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Herpes simplex virus type 1 nucleocapsids are released from the host nucleus by a budding process through the nuclear envelope called nuclear egress. Two viral proteins, the integral membrane proteins pUL34 and pUL31, form the nuclear egress complex at the inner nuclear membrane, which is critical for this process. The nuclear import of both proteins ensues separately from each other: pUL31 is actively imported through the central pore channel, while pUL34 is transported along the peripheral pore membrane. With this study, we identified a functional bipartite NLS between residues 178 and 194 of pUL34. pUL34 lacking its NLS is mislocalized to the TGN but retargeted to the ER upon insertion of the authentic NLS or a mimic NLS, independent of the insertion site. If co-expressed with pUL31, either of the pUL34-NLS variants is efficiently, although not completely, targeted to the nuclear rim where co-localization with pUL31 and membrane budding seem to occur, comparable to the wild-type. The viral mutant HSV1(17+)Lox-UL34-NLS mt is modestly attenuated but viable and associated with localization of pUL34-NLS mt to both the nuclear periphery and cytoplasm. We propose that targeting of pUL34 to the INM is facilitated by, but not dependent on, the presence of an NLS, thereby supporting NEC formation and viral replication.
Christina Funk; Débora Marques Da Silveira E Santos; Melanie Ott; Verena Raschbichler; Susanne Bailer. The HSV1 Tail-Anchored Membrane Protein pUL34 Contains a Basic Motif That Supports Active Transport to the Inner Nuclear Membrane Prior to Formation of the Nuclear Egress Complex. Viruses 2021, 13, 1544 .
AMA StyleChristina Funk, Débora Marques Da Silveira E Santos, Melanie Ott, Verena Raschbichler, Susanne Bailer. The HSV1 Tail-Anchored Membrane Protein pUL34 Contains a Basic Motif That Supports Active Transport to the Inner Nuclear Membrane Prior to Formation of the Nuclear Egress Complex. Viruses. 2021; 13 (8):1544.
Chicago/Turabian StyleChristina Funk; Débora Marques Da Silveira E Santos; Melanie Ott; Verena Raschbichler; Susanne Bailer. 2021. "The HSV1 Tail-Anchored Membrane Protein pUL34 Contains a Basic Motif That Supports Active Transport to the Inner Nuclear Membrane Prior to Formation of the Nuclear Egress Complex." Viruses 13, no. 8: 1544.
In previous studies, cold atmospheric plasma (CAP) was explored as an antibacterial and antiviral agent for the treatment of chronic wounds. The aim of the present study was to investigate whether CAP may also be suitable as an antiviral therapy against herpes simplex virus type 1 (HSV-1). HSV-1 most frequently manifests as recurrent herpes labialis, but it can also cause encephalitis, conjunctivitis or herpes neonatorum as a perinatal infection. HSV-1 encoding the reporter gene GFP was propagated. The CAP dose for HSV-1 treatment was gradually increased, ranging from 0–150 s, and aciclovir was used as a positive control. After CAP treatment, the virus suspension was applied to a standard HSV research cell line (Vero cells) and the neuroblastoma cell line SH-SY5Y as a model for neuronal infection. The results showed that plasma treatment had a negligible antiviral effect on HSV-1 in both Vero- and SH-SY5Y cells at high dose. However, when we lowered the viral load 100-fold, we observed a significantly decreased number of internalized HSV-1 genomes 3 h post-infection for CAP-treated viruses. This difference was less pronounced with respect to GFP expression levels 24 h post-infection, which was in sharp contrast to the acyclovir-treated positive control, for which the viral load was reduced from 95 to 25%. In summary, we observed a low but measurable antiviral effect of CAP on HSV-1.
Oskar Bunz; Kemal Mese; Christina Funk; Maximilan Wulf; Susanne M. Bailer; Andree Piwowarczyk; Anja Ehrhardt. Cold atmospheric plasma as antiviral therapy – effect on human herpes simplex virus type 1. Journal of General Virology 2020, 101, 208 -215.
AMA StyleOskar Bunz, Kemal Mese, Christina Funk, Maximilan Wulf, Susanne M. Bailer, Andree Piwowarczyk, Anja Ehrhardt. Cold atmospheric plasma as antiviral therapy – effect on human herpes simplex virus type 1. Journal of General Virology. 2020; 101 (2):208-215.
