scholarly journals The KSHV ORF20 Protein Interacts With The Viral Processivity Factor ORF59 And Promote Viral Reactivation

2020 ◽  
Author(s):  
D. Hoffman ◽  
W. Rodriguez ◽  
D. Macveigh-Fierro ◽  
J. Miles ◽  
M. Muller
Keyword(s):  
Gene Expression ◽  
Viral Replication ◽  
Viral Proteins ◽  
Lytic Replication ◽  
Viral Reactivation ◽  
Wild Type Virus ◽  
Viral Gene ◽  
Late Gene Expression ◽  
Lytic Gene ◽  
Processivity Factor

AbstractUpon KSHV lytic reactivation, rapid and widespread amplification of viral DNA (vDNA) triggers significant nuclear reorganization. As part of this striking shift in nuclear architecture, viral replication compartments are formed as sites of lytic vDNA production along with remarkable spatial remodeling and relocalization of cellular and viral proteins. These viral replication compartments house several lytic gene products that coordinate viral gene expression, vDNA replication, and nucleocapsid assembly. The viral proteins and mechanisms that regulate this overhaul of the nuclear landscape during KSHV replication remain largely unknown. KSHV’s ORF20 is a widely conserved lytic gene among all herpesviruses suggesting it may have a fundamental contribution to the progression of herpesviral infection. Here, we utilized a promiscuous biotin ligase proximity labeling method to identify the proximal interactome of ORF20, which includes several replication-associated viral proteins, one of which is ORF59, the KSHV DNA processivity factor. Using co-immunoprecipitation and immunofluorescence assays, we confirmed the interaction between ORF20 and ORF59 and tracked the localization of both proteins to KSHV replication compartments. To further characterize the function of ORF20, we generated an ORF20-deficient KSHV and compared its replicative fitness relative to wild type virus. Virion production was significantly diminished in the ORF20-deficient virus as observed by supernatant transfer assays. Additionally, we tied this defect in viable virion formation to a reduction in viral late gene expression. Lastly, we observed an overall reduction in vDNA replication in the ORF20-deficient virus implying a key role for ORF20 in the regulation of lytic replication. Taken together, these results capture the essential role of KSHV ORF20 in progressing viral lytic infection by regulating vDNA replication alongside other crucial lytic proteins within KSHV replication compartments.

scholarly journals Cellular Protein WDR11 Interacts with Specific Herpes Simplex Virus Proteins at thetrans-Golgi Network To Promote Virus Replication

2015 ◽  
Vol 89 (19) ◽  
pp. 9841-9852 ◽  
Author(s):  
Kathryne E. Taylor ◽  
Karen L. Mossman
Keyword(s):  
Gene Expression ◽  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Viral Replication ◽  
Cellular Protein ◽  
Viral Gene ◽  
Late Gene Expression ◽  
Simplex Virus ◽  
Golgi Network ◽  
Hsv 1

ABSTRACTIt has recently been proposed that the herpes simplex virus (HSV) protein ICP0 has cytoplasmic roles in blocking antiviral signaling and in promoting viral replication in addition to its well-known proteasome-dependent functions in the nucleus. However, the mechanisms through which it produces these effects remain unclear. While investigating this further, we identified a novel cytoplasmic interaction between ICP0 and the poorly characterized cellular protein WDR11. During an HSV infection, WDR11 undergoes a dramatic change in localization at late times in the viral replication cycle, moving from defined perinuclear structures to a dispersed cytoplasmic distribution. While this relocation was not observed during infection with viruses other than HSV-1 and correlated with efficient HSV-1 replication, the redistribution was found to occur independently of ICP0 expression, instead requiring viral late gene expression. We demonstrate for the first time that WDR11 is localized to thetrans-Golgi network (TGN), where it interacts specifically with some, but not all, HSV virion components, in addition to ICP0. Knockdown of WDR11 in cultured human cells resulted in a modest but consistent decrease in yields of both wild-type and ICP0-null viruses, in the supernatant and cell-associated fractions, without affecting viral gene expression. Although further study is required, we propose that WDR11 participates in viral assembly and/or secondary envelopment.IMPORTANCEWhile the TGN has been proposed to be the major site of HSV-1 secondary envelopment, this process is incompletely understood, and in particular, the role of cellular TGN components in this pathway is unknown. Additionally, little is known about the cellular functions of WDR11, although the disruption of this protein has been implicated in multiple human diseases. Therefore, our finding that WDR11 is a TGN-resident protein that interacts with specific viral proteins to enhance viral yields improves both our understanding of basic cellular biology as well as how this protein is co-opted by HSV.

