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Nuclear pore complex

Paul A Rowley, Kurt Patterson, Suzanne B Sandmeyer, Sara L Sawyer
Yeasts serve as hosts to several types of genetic parasites. Few studies have addressed the evolutionary trajectory of yeast genes that control the stable co-existence of these parasites with their host cell. In Saccharomyces yeasts, the retrovirus-like Ty retrotransposons must access the nucleus. We show that several genes encoding components of the yeast nuclear pore complex have experienced natural selection for substitutions that change the encoded protein sequence. By replacing these S. cerevisiae genes with orthologs from other Saccharomyces species, we discovered that natural sequence changes have affected the mobility of Ty retrotransposons...
April 2018: PLoS Genetics
Pier Cacciali, Gunther KÖhler
Tropidurus is a Neotropical genus of iguanoid lizards characterized by a conspicuously enlarged interparietal plate, the presence of gular folds, presence of infradigital keels, and the absence of femoral pores. Currently, 29 species are recognized within the genus, seven of which are present in Paraguay: T. etheridgei, T. torquatus, T. guarani, T. lagunablanca, T. spinulosus, T. tarara, and T. teyumirim. We generated genetic data based on two DNA mitochondrial markers (16S and COI) and one nuclear (PRLR) marker for all the seven Paraguayan species with the goal to identify the taxonomic relationships among taxa based on the intra- and interspecific genetic variation and the construction of molecular clusters...
January 25, 2018: Zootaxa
Paola De Magistris, Wolfram Antonin
Eukaryotes characteristically organize their genome in a separate compartment, the nucleus, which is surrounded by the nuclear envelope as a barrier. Ruptures of the nuclear envelope and exposure of chromatin threaten cell viability and cause genome instability. Despite its essential boundary function, the nuclear envelope undergoes remarkable morphological changes, most noticeable during mitosis. Here we summarize our current understanding of nuclear envelope dynamics and its mutable relationship to the endoplasmic reticulum...
April 23, 2018: Current Biology: CB
Shoshiro Hirayama, Munechika Sugihara, Daisuke Morito, Shun-Ichiro Iemura, Tohru Natsume, Shigeo Murata, Kazuhiro Nagata
Although mechanisms for protein homeostasis in the cytosol have been studied extensively, those in the nucleus remain largely unknown. Here, we identified that a protein complex mediates export of polyubiquitinated proteins from the nucleus to the cytosol. UBIN, a ubiquitin-associated (UBA) domain-containing protein, shuttled between the nucleus and the cytosol in a CRM1-dependent manner, despite the lack of intrinsic nuclear export signal (NES). Instead, the UBIN binding protein polyubiquitinated substrate transporter (POST) harboring an NES shuttled UBIN through nuclear pores...
April 16, 2018: Proceedings of the National Academy of Sciences of the United States of America
Ashwanth C Francis, Gregory B Melikyan
The HIV-1 core consists of capsid proteins (CA) surrounding viral genomic RNA. After virus-cell fusion, the core enters the cytoplasm and the capsid shell is lost through uncoating. CA loss precedes nuclear import and HIV integration into the host genome, but the timing and location of uncoating remain unclear. By visualizing single HIV-1 infection, we find that CA is required for core docking at the nuclear envelope (NE), whereas early uncoating in the cytoplasm promotes proteasomal degradation of viral complexes...
April 11, 2018: Cell Host & Microbe
Xinlong Luo, Wei Yang, Guangxia Gao
HIV-1 can infect non-dividing cells via passing through the nuclear pore complex. The nuclear membrane imbedded protein SUN2 was recently reported to be involved in the nuclear import of HIV-1. Whether SUN1, which shares many functional similarities with SUN2, is involved in this process remained to be explored. Here, we report that overexpression of SUN1 specifically inhibited the infection of HIV-1, but not simian immunodeficiency virus (SIV) or murine leukemia virus (MLV). Overexpression of SUN1 did not affect reverse transcription, but led to reduced accumulation of the 2-LTR circular DNA and integrated viral DNA, suggesting a block in the process of nuclear import...
April 11, 2018: Journal of Virology
Melpomeni Platani, Itaru Samejima, Kumiko Samejima, Masato T Kanemaki, W C Earnshaw
In metazoa the Nup107-160 nucleoporin Y complex plays a major role in formation of the nuclear pore complex in interphase and is localised to kinetochores in mitosis. The Nup107-160 complex shares a single highly conserved subunit, Seh1, with the GATOR2 complex, an essential activator of mTORC1 kinase. mTORC1/GATOR2 has a central role in the coordination of cell growth and proliferation. Here we use chemical genetics and quantitative chromosome proteomics to study the role of the Seh1 protein in mitosis. Surprisingly, Seh1 is not required for the association of the Nup107-160 complex with mitotic chromosomes, but it is essential for the association of both GATOR2 complex and nucleoporin Nup153 with mitotic chromosomes...