Chicago/Turabian StyleOskar Bunz; Kemal Mese; Christina Funk; Maximilan Wulf; Susanne M. Bailer; Andree Piwowarczyk; Anja Ehrhardt. 2020. "Cold atmospheric plasma as antiviral therapy – effect on human herpes simplex virus type 1." Journal of General Virology 101, no. 2: 208-215.
Morphogenesis of herpesviral virions is initiated in the nucleus but completed in the cytoplasm. Mature virions contain more than 25 tegument proteins many of which perform both nuclear and cytoplasmic functions suggesting they shuttle between these compartments. While nuclear import of herpesviral proteins was shown to be crucial for viral propagation, active nuclear export and its functional impact are still poorly understood. To systematically analyse nuclear export of tegument proteins present in virions of Herpes simplex virus type 1 (HSV1) and Epstein Barr virus (EBV), the Nuclear EXport Trapped by RAPamycin assay (NEX‐TRAP) was applied. Nine of the 22 investigated HSV1 tegument proteins including pUL4, pUL7, pUL11, pUL13, pUL21, pUL37d11, pUL47, pUL48, and pUS2 as well as two out of six EBV orthologs harbor nuclear export activity. A functional leucine‐rich nuclear export sequence (NES) recognized by the export factor CRM1/Xpo1 was identified in six of them. The comparison between experimental and bioinformatic data indicates that experimental validation of predicted NESes is required. Mutational analysis of the pUL48/VP16 NES revealed its importance for herpesviral propagation. Together our data suggest that nuclear export is an important feature of the herpesviral life cycle required to coordinate nuclear and cytoplasmic processes. This article is protected by copyright. All rights reserved.
Christina Funk; Verena Raschbichler; Diana Lieber; Jens Wetschky; Eileen K. Arnold; Jacqueline Leimser; Michael Biggel; Caroline C. Friedel; Zsolt Ruzsics; Susanne M. Bailer. Comprehensive analysis of nuclear export of herpes simplex virus type 1 tegument proteins and their Epstein‐Barr virus orthologs. Traffic 2018, 20, 152 -167.
AMA StyleChristina Funk, Verena Raschbichler, Diana Lieber, Jens Wetschky, Eileen K. Arnold, Jacqueline Leimser, Michael Biggel, Caroline C. Friedel, Zsolt Ruzsics, Susanne M. Bailer. Comprehensive analysis of nuclear export of herpes simplex virus type 1 tegument proteins and their Epstein‐Barr virus orthologs. Traffic. 2018; 20 (2):152-167.
Chicago/Turabian StyleChristina Funk; Verena Raschbichler; Diana Lieber; Jens Wetschky; Eileen K. Arnold; Jacqueline Leimser; Michael Biggel; Caroline C. Friedel; Zsolt Ruzsics; Susanne M. Bailer. 2018. "Comprehensive analysis of nuclear export of herpes simplex virus type 1 tegument proteins and their Epstein‐Barr virus orthologs." Traffic 20, no. 2: 152-167.
TDP-43 and FUS are nuclear proteins with multiple functions in mRNA processing. They play key roles in ALS (amyotrophic lateral sclerosis) and FTD (frontotemporal dementia), where they are partially lost from the nucleus and aggregate in the cytoplasm of neurons and glial cells. Defects in nucleocytoplasmic transport contribute to this pathology, hence nuclear import of both proteins has been studied in detail. However, their nuclear export routes remain poorly characterized and it is unclear whether aberrant nuclear export contributes to TDP-43 or FUS pathology. Here we show that predicted nuclear export signals in TDP-43 and FUS are non-functional and that both proteins are exported independently of the export receptor CRM1/Exportin-1. Silencing of Exportin-5 or the mRNA export factor Aly/REF, as well as mutations that abrogate RNA-binding do not impair export of TDP-43 and FUS. However, artificially enlarging TDP-43 or FUS impairs their nuclear egress, suggesting that they could leave the nucleus by passive diffusion. Finally, we found that inhibition of transcription causes accelerated nuclear egress of TDP-43, suggesting that newly synthesized RNA retains TDP-43 in the nucleus, limiting its egress into the cytoplasm. Our findings implicate reduced nuclear retention as a possible factor contributing to mislocalization of TDP-43 in ALS/FTD.
