sequence, and it is unclear how this enzyme is transported into the nucleus. Here, we show for the first time that PAD2 translocates into the nucleus in response to calcium signaling. Using BioID2, a proximity-dependent biotinylation method for identifying interacting proteins, we found that PAD2 preferentially associates with ANXA5 in the cytoplasm. Binding of calcium to PAD2 weakens this cytoplasmic interaction, which generates a pool of calcium-bound PAD2 that can interact with Ran. We hypothesize that this latter interaction promotes the translocation of PAD2 into the nucleus. These findings highlight a critical role for ANXA5 in regulating PAD2 and identify an unusual mechanism whereby proteins translocate between the cytosol and nucleus.
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Affiliation(s)
- Li Zheng
- Department of Biochemistry and Pharmacology , University of Massachusetts Medical School , Worcester , Massachusetts 01605 , United States.,Program in Chemical Biology , University of Massachusetts Medical School , 364 Plantation Street , Worcester , Massachusetts 01605 , United States
| | - Mitesh Nagar
- Department of Biochemistry and Pharmacology , University of Massachusetts Medical School , Worcester , Massachusetts 01605 , United States.,Program in Chemical Biology , University of Massachusetts Medical School , 364 Plantation Street , Worcester , Massachusetts 01605 , United States
| | - Aaron J Maurais
- Department of Chemistry , Boston College , Chestnut Hill , Massachusetts 02467 , United States
| | - Daniel J Slade
- Department of Biochemistry , Virginia Polytechnic Institute and State University , Blacksburg , Virginia 24061 , United States
| | - Sangram S Parelkar
- Department of Biochemistry and Pharmacology , University of Massachusetts Medical School , Worcester , Massachusetts 01605 , United States
| | - Scott A Coonrod
- James A. Baker Institute for Animal Health, College of Veterinary Medicine , Cornell University , Ithaca , New York 14853 , United States
| | - Eranthie Weerapana
- Department of Chemistry , Boston College , Chestnut Hill , Massachusetts 02467 , United States
| | - Paul R Thompson
- Department of Biochemistry and Pharmacology , University of Massachusetts Medical School , Worcester , Massachusetts 01605 , United States.,Program in Chemical Biology , University of Massachusetts Medical School , 364 Plantation Street , Worcester , Massachusetts 01605 , United States
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24
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Abstract
The nuclear pore complex (NPC) serves as the sole bidirectional gateway of macromolecules in and out of the nucleus. Owing to its size and complexity (∼1,000 protein subunits, ∼110 MDa in humans), the NPC has remained one of the foremost challenges for structure determination. Structural studies have now provided atomic-resolution crystal structures of most nucleoporins. The acquisition of these structures, combined with biochemical reconstitution experiments, cross-linking mass spectrometry, and cryo-electron tomography, has facilitated the determination of the near-atomic overall architecture of the symmetric core of the human, fungal, and algal NPCs. Here, we discuss the insights gained from these new advances and outstanding issues regarding NPC structure and function. The powerful combination of bottom-up and top-down approaches toward determining the structure of the NPC offers a paradigm for uncovering the architectures of other complex biological machines to near-atomic resolution.
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Affiliation(s)
- Daniel H Lin
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA;
| | - André Hoelz
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA;
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25
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Fantastic nuclear envelope herniations and where to find them. Biochem Soc Trans 2018; 46:877-889. [PMID: 30026368 DOI: 10.1042/bst20170442] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 05/02/2018] [Accepted: 05/04/2018] [Indexed: 12/19/2022]
Abstract
Morphological abnormalities of the bounding membranes of the nucleus have long been associated with human diseases from cancer to premature aging to neurodegeneration. Studies over the past few decades support that there are both cell intrinsic and extrinsic factors (e.g. mechanical force) that can lead to nuclear envelope 'herniations', a broad catch-all term that reveals little about the underlying molecular mechanisms that contribute to these morphological defects. While there are many genetic perturbations that could ultimately change nuclear shape, here, we focus on a subset of nuclear envelope herniations that likely arise as a consequence of disrupting physiological nuclear membrane remodeling pathways required to maintain nuclear envelope homeostasis. For example, stalling of the interphase nuclear pore complex (NPC) biogenesis pathway and/or triggering of NPC quality control mechanisms can lead to herniations in budding yeast, which are remarkably similar to those observed in human disease models of early-onset dystonia. By also examining the provenance of nuclear envelope herniations associated with emerging nuclear autophagy and nuclear egress pathways, we will provide a framework to help understand the molecular pathways that contribute to nuclear deformation.
