scholarly journals The RNA export factor Mex67 functions as a mobile nucleoporin

2019 ◽  
Author(s):  
Carina Patrizia Derrer ◽  
Roberta Mancini ◽  
Pascal Vallotton ◽  
Sébastien Huet ◽  
Karsten Weis ◽  
...  
Keyword(s):  
Molecular Mechanism ◽  
Nuclear Pore Complex ◽  
Binding Sites ◽  
Mrna Export ◽  
Yeast Cells ◽  
Nuclear Pore ◽  
Central Channel ◽  
Rna Export ◽  
Essential Function ◽  
Quantitative Fluorescence

AbstractThe RNA export factor Mex67 is essential for the transport of mRNA through the nuclear pore complex (NPC) in yeast, but the molecular mechanism of this export process remains poorly understood. Here, we use quantitative fluorescence micro-scopy techniques in live budding yeast cells to investigate how Mex67 facilitates mRNA export. We show that Mex67 exhibits little interaction with mRNA in the nucleus and localizes to the NPC independently of mRNA, occupying a set of binding sites offered by FG repeats in the NPC. The ATPase Dbp5, which is thought to remove Mex67 from transcripts, does not affect the interaction of Mex67 with the NPC. Strikingly, we find that the essential function of Mex67 is spatially restricted to the NPC since a fusion of Mex67 to the nucleoporin Nup116 rescues a deletion of MEX67. Thus, Mex67 functions as a mobile nuclear pore component, which receives mRNA export substrates in the central channel of the NPC to facilitate their translocation to the cytoplasm.

scholarly journals The RNA export factor Mex67 functions as a mobile nucleoporin

2019 ◽  
Vol 218 (12) ◽  
pp. 3967-3976 ◽  
Author(s):  
Carina Patrizia Derrer ◽  
Roberta Mancini ◽  
Pascal Vallotton ◽  
Sébastien Huet ◽  
Karsten Weis ◽  
...  
Keyword(s):  
Nuclear Pore Complex ◽  
Binding Sites ◽  
Mrna Export ◽  
Yeast Cells ◽  
Nuclear Pore ◽  
Central Channel ◽  
Rna Export ◽  
Essential Function ◽  
Microscopy Techniques ◽  
Quantitative Fluorescence

The RNA export factor Mex67 is essential for the transport of mRNA through the nuclear pore complex (NPC) in yeast, but the molecular mechanism of this export process remains poorly understood. Here, we use quantitative fluorescence microscopy techniques in live budding yeast cells to investigate how Mex67 facilitates mRNA export. We show that Mex67 exhibits little interaction with mRNA in the nucleus and localizes to the NPC independently of mRNA, occupying a set of binding sites offered by FG repeats in the NPC. The ATPase Dbp5, which is thought to remove Mex67 from transcripts, does not affect the interaction of Mex67 with the NPC. Strikingly, we find that the essential function of Mex67 is spatially restricted to the NPC since a fusion of Mex67 to the nucleoporin Nup116 rescues a deletion of MEX67. Thus, Mex67 functions as a mobile NPC component, which receives mRNA export substrates in the central channel of the NPC to facilitate their translocation to the cytoplasm.

scholarly journals An agent-based model for mRNA export through the nuclear pore complex

2014 ◽  
Vol 25 (22) ◽  
pp. 3643-3653 ◽  
Author(s):  
Mohammad Azimi ◽  
Evgeny Bulat ◽  
Karsten Weis ◽  
Mohammad R. K. Mofrad
Keyword(s):  
Nuclear Pore Complex ◽  
Mrna Export ◽  
Nuclear Pore ◽  
Central Channel ◽  
Agent Based Model ◽  
Agent Based ◽  
Transport Dynamics ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Rate Limiting

