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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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2
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Amm I, Weberruss M, Hellwig A, Schwarz J, Tatarek-Nossol M, Lüchtenborg C, Kallas M, Brügger B, Hurt E, Antonin W. Distinct domains in Ndc1 mediate its interaction with the Nup84 complex and the nuclear membrane. J Cell Biol 2023; 222:e202210059. [PMID: 37154843 PMCID: PMC10165475 DOI: 10.1083/jcb.202210059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 01/31/2023] [Accepted: 03/17/2023] [Indexed: 05/10/2023] Open
Abstract
Nuclear pore complexes (NPCs) are embedded in the nuclear envelope and built from ∼30 different nucleoporins (Nups) in multiple copies, few are integral membrane proteins. One of these transmembrane nucleoporins, Ndc1, is thought to function in NPC assembly at the fused inner and outer nuclear membranes. Here, we show a direct interaction of Ndc1's transmembrane domain with Nup120 and Nup133, members of the pore membrane coating Y-complex. We identify an amphipathic helix in Ndc1's C-terminal domain binding highly curved liposomes. Upon overexpression, this amphipathic motif is toxic and dramatically alters the intracellular membrane organization in yeast. Ndc1's amphipathic motif functionally interacts with related motifs in the C-terminus of the nucleoporins Nup53 and Nup59, important for pore membrane binding and interconnecting NPC modules. The essential function of Ndc1 can be suppressed by deleting the amphipathic helix from Nup53. Our data indicate that nuclear membrane and presumably NPC biogenesis depends on a balanced ratio between amphipathic motifs in diverse nucleoporins.
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Affiliation(s)
- Ingo Amm
- Heidelberg University Biochemistry Center (BZH), University of Heidelberg, Heidelberg, Germany
| | - Marion Weberruss
- Institute of Biochemistry and Molecular Cell Biology, Medical School, RWTH Aachen University, Aachen, Germany
| | - Andrea Hellwig
- Department of Neurobiology, Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
| | - Johannes Schwarz
- Heidelberg University Biochemistry Center (BZH), University of Heidelberg, Heidelberg, Germany
| | - Marianna Tatarek-Nossol
- Institute of Biochemistry and Molecular Cell Biology, Medical School, RWTH Aachen University, Aachen, Germany
| | - Christian Lüchtenborg
- Heidelberg University Biochemistry Center (BZH), University of Heidelberg, Heidelberg, Germany
| | - Martina Kallas
- Heidelberg University Biochemistry Center (BZH), University of Heidelberg, Heidelberg, Germany
| | - Britta Brügger
- Heidelberg University Biochemistry Center (BZH), University of Heidelberg, Heidelberg, Germany
| | - Ed Hurt
- Heidelberg University Biochemistry Center (BZH), University of Heidelberg, Heidelberg, Germany
| | - Wolfram Antonin
- Institute of Biochemistry and Molecular Cell Biology, Medical School, RWTH Aachen University, Aachen, Germany
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3
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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: 47] [Impact Index Per Article: 23.5] [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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4
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Raices M, D'Angelo MA. Structure, Maintenance, and Regulation of Nuclear Pore Complexes: The Gatekeepers of the Eukaryotic Genome. Cold Spring Harb Perspect Biol 2022; 14:a040691. [PMID: 34312247 PMCID: PMC8789946 DOI: 10.1101/cshperspect.a040691] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In eukaryotic cells, the genetic material is segregated inside the nucleus. This compartmentalization of the genome requires a transport system that allows cells to move molecules across the nuclear envelope, the membrane-based barrier that surrounds the chromosomes. Nuclear pore complexes (NPCs) are the central component of the nuclear transport machinery. These large protein channels penetrate the nuclear envelope, creating a passage between the nucleus and the cytoplasm through which nucleocytoplasmic molecule exchange occurs. NPCs are one of the largest protein assemblies of eukaryotic cells and, in addition to their critical function in nuclear transport, these structures also play key roles in many cellular processes in a transport-independent manner. Here we will review the current knowledge of the NPC structure, the cellular mechanisms that regulate their formation and maintenance, and we will provide a brief description of a variety of processes that NPCs regulate.
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Affiliation(s)
- Marcela Raices
- Cell and Molecular Biology of Cancer Program, NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California 92037, USA
| | - Maximiliano A D'Angelo
- Cell and Molecular Biology of Cancer Program, NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California 92037, USA
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5
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Koch BA, Staley E, Jin H, Yu HG. The ESCRT-III complex is required for nuclear pore complex sequestration and regulates gamete replicative lifespan in budding yeast meiosis. Nucleus 2021; 11:219-236. [PMID: 32893723 PMCID: PMC7529410 DOI: 10.1080/19491034.2020.1812872] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Cellular aging occurs as a cell loses its ability to maintain homeostasis. Aging cells eliminate damaged cellular compartments and other senescence factors via self-renewal. The mechanism that regulates cellular rejuvenation remains to be further elucidated. Using budding yeast gametogenesis as a model, we show here that the endosomal sorting complex required for transport (ESCRT) III regulates nuclear envelope organization. During gametogenesis, the nuclear pore complex (NPC) and other senescence factors are sequestered away from the prospore nuclei. We show that the LEM-domain protein Heh1 (Src1) facilitates the nuclear recruitment of ESCRT-III, which is required for meiotic NPC sequestration and nuclear envelope remodeling. Furthermore, ESCRT-III-mediated nuclear reorganization appears to be critical for gamete rejuvenation, as hindering this process curtails either directly or indirectly the replicative lifespan in gametes. Our findings demonstrate the importance of ESCRT-III in nuclear envelope remodeling and its potential role in eliminating senescence factors during gametogenesis.
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Affiliation(s)
- Bailey A Koch
- Department of Biological Science, The Florida State University , Tallahassee, FL, USA
| | - Elizabeth Staley
- Department of Biological Science, The Florida State University , Tallahassee, FL, USA
| | - Hui Jin
- Department of Biological Science, The Florida State University , Tallahassee, FL, USA
| | - Hong-Guo Yu
- Department of Biological Science, The Florida State University , Tallahassee, FL, USA
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6
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Ergüden B. Dhh1 is a member of the SESA network. Yeast 2018; 36:99-105. [PMID: 30346046 DOI: 10.1002/yea.3363] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 10/10/2018] [Accepted: 10/16/2018] [Indexed: 11/09/2022] Open
Abstract
The correct separation of chromosomes during mitosis is necessary to prevent genetic instability and aneuploidy, which are responsible for cancer and other diseases, and it depends on proper centrosome duplication. In a recent study, we found that Smy2 can suppress the essential role of Mps2 in the insertion of yeast centrosome into the nuclear membrane by interacting with Eap1, Scp160, and Asc1 and designated this network as SESA (Smy2, Eap1, Scp160, Asc1). Detailed analysis showed that the SESA network is part of a mechanism which regulates translation of POM34 mRNA. Thus, SESA is a system that suppresses spindle pole body duplication defects by repressing the translation of POM34 mRNA. In this study, we performed a genome-wide screening in order to identify new members of the SESA network and confirmed Dhh1 as a putative member. Dhh1 is a cytoplasmic DEAD-box helicase known to regulate translation. Therefore, we hypothesized that Dhh1 is responsible for the highly selective inhibition of POM34 mRNA by SESA.