April 3, 2018: Journal of Cell Science
Guo-Hua Qiu, Cuiqin Huang, Xintian Zheng, Xiaoyan Yang
Peripheral and abundant noncoding DNA has been hypothesized to protect the genome and the central protein-coding sequences against DNA damage in somatic genome. In the cytosol, invading exogenous nucleic acids may first be deactivated by small RNAs encoded by noncoding DNA via mechanisms similar to the prokaryotic CRISPR-Cas system. In the nucleus, the radicals generated by radiation in the cytosol, radiation energy and invading exogenous nucleic acids are absorbed, blocked and/or reduced by peripheral heterochromatin, and damaged DNA in heterochromatin is removed and excluded from the nucleus to the cytoplasm through nuclear pore complexes...
April 4, 2018: Epigenomics
Philipp Hoess, Markus Mund, Manuel Reitberger, Jonas Ries
Breaking the resolution limit of conventional microscopy by super-resolution microscopy (SRM) led to many new biological insights into protein assemblies at the nanoscale. Here we provide detailed protocols for single-molecule localization microscopy (SMLM) to image the structure of a protein complex. As examples, we show how to acquire single- and dual-color super-resolution images of the nuclear pore complex (NPC) and dual-color 3D data on actin and paxillin in focal adhesions.
2018: Methods in Molecular Biology
Anna Lång, Alexander Øye, Jens Eriksson, Alexander D Rowe, Emma Lång, Stig Ove Bøe
During cell division, a large number of nuclear proteins are released into the cytoplasm due to nuclear envelope breakdown. Timely nuclear import of these proteins following exit from mitosis is critical for establishment of the G1 nuclear environment. Dysregulation of post-mitotic nuclear import may affect the fate of newly divided stem or progenitor cells and may lead to cancer. Acute promyelocytic leukemia (APL) is a malignant disorder that involves a defect in blood cell differentiation at the promyelocytic stage...
March 26, 2018: Biochemical and Biophysical Research Communications
Piau Siong Tan, Iker Valle Aramburu, Davide Mercadante, Swati Tyagi, Aritra Chowdhury, Daniel Spitz, Sarah L Shammas, Frauke Gräter, Edward A Lemke
Phenylalanine-glycine-rich nucleoporins (FG-Nups) are intrinsically disordered proteins, constituting the selective barrier of the nuclear pore complex (NPC). Previous studies showed that nuclear transport receptors (NTRs) were found to interact with FG-Nups by forming an "archetypal-fuzzy" complex through the rapid formation and breakage of interactions with many individual FG motifs. Here, we use single-molecule studies combined with atomistic simulations to show that, in sharp contrast, FG-Nup214 undergoes a coupled reconfiguration-binding mechanism when interacting with the export receptor CRM1...
March 27, 2018: Cell Reports
Alexander Pfab, Astrid Bruckmann, Julian Nazet, Rainer Merkl, Klaus D Grasser
The conserved nuclear protein ENY2 (Sus1 in yeast) is involved in coupling transcription and mRNA export in yeast and metazoa, as it is a component both of the transcriptional co-activator complex SAGA and of the mRNA export complex TREX-2. Arabidopsis thaliana ENY2 is widely expressed in the plant and it localises to the nucleoplasm, but unlike its yeast/metazoan orthologues it is not enriched in the nuclear envelope. Affinity purification of ENY2 in combination with mass spectrometry revealed that it co-purified with SAGA components, but not with the nuclear pore-associated TREX-2...
March 24, 2018: Journal of Molecular Biology
Frans A A Mulder
Exchange of macromolecules between the cytoplasm and the nucleus of all eukaryotic cells is controlled by nuclear pore complexes, which form a selective permeability barrier. The requirement for rapid but selective transport leads to a "transport paradox." A new experimental study now provides a thermodynamic explanation.
March 23, 2018: Journal of Biological Chemistry
Seung Joong Kim, Javier Fernandez-Martinez, Ilona Nudelman, Yi Shi, Wenzhu Zhang, Barak Raveh, Thurston Herricks, Brian D Slaughter, Joanna A Hogan, Paula Upla, Ilan E Chemmama, Riccardo Pellarin, Ignacia Echeverria, Manjunatha Shivaraju, Azraa S Chaudhury, Junjie Wang, Rosemary Williams, Jay R Unruh, Charles H Greenberg, Erica Y Jacobs, Zhiheng Yu, M Jason de la Cruz, Roxana Mironska, David L Stokes, John D Aitchison, Martin F Jarrold, Jennifer L Gerton, Steven J Ludtke, Christopher W Akey, Brian T Chait, Andrej Sali, Michael P Rout
Nuclear pore complexes play central roles as gatekeepers of RNA and protein transport between the cytoplasm and nucleoplasm. However, their large size and dynamic nature have impeded a full structural and functional elucidation. Here we determined the structure of the entire 552-protein nuclear pore complex of the yeast Saccharomyces cerevisiae at sub-nanometre precision by satisfying a wide range of data relating to the molecular arrangement of its constituents. The nuclear pore complex incorporates sturdy diagonal columns and connector cables attached to these columns, imbuing the structure with strength and flexibility...