scholarly journals The Epstein-Barr Virus BDLF4 Gene Is Required for Efficient Expression of Viral Late Lytic Genes

2015 ◽  
Vol 89 (19) ◽  
pp. 10120-10124 ◽  
Author(s):  
Takahiro Watanabe ◽  
Yohei Narita ◽  
Masahiro Yoshida ◽  
Yoshitaka Sato ◽  
Fumi Goshima ◽  
...  
Keyword(s):  
Gene Expression ◽  
Epstein Barr Virus ◽  
Lytic Replication ◽  
Late Gene ◽  
Late Gene Expression ◽  
Lytic Gene ◽  
Barr Virus ◽  
Efficient Expression ◽  
Epstein Barr ◽  
Lytic Genes

Epstein-Barr virus (EBV) is a gammaherpesvirus, associated with infectious mononucleosis and various types of malignancy. We focused here on the BDLF4 gene of EBV and identified it as a lytic gene, expressed with early kinetics. Viral late gene expression of the BDLF4 knockout strain was severely restricted; this could be restored by an exogenous supply of BDLF4. These results indicate that BDLF4 is important for the EBV lytic replication cycle, especially in late gene expression.

scholarly journals The KSHV ORF20 Protein Interacts with the Viral Processivity Factor ORF59 and Promotes Viral Reactivation

2021 ◽  
Author(s):  
D. Hoffman ◽  
W. Rodriguez ◽  
D. Macveigh-Fierro ◽  
J. Miles ◽  
M. Muller
Keyword(s):  
Life Cycle ◽  
Dna Replication ◽  
Viral Proteins ◽  
Lytic Replication ◽  
Viral Reactivation ◽  
Viral Dna ◽  
Viral Dna Replication ◽  
New Hosts ◽  
Processivity Factor

Kaposi’s Sarcoma-associated herpesvirus (KSHV) is a herpesvirus that induces lifelong infection, and as such, its lytic replication is carefully controlled to allow for efficient dissemination from its long-term reservoir and for the spread of the virus to new hosts. Viral DNA replication involves many host and viral proteins, coordinating both in time and space to successfully progress through the viral life cycle.

scholarly journals Prolonged activation of NF-κB by human cytomegalovirus promotes efficient viral replication and late gene expression

Virology ◽  
2006 ◽  
Vol 346 (1) ◽  
pp. 15-31 ◽  
Author(s):  
Ian B. DeMeritt ◽  
Jagat P. Podduturi ◽  
A. Michael Tilley ◽  
Maciej T. Nogalski ◽  
Andrew D. Yurochko
Keyword(s):  
Gene Expression ◽  
Viral Replication ◽  
Human Cytomegalovirus ◽  
Late Gene ◽  
Late Gene Expression ◽  
Efficient Viral Replication

scholarly journals Bacteriophage self-counting in the presence of viral replication

2021 ◽  
Vol 118 (51) ◽  
pp. e2104163118
Author(s):  
Tianyou Yao ◽  
Seth Coleman ◽  
Thu Vu Phuc Nguyen ◽  
Ido Golding ◽  
Oleg A. Igoshin
Keyword(s):  
Gene Expression ◽  
Viral Replication ◽  
Viral Gene Expression ◽  
Host Cells ◽  
Optimal Decision ◽  
Viral Gene ◽  
Viral Genomes ◽  
Viral Copy Number ◽  
Viral Copy ◽  
Type Phage

When host cells are in low abundance, temperate bacteriophages opt for dormant (lysogenic) infection. Phage lambda implements this strategy by increasing the frequency of lysogeny at higher multiplicity of infection (MOI). However, it remains unclear how the phage reliably counts infecting viral genomes even as their intracellular number increases because of replication. By combining theoretical modeling with single-cell measurements of viral copy number and gene expression, we find that instead of hindering lambda’s decision, replication facilitates it. In a nonreplicating mutant, viral gene expression simply scales with MOI rather than diverging into lytic (virulent) and lysogenic trajectories. A similar pattern is followed during early infection by wild-type phage. However, later in the infection, the modulation of viral replication by the decision genes amplifies the initially modest gene expression differences into divergent trajectories. Replication thus ensures the optimal decision—lysis upon single-phage infection and lysogeny at higher MOI.

scholarly journals Murine Cytomegalovirus Protein pM91 Interacts with pM79 and Is Critical for Viral Late Gene Expression