Helena Ederle; Christina Funk; Claudia Abou-Ajram; Saskia Hutten; Eva B. E. Funk; Ralph H. Kehlenbach; Susanne M. Bailer; Dorothee Dormann. Nuclear egress of TDP-43 and FUS occurs independently of Exportin-1/CRM1. Scientific Reports 2018, 8, 1 -18.
AMA StyleHelena Ederle, Christina Funk, Claudia Abou-Ajram, Saskia Hutten, Eva B. E. Funk, Ralph H. Kehlenbach, Susanne M. Bailer, Dorothee Dormann. Nuclear egress of TDP-43 and FUS occurs independently of Exportin-1/CRM1. Scientific Reports. 2018; 8 (1):1-18.
Chicago/Turabian StyleHelena Ederle; Christina Funk; Claudia Abou-Ajram; Saskia Hutten; Eva B. E. Funk; Ralph H. Kehlenbach; Susanne M. Bailer; Dorothee Dormann. 2018. "Nuclear egress of TDP-43 and FUS occurs independently of Exportin-1/CRM1." Scientific Reports 8, no. 1: 1-18.
Geminiviral single-stranded circular DNA genomes replicate in nuclei so that the progeny DNA has to cross both the nuclear envelope and the plasmodesmata for systemic spread within plant tissues. For intra- and intercellular transport, two proteins are required: a nuclear shuttle protein (NSP) and a movement protein (MP). New characteristics of ectopically produced Abutilon mosaic virus (AbMV) MP (MPAbMV), either authentically expressed or fused to a yellow fluorescent protein or epitope tags, respectively, were determined by localization studies in mammalian cell lines in comparison to plant cells. Wild-type MPAbMV and the distinct MPAbMV: reporter protein fusions appeared as curled threads throughout mammalian cells. Co-staining with cytoskeleton markers for actin, intermediate filaments, or microtubules identified these threads as re-organized microtubules. These were, however, not stabilized by the viral MP, as demonstrated by nocodazole treatment. The MP of a related bipartite New World begomovirus, Cleome leaf crumple virus (ClLCrV), resulted in the same intensified microtubule bundling, whereas that of a nanovirus did not. The C-terminal section of MPAbMV, i.e., the protein’s oligomerization domain, was dispensable for the effect. However, MP expression in plant cells did not affect the microtubules network. Since plant epidermal cells are quiescent whilst mammalian cells are proliferating, the replication-associated protein RepAbMV protein was then co-expressed with MPAbMV to induce cell progression into S-phase, thereby inducing distinct microtubule bundling without MP recruitment to the newly formed threads. Co-immunoprecipitation of MPAbMV in the presence of RepAbMV, followed by mass spectrometry identified potential novel MPAbMV-host interaction partners: the peptidyl-prolyl cis-trans isomerase NIMA-interacting 4 (Pin4) and stomatal cytokinesis defective 2 (SCD2) proteins. Possible roles of these putative interaction partners in the begomoviral life cycle and cytoskeletal association modes are discussed.
Susanna Krapp; Christian Schuy; Eva Greiner; Irina Stephan; Barbara Alberter; Christina Funk; Manfred Marschall; Christina Wege; Susanne M. Bailer; Tatjana Kleinow; Björn Krenz. Begomoviral Movement Protein Effects in Human and Plant Cells: Towards New Potential Interaction Partners. Viruses 2017, 9, 334 .
AMA StyleSusanna Krapp, Christian Schuy, Eva Greiner, Irina Stephan, Barbara Alberter, Christina Funk, Manfred Marschall, Christina Wege, Susanne M. Bailer, Tatjana Kleinow, Björn Krenz. Begomoviral Movement Protein Effects in Human and Plant Cells: Towards New Potential Interaction Partners. Viruses. 2017; 9 (11):334.
Chicago/Turabian StyleSusanna Krapp; Christian Schuy; Eva Greiner; Irina Stephan; Barbara Alberter; Christina Funk; Manfred Marschall; Christina Wege; Susanne M. Bailer; Tatjana Kleinow; Björn Krenz. 2017. "Begomoviral Movement Protein Effects in Human and Plant Cells: Towards New Potential Interaction Partners." Viruses 9, no. 11: 334.
