The Kaposi’s Sarcoma-Associated Herpesvirus Protein ORF42 Is Required for Efficient Virion Production and Expression of Viral Proteins

Butnaru, Matthew; Gaglia, Marta Maria

doi:10.3390/v11080711

Cited by 12 publications

(14 citation statements)

References 60 publications

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“…To elucidate the mechanism of late gene expression upregulation in the context of PPD inactivation, we first focused our attention on the requirements for late gene expression. In KSHV, transcription of late genes takes place after initiation of viral DNA replication, and their expression requires the action of several viral transactivation factors (vTF) (48–53). The viral TATA box-binding protein homolog, ORF24, is a KSHV transactivation factor that plays a critical role when the virus progresses from DNA replication to expression of late genes.…”

Section: Resultsmentioning

confidence: 99%

“…KSHV late genes are expressed after the initiation of viral genome replication (48–52), which occurs prior to 48 hpi in our iSLK WT cells. As PPD inactivation increases late gene expression at 24 hpi, we tested whether the expression of late genes at 48 and 72 hpi is also affected by PPD inactivation.…”

Section: Resultsmentioning

confidence: 99%

“…Additional factors may contribute to protection of late transcripts from PPD during late phases of KSHV reactivation. For example, expression of KSHV late genes requires the action of several viral transactivation factors (48–52). ORF24 is essential to recruit RNA pol II and other viral transactivation factors to late gene promoters (51).…”

Section: Discussionmentioning

confidence: 99%

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Kaposi’s sarcoma-associated herpesvirus fine-tunes the temporal expression of late genes by manipulating a host RNA quality control pathway

Ruiz

Devlin

Kim

et al. 2020

Preprint

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AbstractKaposi’s sarcoma-associated herpesvirus (KSHV) is a human oncogenic nuclear DNA virus that expresses its genes using the host cell transcription and RNA processing machinery. As a result, KSHV transcripts are subject to degradation by at least two host-mediated nuclear RNA decay pathways, PABPN1 and PAPα/γ-mediated RNA decay (PPD) and an ARS2-dependent decay pathway. Here, we present global analyses of viral transcript levels to further understand the roles of these decay pathways in KSHV gene expression. Consistent with our recent report that the KSHV ORF57 protein increases viral transcript stability by impeding ARS2-dependent decay, ARS2 knockdown has little effect on viral gene expression 24 hours after lytic reactivation of wild-type virus. In contrast, inactivation of PPD results in premature accumulation of late transcripts. The up-regulation of late transcripts does not require the primary late gene-specific viral transactivation factor, suggesting that cryptic transcription produces the transcripts that then succumb to PPD. Remarkably, PPD inactivation has no effect on late transcripts at their proper time of expression. We show that this time-dependent PPD evasion by late transcripts requires the host factor NRDE2, which has previously been reported to protect cellular RNAs by sequestering decay factors. From these studies, we conclude that KSHV uses PPD to fine-tune the temporal expression of its genes by preventing their premature accumulation.ImportanceKaposi’s sarcoma-associated herpesvirus (KSHV) is an oncogenic gammaherpesvirus that causes Kaposi’s sarcoma and other lymphoproliferative disorders. Nuclear expression of KSHV genes results in exposure to at least two host-mediated nuclear RNA decay pathways, PABPN1 and PAPα/γ-mediated RNA decay (PPD) and an ARS2-mediated decay pathway. Perhaps unsurprisingly, we previously found that KSHV uses specific mechanisms to protect its transcripts from ARS2-mediated decay. In contrast, here we show that PPD is required to dampen the expression of viral late transcripts that are prematurely transcribed, presumably due to cryptic transcription early in infection. At the proper time for their expression, KSHV late transcripts evade PPD through the activity of the host factor NRDE2. We conclude that KSHV fine-tunes the temporal expression of its genes by modulating PPD activity. Thus, the virus both protects from and exploits the host nuclear RNA decay machinery for proper expression of its genes.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Kaposi’s sarcoma-associated herpesvirus fine-tunes the temporal expression of late genes by manipulating a host RNA quality control pathway

Ruiz

Devlin

Kim

et al. 2020

Preprint

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“…The putative pUL51 homologue BSRF1 from Epstein-Barr virus associates with Golgi membranes and siRNA knock-down of BSRF1 in B95-8 cells prevents virion production (23). The KSHV homologue of pUL7, pORF42, is similarly required for efficient virion production (24). While a direct interaction has not been shown for the pUL7 and pUL51 homologues from β-or γ-herpesviruses, the EBV homologues BBRF2 and BSRF1 have been shown to co-precipitate from transfected cells (23).…”

Section: Main Text Introductionmentioning

confidence: 99%

Structure of herpes simplex virus pUL7:pUL51, a conserved complex required for efficient herpesvirus assembly

