scholarly journals Transcription of Hepatitis Delta Virus RNA by RNA Polymerase II

2007 ◽  
Vol 82 (3) ◽  
pp. 1118-1127 ◽  
Author(s):  
Jinhong Chang ◽  
Xingcao Nie ◽  
Ho Eun Chang ◽  
Ziying Han ◽  
John Taylor
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Hepatitis Delta Virus ◽  
Cell System ◽  
Hepatitis Delta ◽  
Pol Ii ◽  
Delta Antigen ◽  
Nuclear Extracts ◽  
Virus Rna ◽  
Delta Virus

ABSTRACT Previous studies have indicated that the replication of the RNA genome of hepatitis delta virus (HDV) involves redirection of RNA polymerase II (Pol II), a host enzyme that normally uses DNA as a template. However, there has been some controversy about whether in one part of this HDV RNA transcription, a polymerase other than Pol II is involved. The present study applied a recently described cell system (293-HDV) of tetracycline-inducible HDV RNA replication to provide new data regarding the involvement of host polymerases in HDV transcription. The data generated with a nuclear run-on assay demonstrated that synthesis not only of genomic RNA but also of its complement, the antigenome, could be inhibited by low concentrations of amanitin specific for Pol II transcription. Subsequent studies used immunoprecipitation and rate-zonal sedimentation of nuclear extracts together with double immunostaining of 293-HDV cells, in order to examine the associations between Pol II and HDV RNAs, as well as the small delta antigen, an HDV-encoded protein known to be essential for replication. Findings include evidence that HDV replication is somehow able to direct the available delta antigen to sites in the nucleoplasm, almost exclusively colocalized with Pol II in what others have described as transcription factories.

scholarly journals The human RNA polymerase II interacts with the terminal stem–loop regions of the hepatitis delta virus RNA genome

Virology ◽  
2007 ◽  
Vol 357 (1) ◽  
pp. 68-78 ◽  
Author(s):  
Valerie S. Greco-Stewart ◽  
Paul Miron ◽  
Abrahem Abrahem ◽  
Martin Pelchat
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Hepatitis Delta Virus ◽  
Hepatitis Delta ◽  
Stem Loop ◽  
Virus Rna ◽  
Loop Regions ◽  
Rna Genome ◽  
Delta Virus

scholarly journals Intracellular Localization of Hepatitis Delta Virus Proteins in the Presence and Absence of Viral RNA Accumulation

2009 ◽  
Vol 83 (13) ◽  
pp. 6457-6463 ◽  
Author(s):  
Ziying Han ◽  
Carolina Alves ◽  
Severin Gudima ◽  
John Taylor
Keyword(s):  
Rna Polymerase Ii ◽  
Protein Function ◽  
Hepatitis Delta Virus ◽  
Rna Binding ◽  
Intracellular Localization ◽  
Genome Replication ◽  
Hepatitis Delta ◽  
Pol Ii ◽  
Presence And Absence ◽  
Delta Virus

ABSTRACT Hepatitis delta virus (HDV) encodes one protein, hepatitis delta antigen (δAg), a 195-amino-acid RNA binding protein essential for the accumulation of HDV RNA-directed RNA transcripts. It has been accepted that δAg localizes predominantly to the nucleolus in the absence of HDV genome replication while in the presence of replication, δAg facilitates HDV RNA transport to the nucleoplasm and helps redirect host RNA polymerase II (Pol II) to achieve transcription and accumulation of processed HDV RNA species. This study used immunostaining and confocal microscopy to evaluate factors controlling the localization of δAg in the presence and absence of replicating and nonreplicating HDV RNAs. When δAg was expressed in the absence of full-length HDV RNAs, it colocalized with nucleolin, a predominant nucleolar protein. With time, or more quickly after induced cell stress, there was a redistribution of both δAg and nucleolin to the nucleoplasm. Following expression of nonreplicating HDV RNAs, δAg moved to the nucleoplasm, but nucleolin was unchanged. When δAg was expressed along with replicating HDV RNA, it was found predominantly in the nucleoplasm along with Pol II. This localization was insensitive to inhibitors of HDV replication, suggesting that the majority of δAg in the nucleoplasm reflects ribonucleoprotein accumulation rather than ongoing transcription. An additional approach was to reevaluate several forms of δAg altered at specific locations considered to be essential for protein function. These studies provide evidence that δAg does not interact directly with either Pol II or nucleolin and that forms of δAg which support replication are also capable of prior nucleolar transit.

scholarly journals Origin of Hepatitis Delta Virus mRNA

2000 ◽  
Vol 74 (16) ◽  
pp. 7204-7210 ◽  
Author(s):  
Severin Gudima ◽  
Shwu-Yuan Wu ◽  
Cheng-Ming Chiang ◽  
Gloria Moraleda ◽  
John Taylor
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Hepatitis Delta Virus ◽  
Rna Synthesis ◽  
Genome Replication ◽  
Rna Transcription ◽  
Hepatitis Delta ◽  
New Findings ◽  
Delta Virus

