Membrane deformation and scission by the HSV-1 nuclear egress complex

Bigalke, Janna M.; Heuser, Thomas; Nicastro, Daniela; Heldwein, Ekaterina E.

doi:10.1038/ncomms5131

Cited by 136 publications

(394 citation statements)

References 40 publications

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“…This might occur under molecular crowding during steps of viral nuclear replication, specifically the nuclear rim recruitment of pUL53 by pUL50. Moreover, the hexameric arrangement of pUL50-pUL53 matches the honeycomb pattern observed for the homologous herpes simplex virus (HSV-1) NEC core proteins, pUL34-pUL31, in cryo-electron micrographs (41). Also the observed diameter of ϳ11 nm of the pores of the ring-like arrays of pUL34-pUL31 is consistent with our findings (Fig.…”

Section: Resultssupporting

confidence: 91%

Crystal Structure of the Human Cytomegalovirus pUL50-pUL53 Core Nuclear Egress Complex Provides Insight into a Unique Assembly Scaffold for Virus-Host Protein Interactions

Walzer

Egerer-Sieber

Sticht

et al. 2015

Journal of Biological Chemistry

139

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Background:The conserved cytomegalovirus proteins pUL50 and pUL53 heterodimerize and form a core nuclear egress complex. Results: The crystal structure of pUL50-pUL53 was solved at 2.44 Å resolution, revealing an N-terminal hooklike extension of pUL53. Conclusion: Data unravel the core NEC architecture, providing a scaffold for viral-cellular NEC protein interactions. Significance: The identified NEC structure will stimulate the development of novel antiviral strategies.

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Section: Resultssupporting

confidence: 91%

Crystal Structure of the Human Cytomegalovirus pUL50-pUL53 Core Nuclear Egress Complex Provides Insight into a Unique Assembly Scaffold for Virus-Host Protein Interactions

Walzer

Egerer-Sieber

Sticht

et al. 2015

Journal of Biological Chemistry

139

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“…The membrane budding efficiency was similar regardless of whether we used the soluble NEC and acidic membranes versus the His-tagged NEC and Ni-containing membranes, which confirmed that the UL34 TM region does not play an active role in budding beyond anchoring the NEC into the INM. By reconstituting the budding process in vitro using the purified NEC and synthetic liposomes, we showed that the HSV-1 NEC has an intrinsic ability to mediate budding and scission (10). This finding was subsequently confirmed for the pseudorabies virus NEC (11).…”

mentioning

confidence: 62%

“…Using cryoelectron microscopy, we found that the NEC, although heterodimeric in solution, forms an ordered array on the inner surface of the budded vesicles ( Fig. 2B) (10). Images showed that the NEC formed spikes emanating from the membrane toward the interior of the vesicle, as well as a hexagonal honeycomb lattice that is related to the spikes by a 90°rotation.…”

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confidence: 96%

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The Great (Nuclear) Escape: New Insights into the Role of the Nuclear Egress Complex of Herpesviruses

Bigalke

Heldwein

2015

J Virol

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Herpesviruses are unusual among enveloped viruses because they bud twice yet acquire a single envelope. They are also the only known viruses that bud into the nuclear envelope. We discovered that the herpesvirus nuclear egress complex could bud membranes without the help of other proteins by forming a coat-like hexagonal scaffold inside the budding membrane. This finding raises the possibility that a phenotypically similar nuclear export of large RNAs is cargo driven. Most enveloped viruses acquire their envelopes by capsid budding into a cellular membrane. Some viruses, such as HIV or influenza virus, bud into the plasma membrane while other viruses, such as flaviviruses, bud into intracellular membranes such as the endoplasmic reticulum, the Golgi compartment, or others, depending on the virus. Herpesviruses represent an unusual case. Despite having a single envelope, these double-stranded DNA viruses undergo two rounds of budding; they bud first into the inner nuclear membrane (INM) and later into cytoplasmic membranes derived from the trans-Golgi network or early endosomes (1). This also makes them the only known viruses to use the nuclear membrane for budding. Yet, the envelope acquired during the first budding event at the INM does not end up in the mature viral particle. Only the second and final round of budding in the cytosol generates the single-layer envelope of the mature virus. Instead, the unusual nuclear budding allows the viral capsid to escape from the nucleus.Herpesvirus genomes are replicated and encapsidated in the nucleus. The nucleus is surrounded by the INM and outer nuclear membrane (ONM), and most traffic in and out of the nucleus occurs through the nuclear pores. The diameter of herpesvirus capsids (125 nm in HSV-1) is considerably larger than that of the nuclear pore channels (52 nm), and thus, the capsids cannot fit through them. To escape from the nucleus, nucleocapsids bud into the INM, forming perinuclear immature viral particlesintermediates that are different from the mature, infectious viruses-that then fuse with the ONM, releasing the naked capsids into the cytosol (Fig. 1). As a result of this process, termed nuclear egress, nucleocapsids are translocated from the nucleus into the cytoplasm, where they mature into final, infectious virions.Efficient exit of nascent capsids from the nucleus requires the virus-encoded nuclear egress complex (NEC) (reviewed in reference 1). The NEC consists of conserved viral proteins UL31 and UL34. UL34 is anchored to the INM by a C-terminal transmembrane (TM) helix with three residues extending into the perinuclear space (3). UL31 is a nuclear phosphoprotein that localizes to the INM through interaction with UL34 (4, 5). Formation of the NEC is a prerequisite for efficient nuclear egress. In the absence of either UL31 or UL34, viral replication is impaired and most capsids are retained in the nucleus (6, 7). The NEC is also sufficient to drive the formation of perinuclear vesicles in transfected cells (8,9), which demonstrated that UL31 and UL3...

