scholarly journals Mechanisms Mediating Nuclear Trafficking Involved in Viral Propagation by DNA Viruses

Viruses ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1035
Author(s):  
Guohui Li ◽  
Xinyu Qi ◽  
Zhaoyang Hu ◽  
Qi Tang
Keyword(s):  
Nuclear Localization ◽  
Viral Entry ◽  
Current Knowledge ◽  
Viral Proteins ◽  
Nuclear Pore ◽  
Nuclear Trafficking ◽  
Dna Viruses ◽  
Virion Assembly ◽  
Nuclear Localization Signals ◽  
Viral Propagation

Typical viral propagation involves sequential viral entry, uncoating, replication, gene transcription and protein synthesis, and virion assembly and release. Some viral proteins must be transported into host nucleus to facilitate viral propagation, which is essential for the production of mature virions. During the transport process, nuclear localization signals (NLSs) play an important role in guiding target proteins into nucleus through the nuclear pore. To date, some classical nuclear localization signals (cNLSs) and non-classical NLSs (ncNLSs) have been identified in a number of viral proteins. These proteins are involved in viral replication, expression regulation of viral genes and virion assembly. Moreover, other proteins are transported into nucleus with unknown mechanisms. This review highlights our current knowledge about the nuclear trafficking of cellular proteins associated with viral propagation.

scholarly journals Pairs of Vp1 Cysteine Residues Essential for Simian Virus 40 Infection

2005 ◽  
Vol 79 (6) ◽  
pp. 3859-3864 ◽  
Author(s):  
Peggy P. Li ◽  
Akira Nakanishi ◽  
Vanessa Fontanes ◽  
Harumi Kasamatsu
Keyword(s):  
Nuclear Localization ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Dominant Negative ◽  
Capsid Proteins ◽  
Cysteine Residues ◽  
Nuclear Trafficking ◽  
Virion Assembly ◽  
Capsid Protein Vp1 ◽  
Sv40 Infection

ABSTRACT Transient disulfide bonding occurs during the intracellular folding and pentamerization of simian virus 40 (SV40) major capsid protein Vp1 (P. P. Li, A. Nakanishi, S. W. Clark, and H. Kasamatsu, Proc. Natl. Acad. Sci. USA 99:1353-1358, 2002). We investigated the requirement for Vp1 cysteine pairs during SV40 infection. Our analysis identified three Vp1 double-cysteine mutant combinations that abolished viability as assayed by plaque formation. Mutating the Cys49-Cys87 pair or the Cys87-Cys254 pair led to ineffective nuclear localization and diminished accumulation of the mutant Vp1s, and the defect extended in a dominant-negative manner to the wild-type minor capsid proteins Vp2/3 and an affinity-tagged recombinant Vp1 expressed in the same cells. Mutating the Cys87-Cys207 pair preserved the nuclear localization and normal accumulation of the capsid proteins but diminished the production of virus-like particles. Our results are consistent with a role for Cys49, Cys87, and Cys254 in the folding and cytoplasmic-nuclear trafficking of Vp1 and with a role for Cys87 and Cys207 in the assembly of infectious particles. These findings suggest that transient disulfide bond formation between certain Vp1 cysteine residues functions at two stages of SV40 infection: during Vp1 folding and oligomerization in the cytoplasm and during virion assembly in the nucleus.

scholarly journals Epstein–Barr virus nuclear antigen 3A contains six nuclear-localization signals

2006 ◽  
Vol 87 (10) ◽  
pp. 2879-2884 ◽  
Author(s):  
Marion Buck ◽  
Anita Burgess ◽  
Roslynn Stirzaker ◽  
Kenia Krauer ◽  
Tom Sculley
Keyword(s):  
Nuclear Localization ◽  
Epstein Barr Virus ◽  
Fluorescent Protein ◽  
Viral Proteins ◽  
Site Directed Mutagenesis ◽  
Nuclear Antigen ◽  
Nuclear Localization Signals ◽  
Barr Virus ◽  
Epstein Barr