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26
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Dai XX, Xiong H, Zhang M, Sun S, Xiong B. Zfp207 is a Bub3 binding protein regulating meiotic chromosome alignment in mouse oocytes. Oncotarget 2017; 7:30155-65. [PMID: 27177335 PMCID: PMC5058671 DOI: 10.18632/oncotarget.9310] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 05/01/2016] [Indexed: 02/07/2023] Open
Abstract
Zinc finger proteins are a massive, diverse family of proteins that serve a wide variety of biological functions. However, the roles of them during meiosis are not yet clearly defined. Here, we report that Zfp207 localizes at the kinetochores during mouse oocyte meiotic maturation. Depletion of Zfp207 leads to a significantly higher proportion of impaired spindle organization and misaligned chromosomes in oocytes. This is coupled with the defective kinetochore-microtubule attachments, and resultantly increasing incidence of aneuploid metaphase II eggs. The precocious polar body extrusion and escape of metaphase I arrest induced by nocodazole treatment in Zfp207-depleted oocytes indicates that Zfp207 is essential for activation of SAC (Spindle Assembly Checkpoint) activity. Notably, we find that Zfp207 binds to Bub3 to form a complex and maintains its protein level in oocytes, and that overexpression of Bub3 is able to partially rescue the occurrence of aneuploid eggs in Zfp207-depleted oocytes. Collectively, we identify Zfp207 as a novel Bub3 binding protein in oocytes which plays an important role in controlling meiotic chromosome alignment and SAC function.
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Affiliation(s)
- Xiao Xin Dai
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Hao Xiong
- The First Clinical Medical College, School of Medicine, Nanchang University, Nanchang, China
| | - Mianqun Zhang
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Shaochen Sun
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Bo Xiong
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
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27
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Onischenko E, Tang JH, Andersen KR, Knockenhauer KE, Vallotton P, Derrer CP, Kralt A, Mugler CF, Chan LY, Schwartz TU, Weis K. Natively Unfolded FG Repeats Stabilize the Structure of the Nuclear Pore Complex. Cell 2017; 171:904-917.e19. [PMID: 29033133 DOI: 10.1016/j.cell.2017.09.033] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Revised: 08/25/2017] [Accepted: 09/19/2017] [Indexed: 12/30/2022]
Abstract
Nuclear pore complexes (NPCs) are ∼100 MDa transport channels assembled from multiple copies of ∼30 nucleoporins (Nups). One-third of these Nups contain phenylalanine-glycine (FG)-rich repeats, forming a diffusion barrier, which is selectively permeable for nuclear transport receptors that interact with these repeats. Here, we identify an additional function of FG repeats in the structure and biogenesis of the yeast NPC. We demonstrate that GLFG-containing FG repeats directly bind to multiple scaffold Nups in vitro and act as NPC-targeting determinants in vivo. Furthermore, we show that the GLFG repeats of Nup116 function in a redundant manner with Nup188, a nonessential scaffold Nup, to stabilize critical interactions within the NPC scaffold needed for late steps of NPC assembly. Our results reveal a previously unanticipated structural role for natively unfolded GLFG repeats as Velcro to link NPC subcomplexes and thus add a new layer of connections to current models of the NPC architecture.
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Affiliation(s)
- Evgeny Onischenko
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule Zürich, Otto-Stern-Weg 3, CH-8093 Zurich, Switzerland
| | - Jeffrey H Tang
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule Zürich, Otto-Stern-Weg 3, CH-8093 Zurich, Switzerland
| | - Kasper R Andersen
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Kevin E Knockenhauer
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Pascal Vallotton
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule Zürich, Otto-Stern-Weg 3, CH-8093 Zurich, Switzerland
| | - Carina P Derrer
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule Zürich, Otto-Stern-Weg 3, CH-8093 Zurich, Switzerland
| | - Annemarie Kralt
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule Zürich, Otto-Stern-Weg 3, CH-8093 Zurich, Switzerland
| | - Christopher F Mugler
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Leon Y Chan
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Thomas U Schwartz
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Karsten Weis
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule Zürich, Otto-Stern-Weg 3, CH-8093 Zurich, Switzerland.
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28
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Zander G, Kramer W, Seel A, Krebber H. Saccharomyces cerevisiae Gle2/Rae1 is involved in septin organization, essential for cell cycle progression. Yeast 2017; 34:459-470. [PMID: 28776765 PMCID: PMC6472880 DOI: 10.1002/yea.3249] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 06/29/2017] [Accepted: 07/28/2017] [Indexed: 01/22/2023] Open
Abstract
Gle2/Rae1 is highly conserved from yeast to humans and has been described as an mRNA export factor. Additionally, it is implicated in the anaphase-promoting complex-mediated cell cycle regulation in higher eukaryotes. Here we identify an involvement for Saccharomyces cerevisiae Gle2 in septin organization, which is crucial for cell cycle progression and cell division. Gle2 genetically and physically interacts with components of the septin ring. Importantly, deletion of GLE2 leads to elongated buds, severe defects in septin-assembly and their cellular mislocalization. Septin-ring formation is triggered by the septin-regulating GTPase Cdc42, which establishes and maintains cell polarity. Additionally, activity of the master cell cycle regulator Cdc28 (Cdk1) is needed, which is, besides other functions, also required for G2 /M-transition, and in yeast particularly responsible for initiating the apical-isotropic switch. We show genetic and physical interactions of Gle2 with both Cdc42 and Cdc28. Most importantly, we find that gle2∆ severely mislocalizes Cdc42, leading to defects in septin-complex formation and cell division. Thus, our findings suggest that Gle2 participates in the efficient organization of the septin assembly network, where it might act as a scaffold protein. © 2017 The Authors. Yeast published by John Wiley & Sons, Ltd.