2018 ◽  
Vol 92 (18) ◽  
Author(s):  
Deng Pan ◽  
Tian Han ◽  
Shubing Tang ◽  
Wenjia Xu ◽  
Qunchao Bao ◽  
...  
Keyword(s):  
Gene Expression ◽  
Viral Replication ◽  
Gene Transcription ◽  
Virus Production ◽  
Progeny Virus ◽  
Late Gene ◽  
Cmv Infection ◽  
Late Gene Expression ◽  
Viral Dna ◽  
Progeny Virus Production

ABSTRACTViral gene expression is tightly regulated during cytomegalovirus (CMV) lytic replication, but the detailed mechanism of late gene transcription remains to be fully understood. Previous studies reported that six viral proteins (named viral transactivation factors [vTFs]) supporting late gene expression were conserved in beta- and gammaherpesviruses but not in alphaherpesviruses. Here, we performed coimmunoprecipitation experiments to elucidate the organization of these six proteins in murine CMV. Our results showed that these proteins formed a complex by both direct and indirect interactions. Specifically, pM91 strongly bound to pM79 even in the absence of other vTFs. Similar to pM79, pM91 exhibited early-late expression kinetics and localized within nuclear viral replication compartments during infection. Functional analysis was also performed using the pM91-deficient virus. Real-time PCR results revealed that abrogation of M91 expression markedly reduced viral late gene expression and progeny virus production without affecting viral DNA synthesis. Using mutagenesis, we found that residues E61, D62, D89, and D96 in pM91 were required for the pM91-pM79 interaction. Disruption of the interaction via E61A/D62A or D89A/D96A double mutation in the context of virus infection inhibited progeny virus production. Our data indicate that pM91 is a component of the viral late gene transcription factor complex and that the pM91-pM79 interaction is essential for viral late gene expression.IMPORTANCECytomegalovirus (CMV) infection is the leading cause of birth defects and causes morbidity and mortality in immunocompromised patients. The regulation of viral late gene transcription is not well elucidated, and understanding of this process benefits the development of novel therapeutics against CMV infection. This study (i) identified that six viral transactivation factors encoded by murine CMV form a complex, (ii) demonstrated that pM91 interacts with pM79 and that pM91 and pM79 colocalize in the nuclear viral replication compartments, (iii) confirmed that pM91 is critical for viral late gene expression but dispensable for viral DNA replication, and (iv) revealed that the pM91-pM79 interaction is required for progeny virus production. These findings give an explanation of how CMV regulates late gene expression and have important implications for the design of antiviral strategies.

B-Catenin Signaling Regulates the In Vivo Distribution of Hepatitis B Virus Biosynthesis across the Liver Lobule

2021 ◽  
Author(s):  
Grant Tarnow ◽  
Alan McLachlan
Keyword(s):  
Gene Expression ◽  
Transgenic Mice ◽  
Viral Replication ◽  
Viral Gene Expression ◽  
Viral Gene ◽  
Central Vein ◽  
Liver Lobule ◽  
Liver Gene ◽  
Mice Liver

β-catenin (Ctnnb1) supports high levels of liver gene expression in hepatocytes in proximity to the central vein functionally defining zone 3 of the liver lobule. This region of the liver lobule supports the highest levels of viral biosynthesis in wildtype HBV transgenic mice. Liver-specific β-catenin-null HBV transgenic mice exhibit a stark loss of high levels of pericentral viral biosynthesis. Additionally, viral replication that does not depend directly on β-catenin activity appears to expand to include hepatocytes of zone 1 of the liver lobule in proximity to the portal vein, a region of the liver that typically lacks significant HBV biosynthesis in wildtype HBV transgenic mice. While the average amount of viral RNA transcripts does not change, viral DNA replication is reduced approximately three-fold. Together, these observations demonstrate that β-catenin signaling represents a major determinant of HBV biosynthesis governing the magnitude and distribution of viral replication across the liver lobule in vivo. Additionally, these findings reveal a novel mechanism for the regulation of HBV biosynthesis that is potentially relevant to the expression of additional liver-specific genes. IMPORTANCE Viral biosynthesis is highest around the central vein in the HBV transgenic mouse model of chronic infection. The associated HBV biosynthetic gradient across the liver lobule is primarily dependent upon β-catenin. In the absence of β-catenin, the gradient of viral gene expression spanning the liver lobule is absent and HBV replication is reduced. Therefore, therapeutically manipulating β-catenin activity in the liver of chronic HBV carriers may reduce circulating infectious virions without greatly modulating viral protein production. Together, these change in viral biosynthesis might limit infection of additional hepatocytes while permitting immunological clearance of previously infected cells, potentially limiting disease persistence.