The Epstein–Barr nuclear antigen 3A (EBNA3A) is one of only six viral proteins essential for Epstein–Barr virus-induced transformation of primary human B cells in vitro. Viral proteins such as EBNA3A are able to interact with cellular proteins, manipulating various biochemical and signalling pathways to initiate and maintain the transformed state of infected cells. EBNA3A has been reported to have one nuclear-localization signal and is targeted to the nucleus during transformation, where it associates with components of the nuclear matrix. By using enhanced green fluorescent protein-tagged deletion mutants of EBNA3A in combination with site-directed mutagenesis, an additional five functional nuclear-localization signals have been identified in the EBNA3A protein. Two of these (aa 63–66 and 375–381) were computer-predicted, whilst the remaining three (aa 394–398, 573–578 and 598–603) were defined functionally in this study.

scholarly journals Simple kinetic relationships and nonspecific competition govern nuclear import rates in vivo

2006 ◽  
Vol 175 (4) ◽  
pp. 579-593 ◽  
Author(s):  
Benjamin L. Timney ◽  
Jaclyn Tetenbaum-Novatt ◽  
Diana S. Agate ◽  
Rosemary Williams ◽  
Wenzhu Zhang ◽  
...  
Keyword(s):  
Nuclear Localization ◽  
Nuclear Pore Complex ◽  
Nuclear Import ◽  
Yeast Cells ◽  
Limiting Factor ◽  
Nuclear Pore ◽  
Nuclear Localization Signals ◽  
The Poor ◽  
Cytoplasmic Proteins

Many cargoes destined for nuclear import carry nuclear localization signals that are recognized by karyopherins (Kaps). We present methods to quantitate import rates and measure Kap and cargo concentrations in single yeast cells in vivo, providing new insights into import kinetics. By systematically manipulating the amounts, types, and affinities of Kaps and cargos, we show that import rates in vivo are simply governed by the concentrations of Kaps and their cargo and the affinity between them. These rates fit to a straightforward pump–leak model for the import process. Unexpectedly, we deduced that the main limiting factor for import is the poor ability of Kaps and cargos to find each other in the cytoplasm in a background of overwhelming nonspecific competition, rather than other more obvious candidates such as the nuclear pore complex and Ran. It is likely that most of every import round is taken up by Kaps and nuclear localization signals sampling other cytoplasmic proteins as they locate each other in the cytoplasm.

Dependence on Nuclear Localization Signals of the Opioid Growth Factor Receptor in the Regulation of Cell Proliferation

2009 ◽  
Vol 234 (5) ◽  
pp. 532-541 ◽  
Author(s):  
Fan Cheng ◽  
Patricia J. McLaughlin ◽  
Michael F. Verderame ◽  
Ian S. Zagon
Keyword(s):  
Cell Proliferation ◽  
Growth Factor ◽  
Nuclear Localization ◽  
Fluorescent Protein ◽  
Growth Factor Receptor ◽  
Full Length ◽  
Nuclear Pore ◽  
Nucleocytoplasmic Trafficking ◽  
Nuclear Localization Signals ◽  
Opioid Growth Factor

The opioid growth factor receptor (OGFr) mediates the inhibitory action of OGF on cell replication of normal and neoplastic cells. The spatiotemporal course of OGFr nucleocytoplasmic trafficking was determined with a probe of full-length OGFr fused to enhanced green fluorescent protein (eGFP). Translation of OGFr required 8.5 hours, and transit into the nucleus required 8 hours; OGFr remained in the nucleus for 8 days. OGFr was initially expressed on the outer nuclear envelope, transited to the paranuclear cytoplasm, and into the nucleus. Transport through the nuclear pore was elucidated by mutation of the nuclear localization signal (NLS) sequences in full-length OGFr. Mutation of each NLS reduced nuclear localization by 5%–50%, whereas simultaneous mutation of NLS383–386 and NLS456–460 abolished OGFr-eGFP nuclear localization in 80% of the cells. To determine whether intact NLSs are important for the inhibition of cell proliferation, DNA synthesis was monitored with BrdU. Wild-type OGFr-eGFP–transfected cells had 20% BrdU-positive cells, whereas cells with simultaneous mutation of all three NLS sites had a 70% labeling index. These results indicate that the regulation of cell proliferation by the OGF-OGFr axis is dependent on nucleocytoplasmic translocation and reliant on the integrity of two NLSs in OGFr to interact with transport receptors.