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Affiliation(s)
- Bengü Ergüden
- Department of Bioengineering, Gebze Technical University, Kocaeli, Turkey
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7
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Duplication and Nuclear Envelope Insertion of the Yeast Microtubule Organizing Centre, the Spindle Pole Body. Cells 2018; 7:cells7050042. [PMID: 29748517 PMCID: PMC5981266 DOI: 10.3390/cells7050042] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 05/04/2018] [Accepted: 05/08/2018] [Indexed: 11/16/2022] Open
Abstract
The main microtubule organizing centre in the unicellular model organisms Saccharomyces cerevisiae and Schizosaccharomyces pompe is the spindle pole body (SPB). The SPB is a multilayer structure, which duplicates exactly once per cell cycle. Unlike higher eukaryotic cells, both yeast model organisms undergo mitosis without breakdown of the nuclear envelope (NE), a so-called closed mitosis. Therefore, in order to simultaneously nucleate nuclear and cytoplasmic MTs, it is vital to embed the SPB into the NE at least during mitosis, similarly to the nuclear pore complex (NPC). This review aims to embrace the current knowledge of the SPB duplication cycle with special emphasis on the critical step of the insertion of the new SPB into the NE.
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8
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Zhang W, Neuner A, Rüthnick D, Sachsenheimer T, Lüchtenborg C, Brügger B, Schiebel E. Brr6 and Brl1 locate to nuclear pore complex assembly sites to promote their biogenesis. J Cell Biol 2018; 217:877-894. [PMID: 29439116 PMCID: PMC5839787 DOI: 10.1083/jcb.201706024] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 11/21/2017] [Accepted: 01/10/2018] [Indexed: 12/30/2022] Open
Abstract
The conserved paralogous Brr6 and Brl1 promote NPC biogenesis in an unclear manner. Here, Zhang et al. show that both transmembrane proteins transiently associate with NPC assembly intermediates and directly promote NPC biogenesis. The paralogous Brr6 and Brl1 are conserved integral membrane proteins of the nuclear envelope (NE) with an unclear role in nuclear pore complex (NPC) biogenesis. Here, we analyzed double-degron mutants of Brr6/Brl1 to understand this function. Depletion of Brr6 and Brl1 caused defects in NPC biogenesis, whereas the already assembled NPCs remained unaffected. This NPC biogenesis defect was not accompanied by a change in lipid composition. However, Brl1 interacted with Ndc1 and Nup188 by immunoprecipitation, and with transmembrane and outer and inner ring NPC components by split yellow fluorescent protein analysis, indicating a direct role in NPC biogenesis. Consistently, we found that Brr6 and Brl1 associated with a subpopulation of NPCs and emerging NPC assembly sites. Moreover, BRL1 overexpression affected NE morphology without a change in lipid composition and completely suppressed the nuclear pore biogenesis defect of nup116Δ and gle2Δ cells. We propose that Brr6 and Brl1 transiently associate with NPC assembly sites where they promote NPC biogenesis.
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Affiliation(s)
- Wanlu Zhang
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Annett Neuner
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Diana Rüthnick
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | | | | | - Britta Brügger
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - Elmar Schiebel
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
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9
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De Magistris P, Tatarek-Nossol M, Dewor M, Antonin W. A self-inhibitory interaction within Nup155 and membrane binding are required for nuclear pore complex formation. J Cell Sci 2018; 131:jcs.208538. [PMID: 29150488 DOI: 10.1242/jcs.208538] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 11/13/2017] [Indexed: 01/02/2023] Open
Abstract
Nuclear pore complexes (NPCs) are gateways through the nuclear envelope. How they form into a structure containing three rings and integrate into the nuclear envelope remains a challenging paradigm for coordinated assembly of macro-complexes. In vertebrates, the cytoplasmic and nucleoplasmic rings of NPCs are mostly formed by multiple copies of the Nup107-Nup160 complex, whereas the central, or inner ring is composed of Nup53, Nup93, Nup155 and the two paralogues Nup188 and Nup205. Inner ring assembly is only partially understood. Using in vitro nuclear assembly reactions, we show that direct pore membrane binding of Nup155 is crucial for NPC formation. Replacing full-length Nup155 with its N-terminal β-propeller allows assembly of the outer ring components to the NPC backbone that also contains Nup53. However, further assembly, especially recruitment of the Nup93 and Nup62 complexes, is blocked. Self-interaction between the N- and C-terminal domains of Nup155 has an auto-inhibitory function that prevents interaction between the N-terminus of Nup155 and the C-terminal region of Nup53. Nup93 can overcome this block by binding to Nup53, thereby promoting formation of the inner ring and the NPC.
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Affiliation(s)
- Paola De Magistris
- Friedrich Miescher Laboratory of the Max Planck Society, Spemannstraße 39, 72076 Tübingen, Germany.,Institute of Biochemistry and Molecular Cell Biology, Medical School, RWTH Aachen University, 52074 Aachen, Germany
| | - Marianna Tatarek-Nossol
- Institute of Biochemistry and Molecular Cell Biology, Medical School, RWTH Aachen University, 52074 Aachen, Germany
| | - Manfred Dewor
- Institute of Biochemistry and Molecular Cell Biology, Medical School, RWTH Aachen University, 52074 Aachen, Germany
| | - Wolfram Antonin
- Friedrich Miescher Laboratory of the Max Planck Society, Spemannstraße 39, 72076 Tübingen, Germany .,Institute of Biochemistry and Molecular Cell Biology, Medical School, RWTH Aachen University, 52074 Aachen, Germany
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10
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Iwamoto M, Osakada H, Mori C, Fukuda Y, Nagao K, Obuse C, Hiraoka Y, Haraguchi T. Compositionally distinct nuclear pore complexes of functionally distinct dimorphic nuclei in the ciliate Tetrahymena. J Cell Sci 2017; 130:1822-1834. [PMID: 28386019 PMCID: PMC5450191 DOI: 10.1242/jcs.199398] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 04/04/2017] [Indexed: 12/14/2022] Open
Abstract
The nuclear pore complex (NPC), a gateway for nucleocytoplasmic trafficking, is composed of ∼30 different proteins called nucleoporins. It remains unknown whether the NPCs within a species are homogeneous or vary depending on the cell type or physiological condition. Here, we present evidence for compositionally distinct NPCs that form within a single cell in a binucleated ciliate. In Tetrahymena thermophila, each cell contains both a transcriptionally active macronucleus (MAC) and a germline micronucleus (MIC). By combining in silico analysis, mass spectrometry analysis for immuno-isolated proteins and subcellular localization analysis of GFP-fused proteins, we identified numerous novel components of MAC and MIC NPCs. Core members of the Nup107-Nup160 scaffold complex were enriched in MIC NPCs. Strikingly, two paralogs of Nup214 and of Nup153 localized exclusively to either the MAC or MIC NPCs. Furthermore, the transmembrane components Pom121 and Pom82 localize exclusively to MAC and MIC NPCs, respectively. Our results argue that functional nuclear dimorphism in ciliates is likely to depend on the compositional and structural specificity of NPCs.