March 14, 2018: Nature
Arun Kumar, Priyanka Sharma, Mercè Gomar-Alba, Zhanna Shcheprova, Anne Daulny, Trinidad Sanmartín, Irene Matucci, Charlotta Funaya, Miguel Beato, Manuel Mendoza
The acquisition of cellular identity is coupled to changes in the nuclear periphery and nuclear pore complexes (NPCs). Whether and how these changes determine cell fate remain unclear. We have uncovered a mechanism that regulates NPC acetylation to direct cell fate after asymmetric division in budding yeast. The lysine deacetylase Hos3 associates specifically with daughter cell NPCs during mitosis to delay cell cycle entry (Start). Hos3-dependent deacetylation of nuclear basket and central channel nucleoporins establishes daughter-cell-specific nuclear accumulation of the transcriptional repressor Whi5 during anaphase and perinuclear silencing of the G1/S cyclin gene CLN2 in the following G1 phase...
March 12, 2018: Nature Cell Biology
Taewook Kang, Pia Jensen, Vita Solovyeva, Jonathan R Brewer, Martin R Larsen
Characterization of molecular mechanisms underlying pancreatic β-cell function in relation to glucose-stimulated insulin secretion is incomplete, especially with respect to global response in the nuclear environment. Here, we focus on the characterization of proteins in the nuclear environment of β-cells after brief, high glucose-stimulation. We compared purified nuclei derived from β-cells stimulated with 17mM glucose for 0, 2, and 5 minutes using quantitative proteomics, a time frame that most likely does not result in translation of new protein in the cell...
March 8, 2018: Journal of Proteome Research
Nicholas R Meyerson, Cody J Warren, Daniel A S A Vieira, Felipe Diaz-Griferro, Sara L Sawyer
HIV-1 arose as the result of spillover of simian immunodeficiency viruses (SIVs) from great apes in Africa, namely from chimpanzees and gorillas. Chimpanzees and gorillas were, themselves, infected with SIV after virus spillover from African monkeys. During spillover events, SIV is thought to require adaptation to the new host species. The host barriers that drive viral adaptation have predominantly been attributed to restriction factors, rather than cofactors (host proteins exploited to promote viral replication)...
March 2018: PLoS Pathogens
Savrina Manhas, Lina Ma, Vivien Measday
Nuclear pore complexes (NPCs) orchestrate cargo between the cytoplasm and nucleus and regulate chromatin organization. NPC proteins, or nucleoporins (Nups), are required for human immunodeficiency virus type 1 (HIV-1) gene expression and genomic integration of viral DNA. We utilize the Ty1 retrotransposon of Saccharomyces cerevisiae (S. cerevisiae) to study retroviral integration because retrotransposons are the progenitors of retroviruses and have conserved integrase (IN) enzymes. Ty1-IN targets Ty1 elements into the genome upstream of RNA polymerase (Pol) III transcribed genes such as transfer RNA (tRNA) genes...
March 5, 2018: Nucleic Acids Research
Philip Ketterer, Adithya N Ananth, Diederik S Laman Trip, Ankur Mishra, Eva Bertosin, Mahipal Ganji, Jaco van der Torre, Patrick Onck, Hendrik Dietz, Cees Dekker
The nuclear pore complex (NPC) is the gatekeeper for nuclear transport in eukaryotic cells. A key component of the NPC is the central shaft lined with intrinsically disordered proteins (IDPs) known as FG-Nups, which control the selective molecular traffic. Here, we present an approach to realize artificial NPC mimics that allows controlling the type and copy number of FG-Nups. We constructed 34 nm-wide 3D DNA origami rings and attached different numbers of NSP1, a model yeast FG-Nup, or NSP1-S, a hydrophilic mutant...
March 2, 2018: Nature Communications
Jennifer M Holden, Ludek Koreny, Samson Obado, Alexander V Ratushny, Wei-Ming Chen, Jean-Mathieu Bart, Miguel Navarro, Brian T Chait, John D Aitchison, Michael P Rout, Mark C Field
Components of the nuclear periphery coordinate a multitude of activities, including macromolecular transport, cell-cycle progression and chromatin organization. Nuclear pore complexes (NPCs) mediate nucleocytoplasmic transport, mRNA processing and transcriptional regulation, and NPC components can define regions of high transcriptional activity in some organisms at the nuclear periphery and nucleoplasm. Lineage-specific features underpin several core nuclear functions, and in trypanosomatids, which branched very early from other eukaryotes, unique protein components constitute the lamina, kinetochores and parts of the NPCs...
March 1, 2018: Molecular Biology of the Cell
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