scholarly journals Passive diffusion through nuclear pore complexes regulates levels of the yeast SAGA and SLIK coactivators complexes

2019 ◽  
Author(s):  
Tadashi Makio ◽  
Richard W. Wozniak
Keyword(s):  
Target Genes ◽  
Passive Diffusion ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Saga Complex ◽  
Nuclear Entry ◽  
Diffusion Channel ◽  
Nuclear Activity ◽  
Diffusion Rates ◽  
Pore Complexes

AbstractNuclear pore complexes (NPCs) control gene expression by regulating the bi-directional exchange of proteins and RNAs between nuclear and cytoplasmic compartments, including access of transcriptional regulators to the nucleoplasm. Here we show that the yeast nucleoporin Nup170, in addition to binding and silencing subtelomeric genes, supports transcription of genes regulated by the SAGA transcriptional activator. Specifically, we show that less SAGA complex is bound to target genes in the absence Nup170. Consistent with this observation, levels of the SAGA complex are decreased in cells lacking Nup170, while SAGA-related SLIK complexes are increased. This change in the ratio of SAGA to SLIK complexes is due to increased nuclear activity of Pep4, a protease responsible for production of the SLIK complex. Further analyses of various nucleoporin mutants revealed that the increased nuclear entry of Pep4 observed in the nup170Δ mutant likely occurs as consequence of an increase in the sieving limits of the NPC diffusion channel. On the basis of these results, we propose that changes in passive diffusion rates represents a mechanism for regulating SAGA/SLIK complex-mediated transcriptional events.

scholarly journals Simple rules for passive diffusion through the nuclear pore complex

2016 ◽  
Vol 215 (1) ◽  
pp. 57-76 ◽  
Author(s):  
Benjamin L. Timney ◽  
Barak Raveh ◽  
Roxana Mironska ◽  
Jill M. Trivedi ◽  
Seung Joong Kim ◽  
...  
Keyword(s):  
Brownian Dynamics ◽  
Passive Diffusion ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Entropic Repulsion ◽  
Time Resolved ◽  
Dynamics Simulations ◽  
Pore Complexes ◽  
Size Threshold

Passive macromolecular diffusion through nuclear pore complexes (NPCs) is thought to decrease dramatically beyond a 30–60-kD size threshold. Using thousands of independent time-resolved fluorescence microscopy measurements in vivo, we show that the NPC lacks such a firm size threshold; instead, it forms a soft barrier to passive diffusion that intensifies gradually with increasing molecular mass in both the wild-type and mutant strains with various subsets of phenylalanine-glycine (FG) domains and different levels of baseline passive permeability. Brownian dynamics simulations replicate these findings and indicate that the soft barrier results from the highly dynamic FG repeat domains and the diffusing macromolecules mutually constraining and competing for available volume in the interior of the NPC, setting up entropic repulsion forces. We found that FG domains with exceptionally high net charge and low hydropathy near the cytoplasmic end of the central channel contribute more strongly to obstruction of passive diffusion than to facilitated transport, revealing a compartmentalized functional arrangement within the NPC.

scholarly journals The HIV-1 capsid core is an opportunistic nuclear import receptor

2021 ◽  
Author(s):  
Guangai Xue ◽  
Hyun Jae Yu ◽  
Shih Lin Goh ◽  
Anna T. Gres ◽  
Mehmet Hakan Guney ◽  
...  
Keyword(s):  
Nuclear Transport ◽  
Host Factors ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Nuclear Entry ◽  
Critical Determinant ◽  
Subsequent Work ◽  
Biological Assays ◽  
Pore Complexes ◽  
Hiv 1

The movement of viruses and other large macromolecular cargo through nuclear pore complexes (NPCs) is poorly understood. The human immunodeficiency virus type 1 (HIV-1) provides an attractive model to interrogate this process due to the genetic and cell biological assays to score virus nuclear entry in living cells. Although initial studies of HIV-1 infection of nondividing cells focused on karyophilic virion proteins, subsequent work revealed the viral capsid (CA), the chief structural component of the pre-integration complex (PIC), to be a critical determinant in nuclear transport1. In support of this model, HIV-1 interactions with NPCs can be altered through CA mutation2, which makes direct contact with nucleoporins (Nups)3–5. Here we identify Nup35, Nup153, and POM121 to coordinately support HIV-1 nuclear entry. For Nup35 and POM121, this dependence was strongly dependent cyclophilin A (CypA) interaction with CA. Mutation of CA or removal of soluble host factors changed the interaction with the NPC. Collectively, these findings implicate the HIV-1 CA hexameric lattice that encapsulates the viral genome as a macromolecular nuclear transport receptor (NTR) that exploits soluble host factors to modulate NPC requirements during nuclear invasion.

scholarly journals Role of SAGA in the asymmetric segregation of DNA circles during yeast ageing