ABSTRACT Hepatitis delta virus (HDV) is unique relative to all known animal viruses, especially in terms of its ability to redirect host RNA polymerase(s) to transcribe its 1,679-nucleotide (nt) circular RNA genome. During replication there accumulates not only more molecules of the genome but also its exact complement, the antigenome. In addition, there are relatively smaller amounts of an 800-nt RNA of antigenomic polarity that is polyadenylated and considered to act as mRNA for translation of the single and essential HDV protein, the delta antigen. Characterization of this mRNA could provide insights into the in vivo mechanism of HDV RNA-directed RNA transcription and processing. Previously, we showed that the 5′ end of this RNA was located in the majority of species, at nt 1630. The present studies show that (i) at least some of this RNA, as extracted from the liver of an HDV-infected woodchuck, behaved as if it contained a 5′-cap structure; (ii) in the infected liver there were additional polyadenylated antigenomic HDV RNA species with 5′ ends located at least 202 nt and even 335 nt beyond the nt 1630 site, (iii) the 5′ end at nt 1630 was not detected in transfected cells, following DNA-directed HDV RNA transcription, in the absence of genome replication, and (iv) nevertheless, using in vitro transcription with purified human RNA polymerase II holoenzyme and genomic RNA template, we did not detect initiation of template-dependent RNA synthesis; we observed only low levels of 3′-end addition to the template. These new findings support the interpretation that the 5′ end detected at nt 1630 during HDV replication represents a specific site for the initiation of an RNA-directed RNA synthesis, which is then modified by capping.

scholarly journals Arginine-Rich Motifs Are Not Required for Hepatitis Delta Virus RNA Binding Activity of the Hepatitis Delta Antigen

2013 ◽  
Vol 87 (15) ◽  
pp. 8665-8674 ◽  
Author(s):  
L. H. Daigh ◽  
B. L. Griffin ◽  
A. Soroush ◽  
M. R. Mamedov ◽  
J. L. Casey
Keyword(s):  
Hepatitis Delta Virus ◽  
Rna Binding ◽  
Binding Activity ◽  
Hepatitis Delta ◽  
Delta Antigen ◽  
Virus Rna ◽  
Hepatitis Delta Antigen ◽  
Delta Virus

Hepatitis delta virus genome RNA synthesis initiates at position 1646 with a non-templated guanosine

2021 ◽  
Author(s):  
Susannah Stephenson-Tsoris ◽  
John L. Casey
Keyword(s):  
Liver Disease ◽  
Rna Polymerase ◽  
Hepatitis Delta Virus ◽  
Rna Synthesis ◽  
Viral Rna ◽  
Start Site ◽  
Hepatitis Delta ◽  
Pol Ii ◽  
Infected Cells ◽  
Delta Virus

Hepatitis delta virus (HDV) is a significant human pathogen that causes acute and chronic liver disease; there is no licensed therapy. HDV is a circular negative-sense ssRNA virus that produces three RNAs in infected cells: genome, antigenome and mRNA; the latter encodes hepatitis delta antigen, the viral protein. These RNAs are synthesized by host DNA-dependent RNA polymerase acting as an RNA-dependent RNA polymerase. Although HDV genome RNA accumulates to high levels in infected cells, the mechanism by which this process occurs remains poorly understood. For example, the nature of the 5’ end of the genome, including the synthesis start site and its chemical composition, are not known. Analysis of this process has been challenging because the initiation site is part of an unstable precursor in the rolling circle mechanism by which HDV genome RNA is synthesized. In this study, circular HDV antigenome RNAs synthesized in vitro were used to directly initiate HDV genome RNA synthesis in transfected cells, thus enabling detection of the 5’ end of the genome RNA. The 5’ end of this RNA is capped, as expected for a Pol II product. Initiation begins at position 1646 on the genome, which is located near the loop end proximal to the start site for HDAg mRNA synthesis. Unexpectedly, synthesis begins with a guanosine that is not conventionally templated by the HDV RNA. IMPORTANCE Hepatitis delta virus (HDV) is a unique virus that causes severe liver disease. It uses host RNA Polymerase II to copy its circular RNA genome in a unique and poorly understood process. Although the virus RNA accumulates to high levels within infected cells, it is not known how synthesis of the viral RNA begins, nor even where on the genome synthesis starts. Here, we identify the start site for the initiation of HDV genome RNA synthesis as position 1646, which is at one end of the closed hairpin-like structure of the viral RNA. The 5’ end of the RNA is capped, as expected for Pol II products. However, RNA synthesis begins with a guanosine that is not present in the genome. Thus, although HDV uses Pol II to synthesize the viral genome, some details of the initiation process are different. These differences could be important for successfully targeting virus replication.