mRNA export from the nucleus is an essential step in the expression of every protein- coding gene in eukaryotes, but many aspects of this process remain poorly understood. The density of export receptors that must bind an mRNA to ensure export, as well as how receptor distribution affects transport dynamics, is not known. It is also unclear whether the rate-limiting step for transport occurs at the nuclear basket, in the central channel, or on the cytoplasmic face of the nuclear pore complex. Using previously published biophysical and biochemical parameters of mRNA export, we implemented a three-dimensional, coarse-grained, agent-based model of mRNA export in the nanosecond regime to gain insight into these issues. On running the model, we observed that mRNA export is sensitive to the number and distribution of transport receptors coating the mRNA and that there is a rate-limiting step in the nuclear basket that is potentially associated with the mRNA reconfiguring itself to thread into the central channel. Of note, our results also suggest that using a single location-monitoring mRNA label may be insufficient to correctly capture the time regime of mRNA threading through the pore and subsequent transport. This has implications for future experimental design to study mRNA transport dynamics.

scholarly journals Specialization of chromatin-bound nuclear pore complexes promotes yeast aging

2021 ◽  
Author(s):  
Anne C Meinema ◽  
Theo Aspert ◽  
Sung Sik Lee ◽  
Gilles Charvin ◽  
Yves Barral
Keyword(s):  
Quality Control ◽  
Nuclear Pore Complex ◽  
Mrna Export ◽  
Yeast Cells ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Replicative Lifespan ◽  
Yeast Aging ◽  
Key Drivers ◽  
Pore Complexes

The nuclear pore complex (NPC) mediates nearly all exchanges between nucleus and cytoplasm, and changes composition in many species as the organism ages. However, how these changes arise and whether they contribute themselves to aging is poorly understood. We show that in replicatively aging yeast cells attachment of DNA circles to NPCs drives the displacement of the NPCs’ nuclear basket and cytoplasmic complexes. Remodeling of the NPC resulted from the regulation of basket components by SAGA, rather than from damages. These changes affected NPC interaction with mRNA export factors, without affecting the residence of import factors or engaging the NPC quality control machinery. Mutations preventing NPC remodeling extended the replicative lifespan of the cells. Thus, our data indicate that DNA circles accumulating in the mother cell drive aging at least in part by triggering NPC specialization. We suggest that antagonistic pleiotropic effects of NPC specialization are key drivers of aging.

scholarly journals Sem1 is a functional component of the nuclear pore complex–associated messenger RNA export machinery

2009 ◽  
Vol 184 (6) ◽  
pp. 833-846 ◽  
Author(s):  
Marius Boulos Faza ◽  
Stefan Kemmler ◽  
Sonia Jimeno ◽  
Cristina González-Aguilera ◽  
Andrés Aguilera ◽  
...  
Keyword(s):  
Nuclear Pore Complex ◽  
Messenger Rna ◽  
Mammalian Cells ◽  
Genome Instability ◽  
Protein Complexes ◽  
Mrna Export ◽  
Nuclear Pore ◽  
Multiple Protein ◽  
Rna Export ◽  
Biochemical Analyses

The evolutionarily conserved protein Sem1/Dss1 is a subunit of the regulatory particle (RP) of the proteasome, and, in mammalian cells, binds the tumor suppressor protein BRCA2. Here, we describe a new function for yeast Sem1. We show that sem1 mutants are impaired in messenger RNA (mRNA) export and transcription elongation, and induce strong transcription-associated hyper-recombination phenotypes. Importantly, Sem1, independent of the RP, is functionally linked to the mRNA export pathway. Biochemical analyses revealed that, in addition to the RP, Sem1 coenriches with components of two other multisubunit complexes: the nuclear pore complex (NPC)-associated TREX-2 complex that is required for transcription-coupled mRNA export, and the COP9 signalosome, which is involved in deneddylation. Notably, targeting of Thp1, a TREX-2 component, to the NPC is perturbed in a sem1 mutant. These findings reveal an unexpected nonproteasomal function of Sem1 in mRNA export and in prevention of transcription-associated genome instability. Thus, Sem1 is a versatile protein that might stabilize multiple protein complexes involved in diverse pathways.