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Annina Denoth-Lippuner ◽  
Marek Konrad Krzyzanowski ◽  
Catherine Stober ◽  
Yves Barral
Keyword(s):  
Mother Cell ◽  
Nuclear Organization ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Saga Complex ◽  
Chromosomal Dna ◽  
Pore Complexes ◽  
Chromosomal Recombination

In eukaryotes, intra-chromosomal recombination generates DNA circles, but little is known about how cells react to them. In yeast, partitioning of such circles to the mother cell at mitosis ensures their loss from the population but promotes replicative ageing. Nevertheless, the mechanisms of partitioning are debated. In this study, we show that the SAGA complex mediates the interaction of non-chromosomal DNA circles with nuclear pore complexes (NPCs) and thereby promotes their confinement in the mother cell. Reciprocally, this causes retention and accumulation of NPCs, which affects the organization of ageing nuclei. Thus, SAGA prevents the spreading of DNA circles by linking them to NPCs, but unavoidably causes accumulation of circles and NPCs in the mother cell, and thereby promotes ageing. Together, our data provide a unifying model for the asymmetric segregation of DNA circles and how age affects nuclear organization.

scholarly journals HIV-1 nuclear import in macrophages is regulated by CPSF6-capsid interactions at the nuclear pore complex

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
David Alejandro Bejarano ◽  
Ke Peng ◽  
Vibor Laketa ◽  
Kathleen Börner ◽  
K Laurence Jost ◽  
...  
Keyword(s):  
Stimulated Emission ◽  
Host Protein ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Protein Cleavage ◽  
Nuclear Entry ◽  
Successful Infection ◽  
Specificity Factor ◽  
Pore Complexes ◽  
Hiv 1

Nuclear entry of HIV-1 replication complexes through intact nuclear pore complexes is critical for successful infection. The host protein cleavage-and-polyadenylation-specificity-factor-6 (CPSF6) has been implicated in different stages of early HIV-1 replication. Applying quantitative microscopy of HIV-1 reverse-transcription and pre-integration-complexes (RTC/PIC), we show that CPSF6 is strongly recruited to nuclear replication complexes but absent from cytoplasmic RTC/PIC in primary human macrophages. Depletion of CPSF6 or lack of CPSF6 binding led to accumulation of HIV-1 subviral complexes at the nuclear envelope of macrophages and reduced infectivity. Two-color stimulated-emission-depletion microscopy indicated that under these circumstances HIV-1 complexes are retained inside the nuclear pore and undergo CA-multimer dependent CPSF6 clustering adjacent to the nuclear basket. We propose that nuclear entry of HIV-1 subviral complexes in macrophages is mediated by consecutive binding of Nup153 and CPSF6 to the hexameric CA lattice.

scholarly journals Ty3 Nuclear Entry Is Initiated by Viruslike Particle Docking on GLFG Nucleoporins

2009 ◽  
Vol 83 (22) ◽  
pp. 11914-11925 ◽  
Author(s):  
Nadejda Beliakova-Bethell ◽  
Laura J. Terry ◽  
Virginia Bilanchone ◽  
Rhonda DaSilva ◽  
Kunio Nagashima ◽  
...  
Keyword(s):  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Nuclear Entry ◽  
Preintegration Complex ◽  
Nuclear Localization Signals ◽  
Amino Terminal ◽  
Virus Like Particle ◽  
Viruslike Particles ◽  
Pore Complexes

ABSTRACT Yeast retrotransposons form intracellular particles within which replication occurs. Because fungal nuclear membranes do not break down during mitosis, similar to retroviruses infecting nondividing cells, the cDNA produced must be translocated through nuclear pore complexes. The Saccharomyces cerevisiae long terminal repeat retrotransposon Ty3 assembles its Gag3 and Gag3-Pol3 precursor polyproteins into viruslike particles in association with perinuclear P-body foci. These perinuclear clusters of Ty3 viruslike particles localized to sites of clustered nuclear pore complexes (NPCs) in a nup120Δ mutant, indicating that Ty3 particles and NPCs interact physically. The NPC channels are lined with nucleoporins (Nups) with extended FG (Phe-Gly) motif repeat domains, further classified as FG, FxFG, or GLFG repeat types. These domains mediate partitioning of proteins between the cytoplasm and the nucleus. Here we have systematically examined the requirements for FG repeat domains in Ty3 nuclear transport. The GLFG domains interacted in vitro with virus-like particle Gag3, and this interaction was disrupted by mutations in the amino-terminal domain of Gag3, which is predicted to lie on the external surface of the particles. Accordingly, Ty3 transposition was decreased in strains with the GLFG repeats deleted. The spacer-nucleocapsid domain of Gag3, which is predicted to be internal to the particle, interacted with GLFG repeats and nucleocapsid localized to the nucleus. We conclude that Ty3 particle docking on nuclear pores is facilitated by interactions between Gag3 and GLFG Nups and that nuclear entry of the preintegration complex is further promoted by nuclear localization signals within the nucleocapsid and integrase.

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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