scholarly journals Nuclear Import of the Retrotransposon Tf1 Is Governed by a Nuclear Localization Signal That Possesses a Unique Requirement for the FXFG Nuclear Pore Factor Nup124p

2000 ◽  
Vol 20 (20) ◽  
pp. 7798-7812 ◽  
Author(s):  
Van-Dinh Dang ◽  
Henry L. Levin
Keyword(s):  
Amino Acid ◽  
Nuclear Envelope ◽  
Nuclear Localization ◽  
Nuclear Import ◽  
Heterologous Protein ◽  
Simian Virus 40 ◽  
Nuclear Pore ◽  
Surprising Result ◽  
Gag Protein ◽  
Nuclear Localization Signals

ABSTRACT Retroviruses, such as human immunodeficiency virus, that infect nondividing cells generate integration precursors that must cross the nuclear envelope to reach the host genome. As a model for retroviruses, we investigated the nuclear entry of Tf1, a long-terminal-repeat-containing retrotransposon of the fission yeastSchizosaccharomyces pombe. Because the nuclear envelope of yeasts remains intact throughout the cell cycle, components of Tf1 must be transported through the envelope before integration can occur. The nuclear localization of the Gag protein of Tf1 is different from that of other proteins tested in that it has a specific requirement for the FXFG nuclear pore factor, Nup124p. Using extensive mutagenesis, we found that Gag contained three nuclear localization signals (NLSs) which, when included individually in a heterologous protein, were sufficient to direct nuclear import. In the context of the intact transposon, mutations in the NLS that mapped to the first 10 amino acid residues of Gag significantly impaired Tf1 retrotransposition and abolished nuclear localization of Gag. Interestingly, this NLS activity in the heterologous protein was specifically dependent upon the presence of Nup124p. Deletion analysis of heterologous proteins revealed the surprising result that the residues in Gag with the NLS activity were independent from the residues that conveyed the requirement for Nup124p. In fact, a fragment of Gag that lacked NLS activity, residues 10 to 30, when fused to a heterologous protein, was sufficient to cause the classical NLS of simian virus 40 to require Nup124p for nuclear import. Within the context of the current understanding of nuclear import, these results represent the novel case of a short amino acid sequence that specifies the need for a particular nuclear pore complex protein.

scholarly journals Origin of the nuclear proteome on the basis of pre-existing nuclear localization signals in prokaryotic proteins

2020 ◽  
Author(s):  
Olga M. Lisitsyna ◽  
Margarita A. Kurnaeva ◽  
Eugene A. Arifulin ◽  
Maria Y. Shubina ◽  
Yana R. Musinova ◽  
...  
Keyword(s):  
Nuclear Localization ◽  
Protein Import ◽  
Eukaryotic Cell ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Nuclear Localization Signals ◽  
Binding Domains ◽  
Nuclear Proteome ◽  
Pore Complexes ◽  
Open Question

AbstractThe origin of the selective nuclear protein import machinery, which consists of nuclear pore complexes and adaptor molecules interacting with the nuclear localization signals (NLSs) of cargo molecules, was one of the most important events in the evolution of the eukaryotic cell. How the proteins were selected for import into the forming nuclei remains an open question. Here, we demonstrate that functional NLSs may be integrated inside nucleotide-binding domains of both eukaryotic and prokaryotic proteins and may co-evolve with these domains. We propose that the pre-existence of NLSs inside prokaryotic proteins dictated, at least partially, the nuclear proteome composition.