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Affiliation(s)
- Masaaki Iwamoto
- Advanced ICT Research Institute, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan
| | - Hiroko Osakada
- Advanced ICT Research Institute, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan
| | - Chie Mori
- Advanced ICT Research Institute, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan
| | - Yasuhiro Fukuda
- Graduate School of Agriculture, Tohoku University, Osaki, Miyagi 989-6711, Japan
| | - Koji Nagao
- Graduate School of Life Science, Hokkaido University, Sapporo 001-0021, Japan
| | - Chikashi Obuse
- Graduate School of Life Science, Hokkaido University, Sapporo 001-0021, Japan
| | - Yasushi Hiraoka
- Advanced ICT Research Institute, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan.,Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan.,Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan
| | - Tokuko Haraguchi
- Advanced ICT Research Institute, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan .,Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan.,Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan
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11
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Molecular Architecture of the Major Membrane Ring Component of the Nuclear Pore Complex. Structure 2017; 25:434-445. [PMID: 28162953 DOI: 10.1016/j.str.2017.01.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 01/06/2017] [Accepted: 01/19/2017] [Indexed: 02/06/2023]
Abstract
The membrane ring that equatorially circumscribes the nuclear pore complex (NPC) in the perinuclear lumen of the nuclear envelope is composed largely of Pom152 in yeast and its ortholog Nup210 (or Gp210) in vertebrates. Here, we have used a combination of negative-stain electron microscopy, nuclear magnetic resonance, and small-angle X-ray scattering methods to determine an integrative structure of the ∼120 kDa luminal domain of Pom152. Our structural analysis reveals that the luminal domain is formed by a flexible string-of-pearls arrangement of nine repetitive cadherin-like Ig-like domains, indicating an evolutionary connection between NPCs and the cell adhesion machinery. The 16 copies of Pom152 known to be present in the yeast NPC are long enough to form the observed membrane ring, suggesting how interactions between Pom152 molecules help establish and maintain the NPC architecture.
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12
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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: 423] [Impact Index Per Article: 52.9] [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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13
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Sec66-Dependent Regulation of Yeast Spindle-Pole Body Duplication Through Pom152. Genetics 2015; 201:1479-95. [PMID: 26510791 PMCID: PMC4676539 DOI: 10.1534/genetics.115.178012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 10/23/2015] [Indexed: 02/06/2023] Open
Abstract
In closed mitotic systems such as Saccharomyces cerevisiae, the nuclear envelope (NE) does not break down during mitosis, so microtubule-organizing centers such as the spindle-pole body (SPB) must be inserted into the NE to facilitate bipolar spindle formation and chromosome segregation. The mechanism of SPB insertion has been linked to NE insertion of nuclear pore complexes (NPCs) through a series of genetic and physical interactions between NPCs and SPB components. To identify new genes involved in SPB duplication and NE insertion, we carried out genome-wide screens for suppressors of deletion alleles of SPB components, including Mps3 and Mps2. In addition to the nucleoporins POM152 and POM34, we found that elimination of SEC66/SEC71/KAR7 suppressed lethality of cells lacking MPS2 or MPS3. Sec66 is a nonessential subunit of the Sec63 complex that functions together with the Sec61 complex in import of proteins into the endoplasmic reticulum (ER). Cells lacking Sec66 have reduced levels of Pom152 protein but not Pom34 or Ndc1, a shared component of the NPC and SPB. The fact that Sec66 but not other subunits of the ER translocon bypass deletion mutants in SPB genes suggests a specific role for Sec66 in the control of Pom152 levels. Based on the observation that sec66∆ does not affect the distribution of Ndc1 on the NE or Ndc1 binding to the SPB, we propose that Sec66-mediated regulation of Pom152 plays an NPC-independent role in the control of SPB duplication.
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14
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Mészáros N, Cibulka J, Mendiburo MJ, Romanauska A, Schneider M, Köhler A. Nuclear pore basket proteins are tethered to the nuclear envelope and can regulate membrane curvature. Dev Cell 2015; 33:285-98. [PMID: 25942622 PMCID: PMC4425464 DOI: 10.1016/j.devcel.2015.02.017] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 01/11/2015] [Accepted: 02/20/2015] [Indexed: 01/28/2023]
Abstract
Nuclear pore complexes (NPCs) are selective transport channels embedded in the nuclear envelope. The cylindrical NPC core forms a protein coat lining a highly curved membrane opening and has a basket-like structure appended to the nucleoplasmic side. How NPCs interact with lipids, promoting membrane bending and NPC integrity, is poorly understood. Here we show that the NPC basket proteins Nup1 and Nup60 directly induce membrane curvature by amphipathic helix insertion into the lipid bilayer. In a cell-free system, both Nup1 and Nup60 transform spherical liposomes into highly curved membrane structures. In vivo, high levels of the Nup1/Nup60 amphipathic helices cause deformation of the yeast nuclear membrane, whereas adjacent helical regions contribute to anchoring the basket to the NPC core. Basket amphipathic helices are functionally linked to distinct transmembrane nucleoporins of the NPC core, suggesting a key contribution to the membrane remodeling events that underlie NPC assembly. The nuclear pore basket is tethered to the nuclear envelope Amphipathic helices within Nup1 and Nup60 bind and bend membranes Basket-lipid interactions contribute to NPC integrity
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Affiliation(s)
- Noémi Mészáros
- Max F. Perutz Laboratories, Medical University of Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 9/3, 1030 Vienna, Austria
| | - Jakub Cibulka
- Max F. Perutz Laboratories, Medical University of Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 9/3, 1030 Vienna, Austria
| | - Maria Jose Mendiburo
- Max F. Perutz Laboratories, Medical University of Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 9/3, 1030 Vienna, Austria
| | - Anete Romanauska
- Max F. Perutz Laboratories, Medical University of Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 9/3, 1030 Vienna, Austria
| | - Maren Schneider
- Max F. Perutz Laboratories, Medical University of Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 9/3, 1030 Vienna, Austria
| | - Alwin Köhler
- Max F. Perutz Laboratories, Medical University of Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 9/3, 1030 Vienna, Austria.
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15
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Casey AK, Chen S, Novick P, Ferro-Novick S, Wente SR. Nuclear pore complex integrity requires Lnp1, a regulator of cortical endoplasmic reticulum. Mol Biol Cell 2015; 26:2833-44. [PMID: 26041935 PMCID: PMC4571342 DOI: 10.1091/mbc.e15-01-0053] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 04/21/2015] [Accepted: 05/27/2015] [Indexed: 12/31/2022] Open
Abstract
The nuclear envelope (NE) and endoplasmic reticulum (ER) are components of the same contiguous membrane system and yet have distinct cellular functions. Mounting evidence suggests roles for some ER proteins in the NE for proper nuclear pore complex (NPC) structure and function. In this study, we identify a NE role in Saccharomyces cerevisiae for Lnp1 and Sey1, proteins required for proper cortical ER formation. Both lnp1Δ and sey1Δ mutants exhibit synthetic genetic interactions with mutants in genes encoding key NPC structural components. Both Lnp1 and Sey1 physically associate with other ER components that have established NPC roles, including Rtn1, Yop1, Pom33, and Per33. Of interest, lnp1Δ rtn1Δ mutants but not rtn1Δ sey1Δ mutants exhibit defects in NPC distribution. Furthermore, the essential NPC assembly factor Ndc1 has altered interactions in the absence of Sey1. Lnp1 dimerizes in vitro via its C-terminal zinc finger motif, a property that is required for proper ER structure but not NPC integrity. These findings suggest that Lnp1's role in NPC integrity is separable from functions in the ER and is linked to Ndc1 and Rtn1 interactions.