Herpesviruses are enveloped DNA viruses that infect vertebrate cells. Their high potential cloning capacity and the lifelong persistence of their genomes in various host cells make them attractive platforms for vector-based therapy. In this review, we would like to highlight recent advances of three major areas of herpesvirus vector development and application: (i) oncolytic therapy, (ii) recombinant vaccines, and (iii) large capacity gene transfer vehicles.
Susanne M. Bailer; Christina Funk; André Riedl; Zsolt Ruzsics. Herpesviral vectors and their application in oncolytic therapy, vaccination, and gene transfer. Virus Genes 2017, 53, 741 -748.
AMA StyleSusanne M. Bailer, Christina Funk, André Riedl, Zsolt Ruzsics. Herpesviral vectors and their application in oncolytic therapy, vaccination, and gene transfer. Virus Genes. 2017; 53 (5):741-748.
Chicago/Turabian StyleSusanne M. Bailer; Christina Funk; André Riedl; Zsolt Ruzsics. 2017. "Herpesviral vectors and their application in oncolytic therapy, vaccination, and gene transfer." Virus Genes 53, no. 5: 741-748.
Herpes simplex virus type 1 (HSV1), a member of the alphaherpesvirinae, can cause recurrent facial lesions and encephalitis. Two membrane envelopment processes, one at the inner nuclear membrane and a second at cytoplasmic membranes are crucial for a productive viral infection. Depending on the subfamily, herpesviruses encode more than 11 different transmembrane proteins including members of the tail-anchored protein family. HSV1 encodes three tail-anchored proteins pUL34, pUL56 and pUS9 characterized by a single hydrophobic region positioned at their C-terminal end that needs to be released from the ribosome prior to posttranslational membrane insertion. Asna1/TRC40 is an ATPase that targets tail-anchored proteins to the endoplasmic reticulum in a receptor-dependent manner. Cell biological data point to a critical and general role of Asna1/TRC40 in tail-anchored protein biogenesis. With this study, we aimed to determine the importance of the tail-anchored insertion machinery for HSV1 infection. To determine protein-protein interactions, the yeast-two hybrid system was applied. Asna1/TRC40 was depleted using RNA interference. Transient transfection and virus infection experiments followed by indirect immunofluorescence analysis were applied to analyse the localization of viral proteins as well as the impact of Asna1/TRC40 depletion on virus infection. All HSV1 tail-anchored proteins specifically bound to Asna1/TRC40 but independently localized to their target membranes. While non-essential for cell viability, Asna1/TRC40 is required for efficient HSV1 replication. We show that early events of the replication cycle like virion entry and overall viral gene expression were unaffected by depletion of Asna1/TRC40. Furthermore, equal amounts of infectious virions were formed and remained cell-associated. This indicated that both nuclear egress of capsids that requires the essential tail-anchored protein pUL34, and secondary envelopment to form infectious virions were successfully completed. Despite large part of the virus life cycle proceeding normally, viral propagation was more than 10 fold reduced. We show that depletion of Asna1/TRC40 specifically affected a step late in infection during release of infectious virions to the extracellular milieu. Asna1/TRC40 is required at a late step of herpesviral infection for efficient release of mature virions to the extracellular milieu. This study reveals novel tools to decipher exocytosis of newly formed virions as well as hitherto unknown cellular targets for antiviral therapy.
Melanie Ott; Débora Marques; Christina Funk; Susanne M. Bailer. Asna1/TRC40 that mediates membrane insertion of tail-anchored proteins is required for efficient release of Herpes simplex virus 1 virions. Virology Journal 2016, 13, 175 .
AMA StyleMelanie Ott, Débora Marques, Christina Funk, Susanne M. Bailer. Asna1/TRC40 that mediates membrane insertion of tail-anchored proteins is required for efficient release of Herpes simplex virus 1 virions. Virology Journal. 2016; 13 (1):175.
Chicago/Turabian StyleMelanie Ott; Débora Marques; Christina Funk; Susanne M. Bailer. 2016. "Asna1/TRC40 that mediates membrane insertion of tail-anchored proteins is required for efficient release of Herpes simplex virus 1 virions." Virology Journal 13, no. 1: 175.