scholarly journals Karyopherin α-3 is a key protein in the pathogenesis of spinocerebellar ataxia type 3 controlling the nuclear localization of ataxin-3

2018 ◽  
Vol 115 (11) ◽  
pp. E2624-E2633 ◽  
Author(s):  
Anna Sergeevna Sowa ◽  
Elodie Martin ◽  
Inês Morgado Martins ◽  
Jana Schmidt ◽  
Reinhard Depping ◽  
...  
Keyword(s):  
Spinocerebellar Ataxia ◽  
Nuclear Localization ◽  
Neurodegenerative Disorder ◽  
Nucleocytoplasmic Transport ◽  
Spinocerebellar Ataxia Type ◽  
Nuclear Pore ◽  
Spinocerebellar Ataxia Type 3 ◽  
Nuclear Localization Signals ◽  
Positive Effects ◽  
Type 3

Spinocerebellar ataxia type 3 (SCA3) is a neurodegenerative disorder caused by a CAG expansion in the ATXN3 gene leading to a polyglutamine expansion in the ataxin-3 protein. The nuclear presence and aggregation of expanded ataxin-3 are critical steps in disease pathogenesis. To identify novel therapeutic targets, we investigated the nucleocytoplasmic transport system by screening a collection of importins and exportins that potentially modulate this nuclear localization. Using cell, Drosophila, and mouse models, we focused on three transport proteins, namely, CRM1, IPO13, KPNA3, and their respective Drosophila orthologs Emb, Cdm, and Kap-α3. While overexpression of CRM1/Emb demonstrated positive effects in Drosophila, KPNA3/Kap-α3 emerged as the most promising target, as knockdown via multiple RNAi lines demonstrated its ability to shuttle both truncated and full-length expanded ataxin-3, rescue neurodegeneration, restore photoreceptor formation, and reduce aggregation. Furthermore, KPNA3 knockout in SCA3 mice resulted in an amelioration of molecular and behavioral disturbances such as total activity, anxiety, and gait. Since KPNA3 is known to function as an import protein and recognize nuclear localization signals (NLSs), this work unites ataxin-3 structure to the nuclear pore machinery and provides a link between karyopherins, NLS signals, and polyglutamine disease, as well as demonstrates that KPNA3 is a key player in the pathogenesis of SCA3.

scholarly journals The Fate of Speckled Protein 100 (Sp100) During Herpesviruses Infection

2021 ◽  
Vol 10 ◽  
Author(s):  
Mila Collados Rodríguez
Keyword(s):  
Current Knowledge ◽  
Single Gene ◽  
Constitutive Expression ◽  
Immune Defense ◽  
Post Translational Modification ◽  
Dna Viruses ◽  
Viral Propagation ◽  
Dna Binding Domains ◽  
Binding Domains ◽  
Multiple Protein

The constitutive expression of Speckled-100 (Sp100) is known to restrict the replication of many clinically important DNA viruses. This pre-existing (intrinsic) immune defense to virus infection can be further upregulated upon interferon (IFN) stimulation as a component of the innate immune response. In humans, Sp100 is encoded by a single gene locus, which can produce alternatively spliced isoforms. The widely studied Sp100A, Sp100B, Sp100C and Sp100HMG have functions associated with the transcriptional regulation of viral and cellular chromatin, either directly through their characteristic DNA-binding domains, or indirectly through post-translational modification (PTM) and associated protein interaction networks. Sp100 isoforms are resident component proteins of promyelocytic leukemia-nuclear bodies (PML-NBs), dynamic nuclear sub-structures which regulate host immune defenses against many pathogens. In the case of human herpesviruses, multiple protein antagonists are expressed to relieve viral DNA genome transcriptional silencing imposed by PML-NB and Sp100-derived proteinaceous structures, thereby stimulating viral propagation, pathogenesis, and transmission to new hosts. This review details how different Sp100 isoforms are manipulated during herpesviruses HSV1, VZV, HCMV, EBV, and KSHV infection, identifying gaps in our current knowledge, and highlighting future areas of research.