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Affiliation(s)
- Gesa Zander
- Abteilung für Molekulare Genetik, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August Universität Göttingen, Göttingen, Germany
| | - Wilfried Kramer
- Abteilung für Molekulare Genetik, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August Universität Göttingen, Göttingen, Germany
| | - Anika Seel
- Abteilung für Molekulare Genetik, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August Universität Göttingen, Göttingen, Germany
| | - Heike Krebber
- Abteilung für Molekulare Genetik, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August Universität Göttingen, Göttingen, Germany
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29
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Beck M, Hurt E. The nuclear pore complex: understanding its function through structural insight. Nat Rev Mol Cell Biol 2016; 18:73-89. [PMID: 27999437 DOI: 10.1038/nrm.2016.147] [Citation(s) in RCA: 422] [Impact Index Per Article: 52.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Nuclear pore complexes (NPCs) fuse the inner and outer nuclear membranes to form channels across the nuclear envelope. They are large macromolecular assemblies with a complex composition and diverse functions. Apart from facilitating nucleocytoplasmic transport, NPCs are involved in chromatin organization, the regulation of gene expression and DNA repair. Understanding the molecular mechanisms underlying these functions has been hampered by a lack of structural knowledge about the NPC. The recent convergence of crystallographic and biochemical in vitro analysis of nucleoporins (NUPs), the components of the NPC, with cryo-electron microscopic imaging of the entire NPC in situ has provided first pseudo-atomic view of its central core and revealed that an unexpected network of short linear motifs is an important spatial organization principle. These breakthroughs have transformed the way we understand NPC structure, and they provide an important base for functional investigations, including the elucidation of the molecular mechanisms underlying clinically manifested mutations of the nucleocytoplasmic transport system.
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Affiliation(s)
- Martin Beck
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, Meyerhofstrasse 1, Heidelberg D-69117, Germany
| | - Ed Hurt
- Biochemistry Center of Heidelberg University, INF328, Heidelberg D-69120, Germany
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30
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Abstract
The spindle assembly checkpoint is a safeguard mechanism that coordinates cell-cycle progression during mitosis with the state of chromosome attachment to the mitotic spindle. The checkpoint prevents mitotic cells from exiting mitosis in the presence of unattached or improperly attached chromosomes, thus avoiding whole-chromosome gains or losses and their detrimental effects on cell physiology. Here, I review a considerable body of recent progress in the elucidation of the molecular mechanisms underlying checkpoint signaling, and identify a number of unresolved questions.
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Affiliation(s)
- Andrea Musacchio
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany; Centre for Medical Biotechnology, Faculty of Biology, University Duisburg-Essen, Essen, Germany.
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31
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Linker Nups connect the nuclear pore complex inner ring with the outer ring and transport channel. Nat Struct Mol Biol 2015; 22:774-81. [DOI: 10.1038/nsmb.3084] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 08/10/2015] [Indexed: 11/08/2022]
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32
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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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33
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Schmidt HB, Görlich D. Nup98 FG domains from diverse species spontaneously phase-separate into particles with nuclear pore-like permselectivity. eLife 2015; 4. [PMID: 25562883 PMCID: PMC4283134 DOI: 10.7554/elife.04251] [Citation(s) in RCA: 217] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 11/20/2014] [Indexed: 01/28/2023] Open
Abstract
Nuclear pore complexes (NPCs) conduct massive transport mediated by shuttling nuclear transport receptors (NTRs), while keeping nuclear and cytoplasmic contents separated. The NPC barrier in Xenopus relies primarily on the intrinsically disordered FG domain of Nup98. We now observed that Nup98 FG domains of mammals, lancelets, insects, nematodes, fungi, plants, amoebas, ciliates, and excavates spontaneously and rapidly phase-separate from dilute (submicromolar) aqueous solutions into characteristic 'FG particles'. This required neither sophisticated experimental conditions nor auxiliary eukaryotic factors. Instead, it occurred already during FG domain expression in bacteria. All Nup98 FG phases rejected inert macromolecules and yet allowed far larger NTR cargo complexes to rapidly enter. They even recapitulated the observations that large cargo-domains counteract NPC passage of NTR⋅cargo complexes, while cargo shielding and increased NTR⋅cargo surface-ratios override this inhibition. Their exquisite NPC-typical sorting selectivity and strong intrinsic assembly propensity suggest that Nup98 FG phases can form in authentic NPCs and indeed account for the permeability properties of the pore.
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Affiliation(s)
- Hermann Broder Schmidt
- Department of Cellular Logistics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Dirk Görlich
- Department of Cellular Logistics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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34
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Toledo CM, Herman JA, Olsen JB, Ding Y, Corrin P, Girard EJ, Olson JM, Emili A, DeLuca JG, Paddison PJ. BuGZ is required for Bub3 stability, Bub1 kinetochore function, and chromosome alignment. Dev Cell 2014; 28:282-94. [PMID: 24462187 DOI: 10.1016/j.devcel.2013.12.014] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Revised: 12/12/2013] [Accepted: 12/20/2013] [Indexed: 01/01/2023]
Abstract
During mitosis, the spindle assembly checkpoint (SAC) monitors the attachment of kinetochores (KTs) to the plus ends of spindle microtubules (MTs) and prevents anaphase onset until chromosomes are aligned and KTs are under proper tension. Here, we identify a SAC component, BuGZ/ZNF207, from an RNAi viability screen in human glioblastoma multiforme (GBM) brain tumor stem cells. BuGZ binds to and stabilizes Bub3 during interphase and mitosis through a highly conserved GLE2p-binding sequence (GLEBS) domain. Inhibition of BuGZ results in loss of both Bub3 and its binding partner Bub1 from KTs, reduction of Bub1-dependent phosphorylation of centromeric histone H2A, attenuation of KT-based Aurora B kinase activity, and lethal chromosome congression defects in cancer cells. Phylogenetic analysis indicates that BuGZ orthologs are highly conserved among eukaryotes, but are conspicuously absent from budding and fission yeasts. These findings suggest that BuGZ has evolved to facilitate Bub3 activity and chromosome congression in higher eukaryotes.