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“…It is generally accepted that, after assembly in the nucleus, the viral nucleocapsid undergoes envelopment to cross the inner nuclear membrane (INM) followed by deenvelopment to cross the outer nuclear membrane, resulting in release into the cytoplasm for continuation of the virion maturation process (4). Nuclear egress is orchestrated by a highly conserved, heterodimeric nuclear egress complex (NEC), which recruits one or more protein kinases to disrupt the nuclear lamina, permitting access of nucleocapsids to the INM, where the NEC induces budding of the nucleocapsid into the perinuclear space (5)(6)(7)(8)(9)(10)(11)(12)(13). In HCMV, the NEC is comprised of UL50, which is an INM protein, and UL53, which is a nucleoplasmic protein that is brought to the INM by its interaction with UL50.…”

mentioning

confidence: 99%

Structure of a herpesvirus nuclear egress complex subunit reveals an interaction groove that is essential for viral replication

Leigh

Sharma

Mansueto

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Herpesviruses require a nuclear egress complex (NEC) for efficient transit of nucleocapsids from the nucleus to the cytoplasm. The NEC orchestrates multiple steps during herpesvirus nuclear egress, including disruption of nuclear lamina and particle budding through the inner nuclear membrane. In the important human pathogen human cytomegalovirus (HCMV), this complex consists of nuclear membrane protein UL50, and nucleoplasmic protein UL53, which is recruited to the nuclear membrane through its interaction with UL50. Here, we present an NMR-determined solution-state structure of the murine CMV homolog of UL50 (M50; residues 1-168) with a strikingly intricate protein fold that is matched by no other known protein folds in its entirety. Using NMR methods, we mapped the interaction of M50 with a highly conserved UL53-derived peptide, corresponding to a segment that is required for heterodimerization. The UL53 peptide binding site mapped onto an M50 surface groove, which harbors a large cavity. Point mutations of UL50 residues corresponding to surface residues in the characterized M50 heterodimerization interface substantially decreased UL50-UL53 binding in vitro, eliminated UL50-UL53 colocalization, prevented disruption of nuclear lamina, and halted productive virus replication in HCMV-infected cells. Our results provide detailed structural information on a key protein-protein interaction involved in nuclear egress and suggest that NEC subunit interactions can be an attractive drug target.H erpesviruses encompass a large family of infectious agents, including important veterinary and human pathogens (1). Among the latter is human cytomegalovirus (HCMV), which can cause serious disease, particularly in immunocompromised individuals and newborns (2). Despite the importance of HCMV in these medically vulnerable populations, currently available treatment options suffer from issues with toxicities, drug resistance, and/or pharmacokinetics (2, 3), motivating the identification of new drug targets.All herpesviruses of mammals, birds, and reptiles undergo a remarkable process known as nuclear egress as part of the viral lifecycle. It is generally accepted that, after assembly in the nucleus, the viral nucleocapsid undergoes envelopment to cross the inner nuclear membrane (INM) followed by deenvelopment to cross the outer nuclear membrane, resulting in release into the cytoplasm for continuation of the virion maturation process (4). Nuclear egress is orchestrated by a highly conserved, heterodimeric nuclear egress complex (NEC), which recruits one or more protein kinases to disrupt the nuclear lamina, permitting access of nucleocapsids to the INM, where the NEC induces budding of the nucleocapsid into the perinuclear space (5-13). In HCMV, the NEC is comprised of UL50, which is an INM protein, and UL53, which is a nucleoplasmic protein that is brought to the INM by its interaction with UL50. These two proteins and their murine CMV (MCMV) homologues, M50 and M53, are essential for replication and nuclear egress (8, 14-17) of ...

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Membrane deformation and scission by the HSV-1 nuclear egress complex

Cited by 136 publications

References 40 publications

Crystal Structure of the Human Cytomegalovirus pUL50-pUL53 Core Nuclear Egress Complex Provides Insight into a Unique Assembly Scaffold for Virus-Host Protein Interactions

Crystal Structure of the Human Cytomegalovirus pUL50-pUL53 Core Nuclear Egress Complex Provides Insight into a Unique Assembly Scaffold for Virus-Host Protein Interactions

The Great (Nuclear) Escape: New Insights into the Role of the Nuclear Egress Complex of Herpesviruses

Structure of a herpesvirus nuclear egress complex subunit reveals an interaction groove that is essential for viral replication

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