scholarly journals Selected mutations of the duck hepatitis B virus P gene RNase H domain affect both RNA packaging and priming of minus-strand DNA synthesis.

1994 ◽  
Vol 68 (8) ◽  
pp. 5232-5238 ◽  
Author(s):  
Y Chen ◽  
W S Robinson ◽  
P L Marion
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Dna Synthesis ◽  
Rnase H ◽  
Minus Strand ◽  
Rna Packaging ◽  
Duck Hepatitis B Virus ◽  
P Gene ◽  
Duck Hepatitis ◽  
B Virus

The duck hepatitis B virus P-gene codes for protein strongly associated with the 5′-end of the viral dna minus strand

Virology ◽  
1988 ◽  
Vol 166 (2) ◽  
pp. 475-485 ◽  
Author(s):  
Valerie Bosch ◽  
Ralf Bartenschlager ◽  
Gerald Radziwill ◽  
Heinz Schaller
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Minus Strand ◽  
Viral Dna ◽  
Duck Hepatitis B Virus ◽  
P Gene ◽  
Duck Hepatitis ◽  
B Virus

scholarly journals Analysis of Duck Hepatitis B Virus Reverse Transcription Indicates a Common Mechanism for the Two Template Switches during Plus-Strand DNA Synthesis

2002 ◽  
Vol 76 (6) ◽  
pp. 2763-2769 ◽  
Author(s):  
Michael B. Havert ◽  
Lin Ji ◽  
Daniel D. Loeb
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Dna Synthesis ◽  
Minus Strand ◽  
Duck Hepatitis B Virus ◽  
Circular Dna ◽  
Duck Hepatitis ◽  
Donor And Acceptor ◽  
B Virus ◽  
Template Switches

ABSTRACT The synthesis of the hepadnavirus relaxed circular DNA genome requires two template switches, primer translocation and circularization, during plus-strand DNA synthesis. Repeated sequences serve as donor and acceptor templates for these template switches, with direct repeat 1 (DR1) and DR2 for primer translocation and 5′r and 3′r for circularization. These donor and acceptor sequences are at, or near, the ends of the minus-strand DNA. Analysis of plus-strand DNA synthesis of duck hepatitis B virus (DHBV) has indicated that there are at least three other cis-acting sequences that make contributions during the synthesis of relaxed circular DNA. These sequences, 5E, M, and 3E, are located near the 5′ end, the middle, and the 3′ end of minus-strand DNA, respectively. The mechanism by which these sequences contribute to the synthesis of plus-strand DNA was unclear. Our aim was to better understand the mechanism by which 5E and M act. We localized the DHBV 5E element to a short sequence of approximately 30 nucleotides that is 100 nucleotides 3′ of DR2 on minus-strand DNA. We found that the new 5E mutants were partially defective for primer translocation/utilization at DR2. They were also invariably defective for circularization. In addition, examination of several new DHBV M variants indicated that they too were defective for primer translocation/utilization and circularization. Thus, this analysis indicated that 5E and M play roles in both primer translocation/utilization and circularization. In conjunction with earlier findings that 3E functions in both template switches, our findings indicate that the processes of primer translocation and circularization share a common underlying mechanism.

scholarly journals Evidence that the first strand-transfer reaction of duck hepatitis B virus reverse transcription requires the polymerase and that strand transfer is not needed for the switch of the polymerase to the elongation mode of DNA synthesis

2000 ◽  
Vol 81 (8) ◽  
pp. 2059-2065 ◽  
Author(s):  
Yunhao Gong ◽  
Ermei Yao ◽  
Melissa Stevens ◽  
John E. Tavis
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Dna Synthesis ◽  
Reverse Transcription ◽  
Transfer Reaction ◽  
Strand Transfer ◽  
Minus Strand ◽  
Duck Hepatitis B Virus ◽  
Duck Hepatitis ◽  
B Virus

Deletion of amino acids 79–88 in the duck hepatitis B virus reverse transcriptase had minimal effects on polymerase activities prior to the minus-strand DNA transfer reaction, yet it greatly diminished strand transfer and subsequent DNA synthesis. This mutation also reduced reverse transcription on exogenous RNA templates. The reaction on exogenous RNAs employed the phosphonoformic acid (PFA)-sensitive elongation mode of DNA synthesis rather than the PFA-resistant priming mode, despite the independence of DNA synthesis in this assay from the priming and minus-strand transfer reactions. These data provide experimental evidence that the polymerase is involved directly in the minus-strand transfer reaction and that the switch of the polymerase from the early PFA-resistant mode of DNA synthesis to the later PFA-sensitive elongation mode does not require the strand-transfer reaction.

scholarly journals Template Switches during Plus-Strand DNA Synthesis of Duck Hepatitis B Virus Are Influenced by the Base Composition of the Minus-Strand Terminal Redundancy

2003 ◽  
Vol 77 (23) ◽  
pp. 12412-12420 ◽  
Author(s):  
Jeffrey W. Habig ◽  
Daniel D. Loeb
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Dna Synthesis ◽  
Base Composition ◽  
Minus Strand ◽  
Duck Hepatitis B Virus ◽  
Duck Hepatitis ◽  
B Virus ◽  
Template Switch ◽  
Template Switches