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Affiliation(s)
- Chad M Toledo
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195, USA
| | - Jacob A Herman
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Jonathan B Olsen
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Yu Ding
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Philip Corrin
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Emily J Girard
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - James M Olson
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Andrew Emili
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Jennifer G DeLuca
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA.
| | - Patrick J Paddison
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195, USA.
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35
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Yarbrough ML, Mata MA, Sakthivel R, Fontoura BMA. Viral subversion of nucleocytoplasmic trafficking. Traffic 2013; 15:127-40. [PMID: 24289861 PMCID: PMC3910510 DOI: 10.1111/tra.12137] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 10/27/2013] [Accepted: 10/31/2013] [Indexed: 12/22/2022]
Abstract
Trafficking of proteins and RNA into and out of the nucleus occurs through the nuclear pore complex (NPC). Because of its critical function in many cellular processes, the NPC and transport factors are common targets of several viruses that disrupt key constituents of the machinery to facilitate viral replication. Many viruses such as poliovirus and severe acute respiratory syndrome (SARS) virus inhibit protein import into the nucleus, whereas viruses such as influenza A virus target and disrupt host mRNA nuclear export. Current evidence indicates that these viruses may employ such strategies to avert the host immune response. Conversely, many viruses co‐opt nucleocytoplasmic trafficking to facilitate transport of viral RNAs. As viral proteins interact with key regulators of the host nuclear transport machinery, viruses have served as invaluable tools of discovery that led to the identification of novel constituents of nuclear transport pathways. This review explores the importance of nucleocytoplasmic trafficking to viral pathogenesis as these studies revealed new antiviral therapeutic strategies and exposed previously unknown cellular mechanisms. Further understanding of nuclear transport pathways will determine whether such therapeutics will be useful treatments for important human pathogens.
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Affiliation(s)
- Melanie L Yarbrough
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, 75390-9039, USA
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36
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Insights into dynamic mitotic chromatin organization through the NIMA kinase suppressor SonC, a chromatin-associated protein involved in the DNA damage response. Genetics 2013; 196:177-95. [PMID: 24214344 DOI: 10.1534/genetics.113.156745] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The nuclear pore complex proteins SonA and SonB, the orthologs of mammalian RAE1 and NUP98, respectively, were identified in Aspergillus nidulans as cold-sensitive suppressors of a temperature-sensitive allele of the essential mitotic NIMA kinase (nimA1). Subsequent analyses found that sonB1 mutants exhibit temperature-dependent DNA damage sensitivity. To understand this pathway further, we performed a genetic screen to isolate additional conditional DNA damage-sensitive suppressors of nimA1. We identified two new alleles of SonA and four intragenic nimA mutations that suppress the temperature sensitivity of the nimA1 mutant. In addition, we identified SonC, a previously unstudied binuclear zinc cluster protein involved with NIMA and the DNA damage response. Like sonA and sonB, sonC is an essential gene. SonC localizes to nuclei and partially disperses during mitosis. When the nucleolar organizer region (NOR) undergoes mitotic condensation and removal from the nucleolus, nuclear SonC and histone H1 localize in a mutually exclusive manner with H1 being removed from the NOR region and SonC being absent from the end of the chromosome beyond the NOR. This region of chromatin is adjacent to a cluster of nuclear pore complexes to which NIMA localizes last during its progression around the nuclear envelope during initiation of mitosis. The results genetically extend the NIMA regulatory system to include a protein with selective large-scale chromatin location observed during mitosis. The data suggest a model in which NIMA and SonC, its new chromatin-associated suppressor, might help to orchestrate global chromatin states during mitosis and the DNA damage response.