scholarly journals Evolutionary development of redundant nuclear localization signals in the mRNA export factor NXF1

2011 ◽  
Vol 22 (23) ◽  
pp. 4657-4668 ◽  
Author(s):  
Zi Chao Zhang ◽  
Neal Satterly ◽  
Beatriz M. A. Fontoura ◽  
Yuh Min Chook
Keyword(s):  
Nuclear Localization ◽  
Nuclear Import ◽  
Mrna Export ◽  
Evolutionary Development ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Nuclear Localization Signals ◽  
Basic Segment ◽  
Importin Α ◽  
Pore Complexes

In human cells, the mRNA export factor NXF1 resides in the nucleoplasm and at nuclear pore complexes. Karyopherin β2 or transportin recognizes a proline–tyrosine nuclear localization signal (PY-NLS) in the N-terminal tail of NXF1 and imports it into the nucleus. Here biochemical and cellular studies to understand the energetic organization of the NXF1 PY-NLS reveal unexpected redundancy in the nuclear import pathways used by NXF1. Human NXF1 can be imported via importin β, karyopherin β2, importin 4, importin 11, and importin α. Two NLS epitopes within the N-terminal tail, an N-terminal basic segment and a C-terminal R-X2-5-P-Y motif, provide the majority of binding energy for all five karyopherins. Mutation of both NLS epitopes abolishes binding to the karyopherins, mislocalized NXF1 to the cytoplasm, and significantly compromised its mRNA export function. The understanding of how different karyopherins recognize human NXF1, the examination of NXF1 sequences from divergent eukaryotes, and the interactions of NXF1 homologues with various karyopherins reveals the evolutionary development of redundant NLSs in NXF1 of higher eukaryotes. Redundancy of nuclear import pathways for NXF1 increases progressively from fungi to nematodes and insects to chordates, potentially paralleling the increasing complexity in mRNA export regulation and the evolution of new nuclear functions for NXF1.

scholarly journals Structural basis for nuclear import selectivity of pioneer transcription factor SOX2

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Bikshapathi Jagga ◽  
Megan Edwards ◽  
Miriam Pagin ◽  
Kylie M. Wagstaff ◽  
David Aragão ◽  
...  
Keyword(s):  
Nuclear Localization ◽  
Nuclear Import ◽  
Protein Localization ◽  
Structural Basis ◽  
Nuclear Targeting ◽  
Nuclear Trafficking ◽  
Hmg Box ◽  
Nuclear Localization Signals ◽  
Pioneer Transcription Factor ◽  
Mechanistic Basis

AbstractSOX (SRY-related HMG-box) transcription factors perform critical functions in development and cell differentiation. These roles depend on precise nuclear trafficking, with mutations in the nuclear targeting regions causing developmental diseases and a range of cancers. SOX protein nuclear localization is proposed to be mediated by two nuclear localization signals (NLSs) positioned within the extremities of the DNA-binding HMG-box domain and, although mutations within either cause disease, the mechanistic basis has remained unclear. Unexpectedly, we find here that these two distantly positioned NLSs of SOX2 contribute to a contiguous interface spanning 9 of the 10 ARM domains on the nuclear import adapter IMPα3. We identify key binding determinants and show this interface is critical for neural stem cell maintenance and for Drosophila development. Moreover, we identify a structural basis for the preference of SOX2 binding to IMPα3. In addition to defining the structural basis for SOX protein localization, these results provide a platform for understanding how mutations and post-translational modifications within these regions may modulate nuclear localization and result in clinical disease, and also how other proteins containing multiple NLSs may bind IMPα through an extended recognition interface.

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