scholarly journals The Nuclear Pore Complex and mRNA Export in Cancer

Cancers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 42
Author(s):  
Katherine L. B. Borden
Keyword(s):  
Nuclear Pore Complex ◽  
Molecular Basis ◽  
Human Cancer ◽  
Mrna Export ◽  
Therapeutic Strategies ◽  
Chromosomal Translocations ◽  
Nuclear Pore ◽  
Specific Effects ◽  
Rna Export ◽  
Aberrant Rna

Export of mRNAs from the nucleus to the cytoplasm is a key regulatory step in the expression of proteins. mRNAs are transported through the nuclear pore complex (NPC). Export of mRNAs responds to a variety of cellular stimuli and stresses. Revelations of the specific effects elicited by NPC components and associated co-factors provides a molecular basis for the export of selected RNAs, independent of bulk mRNA export. Aberrant RNA export has been observed in primary human cancer specimens. These cargo RNAs encode factors involved in nearly all facets of malignancy. Indeed, the NPC components involved in RNA export as well as the RNA export machinery can be found to be dysregulated, mutated, or impacted by chromosomal translocations in cancer. The basic mechanisms associated with RNA export with relation to export machinery and relevant NPC components are described. Therapeutic strategies targeting this machinery in clinical trials is also discussed. These findings firmly position RNA export as a targetable feature of cancer along with transcription and translation.

scholarly journals A novel nuclear pore protein Nup82p which specifically binds to a fraction of Nsp1p.

1995 ◽  
Vol 130 (6) ◽  
pp. 1263-1273 ◽  
Author(s):  
P Grandi ◽  
S Emig ◽  
C Weise ◽  
F Hucho ◽  
T Pohl ◽  
...  
Keyword(s):  
Nucleocytoplasmic Transport ◽  
Yeast Cells ◽  
Stable Complex ◽  
Nuclear Pore ◽  
Nuclear Pore Protein ◽  
Rna Export ◽  
Essential Function ◽  
Heptad Repeats ◽  
Carboxy Terminal ◽  
Pore Protein

Nsp1p interacts with nuclear pore proteins Nup49p, Nup57p and Nic96p in a stable complex which participates in nucleocytoplasmic transport. An additional p80 component is associated with Nsp1p, but does not co-purify with tagged Nup57p, Nup49p and Nic96p. The p80 gene was cloned and encodes a novel essential nuclear pore protein named Nup82p. Immunoprecipitation of tagged Nup82p reveals that it is physically associated with a fraction of Nsp1p which is distinct from Nsp1p found in a complex with Nup57p, Nic96p and Nup49p. The Nup82 protein can be divided into at least two different domains both required for the essential function, but it is only the carboxy-terminal domain, exhibiting heptad repeats, which binds to Nsp1p. Yeast cells depleted of Nup82p stop cell growth and concomitantly show a defect in poly(A)+RNA export, but no major alterations of nuclear envelope structure and nuclear pore density are seen by EM. This shows that Nsp1p participates in multiple interactions at the NPC and thus has the capability to physically interact with different NPC structures.

scholarly journals Stoichiometry and compositional plasticity of the yeast nuclear pore complex revealed by quantitative fluorescence microscopy

2018 ◽  
Vol 115 (17) ◽  
pp. E3969-E3977 ◽  
Author(s):  
Sasikumar Rajoo ◽  
Pascal Vallotton ◽  
Evgeny Onischenko ◽  
Karsten Weis
Keyword(s):  
Nuclear Pore Complex ◽  
Yeast Cells ◽  
Nuclear Pore ◽  
Altered Expression ◽  
Copy Numbers ◽  
Quantitative Image ◽  
Multiple Copies ◽  
Almost All ◽  
High Degree