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37
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Primorac I, Weir JR, Chiroli E, Gross F, Hoffmann I, van Gerwen S, Ciliberto A, Musacchio A. Bub3 reads phosphorylated MELT repeats to promote spindle assembly checkpoint signaling. eLife 2013; 2:e01030. [PMID: 24066227 PMCID: PMC3779320 DOI: 10.7554/elife.01030] [Citation(s) in RCA: 175] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Accepted: 08/21/2013] [Indexed: 12/31/2022] Open
Abstract
Regulation of macromolecular interactions by phosphorylation is crucial in signaling networks. In the spindle assembly checkpoint (SAC), which enables errorless chromosome segregation, phosphorylation promotes recruitment of SAC proteins to tensionless kinetochores. The SAC kinase Mps1 phosphorylates multiple Met-Glu-Leu-Thr (MELT) motifs on the kinetochore subunit Spc105/Knl1. The phosphorylated MELT motifs (MELTP) then promote recruitment of downstream signaling components. How MELTP motifs are recognized is unclear. In this study, we report that Bub3, a 7-bladed β-propeller, is the MELTP reader. It contains an exceptionally well-conserved interface that docks the MELTP sequence on the side of the β-propeller in a previously unknown binding mode. Mutations targeting the Bub3 interface prevent kinetochore recruitment of the SAC kinase Bub1. Crucially, they also cause a checkpoint defect, showing that recognition of phosphorylated targets by Bub3 is required for checkpoint signaling. Our data provide the first detailed mechanistic insight into how phosphorylation promotes recruitment of checkpoint proteins to kinetochores. DOI:http://dx.doi.org/10.7554/eLife.01030.001 The cell cycle is the process by which a cell divides to produce two near-identical daughter cells. Two crucial parts of the cell cycle are the duplication of the chromosomes in the original cell, and the segregation of these chromosomes between the two daughter cells. These and other parts of the cell cycle are strictly regulated to prevent errors, which can lead to cancer and other diseases. After chromosome duplication has taken place, the pairs of identical chromosomes, known as sister chromatids, remain tightly bound to each other. These sister chromatids line up in the middle of the cell, with protein filaments called microtubules connecting them to a bipolar structure called the spindle. For the cell to divide correctly, the sister chromatids in each pair must be connected to opposite poles of the spindle. A signalling network known as the spindle assembly checkpoint (SAC) ensures that the sister chromatids have enough time to line up correctly and to correct possible problems. Once everything is in place, the SAC releases its ‘break’, and the microtubules then pull the sister chromatids away from each other. This way, each daughter cell receives the same complement of chromosomes that was present in the mother cell. The microtubules are not directly attached to the sister chromatids but to protein complexes called kinetochores that assemble on each sister chromatid. In particular, each microtubule binds to a very large protein complex called the KMN network. Knl1, which is part of this network, recruits two SAC proteins–Bub1 and Bub3–to the kinetochore. It is known that a phosphate group is added to Knl1 when the SAC is active, and that Knl1 can only recruit Bub1 and Bub3 after it has been phosphorylated. However, the details of the interactions between Knl1, Bub1 and Bub3 are not understood, and it is not clear whether these interactions are essential for the SAC. Now Primorac et al. have shown that Bub3 binds directly to Knl1 through a region that contains multiple MELT motifs (where M, E, L and T are all amino acids), and that this interaction only happens if these ‘MELT repeats’ have been phosphorylated. Moreover, once bound to the Knl1, Bub3 then recruits Bub1 to the kinetochore. By showing that the recognition of phosphorylated Knl1 by the Bub1-Bub3 complex has a central role in the spindle assembly checkpoint, these results highlight the importance of phosphorylation as a way of regulating the timing of events during the cell cycle. DOI:http://dx.doi.org/10.7554/eLife.01030.002
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Affiliation(s)
- Ivana Primorac
- Department of Mechanistic Cell Biology , Max Planck Institute of Molecular Physiology , Dortmund , Germany
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Occhipinti L, Chang Y, Altvater M, Menet AM, Kemmler S, Panse VG. Non-FG mediated transport of the large pre-ribosomal subunit through the nuclear pore complex by the mRNA export factor Gle2. Nucleic Acids Res 2013; 41:8266-79. [PMID: 23907389 PMCID: PMC3783196 DOI: 10.1093/nar/gkt675] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Multiple export receptors passage bound pre-ribosomes through nuclear pore complexes (NPCs) by transiently interacting with the Phe-Gly (FG) meshwork of their transport channels. Here, we reveal how the non-FG interacting yeast mRNA export factor Gly-Leu-FG lethal 2 (Gle2) functions in the export of the large pre-ribosomal subunit (pre-60S). Structure-guided studies uncovered conserved platforms used by Gle2 to export pre-60S: an uncharacterized basic patch required to bind pre-60S, and a second surface that makes non-FG contacts with the nucleoporin Nup116. A basic patch mutant of Gle2 is able to function in mRNA export, but not pre-60S export. Thus, Gle2 provides a distinct interaction platform to transport pre-60S to the cytoplasm. Notably, Gle2’s interaction platforms become crucial for pre-60S export when FG-interacting receptors are either not recruited to pre-60S or are impaired. We propose that large complex cargos rely on non-FG as well as FG-interactions for their efficient translocation through the nuclear pore complex channel.
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Affiliation(s)
- Laura Occhipinti
- Department of Biology (D-BIOL), Institute of Biochemistry (IBC), ETH Zurich, Schafmattstrasse 18, CH-8093 Zurich, Switzerland and MLS Program, Life Sciences Zurich Graduate School, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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Kuss SK, Mata MA, Zhang L, Fontoura BMA. Nuclear imprisonment: viral strategies to arrest host mRNA nuclear export. Viruses 2013; 5:1824-49. [PMID: 23872491 PMCID: PMC3738964 DOI: 10.3390/v5071824] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 06/27/2013] [Accepted: 07/11/2013] [Indexed: 12/15/2022] Open
Abstract
Viruses possess many strategies to impair host cellular responses to infection. Nuclear export of host messenger RNAs (mRNA) that encode antiviral factors is critical for antiviral protein production and control of viral infections. Several viruses have evolved sophisticated strategies to inhibit nuclear export of host mRNAs, including targeting mRNA export factors and nucleoporins to compromise their roles in nucleo-cytoplasmic trafficking of cellular mRNA. Here, we present a review of research focused on suppression of host mRNA nuclear export by viruses, including influenza A virus and vesicular stomatitis virus, and the impact of this viral suppression on host antiviral responses.