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Affiliation(s)
- Amanda K Casey
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Shuliang Chen
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093
| | - Peter Novick
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093 Howard Hughes Medical Institute, University of California at San Diego, La Jolla, CA 92093
| | - Susan Ferro-Novick
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093
| | - Susan R Wente
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232 )
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16
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Eisenhardt N, Redolfi J, Antonin W. Interaction of Nup53 with Ndc1 and Nup155 is required for nuclear pore complex assembly. J Cell Sci 2013; 127:908-21. [PMID: 24363447 DOI: 10.1242/jcs.141739] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nuclear pore complexes (NPCs) are the gateways for nucleocytoplasmic exchange. The ordered assembly of these huge complexes from several hundred individual components into an intricate protein interaction network which deforms the two membranes of the nuclear envelope into a pore is only rudimentarily understood. Here, we show that the interaction between Nup53 and the integral pore membrane protein Ndc1 is essential for vertebrate NPC assembly. The Ndc1 binding site on Nup53 overlaps with a region that induces membrane bending and is specifically required to modulate this activity, suggesting that the membrane-deforming capability of Nup53 is adjusted during the NPC assembly process. We further demonstrate that the interaction of Nup53 and Nup155 has a crucial role in NPC formation as the main determinant of recruitment of Nup155 to the assembling pore. Overall, our results pinpoint the diversity of interaction modes accomplished by Nup53, highlighting this protein as an essential link between the pore membrane and the NPC, and as a crucial factor in the formation of the pore membrane.
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Affiliation(s)
- Nathalie Eisenhardt
- Friedrich Miescher Laboratory of the Max Planck Society, Spemannstr. 39, 72076 Tübingen, Germany
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17
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Goring ME, Leibovitch M, Gea-Mallorqui E, Karls S, Richard F, Hanic-Joyce PJ, Joyce PBM. The ability of an arginine to tryptophan substitution in Saccharomyces cerevisiae tRNA nucleotidyltransferase to alleviate a temperature-sensitive phenotype suggests a role for motif C in active site organization. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:2097-106. [PMID: 23872483 DOI: 10.1016/j.bbapap.2013.07.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 07/08/2013] [Accepted: 07/10/2013] [Indexed: 11/15/2022]
Abstract
We report that the temperature-sensitive (ts) phenotype in Saccharomyces cerevisiae associated with a variant tRNA nucleotidyltransferase containing an amino acid substitution at position 189 results from a reduced ability to incorporate AMP and CMP into tRNAs. We show that this defect can be compensated for by a second-site suppressor converting residue arginine 64 to tryptophan. The R64W substitution does not alter the structure or thermal stability of the enzyme dramatically but restores catalytic activity in vitro and suppresses the ts phenotype in vivo. R64 is found in motif A known to be involved in catalysis and nucleotide triphosphate binding while E189 lies within motif C previously thought only to connect the head and neck domains of the protein. Although mutagenesis experiments indicate that residues R64 and E189 do not interact directly, our data suggest a critical role for residue E189 in enzyme structure and function. Both R64 and E189 may contribute to the organization of the catalytic domain of the enzyme. These results, along with overexpression and deletion analyses, show that the ts phenotype of cca1-E189F does not arise from thermal instability of the variant tRNA nucleotidyltransferase but instead from the inability of a partially active enzyme to support growth only at higher temperatures.
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Affiliation(s)
- Mark E Goring
- Department of Biology, Concordia University, Montréal, H4B 1R6, Canada
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18
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Affiliation(s)
- C A Niño
- Institut Jacques Monod, Paris Diderot University , Sorbonne Paris Cité, CNRS UMR7592, Equipe labellisée Ligue contre le cancer, 15 rue Hélène Brion, 75205 Paris Cedex 13, France
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19
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Poring over pores: nuclear pore complex insertion into the nuclear envelope. Trends Biochem Sci 2013; 38:292-301. [DOI: 10.1016/j.tibs.2013.04.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2013] [Revised: 03/29/2013] [Accepted: 04/02/2013] [Indexed: 11/18/2022]
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20
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Vollmer B, Schooley A, Sachdev R, Eisenhardt N, Schneider AM, Sieverding C, Madlung J, Gerken U, Macek B, Antonin W. Dimerization and direct membrane interaction of Nup53 contribute to nuclear pore complex assembly. EMBO J 2012; 31:4072-84. [PMID: 22960634 PMCID: PMC3474928 DOI: 10.1038/emboj.2012.256] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 08/21/2012] [Indexed: 11/29/2022] Open
Abstract
Nuclear pore formation depends on membrane curvature. The membrane deforming activity of Nup53 is required for nuclear pore complex (NPC) assembly during interphase. Nuclear pore complexes (NPCs) fuse the two membranes of the nuclear envelope (NE) to a pore, connecting cytoplasm and nucleoplasm and allowing exchange of macromolecules between these compartments. Most NPC proteins do not contain integral membrane domains and thus it is largely unclear how NPCs are embedded and anchored in the NE. Here, we show that the evolutionary conserved nuclear pore protein Nup53 binds independently of other proteins to membranes, a property that is crucial for NPC assembly and conserved between yeast and vertebrates. The vertebrate protein comprises two membrane binding sites, of which the C-terminal domain has membrane deforming capabilities, and is specifically required for de novo NPC assembly and insertion into the intact NE during interphase. Dimerization of Nup53 contributes to its membrane interaction and is crucial for its function in NPC assembly.
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Affiliation(s)
- Benjamin Vollmer
- Friedrich Miescher Laboratory of the Max Planck Society, Tübingen, Germany
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21
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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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22
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Tamm T, Grallert A, Grossman EPS, Alvarez-Tabares I, Stevens FE, Hagan IM. Brr6 drives the Schizosaccharomyces pombe spindle pole body nuclear envelope insertion/extrusion cycle. ACTA ACUST UNITED AC 2012; 195:467-84. [PMID: 22042620 PMCID: PMC3206342 DOI: 10.1083/jcb.201106076] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Insertion into and release of the cytoplasmic domain of the Schizosaccharomyces pombe spindle pole body from a nuclear envelope fenestra during mitosis requires Brr6. The fission yeast interphase spindle pole body (SPB) is a bipartite structure in which a bulky cytoplasmic domain is separated from a nuclear component by the nuclear envelope. During mitosis, the SPB is incorporated into a fenestra that forms within the envelope during mitotic commitment. Closure of this fenestra during anaphase B/mitotic exit returns the cytoplasmic component to the cytoplasmic face of an intact interphase nuclear envelope. Here we show that Brr6 is transiently recruited to SPBs at both SPB insertion and extrusion. Brr6 is required for both SPB insertion and nuclear envelope integrity during anaphase B/mitotic exit. Genetic interactions with apq12 and defective sterol assimilation suggest that Brr6 may alter envelope composition at SPBs to promote SPB insertion and extrusion. The restriction of the Brr6 domain to eukaryotes that use a polar fenestra in an otherwise closed mitosis suggests a conserved role in fenestration to enable a single microtubule organizing center to nucleate both cytoplasmic and nuclear microtubules on opposing sides of the nuclear envelope.