The nuclear pore complex (NPC) is an eightfold symmetrical channel providing selective transport of biomolecules across the nuclear envelope. Each NPC consists of ∼30 different nuclear pore proteins (Nups) all present in multiple copies per NPC. Significant progress has recently been made in the characterization of the vertebrate NPC structure. However, because of the estimated size differences between the vertebrate and yeast NPC, it has been unclear whether the NPC architecture is conserved between species. Here, we have developed a quantitative image analysis pipeline, termed nuclear rim intensity measurement (NuRIM), to precisely determine copy numbers for almost all Nups within native NPCs of budding yeast cells. Our analysis demonstrates that the majority of yeast Nups are present at most in 16 copies per NPC. This reveals a dramatic difference to the stoichiometry determined for the human NPC, suggesting that despite a high degree of individual Nup conservation, the yeast and human NPC architecture is significantly different. Furthermore, using NuRIM, we examined the effects of mutations on NPC stoichiometry. We demonstrate for two paralog pairs of key scaffold Nups, Nup170/Nup157 and Nup192/Nup188, that their altered expression leads to significant changes in the NPC stoichiometry inducing either voids in the NPC structure or substitution of one paralog by the other. Thus, our results not only provide accurate stoichiometry information for the intact yeast NPC but also reveal an intriguing compositional plasticity of the NPC architecture, which may explain how differences in NPC composition could arise in the course of evolution.

The diverse roles of the Nup93/Nic96 complex proteins – structural scaffolds of the nuclear pore complex with additional cellular functions

2014 ◽  
Vol 395 (5) ◽  
pp. 515-528 ◽  
Author(s):  
Benjamin Vollmer ◽  
Wolfram Antonin
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Membrane ◽  
Building Blocks ◽  
Transport Processes ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Cellular Functions ◽  
Complex Assembly ◽  
Essential Function ◽  
Pore Complexes

Abstract Nuclear pore complexes mediate the transport between the cell nucleoplasm and cytoplasm. These 125 MDa structures are among the largest assemblies found in eukaryotes, built from proteins organized in distinct subcomplexes that act as building blocks during nuclear pore complex biogenesis. In this review, we focus on one of these subcomplexes, the Nup93 complex in metazoa and its yeast counterpart, the Nic96 complex. We discuss its essential function in nuclear pore complex assembly as a linker between the nuclear membrane and the central part of the pore and its various roles in nuclear transport processes and beyond.

scholarly journals Structural interaction between the nuclear pore complex and a specific translocating RNP particle.

1995 ◽  
Vol 129 (5) ◽  
pp. 1205-1216 ◽  
Author(s):  
H Mehlin ◽  
B Daneholt ◽  
U Skoglund
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Pore ◽  
Initial Contact ◽  
Chironomus Tentans ◽  
Central Channel ◽  
Balbiani Ring ◽  
Salivary Gland Cells ◽  
Larval Salivary Gland ◽  
Nuclear Ring ◽  
Precise Area

The transport of Balbiani ring (BR) premessenger RNP particles in the larval salivary gland cells of the dipteran Chironomus tentans can be followed using electron microscopy. A BR RNP particle consists of an RNP ribbon bent into a ringlike structure. Upon translocation through the nuclear pore complex (NPC), the ribbon is straightened and enters the central channel of the NPC with the 5' end of the transcript in the lead. The translocating ribbon is likely to interact with the central channel but, in addition, the remaining portion of the ribbon ring makes contact with the periphery of the NPC. To determine the nature of this latter interaction, we have now studied the connections between the RNP particle and the border of the NPC during different stages of translocation using electron microscope tomography. It was observed that the 3' terminal domain of the ribbon always touches the nuclear ring of the NPC, but the precise area of contact is variable. Sometimes also a region on the opposite side of the ribbon ring reaches the nuclear ring. The pattern of contacts could be correlated to the stage of translocation, and it was concluded that the particle-nuclear ring interactions reflect a rotation of the ribbon ring in front of the central channel, the rotation being secondary to the successive translocation of the ribbon through the channel. The particle's mode of interaction with the NPC suggests that the initial contact between the 5' end domain of the ribbon and the entrance to the central channel is probably crucial to accomplish the ordered translocation of the premessenger RNP particle through the NPC.

Sign in / Sign up

Export Citation Format

Share Document