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Affiliation(s)
- Sharon K Kuss
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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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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Sampathkumar P, Kim SJ, Manglicmot D, Bain KT, Gilmore J, Gheyi T, Phillips J, Pieper U, Fernandez-Martinez J, Franke JD, Matsui T, Tsuruta H, Atwell S, Thompson DA, Emtage JS, Wasserman SR, Rout MP, Sali A, Sauder JM, Almo SC, Burley SK. Atomic structure of the nuclear pore complex targeting domain of a Nup116 homologue from the yeast, Candida glabrata. Proteins 2012; 80:2110-6. [PMID: 22544723 PMCID: PMC3686472 DOI: 10.1002/prot.24102] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 04/05/2012] [Accepted: 04/11/2012] [Indexed: 01/07/2023]
Abstract
The nuclear pore complex (NPC), embedded in the nuclear envelope, is a large, dynamic molecular assembly that facilitates exchange of macromolecules between the nucleus and the cytoplasm. The yeast NPC is an eightfold symmetric annular structure composed of ~456 polypeptide chains contributed by ~30 distinct proteins termed nucleoporins. Nup116, identified only in fungi, plays a central role in both protein import and mRNA export through the NPC. Nup116 is a modular protein with N-terminal "FG" repeats containing a Gle2p-binding sequence motif and a NPC targeting domain at its C-terminus. We report the crystal structure of the NPC targeting domain of Candida glabrata Nup116, consisting of residues 882-1034 [CgNup116(882-1034)], at 1.94 Å resolution. The X-ray structure of CgNup116(882-1034) is consistent with the molecular envelope determined in solution by small-angle X-ray scattering. Structural similarities of CgNup116(882-1034) with homologous domains from Saccharomyces cerevisiae Nup116, S. cerevisiae Nup145N, and human Nup98 are discussed.
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Stuwe T, von Borzyskowski LS, Davenport AM, Hoelz A. Molecular basis for the anchoring of proto-oncoprotein Nup98 to the cytoplasmic face of the nuclear pore complex. J Mol Biol 2012; 419:330-46. [PMID: 22480613 DOI: 10.1016/j.jmb.2012.03.024] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 03/22/2012] [Accepted: 03/26/2012] [Indexed: 01/09/2023]
Abstract
The cytoplasmic filament nucleoporins of the nuclear pore complex (NPC) are critically involved in nuclear export and remodeling of mRNA ribonucleoprotein particles and are associated with various human malignancies. Here, we report the crystal structure of the Nup98 C-terminal autoproteolytic domain, frequently missing from leukemogenic forms of the protein, in complex with the N-terminal domain of Nup82 and the C-terminal tail fragment of Nup159. The Nup82 β propeller serves as a noncooperative binding platform for both binding partners. Interaction of Nup98 with Nup82 occurs through a reciprocal exchange of loop structures. Strikingly, the same Nup98 groove promiscuously interacts with Nup82 and Nup96 in a mutually excusive fashion. Simultaneous disruption of both Nup82 interactions in yeast causes severe defects in mRNA export, while the severing of a single interaction is tolerated. Thus, the cytoplasmic filament network of the NPC is robust, consistent with its essential function in nucleocytoplasmic transport.
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Affiliation(s)
- Tobias Stuwe
- California Institute of Technology, Division of Chemistry and Chemical Engineering, 1200 East California Boulevard, Pasadena, CA 91125, USA
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Tetenbaum-Novatt J, Hough LE, Mironska R, McKenney AS, Rout MP. Nucleocytoplasmic transport: a role for nonspecific competition in karyopherin-nucleoporin interactions. Mol Cell Proteomics 2012; 11:31-46. [PMID: 22357553 DOI: 10.1074/mcp.m111.013656] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nucleocytoplasmic transport occurs through the nuclear pore complex (NPC), which in yeast is a ~50 MDa complex consisting of ~30 different proteins. Small molecules can freely exchange through the NPC, but macromolecules larger than ~40 kDa must be aided across by transport factors, most of which belong to a related family of proteins termed karyopherins (Kaps). These transport factors bind to the disordered phenylalanine-glycine (FG) repeat domains in a family of NPC proteins termed FG nups, and this specific binding allows the transport factors to cross the NPC. However, we still know little in terms of the molecular and kinetic details regarding how this binding translates to selective passage of transport factors across the NPC. Here we show that the specific interactions between Kaps and FG nups are strongly modulated by the presence of a cellular milieu whose proteins appear to act as very weak competitors that nevertheless collectively can reduce Kap/FG nup affinities by several orders of magnitude. Without such modulation, the avidities between Kaps and FG nups measured in vitro are too tight to be compatible with the rapid transport kinetics observed in vivo. We modeled the multivalent interactions between the disordered repeat binding sites in the FG nups and multiple cognate binding sites on Kap, showing that they should indeed be sensitive to even weakly binding competitors; the introduction of such competition reduces the availability of these binding sites, dramatically lowering the avidity of their specific interactions and allowing rapid nuclear transport.