Butt

Owen

Jeffries³

et al. 2019

Preprint

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Herpesviruses are an ancient family of highly-prevalent human and animal pathogens that acquire their membrane envelopes in the cytoplasm of infected cells. While multiple conserved viral proteins are known to be required for efficient herpesvirus production, many of these proteins lack identifiable structural homologues and the molecular details of herpesvirus assembly remain unclear. We have characterized the complex of assembly proteins pUL7 and pUL51 from herpes simplex virus (HSV)-1, an α-herpesvirus, using multi-angle light scattering and small-angle X-ray scattering with chemical crosslinking. HSV-1 pUL7 and pUL51 form a stable 1:2 complex that is capable of higher-order oligomerization in solution. We solved the crystal structure of this complex, revealing a core heterodimer comprising pUL7 bound to residues 41-125 of pUL51. While pUL7 adopts a previously-unseen compact fold, the extended helix-turn-helix conformation of pUL51 resembles the cellular endosomal complex required for transport (ESCRT)-III component CHMP4B, suggesting a direct role for pUL51 in promoting membrane scission during virus assembly. We demonstrate that the interaction between pUL7 and pUL51 homologues is conserved across human α-, β-and γ-herpesviruses, as is their association with trans-Golgi membranes in cultured cells. However, pUL7 and pUL51 homologues do not form complexes with their respective partners from different virus families, suggesting that the molecular details of the interaction interface have diverged. Our results demonstrate that the pUL7:pUL51 complex is conserved across the herpesviruses and provide a structural framework for understanding its role in herpesvirus assembly. Significance StatementHerpesviruses are extremely common human pathogens that cause diseases ranging from cold sores to cancer. Herpesvirus acquire their membrane envelope in the cytoplasm via a conserved pathway, the molecular details of which remain unclear. We have solved the structure of a complex between herpes simplex virus (HSV)-1 proteins pUL7 and pUL51, two proteins that are required for efficient HSV-1 assembly. We show that formation of this complex is conserved across distantly-related human herpesviruses, as is the association of these homologues with cellular membranes that are used for virion assembly. While pUL7 adopts a previously-unseen fold, pUL51 resembles key cellular membrane-remodeling complex components, suggesting that the pUL7:pUL51 complex may play a direct role in deforming membranes to promote virion assembly.

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“…Complexing of the two proteins alters the subcellular localization of BBRF2, and prevents BSRF1 from degradation, which ultimately augments viral infectivity 15 . The BBRF2 homologue in KSHV, ORF42, has been shown to be required for efficient production of viral particles, but is dispensable for reactivation of the lytic cycle 16 . Tegument proteins pUL7 in HSV and pUL103 in HCMV, which are homologues of BBRF2 in αand β-herpesviruses, have been reported to have similar roles in viral assembly and egress 17,18 .…”

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confidence: 99%

Structure of Epstein-Barr virus tegument protein complex BBRF2-BSRF1 reveals its potential role in viral envelopment

Luo

Cao

et al. 2020

Nat Commun

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Epstein-Barr virus (EBV) is a γ-herpesvirus associated with the occurrence of several human malignancies. BBRF2 and BSRF1 are two EBV tegument proteins that have been suggested to form a hetero-complex and mediate viral envelopment, but the molecular basis of their interaction and the functional mechanism of this complex remains unknown. Here, we present crystal structures of BBRF2 alone and in complex with BSRF1. BBRF2 has a compact globular architecture featuring a central β-sheet that is surrounded by 10 helices, it represents a novel fold distinct from other known protein structures. The central portion of BSRF1 folds into two tightly associated antiparallel α-helices, forming a composite four-helix bundle with two α-helices from BBRF2 via a massive hydrophobic network. In vitro, a BSRF1-derived peptide binds to BBRF2 and reduces the number of viral genome copies in EBV-positive cells. Exogenous BBRF2 and BSRF1 co-localize at the Golgi apparatus. Furthermore, BBRF2 binds capsid and capsid-associated proteins, whereas BSRF1 associates with glycoproteins. These findings indicate that the BBRF2-BSRF1 complex tethers EBV nucleocapsids to the glycoprotein-enriched Golgi membrane, facilitating secondary envelopment.

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The Kaposi’s Sarcoma-Associated Herpesvirus Protein ORF42 Is Required for Efficient Virion Production and Expression of Viral Proteins

Cited by 12 publications

References 60 publications

Kaposi’s sarcoma-associated herpesvirus fine-tunes the temporal expression of late genes by manipulating a host RNA quality control pathway

Kaposi’s sarcoma-associated herpesvirus fine-tunes the temporal expression of late genes by manipulating a host RNA quality control pathway

Structure of herpes simplex virus pUL7:pUL51, a conserved complex required for efficient herpesvirus assembly

Structure of Epstein-Barr virus tegument protein complex BBRF2-BSRF1 reveals its potential role in viral envelopment

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