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Affiliation(s)
- Tiina Tamm
- Cancer Research UK Cell Division Group, Paterson Institute for Cancer Research, Manchester M20 4BX, England, UK
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23
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Capelson M, Doucet C, Hetzer MW. Nuclear pore complexes: guardians of the nuclear genome. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2011; 75:585-97. [PMID: 21502404 DOI: 10.1101/sqb.2010.75.059] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Eukaryotic cell function depends on the physical separation of nucleoplasmic and cytoplasmic components by the nuclear envelope (NE). Molecular communication between the two compartments involves active, signal-mediated trafficking, a function that is exclusively performed by nuclear pore complexes (NPCs). The individual NPC components and the mechanisms that are involved in nuclear trafficking are well documented and have become textbook knowledge. However, in addition to their roles as nuclear gatekeepers, NPC components-nucleoporins-have been shown to have critical roles in chromatin organization and gene regulation. These findings have sparked new enthusiasm to study the roles of this multiprotein complex in nuclear organization and explore novel functions that in some cases appear to go beyond a role in transport. Here, we discuss our present view of NPC biogenesis, which is tightly linked to proper cell cycle progression and cell differentiation. In addition, we summarize new data suggesting that NPCs represent dynamic hubs for the integration of gene regulation and nuclear transport processes.
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Affiliation(s)
- M Capelson
- Salk Institute for Biological Studies, Molecular and Cell Biology Laboratory, La Jolla, California 92037, USA
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24
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Yewdell WT, Colombi P, Makhnevych T, Lusk CP. Lumenal interactions in nuclear pore complex assembly and stability. Mol Biol Cell 2011; 22:1375-88. [PMID: 21346187 PMCID: PMC3078075 DOI: 10.1091/mbc.e10-06-0554] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
A mechanism of nuclear pore complex assembly into intact nuclear envelopes remains elusive. We explore roles of conserved inner nuclear membrane proteins, Heh1p and Heh2p, in this process. The data support the existence of a lumenal bridge between Heh1p and the nucleoporin Pom152p, which might facilitate early nuclear pore complex assembly events. Nuclear pore complexes (NPCs) provide a gateway for the selective transport of macromolecules across the nuclear envelope (NE). Although we have a solid understanding of NPC composition and structure, we do not have a clear grasp of the mechanism of NPC assembly. Here, we demonstrate specific defects in nucleoporin distribution in strains lacking Heh1p and Heh2p—two conserved members of the LEM (Lap2, emerin, MAN1) family of integral inner nuclear membrane proteins. These effects on nucleoporin localization are likely of functional importance as we have defined specific genetic interaction networks between HEH1 and HEH2, and genes encoding nucleoporins in the membrane, inner, and outer ring complexes of the NPC. Interestingly, expression of a domain of Heh1p that resides in the NE lumen is sufficient to suppress both the nucleoporin mislocalization and growth defects in heh1Δpom34Δ strains. We further demonstrate a specific physical interaction between the Heh1p lumenal domain and the massive cadherin-like lumenal domain of the membrane nucleoporin Pom152p. These findings support a role for Heh1p in the assembly or stability of the NPC, potentially through the formation of a lumenal bridge with Pom152p.
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25
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Onischenko E, Weis K. Nuclear pore complex-a coat specifically tailored for the nuclear envelope. Curr Opin Cell Biol 2011; 23:293-301. [PMID: 21296566 DOI: 10.1016/j.ceb.2011.01.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Revised: 12/23/2010] [Accepted: 01/07/2011] [Indexed: 01/08/2023]
Abstract
Nuclear pore complexes (NPCs) are highly selective transport gates that enable the bi-directional traffic of macromolecules across the nuclear envelope (NE). NPCs are located at the fusion pores between the inner and outer membranes of the NE and are built from a common set of ∼30 different proteins, nucleoporins. Remarkably, recent proteomic, bioinformatic, and structural studies have provided firm evidence that key structural nucleoporins share common ancestry with elements of coated vesicles, indicating an evolutionary link between these structures. This has provided novel insight into the origin of NPCs and may help us to better functionally characterize these fundamental components of eukaryotic cells.
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Affiliation(s)
- Evgeny Onischenko
- Department of Molecular and Cell Biology, Division of Cell and Developmental Biology, University of California, Berkeley, CA 94720-3200, United States
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26
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Neumann N, Lundin D, Poole AM. Comparative genomic evidence for a complete nuclear pore complex in the last eukaryotic common ancestor. PLoS One 2010; 5:e13241. [PMID: 20949036 PMCID: PMC2951903 DOI: 10.1371/journal.pone.0013241] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Accepted: 09/15/2010] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND The Nuclear Pore Complex (NPC) facilitates molecular trafficking between nucleus and cytoplasm and is an integral feature of the eukaryote cell. It exhibits eight-fold rotational symmetry and is comprised of approximately 30 nucleoporins (Nups) in different stoichiometries. Nups are broadly conserved between yeast, vertebrates and plants, but few have been identified among other major eukaryotic groups. METHODOLOGY/PRINCIPAL FINDINGS We screened for Nups across 60 eukaryote genomes and report that 19 Nups (spanning all major protein subcomplexes) are found in all eukaryote supergroups represented in our study (Opisthokonts, Amoebozoa, Viridiplantae, Chromalveolates and Excavates). Based on parsimony, between 23 and 26 of 31 Nups can be placed in LECA. Notably, they include central components of the anchoring system (Ndc1 and Gp210) indicating that the anchoring system did not evolve by convergence, as has previously been suggested. These results significantly extend earlier results and, importantly, unambiguously place a fully-fledged NPC in LECA. We also test the proposal that transmembrane Pom proteins in vertebrates and yeasts may account for their variant forms of mitosis (open mitoses in vertebrates, closed among yeasts). The distribution of homologues of vertebrate Pom121 and yeast Pom152 is not consistent with this suggestion, but the distribution of fungal Pom34 fits a scenario wherein it was integral to the evolution of closed mitosis in ascomycetes. We also report an updated screen for vesicle coating complexes, which share a common evolutionary origin with Nups, and can be traced back to LECA. Surprisingly, we find only three supergroup-level differences (one gain and two losses) between the constituents of COPI, COPII and Clathrin complexes. CONCLUSIONS/SIGNIFICANCE Our results indicate that all major protein subcomplexes in the Nuclear Pore Complex are traceable to the Last Eukaryotic Common Ancestor (LECA). In contrast to previous screens, we demonstrate that our conclusions hold regardless of the position of the root of the eukaryote tree.