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Affiliation(s)
- Jaclyn Tetenbaum-Novatt
- The Laboratory of Cellular and Structural Biology, The Rockefeller University, New York, New York 10065, USA
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Nuclear export as a key arbiter of "mRNA identity" in eukaryotes. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1819:566-77. [PMID: 22248619 DOI: 10.1016/j.bbagrm.2011.12.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 12/23/2011] [Accepted: 12/29/2011] [Indexed: 01/15/2023]
Abstract
Over the past decade, various studies have indicated that most of the eukaryotic genome is transcribed at some level. The pervasiveness of transcription might seem surprising when one considers that only a quarter of the human genome comprises genes (including exons and introns) and less than 2% codes for protein. This conundrum is partially explained by the unique evolutionary pressures that are imposed on species with small population sizes, such as eukaryotes. These conditions promote the expansion of introns and non-functional intergenic DNA, and the accumulation of cryptic transcriptional start sites. As a result, the eukaryotic gene expression machinery must effectively evaluate whether or not a transcript has all the hallmarks of a protein-coding mRNA. If a transcript contains these features, then positive feedback loops are activated to further stimulate its transcription, processing, nuclear export and ultimately, translation. However if a transcript lacks features associated with "mRNA identity", then the RNA is degraded and/or used to inhibit further transcription and translation of the gene. Here we discuss how mRNA identity is assessed by the nuclear export machinery in order to extract meaningful information from the eukaryotic genome. In the process, we provide an explanation of why certain sequences that are enriched in protein-coding genes, such as the signal sequence coding region, promote mRNA nuclear export in vertebrates. This article is part of a Special Issue entitled: Nuclear Transport and RNA Processing.
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Structural and functional analysis of an essential nucleoporin heterotrimer on the cytoplasmic face of the nuclear pore complex. Proc Natl Acad Sci U S A 2011; 108:16571-6. [PMID: 21930948 DOI: 10.1073/pnas.1112846108] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
So far, only a few of the interactions between the ≈ 30 nucleoporins comprising the modular structure of the nuclear pore complex have been defined at atomic resolution. Here we report the crystal structure, at 2.6 Å resolution, of a heterotrimeric complex, composed of fragments of three cytoplasmically oriented nucleoporins of yeast: Nup82, Nup116, and Nup159. Our data show that the Nup82 fragment, representing more than the N-terminal half of the molecule, folds into an extensively decorated, seven-bladed β-propeller that forms the centerpiece of this heterotrimeric complex and anchors both a C-terminal fragment of Nup116 and the C-terminal tail of Nup159. Binding between Nup116 and Nup82 is mutually reinforced via two loops, one emanating from the Nup82 β-propeller and the other one from the β-sandwich fold of Nup116, each contacting binding pockets in their counterparts. The Nup82-Nup159 interaction occurs through an amphipathic α-helix of Nup159, which is cradled in a large hydrophobic groove that is generated from several large surface decorations of the Nup82 β-propeller. Although Nup159 and Nup116 fragments bind to the Nup82 β-propeller in close vicinity, there are no direct contacts between them, consistent with the noncooperative binding that was detected biochemically. Extensive mutagenesis delineated hot-spot residues for these interactions. We also showed that the Nup82 β-propeller binds to other yeast Nup116 family members, Nup145N, Nup100 and to the mammalian homolog, Nup98. Notably, each of the three nucleoporins contains additional nuclear pore complex binding sites, distinct from those that were defined here in the heterotrimeric Nup82•Nup159•Nup116 complex.
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Funasaka T, Wong RW. The role of nuclear pore complex in tumor microenvironment and metastasis. Cancer Metastasis Rev 2011; 30:239-51. [PMID: 21298575 DOI: 10.1007/s10555-011-9287-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
One of the main reasons for cancer mortality is caused by the highly invasive behavior of cancer cells, which often due to aggressive metastasis. Metastasis is mediated by various growth factors and cytokines, operating through numerous signaling pathways. Remarkably, all these metastatic signaling pathways must enter the nucleus through a single gatekeeper, the nuclear pore complex (NPC). NPCs are the only gateway between the cytoplasm and the nucleus. NPCs are among the largest proteinaceous assemblies in the cell and are composed of multiple copies of around 30 different proteins called nucleoporins. Here, we review what is currently known about the NPC, and its role in the mechanisms of tumor progression. We will also explore potential strategies to target metastatic pathways by manipulating the karyopherins (importins/exportins) of nucleocytoplasmic traffic through NPCs.