The herpes simplex virus type 1 (HSV-1) glycoprotein N (gN/UL49.5) is a type I transmembrane protein conserved throughout the herpesvirus family. gN is a resident of the endoplasmic reticulum that in the presence of gM is translocated to the trans Golgi network. gM and gN are covalently linked by a single disulphide bond formed between cysteine 46 of gN and cysteine 59 of gM. Exit of gN from the endoplasmic reticulum requires the N-terminal core of gM composed of eight transmembrane domains but is independent of the C-terminal extension of gM. Co-transport of gN and gM to the trans Golgi network also occurs upon replacement of conserved cysteines in gM and gN, suggesting that their physical interaction is mediated by covalent and non-covalent forces. Deletion of gN/UL49.5 using bacterial artificial chromosome (BAC) mutagenesis generated mutant viruses with wild-type growth behaviour, while full deletion of gM/UL10 resulted in an attenuated phenotype. Deletion of gN/UL49.5 in conjunction with various gM/UL10 mutants reduced average plaque sizes to the same extent as either single gM/UL10 mutant, indicating that gN is nonessential for the function performed by gM. We propose that gN functions in gM-dependent as well as gM-independent processes during which it is complemented by other viral factors.
Hannah Striebinger; Christina Funk; Verena Raschbichler; Susanne M. Bailer. Subcellular Trafficking and Functional Relationship of the HSV-1 Glycoproteins N and M. Viruses 2016, 8, 83 .
AMA StyleHannah Striebinger, Christina Funk, Verena Raschbichler, Susanne M. Bailer. Subcellular Trafficking and Functional Relationship of the HSV-1 Glycoproteins N and M. Viruses. 2016; 8 (3):83.
Chicago/Turabian StyleHannah Striebinger; Christina Funk; Verena Raschbichler; Susanne M. Bailer. 2016. "Subcellular Trafficking and Functional Relationship of the HSV-1 Glycoproteins N and M." Viruses 8, no. 3: 83.
The Herpes simplex virus type 1 (HSV-1) glycoprotein M (gM/UL10) is a 473 amino acid type III transmembrane protein that resides in various membrane compartments. HSV-1 gM contains several putative trafficking motifs but their functional relevance remains to be elucidated. We show here that transiently expressed gM 19-343 was sufficient for transport to the TGN, while gM 133-473 where the first two transmembrane domains were deleted, and gM 1-342 that lacked the final residue of the last transmembrane domain, were retained in the ER indicating that all transmembrane domains are required for proper folding and ER exit. A series of BAC mutants revealed that in addition to the authentic start codon, translation of gM can be initiated at methionine 19 and 133/135. While a protein lacking the first 18 residues supported wild type-like growth, gM 133/135-473 resulted in reduced plaque diameters resembling a UL10 deletion mutant. An HSV-1 mutant encoding gM 1-342 showed similar growth characteristics and accumulated un-enveloped cytoplasmic particles while gM 1-343 resulted in a gain of function, indicating that all transmembrane domains of the protein are important for viral growth. A C-terminal extension further supported viral propagation, the C-terminal trafficking motifs (residues 423-473) however were completely dispensable. We propose a functional core within gM 19-343 comprised of all transmembrane domains that is sufficient to target the protein to the TGN, a favoured site for envelopment, and to support viral functions.
Hannah Striebinger; Jie Zhang; Melanie Ott; Christina Funk; Kerstin Radtke; Johanne Duron; Zsolt Ruzsics; Jürgen Haas; Roger Lippé; Susanne M. Bailer. Subcellular trafficking and functional importance of herpes simplex virus type 1 glycoprotein M domains. Journal of General Virology 2015, 96, 3313 -3325.
AMA StyleHannah Striebinger, Jie Zhang, Melanie Ott, Christina Funk, Kerstin Radtke, Johanne Duron, Zsolt Ruzsics, Jürgen Haas, Roger Lippé, Susanne M. Bailer. Subcellular trafficking and functional importance of herpes simplex virus type 1 glycoprotein M domains. Journal of General Virology. 2015; 96 (11):3313-3325.
Chicago/Turabian StyleHannah Striebinger; Jie Zhang; Melanie Ott; Christina Funk; Kerstin Radtke; Johanne Duron; Zsolt Ruzsics; Jürgen Haas; Roger Lippé; Susanne M. Bailer. 2015. "Subcellular trafficking and functional importance of herpes simplex virus type 1 glycoprotein M domains." Journal of General Virology 96, no. 11: 3313-3325.
