scholarly journals Functional evolution of nuclear structure

2011 ◽  
Vol 195 (2) ◽  
pp. 171-181 ◽  
Author(s):  
Katherine L. Wilson ◽  
Scott C. Dawson
Keyword(s):  
Membrane Proteins ◽  
Nuclear Structure ◽  
Common Ancestor ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Chromatin Binding ◽  
Endomembrane System ◽  
Tightly Coupled ◽  
Pore Complexes ◽  
Eukaryotic Supergroup

The evolution of the nucleus, the defining feature of eukaryotic cells, was long shrouded in speculation and mystery. There is now strong evidence that nuclear pore complexes (NPCs) and nuclear membranes coevolved with the endomembrane system, and that the last eukaryotic common ancestor (LECA) had fully functional NPCs. Recent studies have identified many components of the nuclear envelope in living Opisthokonts, the eukaryotic supergroup that includes fungi and metazoan animals. These components include diverse chromatin-binding membrane proteins, and membrane proteins with adhesive lumenal domains that may have contributed to the evolution of nuclear membrane architecture. Further discoveries about the nucleoskeleton suggest that the evolution of nuclear structure was tightly coupled to genome partitioning during mitosis.

scholarly journals Phosphorylation-dependent mitotic SUMOylation drives nuclear envelope–chromatin interactions

2021 ◽  
Vol 220 (12) ◽  
Author(s):  
Christopher Ptak ◽  
Natasha O. Saik ◽  
Ashwini Premashankar ◽  
Diego L. Lapetina ◽  
John D. Aitchison ◽  
...  
Keyword(s):  
Gene Expression ◽  
Nuclear Envelope ◽  
Spatial Organization ◽  
G1 Phase ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Chromatin Binding ◽  
Chromatin Interactions ◽  
Sumo Ligase ◽  
Pore Complexes

In eukaryotes, chromatin binding to the inner nuclear membrane (INM) and nuclear pore complexes (NPCs) contributes to spatial organization of the genome and epigenetic programs important for gene expression. In mitosis, chromatin–nuclear envelope (NE) interactions are lost and then formed again as sister chromosomes segregate to postmitotic nuclei. Investigating these processes in S. cerevisiae, we identified temporally and spatially controlled phosphorylation-dependent SUMOylation events that positively regulate postmetaphase chromatin association with the NE. Our work establishes a phosphorylation-mediated targeting mechanism of the SUMO ligase Siz2 to the INM during mitosis, where Siz2 binds to and SUMOylates the VAP protein Scs2. The recruitment of Siz2 through Scs2 is further responsible for a wave of SUMOylation along the INM that supports the assembly and anchorage of subtelomeric chromatin at the INM and localization of an active gene (INO1) to NPCs during the later stages of mitosis and into G1-phase.

scholarly journals Size-dependent leak of soluble and membrane proteins through the yeast nuclear pore complex

2015 ◽  
Vol 26 (7) ◽  
pp. 1386-1394 ◽  
Author(s):  
Petra Popken ◽  
Ali Ghavami ◽  
Patrick R. Onck ◽  
Bert Poolman ◽  
Liesbeth M. Veenhoff
Keyword(s):  
Molecular Dynamics ◽  
Membrane Proteins ◽  
Coarse Grained ◽  
Nuclear Pore ◽  
Permeability Barrier ◽  
Nuclear Pore Complexes ◽  
Structural And Functional Properties ◽  
Dynamics Simulations ◽  
Pore Complexes

Nuclear pore complexes (NPCs) allow selective import and export while forming a barrier for untargeted proteins. Using fluorescence microscopy, we measured in vivo the permeability of the Saccharomyces cerevisiae NPC for multidomain proteins of different sizes and found that soluble proteins of 150 kDa and membrane proteins with an extralumenal domain of 90 kDa were still partly localized in the nucleus on a time scale of hours. The NPCs thus form only a weak barrier for the majority of yeast proteins, given their monomeric size. Using FGΔ-mutant strains, we showed that specific combinations of Nups, especially with Nup100, but not the total mass of FG-nups per pore, were important for forming the barrier. Models of the disordered phase of wild-type and mutant NPCs were generated using a one bead per amino acid molecular dynamics model. The permeability measurements correlated with the density predictions from coarse-grained molecular dynamics simulations in the center of the NPC. The combined in vivo and computational approach provides a framework for elucidating the structural and functional properties of the permeability barrier of nuclear pore complexes.