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Affiliation(s)
- Tatsuyoshi Funasaka
- Frontier Science Organization, 1/F Cancer Research Institute, Kanazawa University, Kanazawa, Ishikawa, 920-1192, Japan
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Structural and functional analysis of the interaction between the nucleoporin Nup98 and the mRNA export factor Rae1. Proc Natl Acad Sci U S A 2010; 107:10406-11. [PMID: 20498086 DOI: 10.1073/pnas.1005389107] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The export of mRNAs is a multistep process, involving the packaging of mRNAs into messenger ribonucleoprotein particles (mRNPs), their transport through nuclear pore complexes, and mRNP remodeling events prior to translation. Ribonucleic acid export 1 (Rae1) and Nup98 are evolutionarily conserved mRNA export factors that are targeted by the vesicular stomatitis virus matrix protein to inhibit host cell nuclear export. Here, we present the crystal structure of human Rae1 in complex with the Gle2-binding sequence (GLEBS) of Nup98 at 1.65 A resolution. Rae1 forms a seven-bladed beta-propeller with several extensive surface loops. The Nup98 GLEBS motif forms an approximately 50-A-long hairpin that binds with its C-terminal arm to an essentially invariant hydrophobic surface that extends over the entire top face of the Rae1 beta-propeller. The C-terminal arm of the GLEBS hairpin is necessary and sufficient for Rae1 binding, and we identify a tandem glutamate element in this arm as critical for complex formation. The Rae1*Nup98(GLEBS) surface features an additional conserved patch with a positive electrostatic potential, and we demonstrate that the complex possesses single-stranded RNA-binding capability. Together, these data suggest that the Rae1*Nup98 complex directly binds to the mRNP at several stages of the mRNA export pathway.
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Chadrin A, Hess B, San Roman M, Gatti X, Lombard B, Loew D, Barral Y, Palancade B, Doye V. Pom33, a novel transmembrane nucleoporin required for proper nuclear pore complex distribution. ACTA ACUST UNITED AC 2010; 189:795-811. [PMID: 20498018 PMCID: PMC2878943 DOI: 10.1083/jcb.200910043] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A previously unrecognized pore membrane protein, Pom33, stabilizes the interface between the nuclear envelope and the NPC to facilitate NPC biogenesis and spatial organization. The biogenesis of nuclear pore complexes (NPCs) represents a paradigm for the assembly of high-complexity macromolecular structures. So far, only three integral pore membrane proteins are known to function redundantly in NPC anchoring within the nuclear envelope. Here, we describe the identification and functional characterization of Pom33, a novel transmembrane protein dynamically associated with budding yeast NPCs. Pom33 becomes critical for yeast viability in the absence of a functional Nup84 complex or Ndc1 interaction network, which are two core NPC subcomplexes, and associates with the reticulon Rtn1. Moreover, POM33 loss of function impairs NPC distribution, a readout for a subset of genes required for pore biogenesis, including members of the Nup84 complex and RTN1. Consistently, we show that Pom33 is required for normal NPC density in the daughter nucleus and for proper NPC biogenesis and/or stability in the absence of Nup170. We hypothesize that, by modifying or stabilizing the nuclear envelope–NPC interface, Pom33 may contribute to proper distribution and/or efficient assembly of nuclear pores.
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Affiliation(s)
- Anne Chadrin
- Institut Jacques Monod, UMR 7592, Centre National de la Recherche Scientifique/Université Paris Diderot, 75013 Paris, France
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Flexible gates: dynamic topologies and functions for FG nucleoporins in nucleocytoplasmic transport. EUKARYOTIC CELL 2009; 8:1814-27. [PMID: 19801417 DOI: 10.1128/ec.00225-09] [Citation(s) in RCA: 179] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The nuclear envelope is a physical barrier between the nucleus and cytoplasm and, as such, separates the mechanisms of transcription from translation. This compartmentalization of eukaryotic cells allows spatial regulation of gene expression; however, it also necessitates a mechanism for transport between the nucleus and cytoplasm. Macromolecular trafficking of protein and RNA occurs exclusively through nuclear pore complexes (NPCs), specialized channels spanning the nuclear envelope. A novel family of NPC proteins, the FG-nucleoporins (FG-Nups), coordinates and potentially regulates NPC translocation. The extensive repeats of phenylalanine-glycine (FG) in each FG-Nup directly bind to shuttling transport receptors moving through the NPC. In addition, FG-Nups are essential components of the nuclear permeability barrier. In this review, we discuss the structural features, cellular functions, and evolutionary conservation of the FG-Nups.
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Dawson TR, Lazarus MD, Hetzer MW, Wente SR. ER membrane-bending proteins are necessary for de novo nuclear pore formation. ACTA ACUST UNITED AC 2009; 184:659-75. [PMID: 19273614 PMCID: PMC2686408 DOI: 10.1083/jcb.200806174] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Nucleocytoplasmic transport occurs exclusively through nuclear pore complexes (NPCs) embedded in pores formed by inner and outer nuclear membrane fusion. The mechanism for de novo pore and NPC biogenesis remains unclear. Reticulons (RTNs) and Yop1/DP1 are conserved membrane protein families required to form and maintain the tubular endoplasmic reticulum (ER) and the postmitotic nuclear envelope. In this study, we report that members of the RTN and Yop1/DP1 families are required for nuclear pore formation. Analysis of Saccharomyces cerevisiae prp20-G282S and nup133Δ NPC assembly mutants revealed perturbations in Rtn1–green fluorescent protein (GFP) and Yop1-GFP ER distribution and colocalization to NPC clusters. Combined deletion of RTN1 and YOP1 resulted in NPC clustering, nuclear import defects, and synthetic lethality with the additional absence of Pom34, Pom152, and Nup84 subcomplex members. We tested for a direct role in NPC biogenesis using Xenopus laevis in vitro assays and found that anti-Rtn4a antibodies specifically inhibited de novo nuclear pore formation. We hypothesize that these ER membrane–bending proteins mediate early NPC assembly steps.
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Affiliation(s)
- T Renee Dawson
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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