ABSTRACT Two template switches are necessary during plus-strand DNA synthesis of the relaxed circular (RC) form of the hepadnavirus genome. The 3′ end of the minus-strand DNA makes important contributions to both of these template switches. It acts as the donor site for the first template switch, called primer translocation, and subsequently acts as the acceptor site for the second template switch, termed circularization. Circularization involves transfer of the nascent 3′ end of the plus strand from the 5′ end of the minus-strand DNA to the 3′ end, where further elongation can lead to production of RC DNA. In duck hepatitis B virus (DHBV), a small terminal redundancy (5′r and 3′r) on the ends of the minus-strand DNA has been shown to be important, but not sufficient, for circularization. We investigated what contribution, if any, the base composition of the terminal redundancy made to the circularization process. Using a genetic approach, we found a strong positive correlation between the fraction of A and T residues within the terminal redundancy and the efficiency of the circularization process in those variants. Additionally, we found that the level of in situ priming increases, at the expense of primer translocation, as the fraction of A and T residues in the 3′r decreases. Thus, a terminal redundancy rich in A and T residues is important for both plus-strand template switches in DHBV.

scholarly journals Dominant negative mutants of the duck hepatitis B virus core protein interfere with RNA pregenome packaging and viral DNA synthesis

Hepatology ◽  
1999 ◽  
Vol 30 (1) ◽  
pp. 308-315 ◽  
Author(s):  
Fritz von Weizsäcker ◽  
Josef Köck ◽  
Stefan Wieland ◽  
Wolf-Bernhard Offensperger ◽  
Hubert E. Blum
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Dna Synthesis ◽  
Core Protein ◽  
Dominant Negative ◽  
Viral Dna ◽  
Duck Hepatitis B Virus ◽  
Virus Core ◽  
Duck Hepatitis ◽  
B Virus

scholarly journals Duck Hepatitis B Virus Nucleocapsids Formed by N-Terminally Extended or C-Terminally Truncated Core Proteins Disintegrate during Viral DNA Maturation

1998 ◽  
Vol 72 (11) ◽  
pp. 9116-9120 ◽  
Author(s):  
Josef Köck ◽  
Stefan Wieland ◽  
Hubert E. Blum ◽  
Fritz von Weizsäcker
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Dna Synthesis ◽  
Core Protein ◽  
Viral Dna ◽  
Duck Hepatitis B Virus ◽  
Duck Hepatitis ◽  
Core Proteins ◽  
B Virus ◽  
Carboxy Terminal

ABSTRACT Hepadnaviruses are DNA viruses that replicate through reverse transcription of an RNA pregenome. Viral DNA synthesis takes place inside viral nucleocapsids, formed by core protein dimers. Previous studies have identified carboxy-terminal truncations of the core protein that affect viral DNA maturation. Here, we describe the effect of small amino-terminal insertions into the duck hepatitis B virus (DHBV) core protein on viral DNA replication. All insertion mutants formed replication-competent nucleocapsids. Elongation of viral DNA, however, appeared to be incomplete. Increasing the number of additional amino acids and introducing negatively charged residues further reduced the observed size of mature viral DNA species. Mutant core proteins did not inhibit the viral polymerase. Instead, viral DNA synthesis destabilized mutant nucleocapsids, rendering mature viral DNA selectively sensitive to nuclease action. Interestingly, the phenotype of two previously described carboxy-terminal DHBV core protein deletion mutants was found to be based on the same mechanism. These data suggest that (i) the amino- as well as the carboxy-terminal portion of the DHBV core protein plays a critical role in nucleocapsid stabilization, and (ii) the hepadnavirus polymerase can perform partial second-strand DNA synthesis in the absence of intact viral nucleocapsids.

scholarly journals Small DNA Hairpin Negatively Regulates In Situ Priming during Duck Hepatitis B Virus Reverse Transcription

2002 ◽  
Vol 76 (3) ◽  
pp. 980-989 ◽  
Author(s):  
Jeffrey W. Habig ◽  
Daniel D. Loeb
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Dna Synthesis ◽  
Minus Strand ◽  
Dna Hairpin ◽  
Circular Dna ◽  
Duck Hepatitis ◽  
B Virus ◽  
Pairing Potential

ABSTRACT There are two mutually exclusive pathways for plus-strand DNA synthesis in hepadnavirus reverse transcription. The predominant pathway gives rise to relaxed circular DNA, while the other pathway yields duplex linear DNA. Both pathways use the same RNA primer, which is capped and 18 or 19 nucleotides in length. At the completion of minus-strand DNA synthesis, the final RNase H cleavage generates the plus-strand primer. To make relaxed circular DNA, primer translocation must occur, resulting in the transfer of the primer generated at DR1 to the acceptor site (DR2) near the opposite end of the minus-strand DNA. A small fraction of viruses instead make duplex linear DNA after initiating plus-strand DNA synthesis from DR1, a process called in situ priming. We are interested in understanding the mechanism of discrimination between these two pathways. Some variants of duck hepatitis B virus exhibit high levels of in situ priming due to cis-acting mutations. The mechanism by which these mutations act has been obscure. Sequence inspection predicted formation of a small DNA hairpin in the region overlapping these mutations. We have shown that substitutions disrupting base pairing potential in this hairpin led to increased levels of in situ priming. The introduction of compensatory changes to restore base pairing potential led to reduced levels of in situ priming. Thus, formation of the small DNA hairpin overlapping the 5′ end of DR1 in the minus strand contributes to the regulation of primer translocation, at least, through inhibition of in situ priming by making the 3′ end of the minus-strand DNA a poor template for initiation.

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