scholarly journals The Kaposi’s Sarcoma-Associated Herpesvirus ORF34 Protein Interacts and Stabilizes HIF-2α via Binding to the HIF-2α bHLH and PAS Domains

2019 ◽  
Vol 93 (17) ◽  
Author(s):  
Muzammel Haque ◽  
K. G. Kousoulas
Keyword(s):  
Gene Expression ◽  
Life Cycle ◽  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Late Gene Expression ◽  
Lytic Gene ◽  
Lytic Gene Expression ◽  
Proteasome Pathway ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACTHypoxia and hypoxia inducible factors (HIFs) play important roles in the Kaposi’s sarcoma-associated herpesvirus (KSHV) life cycle. KSHV is the causative agent of Kaposi’s sarcoma (KS) and other AIDS-related malignancies. Kaposi’s sarcoma is a highly vascular tumor, which preferentially develops in the lower extremities of the body where blood vessels are often poorly oxygenated. The main cellular responses to hypoxia are mediated mainly by two isoforms of HIF, HIF-1α and HIF-2α. HIF-1α and HIF-2α have common as well as distinct functions, although they are similar in structure and function. Previously, we showed that the KSHV ORF34 protein binds HIF-1α and facilitates its degradation through the ubiquitin-proteasome pathway causing negative regulation of HIF-1α-dependent genes (Haque and Kousoulas, J Virol 87:2164-2173, 2013, https://www.doi.org/10.1128/JVI.02460-12). Herein, we show that theORF34gene is involved in the regulation of KSHV lytic gene expression, since deletion ofORF34resulted in reduced immediate early and early lytic gene expression and blocked late gene expression. Coimmunoprecipitation experiments revealed that the ORF34 protein physically interacted with HIF-2α in transfected as well as in KSHV-infected cells. Utilization of ORF34 truncations revealed that three distinct domains bind HIF-2α and that both bHLH and PAS domains of HIF-2α interacted with ORF34. Unlike HIF-1α, dose-dependent coexpression of ORF34 stabilized the HIF-2α protein, ensuring HIF-2α-dependent transcriptional activity. The ORF34 protein enhanced HIF-2α ubiquitination at the bHLH and PAS domains. The results show that the KSHV ORF34 protein is involved in the KSHV life cycle by regulating the expression of HIF-1α and HIF-2α proteins.IMPORTANCEHypoxia inducible factor 1α (HIF-1α) and HIF-2α are transcription factors which play important roles in the Kaposi’s sarcoma-associated herpesvirus (KSHV) latent and lytic gene replication. Herein, we show that theORF34gene is involved in the regulation of KSHV lytic gene expression, since deletion ofORF34resulted in reduced immediate early and early lytic gene expression and blocked late gene expression. In addition, we demonstrate that the KSHV ORF34 protein binds and stabilizes HIF-2α, in contrast to its role in binding HIF-1α and causing its degradation via the proteasome pathway. Thus, the KSHV ORF34 protein plays a regulatory role in the KSHV life cycle by regulating HIF-1α and HIF-2α expression.

scholarly journals Principal Role of TRAP/Mediator and SWI/SNF Complexes in Kaposi's Sarcoma-Associated Herpesvirus RTA-Mediated Lytic Reactivation

2003 ◽  
Vol 23 (6) ◽  
pp. 2055-2067 ◽  
Author(s):  
Yousang Gwack ◽  
Hwa Jin Baek ◽  
Hiroyuki Nakamura ◽  
Sun Hwa Lee ◽  
Michael Meisterernst ◽  
...  
Keyword(s):  
Gene Expression ◽  
Kaposi's Sarcoma ◽  
Viral Gene Expression ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Viral Gene ◽  
Transcription Activator ◽  
Lytic Reactivation ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT An important step in the herpesvirus life cycle is the switch from latency to lytic reactivation. The RTA transcription activator of Kaposi's sarcoma-associated herpesvirus (KSHV) acts as a molecular switch for lytic reactivation. Here we demonstrate that KSHV RTA recruits CBP, the SWI/SNF chromatin remodeling complex, and the TRAP/Mediator coactivator into viral promoters through interactions with a short acidic sequence in the carboxyl region and that this recruitment is essential for RTA-dependent viral gene expression. The Brg1 subunit of SWI/SNF and the TRAP230 subunit of TRAP/Mediator were shown to interact directly with RTA. Consequently, genetic ablation of these interactions abolished KSHV lytic replication. These results demonstrate that the recruitment of CBP, SWI/SNF, and TRAP/Mediator complexes by RTA is the principal mechanism to direct well-controlled viral gene expression and thereby viral lytic reactivation.

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