scholarly journals Chromatin targeting of nuclear pore proteins induces chromatin decondensation

2019 ◽  
Vol 218 (9) ◽  
pp. 2945-2961 ◽  
Author(s):  
Terra M. Kuhn ◽  
Pau Pascual-Garcia ◽  
Alejandro Gozalo ◽  
Shawn C. Little ◽  
Maya Capelson
Keyword(s):  
Target Gene ◽  
Nuclear Periphery ◽  
Nuclear Pore ◽  
Open Chromatin ◽  
Nuclear Pore Complexes ◽  
Chromatin Binding ◽  
Chromatin Decondensation ◽  
Chromatin Remodeling Complex ◽  
Biochemical Interaction ◽  
Pore Complexes

Nuclear pore complexes have emerged in recent years as chromatin-binding nuclear scaffolds, able to influence target gene expression. However, how nucleoporins (Nups) exert this control remains poorly understood. Here we show that ectopically tethering Drosophila Nups, especially Sec13, to chromatin is sufficient to induce chromatin decondensation. This decondensation is mediated through chromatin-remodeling complex PBAP, as PBAP is both robustly recruited by Sec13 and required for Sec13-induced decondensation. This phenomenon is not correlated with localization of the target locus to the nuclear periphery, but is correlated with robust recruitment of Nup Elys. Furthermore, we identified a biochemical interaction between endogenous Sec13 and Elys with PBAP, and a role for endogenous Elys in global as well as gene-specific chromatin decompaction. Together, these findings reveal a functional role and mechanism for specific nuclear pore components in promoting an open chromatin state.

scholarly journals The nucleoporin Nup188 controls passage of membrane proteins across the nuclear pore complex

2010 ◽  
Vol 189 (7) ◽  
pp. 1129-1142 ◽  
Author(s):  
Gandhi Theerthagiri ◽  
Nathalie Eisenhardt ◽  
Heinz Schwarz ◽  
Wolfram Antonin
Keyword(s):  
Membrane Proteins ◽  
Building Blocks ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Wild Type ◽  
Nuclear Assembly ◽  
Evolutionarily Conserved ◽  
Major Structural Component ◽  
Pore Complexes

All transport across the nuclear envelope (NE) is mediated by nuclear pore complexes (NPCs). Despite their enormous size, ∼60 MD in vertebrates, they are comprised of only ∼30 distinct proteins (nucleoporins or Nups), many of which form subcomplexes that act as building blocks for NPC assembly. One of these evolutionarily conserved subcomplexes, the Nup93 complex, is a major structural component linking the NPC to the membranes of the NE. Using in vitro nuclear assembly assays, we show that two components of the Nup93 complex, Nup188 and Nup205, are dispensable for NPC formation. However, nuclei lacking Nup188 increase in size by several fold compared with wild type. We demonstrate that this phenotype is caused by an accelerated translocation of integral membrane proteins through NPCs, suggesting that Nup188 confines the passage of membrane proteins and is thus crucial for the homeostasis of the different nuclear membranes.

scholarly journals Phosphorylation-dependent mitotic SUMOylation drives nuclear envelope-chromatin interactions

2021 ◽  
Author(s):  
Chris Ptak ◽  
Natasha O Saik ◽  
Ashwini Premashankar ◽  
Diego L Lapetina ◽  
John Aitchison ◽  
...  
Keyword(s):  
Gene Expression ◽  
Nuclear Envelope ◽  
Spatial Organization ◽  
G1 Phase ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Chromatin Binding ◽  
Chromatin Interactions ◽  
Sumo Ligase ◽  
Pore Complexes