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Affiliation(s)
- Nadja Neumann
- Department of Molecular Biology and Functional Genomics, Stockholm University, Stockholm, Sweden
| | - Daniel Lundin
- Department of Molecular Biology and Functional Genomics, Stockholm University, Stockholm, Sweden
| | - Anthony M. Poole
- Department of Molecular Biology and Functional Genomics, Stockholm University, Stockholm, Sweden
- School of Biological Sciences and Biomolecular Interaction Centre, University of Canterbury, Christchurch, New Zealand
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27
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Doucet CM, Hetzer MW. Nuclear pore biogenesis into an intact nuclear envelope. Chromosoma 2010; 119:469-77. [DOI: 10.1007/s00412-010-0289-2] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Revised: 07/15/2010] [Accepted: 07/19/2010] [Indexed: 10/19/2022]
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28
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Changes in the nuclear envelope environment affect spindle pole body duplication in Saccharomyces cerevisiae. Genetics 2010; 186:867-83. [PMID: 20713690 DOI: 10.1534/genetics.110.119149] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Saccharomyces cerevisiae nuclear membrane is part of a complex nuclear envelope environment also containing chromatin, integral and peripheral membrane proteins, and large structures such as nuclear pore complexes (NPCs) and the spindle pole body. To study how properties of the nuclear membrane affect nuclear envelope processes, we altered the nuclear membrane by deleting the SPO7 gene. We found that spo7Δ cells were sickened by the mutation of genes coding for spindle pole body components and that spo7Δ was synthetically lethal with mutations in the SUN domain gene MPS3. Mps3p is required for spindle pole body duplication and for a variety of other nuclear envelope processes. In spo7Δ cells, the spindle pole body defect of mps3 mutants was exacerbated, suggesting that nuclear membrane composition affects spindle pole body function. The synthetic lethality between spo7Δ and mps3 mutants was suppressed by deletion of specific nucleoporin genes. In fact, these gene deletions bypassed the requirement for Mps3p entirely, suggesting that under certain conditions spindle pole body duplication can occur via an Mps3p-independent pathway. These data point to an antagonistic relationship between nuclear pore complexes and the spindle pole body. We propose a model whereby nuclear pore complexes either compete with the spindle pole body for insertion into the nuclear membrane or affect spindle pole body duplication by altering the nuclear envelope environment.
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29
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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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30
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Titus LC, Dawson TR, Rexer DJ, Ryan KJ, Wente SR. Members of the RSC chromatin-remodeling complex are required for maintaining proper nuclear envelope structure and pore complex localization. Mol Biol Cell 2010; 21:1072-87. [PMID: 20110349 PMCID: PMC2836959 DOI: 10.1091/mbc.e09-07-0615] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Genome-wide screening approaches were employed to identify factors required for nuclear pore complex structure and distribution in Saccharomyces cerevisiae. Roles were found for multiple components of the RSC complex, revealing a functional connection between proper chromatin remodeling and nuclear envelope/nuclear pore complex structure. The assembly, distribution, and functional integrity of nuclear pore complexes (NPCs) in the nuclear envelope (NE) are key determinants in the nuclear periphery architecture. However, the mechanisms controlling proper NPC and NE structure are not fully defined. We used two different genetic screening approaches to identify Saccharomyces cerevisiae mutants with defects in NPC localization. The first approach examined green fluorescent protein (GFP)-Nic96 in 531 strains from the yeast Tet-promoters Hughes Collection with individual essential genes expressed from a doxycycline-regulated promoter (TetO7-orf). Under repressive conditions, depletion of the protein encoded by 44 TetO7-orf strains resulted in mislocalized GFP-Nic96. These included STH1, RSC4, RSC8, RSC9, RSC58, ARP7, and ARP9, each encoding components of the RSC chromatin remodeling complex. Second, a temperature-sensitive sth1-F793S (npa18-1) mutant was identified in an independent genetic screen for NPC assembly (npa) mutants. NPC mislocalization in the RSC mutants required new protein synthesis and ongoing transcription, confirming that lack of global transcription did not underlie the phenotypes. Electron microscopy studies showed significantly altered NEs and nuclear morphology, with coincident cytoplasmic membrane sheet accumulation. Strikingly, increasing membrane fluidity with benzyl alcohol treatment prevented the sth1-F793S NE structural defects and NPC mislocalization. We speculate that NE structure is functionally linked to proper chromatin architecture.
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Affiliation(s)
- Laura C Titus
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232-8240, USA
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31
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Sezen B, Seedorf M, Schiebel E. The SESA network links duplication of the yeast centrosome with the protein translation machinery. Genes Dev 2009; 23:1559-70. [PMID: 19571182 DOI: 10.1101/gad.524209] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The yeast spindle pole body (SPB), the functional equivalent of mammalian centrosome, duplicates in G1/S phase of the cell cycle and then becomes inserted into the nuclear envelope. Here we describe a link between SPB duplication and targeted translation control. When insertion of the newly formed SPB into the nuclear envelope fails, the SESA network comprising the GYF domain protein Smy2, the translation inhibitor Eap1, the mRNA-binding protein Scp160 and the Asc1 protein, specifically inhibits initiation of translation of POM34 mRNA that encodes an integral membrane protein of the nuclear pore complex, while having no impact on other mRNAs. In response to SESA, POM34 mRNA accumulates in the cytoplasm and is not targeted to the ER for cotranslational translocation of the protein. Reduced level of Pom34 is sufficient to restore viability of mutants with defects in SPB duplication. We suggest that the SESA network provides a mechanism by which cells can regulate the translation of specific mRNAs. This regulation is used to coordinate competing events in the nuclear envelope.
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Affiliation(s)
- Bengü Sezen
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
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32
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Makio T, Stanton LH, Lin CC, Goldfarb DS, Weis K, Wozniak RW. The nucleoporins Nup170p and Nup157p are essential for nuclear pore complex assembly. ACTA ACUST UNITED AC 2009; 185:459-73. [PMID: 19414608 PMCID: PMC2700392 DOI: 10.1083/jcb.200810029] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We have established that two homologous nucleoporins, Nup170p and Nup157p, play an essential role in the formation of nuclear pore complexes (NPCs) in Saccharomyces cerevisiae. By regulating their synthesis, we showed that the loss of these nucleoporins triggers a decrease in NPCs caused by a halt in new NPC assembly. Preexisting NPCs are ultimately lost by dilution as cells grow, causing the inhibition of nuclear transport and the loss of viability. Significantly, the loss of Nup170p/Nup157p had distinct effects on the assembly of different architectural components of the NPC. Nucleoporins (nups) positioned on the cytoplasmic face of the NPC rapidly accumulated in cytoplasmic foci. These nup complexes could be recruited into new NPCs after reinitiation of Nup170p synthesis, and may represent a physiological intermediate. Loss of Nup170p/Nup157p also caused core and nucleoplasmically positioned nups to accumulate in NPC-like structures adjacent to the inner nuclear membrane, which suggests that these nucleoporins are required for formation of the pore membrane and the incorporation of cytoplasmic nups into forming NPCs.