scholarly journals RNA-Dependent Replication and Transcription of Hepatitis Delta Virus RNA Involve Distinct Cellular RNA Polymerases

2000 ◽  
Vol 20 (16) ◽  
pp. 6030-6039 ◽  
Author(s):  
Lucy E. Modahl ◽  
Thomas B. Macnaughton ◽  
Nongliao Zhu ◽  
Deborah L. Johnson ◽  
Michael M. C. Lai
Keyword(s):  
Rna Polymerase Ii ◽  
Hepatitis Delta Virus ◽  
Molecular Mechanisms ◽  
De Novo ◽  
Full Length ◽  
Supporting Evidence ◽  
Mrna Transcription ◽  
Hepatitis Delta ◽  
Pol Ii ◽  
Delta Virus

ABSTRACT Cellular DNA-dependent RNA polymerase II (pol II) has been postulated to carry out RNA-dependent RNA replication and transcription of hepatitis delta virus (HDV) RNA, generating a full-length (1.7-kb) RNA genome and a subgenomic-length (0.8-kb) mRNA. However, the supporting evidence for this hypothesis was ambiguous because the previous experiments relied on DNA-templated transcription to initiate HDV RNA synthesis. Furthermore, there is no evidence that the same cellular enzyme is involved in the synthesis of both RNA species. In this study, we used a novel HDV RNA-based transfection approach, devoid of any artificial HDV cDNA intermediates, to determine the enzymatic and metabolic requirements for the synthesis of these two RNA species. We showed that HDV subgenomic mRNA transcription was inhibited by a low concentration of α-amanitin (<3 μg/ml) and could be partially restored by an α-amanitin-resistant mutant pol II; however, surprisingly, the synthesis of the full-length (1.7-kb) antigenomic RNA was not affected by α-amanitin to a concentration higher than 25 μg/ml. By several other criteria, such as the differing requirement for the de novo-synthesized hepatitis delta antigen and temperature dependence, we further showed that the metabolic requirements of subgenomic HDV mRNA synthesis are different from those for the synthesis of genomic-length HDV RNA and cellular pol II transcripts. The synthesis of the two HDV RNA species could also be uncoupled under several different conditions. These findings provide strong evidence that pol II, or proteins derived from pol II transcripts, is involved in mRNA transcription from the HDV RNA template. In contrast, the synthesis of the 1.7-kb HDV antigenomic RNA appears not to be dependent on pol II. These results reveal that there are distinct molecular mechanisms for the synthesis of these two RNA species.

scholarly journals Hepatitis Delta Virus RNA Editing Is Highly Specific for the Amber/W Site and Is Suppressed by Hepatitis Delta Antigen

1998 ◽  
Vol 18 (4) ◽  
pp. 1919-1926 ◽  
Author(s):  
Andrew G. Polson ◽  
Herbert L. Ley ◽  
Brenda L. Bass ◽  
John L. Casey
Keyword(s):  
Rna Editing ◽  
Hepatitis Delta Virus ◽  
Hepatitis Delta ◽  
Reading Frame ◽  
Adenosine Deaminases ◽  
Delta Antigen ◽  
Virus Rna ◽  
Hepatitis Delta Antigen ◽  
Delta Virus

ABSTRACT RNA editing at adenosine 1012 (amber/W site) in the antigenomic RNA of hepatitis delta virus (HDV) allows two essential forms of the viral protein, hepatitis delta antigen (HDAg), to be synthesized from a single open reading frame. Editing at the amber/W site is thought to be catalyzed by one of the cellular enzymes known as adenosine deaminases that act on RNA (ADARs). In vitro, the enzymes ADAR1 and ADAR2 deaminate adenosines within many different sequences of base-paired RNA. Since promiscuous deamination could compromise the viability of HDV, we wondered if additional deamination events occurred within the highly base paired HDV RNA. By sequencing cDNAs derived from HDV RNA from transfected Huh-7 cells, we determined that the RNA was not extensively modified at other adenosines. Approximately 0.16 to 0.32 adenosines were modified per antigenome during 6 to 13 days posttransfection. Interestingly, all observed non-amber/W adenosine modifications, which occurred mostly at positions that are highly conserved among naturally occurring HDV isolates, were found in RNAs that were also modified at the amber/W site. Such coordinate modification likely limits potential deleterious effects of promiscuous editing. Neither viral replication nor HDAg was required for the highly specific editing observed in cells. However, HDAg was found to suppress editing at the amber/W site when expressed at levels similar to those found during HDV replication. These data suggest HDAg may regulate amber/W site editing during virus replication.

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