Progeny capsids of herpesviruses leave the nucleus by budding through the nuclear envelope. Two viral proteins, the membrane protein pUL34 and the nucleo-phosphoprotein pUL31 form the nuclear egress complex that is required for capsid egress out of the nucleus. All pUL31 orthologs are composed of a diverse N-terminal domain with 1 to 3 basic patches and a conserved C-terminal domain. To decipher the functions of the N-terminal domain, we have generated several Herpes simplex virus mutants and show here that the N-terminal domain of pUL31 is essential with basic patches being critical for viral propagation. pUL31 and pUL34 entered the nucleus independently of each other via separate routes and the N-terminal domain of pUL31 was required to prevent their premature interaction in the cytoplasm. Unexpectedly, a classical bipartite nuclear localization signal embedded in this domain was not required for nuclear import of pUL31. In the nucleus, pUL31 associated with the nuclear envelope and newly formed capsids. Viral mutants lacking the N-terminal domain or with its basic patches neutralized still associated with nucleocapsids but were unable to translocate them to the nuclear envelope. Replacing the authentic basic patches with a novel artificial one resulted in HSV1(17+)Lox-UL31-hbpmp1mp2, that was viable but delayed in nuclear egress and compromised in viral production. Thus, while the C-terminal domain of pUL31 is sufficient for the interaction with nucleocapsids, the N-terminal domain was essential for capsid translocation to sites of nuclear egress and a coordinated interaction with pUL34. Our data indicate an orchestrated sequence of events with pUL31 binding to nucleocapsids and escorting them to the inner nuclear envelope. We propose a common mechanism for herpesviral nuclear egress: pUL31 is required for intranuclear translocation of nucleocapsids and subsequent interaction with pUL34 thereby coupling capsid maturation with primary envelopment. Herpesviral capsid assembly is initiated in the host nucleus. Due to size constraints, newly formed nucleocapsids are unable to leave the nucleus through the nuclear pore complex. Instead herpesviruses apply an evolutionarily conserved mechanism for nuclear export of capsids called nuclear egress. This process is initiated by docking of capsids at the inner nuclear membrane, budding of enveloped capsids into the perinuclear space followed by de-envelopment and release of capsids to the cytoplasm where further maturation occurs. Two viral proteins conserved throughout the herpesvirus family, the membrane protein pUL34 and the phosphoprotein pUL31 form the nuclear egress complex that is critical for primary envelopment. We show here that pUL31 and pUL34 enter the nucleus independently of each other. pUL31 is targeted to the nucleoplasm where it binds to nucleocapsids via the conserved C-terminal domain, while its N-terminal domain is important for capsid translocation to the nuclear envelope and for a coordinated interaction with pUL34. Our data suggest a mechanism that is apparently conserved among all herpesviruses with pUL31 escorting nucleocapsids to the nuclear envelope in order to couple capsid maturation with primary envelopment.
Christina Funk; Melanie Ott; Verena Raschbichler; Claus-Henning Nagel; Anne Binz; Beate Sodeik; Rudolf Bauerfeind; Susanne M. Bailer. The Herpes Simplex Virus Protein pUL31 Escorts Nucleocapsids to Sites of Nuclear Egress, a Process Coordinated by Its N-Terminal Domain. PLOS Pathogens 2015, 11, e1004957 .
AMA StyleChristina Funk, Melanie Ott, Verena Raschbichler, Claus-Henning Nagel, Anne Binz, Beate Sodeik, Rudolf Bauerfeind, Susanne M. Bailer. The Herpes Simplex Virus Protein pUL31 Escorts Nucleocapsids to Sites of Nuclear Egress, a Process Coordinated by Its N-Terminal Domain. PLOS Pathogens. 2015; 11 (6):e1004957.
Chicago/Turabian StyleChristina Funk; Melanie Ott; Verena Raschbichler; Claus-Henning Nagel; Anne Binz; Beate Sodeik; Rudolf Bauerfeind; Susanne M. Bailer. 2015. "The Herpes Simplex Virus Protein pUL31 Escorts Nucleocapsids to Sites of Nuclear Egress, a Process Coordinated by Its N-Terminal Domain." PLOS Pathogens 11, no. 6: e1004957.