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Affiliation(s)
- Tadashi Makio
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada
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Onischenko E, Stanton LH, Madrid AS, Kieselbach T, Weis K. Role of the Ndc1 interaction network in yeast nuclear pore complex assembly and maintenance. ACTA ACUST UNITED AC 2009; 185:475-91. [PMID: 19414609 PMCID: PMC2700399 DOI: 10.1083/jcb.200810030] [Citation(s) in RCA: 127] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The nuclear pore complex (NPC) mediates all nucleocytoplasmic transport, yet its structure and biogenesis remain poorly understood. In this study, we have functionally characterized interaction partners of the yeast transmembrane nucleoporin Ndc1. Ndc1 forms a distinct complex with the transmembrane proteins Pom152 and Pom34 and two alternative complexes with the soluble nucleoporins Nup53 and Nup59, which in turn bind to Nup170 and Nup157. The transmembrane and soluble Ndc1-binding partners have redundant functions at the NPC, and disruption of both groups of interactions causes defects in Ndc1 targeting and in NPC structure accompanied by significant pore dilation. Using photoconvertible fluorescent protein fusions, we further show that the depletion of Pom34 in cells that lack NUP53 and NUP59 blocks new NPC assembly and leads to the reversible accumulation of newly made nucleoporins in cytoplasmic foci. Therefore, Ndc1 together with its interaction partners are collectively essential for the biosynthesis and structural integrity of yeast NPCs.
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Affiliation(s)
- Evgeny Onischenko
- Department of Molecular and Cell Biology, Division of Cell and Developmental Biology, University of California, Berkeley, Berkeley, CA 94720, USA
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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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Liu HL, De Souza CPC, Osmani AH, Osmani SA. The three fungal transmembrane nuclear pore complex proteins of Aspergillus nidulans are dispensable in the presence of an intact An-Nup84-120 complex. Mol Biol Cell 2008; 20:616-30. [PMID: 19019988 DOI: 10.1091/mbc.e08-06-0628] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
In Aspergillus nidulans nuclear pore complexes (NPCs) undergo partial mitotic disassembly such that 12 NPC proteins (Nups) form a core structure anchored across the nuclear envelope (NE). To investigate how the NPC core is maintained, we affinity purified the major core An-Nup84-120 complex and identified two new fungal Nups, An-Nup37 and An-ELYS, previously thought to be vertebrate specific. During mitosis the An-Nup84-120 complex locates to the NE and spindle pole bodies but, unlike vertebrate cells, does not concentrate at kinetochores. We find that mutants lacking individual An-Nup84-120 components are sensitive to the membrane destabilizer benzyl alcohol (BA) and high temperature. Although such mutants display no defects in mitotic spindle formation, they undergo mitotic specific disassembly of the NPC core and transient aggregation of the mitotic NE, suggesting the An-Nup84-120 complex might function with membrane. Supporting this, we show cells devoid of all known fungal transmembrane Nups (An-Ndc1, An-Pom152, and An-Pom34) are viable but that An-ndc1 deletion combined with deletion of individual An-Nup84-120 components is either lethal or causes sensitivity to treatments expected to destabilize membrane. Therefore, the An-Nup84-120 complex performs roles, perhaps at the NPC membrane as proposed previously, that become essential without the An-Ndc1 transmembrane Nup.
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Affiliation(s)
- Hui-Lin Liu
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
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37
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Centrin 2 localizes to the vertebrate nuclear pore and plays a role in mRNA and protein export. Mol Cell Biol 2008; 28:1755-69. [PMID: 18172010 DOI: 10.1128/mcb.01697-07] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Centrins in vertebrates have traditionally been associated with microtubule-nucleating centers such as the centrosome. Unexpectedly, we found centrin 2 to associate biochemically with nucleoporins, including the Xenopus laevis Nup107-160 complex, a critical subunit of the vertebrate nuclear pore in interphase and of the kinetochores and spindle poles in mitosis. Immunofluorescence of Xenopus cells and in vitro reconstituted nuclei indeed revealed centrin 2 localized at the nuclear pores. Use of the mild detergent digitonin in immunofluorescence also allowed centrin 2 to be clearly visualized at the nuclear pores of human cells. Disruption of nuclear pores using RNA interference of the pore assembly protein ELYS/MEL-28 resulted in a specific decrease of centrin 2 at the nuclear rim of HeLa cells. Functionally, excess expression of either the N- or C-terminal calcium-binding domains of human centrin 2 caused a dominant-negative effect on both mRNA and protein export, leaving protein import intact. The mRNA effect mirrors that found for the Saccharomyes cerevisiae centrin Cdc31p at the yeast nuclear pore, a role until now thought to be unique to yeast. We conclude that in vertebrates, centrin 2 interacts with major subunits of the nuclear pore, exhibits nuclear pore localization, and plays a functional role in multiple nuclear export pathways.
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Lim RYH, Ullman KS, Fahrenkrog B. Biology and biophysics of the nuclear pore complex and its components. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 267:299-342. [PMID: 18544502 DOI: 10.1016/s1937-6448(08)00632-1] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Nucleocytoplasmic exchange of proteins and ribonucleoprotein particles occurs via nuclear pore complexes (NPCs) that reside in the double membrane of the nuclear envelope (NE). Significant progress has been made during the past few years in obtaining better structural resolution of the three-dimensional architecture of NPC with the help of cryo-electron tomography and atomic structures of domains from nuclear pore proteins (nucleoporins). Biophysical and imaging approaches have helped elucidate how nucleoporins act as a selective barrier in nucleocytoplasmic transport. Nucleoporins act not only in trafficking of macromolecules but also in proper microtubule attachment to kinetochores, in the regulation of gene expression and signaling events associated with, for example, innate and adaptive immunity, development and neurodegenerative disorders. Recent research has also been focused on the dynamic processes of NPC assembly and disassembly that occur with each cell cycle. Here we review emerging results aimed at understanding the molecular arrangement of the NPC and how it is achieved, defining the roles of individual nucleoporins both at the NPC and at other sites within the cell, and finally deciphering how the NPC serves as both a barrier and a conduit of active transport.
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Affiliation(s)
- Roderick Y H Lim
- M.E. Müller Institute for Structural Biology, Biozentrum, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland
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Scarcelli JJ, Hodge CA, Cole CN. The yeast integral membrane protein Apq12 potentially links membrane dynamics to assembly of nuclear pore complexes. ACTA ACUST UNITED AC 2007; 178:799-812. [PMID: 17724120 PMCID: PMC2064545 DOI: 10.1083/jcb.200702120] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although the structure and function of components of the nuclear pore complex (NPC) have been the focus of many studies, relatively little is known about NPC biogenesis. In this study, we report that Apq12 is required for efficient NPC biogenesis in Saccharomyces cerevisiae. Apq12 is an integral membrane protein of the nuclear envelope (NE) and endoplasmic reticulum. Cells lacking Apq12 are cold sensitive for growth, and a subset of their nucleoporins (Nups), those that are primarily components of the cytoplasmic fibrils of the NPC, mislocalize to the cytoplasm. APQ12 deletion also causes defects in NE morphology. In the absence of Apq12, most NPCs appear to be associated with the inner but not the outer nuclear membrane. Low levels of benzyl alcohol, which increases membrane fluidity, prevented Nup mislocalization and restored the proper localization of Nups that had accumulated in cytoplasmic foci upon a shift to lower temperature. Thus, Apq12p connects nuclear pore biogenesis to the dynamics of the NE.