In eukaryotes, chromatin binding to the inner nuclear membrane (INM) and nuclear pore complexes (NPCs) contributes to spatial organization of the genome and epigenetic programs important for gene expression. In mitosis, chromatin-nuclear envelope (NE) interactions are lost and then formed again as sister chromosomes segregate to post-mitotic nuclei. Investigating these processes in S. cerevisiae, we identified temporally and spatially controlled phosphorylation-dependent SUMOylation events that positively regulate post-metaphase chromatin association with the NE. Our work establishes a phosphorylation-mediated targeting mechanism of the SUMO ligase Siz2 to the INM during anaphase, where Siz2 binds to and SUMOylates the VAP protein Scs2. The recruitment of Siz2 through Scs2 is further responsible for a wave of SUMOylation along the INM that supports the assembly and anchorage of subtelomeric chromatin at the INM and localization of an active gene (INO1) to NPCs during the later stages of mitosis and into G1-phase.

scholarly journals Pom121 links two essential subcomplexes of the nuclear pore complex core to the membrane

2010 ◽  
Vol 191 (3) ◽  
pp. 505-521 ◽  
Author(s):  
Jana M. Mitchell ◽  
Jörg Mansfeld ◽  
Juliana Capitanio ◽  
Ulrike Kutay ◽  
Richard W. Wozniak
Keyword(s):  
Membrane Proteins ◽  
Nuclear Pore Complex ◽  
Mammalian Cells ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Dramatic Decrease ◽  
Key Players ◽  
Complex Core ◽  
Pore Complexes

Nuclear pore complexes (NPCs) control the movement of molecules across the nuclear envelope (NE). We investigated the molecular interactions that exist at the interface between the NPC scaffold and the pore membrane. We show that key players mediating these interactions in mammalian cells are the nucleoporins Nup155 and Nup160. Nup155 depletion massively alters NE structure, causing a dramatic decrease in NPC numbers and the improper targeting of membrane proteins to the inner nuclear membrane. The role of Nup155 in assembly is likely closely linked to events at the membrane as we show that Nup155 interacts with pore membrane proteins Pom121 and NDC1. Furthermore, we demonstrate that the N terminus of Pom121 directly binds the β-propeller regions of Nup155 and Nup160. We propose a model in which the interactions of Pom121 with Nup155 and Nup160 are predicted to assist in the formation of the nuclear pore and the anchoring of the NPC to the pore membrane.

Nuclear Envelope Dynamics During Mitosis

1988 ◽  
Vol 46 ◽  
pp. 224-225
Author(s):  
Brian Burke
Keyword(s):  
Nuclear Envelope ◽  
Membrane Vesicles ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Animal Cells ◽  
Interphase Chromosome ◽  
Lamin B ◽  
Chromosome Architecture ◽  
Complex Membrane ◽  
Pore Complexes

The nuclear envelope is a complex membrane structure that forms the boundary of the nuclear compartment in eukaryotes. It regulates the passage of macromolecules between the two compartments and may be important for organizing interphase chromosome architecture. In interphase animal cells it forms a remarkably stable structure consisting of a double membrane ouerlying a protein meshwork or lamina and penetrated by nuclear pore complexes. The latter form the channels for nucleocytoplasmic exchange of macromolecules, At the onset of mitosis, however, it rapidly disassembles, the membranes fragment to yield small vesicles and the lamina, which is composed of predominantly three polypeptides, lamins R, B and C (MW approx. 74, 68 and 65 kDa respectiuely), breaks down. Lamins B and C are dispersed as monomers throughout the mitotic cytoplasm, while lamin B remains associated with the nuclear membrane vesicles.

Pore relations: nuclear pore complexes and nucleocytoplasmic exchange

2000 ◽  
Vol 36 ◽  
pp. 75-88 ◽  
Author(s):  
Michael P. Rout ◽  
John D. Aitchison
Keyword(s):  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Pore Complexes
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