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Affiliation(s)
- John J Scarcelli
- Department of Biochemistry, Dartmouth Medical School, Hanover, NH 03755, USA
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Lusk CP, Blobel G, King MC. Highway to the inner nuclear membrane: rules for the road. Nat Rev Mol Cell Biol 2007; 8:414-20. [PMID: 17440484 DOI: 10.1038/nrm2165] [Citation(s) in RCA: 168] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
To enter the nucleus a protein must be chaperoned by a transport factor through the nuclear pore complex or it must be small enough to pass through by diffusion. Although these principles have long described the nuclear import of soluble proteins, recent evidence indicates that they also apply to the import of integral inner nuclear membrane proteins. Here we develop a set of rules that might govern the transport of proteins to the inner nuclear membrane.
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Affiliation(s)
- C Patrick Lusk
- Laboratory of Cell Biology, Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
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Olsson I, Berrez JM, Leipus A, Ostlund C, Mutvei A. The arginine methyltransferase Rmt2 is enriched in the nucleus and co-purifies with the nuclear porins Nup49, Nup57 and Nup100. Exp Cell Res 2007; 313:1778-89. [PMID: 17448464 DOI: 10.1016/j.yexcr.2007.03.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2006] [Revised: 03/06/2007] [Accepted: 03/07/2007] [Indexed: 10/23/2022]
Abstract
Arginine methylation is a post-translational modification of proteins implicated in RNA processing, protein compartmentalization, signal transduction, transcriptional regulation and DNA repair. In a screen for proteins associated with the nuclear envelope in the yeast Saccharomyces cerevisiae, we have identified the arginine methyltransferase Rmt2, previously shown to methylate the ribosomal protein L12. By indirect immunofluorescence and subcellular fractionations we demonstrate here that Rmt2 has nuclear and cytoplasmic localizations. Biochemical analysis of a fraction enriched in nuclei reveals that nuclear Rmt2 is resistant to extractions with salt and detergent, indicating an association with structural components. This was supported by affinity purification experiments with TAP-tagged Rmt2. Rmt2 was found to co-purify with the nucleoporins Nup49, Nup57 and Nup100, revealing a novel link between arginine methyltransferases and the nuclear pore complex. In addition, a genome-wide transcription study of the rmt2Delta mutant shows significant downregulation of the transcription of MYO1, encoding the Type II myosin heavy chain required for cytokinesis and cell separation.
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Affiliation(s)
- Ida Olsson
- School of Life Sciences, Södertörns Högskola, SE-141 89 Huddinge, Sweden
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42
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Current awareness on yeast. Yeast 2006. [DOI: 10.1002/yea.1319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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43
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King MC, Lusk CP, Blobel G. Karyopherin-mediated import of integral inner nuclear membrane proteins. Nature 2006; 442:1003-7. [PMID: 16929305 DOI: 10.1038/nature05075] [Citation(s) in RCA: 229] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Accepted: 07/11/2006] [Indexed: 11/08/2022]
Abstract
Targeting of newly synthesized integral membrane proteins to the appropriate cellular compartment is specified by discrete sequence elements, many of which have been well characterized. An understanding of the signals required to direct integral membrane proteins to the inner nuclear membrane (INM) remains a notable exception. Here we show that integral INM proteins possess basic sequence motifs that resemble 'classical' nuclear localization signals. These sequences can mediate direct binding to karyopherin-alpha and are essential for the passage of integral membrane proteins to the INM. Furthermore, karyopherin-alpha, karyopherin-beta1 and the Ran GTPase cycle are required for INM targeting, underscoring parallels between mechanisms governing the targeting of integral INM proteins and soluble nuclear transport. We also provide evidence that specific nuclear pore complex proteins contribute to this process, suggesting a role for signal-mediated alterations in the nuclear pore complex to allow for passage of INM proteins along the pore membrane.
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Affiliation(s)
- Megan C King
- Laboratory of Cell Biology, Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, New York 10021, USA.
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Mansfeld J, Güttinger S, Hawryluk-Gara LA, Panté N, Mall M, Galy V, Haselmann U, Mühlhäusser P, Wozniak RW, Mattaj IW, Kutay U, Antonin W. The conserved transmembrane nucleoporin NDC1 is required for nuclear pore complex assembly in vertebrate cells. Mol Cell 2006; 22:93-103. [PMID: 16600873 DOI: 10.1016/j.molcel.2006.02.015] [Citation(s) in RCA: 174] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2005] [Revised: 02/03/2006] [Accepted: 02/10/2006] [Indexed: 10/24/2022]
Abstract
Nuclear pore complexes (NPCs) are large proteinaceous channels embedded in the nuclear envelope (NE), through which exchange of molecules between the nucleus and cytosol occurs. Biogenesis of NPCs is complex and poorly understood. In particular, almost nothing is known about how NPCs are anchored in the NE. Here, we characterize vertebrate NDC1--a transmembrane nucleoporin conserved between yeast and metazoans. We show by RNA interference (RNAi) and biochemical depletion that NDC1 plays an important role in NPC and NE assembly in vivo and in vitro. RNAi experiments suggest a functional link between NDC1 and the soluble nucleoporins Nup93, Nup53, and Nup205. Importantly, NDC1 interacts with Nup53 in vitro. This suggests that NDC1 function involves forming a link between the NE membrane and soluble nucleoporins, thereby anchoring the NPC in the membrane.
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Affiliation(s)
- Jörg Mansfeld
- Institute of Biochemistry, ETH Zurich, CH-8093 Zurich, Switzerland
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Stavru F, Hülsmann BB, Spang A, Hartmann E, Cordes VC, Görlich D. NDC1: a crucial membrane-integral nucleoporin of metazoan nuclear pore complexes. ACTA ACUST UNITED AC 2006; 173:509-19. [PMID: 16702233 PMCID: PMC2063861 DOI: 10.1083/jcb.200601001] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
POM121 and gp210 were, until this point, the only known membrane-integral nucleoporins (Nups) of vertebrates and, thus, the only candidate anchors for nuclear pore complexes (NPCs) within the nuclear membrane. In an accompanying study (see Stavru et al. on p. 477 of this issue), we provided evidence that NPCs can exist independently of POM121 and gp210, and we predicted that vertebrate NPCs contain additional membrane-integral constituents. We identify such an additional membrane protein in the NPCs of mammals, frogs, insects, and nematodes as the orthologue to yeast Ndc1p/Cut11p. Human NDC1 (hNDC1) likely possesses six transmembrane segments, and it is located at the nuclear pore wall. Depletion of hNDC1 from human HeLa cells interferes with the assembly of phenylalanine-glycine repeat Nups into NPCs. The loss of NDC1 function in Caenorhabditis elegans also causes severe NPC defects and very high larval and embryonic mortality. However, it is not ultimately lethal. Instead, homozygous NDC1-deficient worms can be propagated. This indicates that none of the membrane-integral Nups is universally essential for NPC assembly, and suggests that NPC biogenesis is an extremely fault-tolerant process.
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Affiliation(s)
- Fabrizia Stavru
- Zentrum für Molekulare Biologie der Universität Heidelberg, D-69120 Heidelberg, Germany
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