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  • American Society for Microbiology  (2)
  • Abraham, Teresa M.  (2)
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  • American Society for Microbiology  (2)
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  • 1
    Online Resource
    Online Resource
    American Society for Microbiology ; 2007
    In:  Journal of Virology Vol. 81, No. 21 ( 2007-11), p. 11577-11584
    In: Journal of Virology, American Society for Microbiology, Vol. 81, No. 21 ( 2007-11), p. 11577-11584
    Abstract: Previous analysis of hepatitis B virus (HBV) indicated base pairing between two cis -acting sequences, the 5′ half of the upper stem of ε and φ, contributes to the synthesis of minus-strand DNA. Our goal was to identify other cis -acting sequences on the pregenomic RNA (pgRNA) involved in the synthesis of minus-strand DNA. We found that large portions of the pgRNA could be deleted or substituted without an appreciable decrease in the level of minus-strand DNA synthesized, indicating that most of the pgRNA is dispensable and that a specific size of the pgRNA is not required for this process. Our results indicated that the cis -acting sequences for the synthesis of minus-strand DNA are present near the 5′ and 3′ ends of the pgRNA. In addition, we found that the first-strand template switch could be directed to a new location when a 72-nucleotide (nt) fragment, which contained the cis -acting sequences present near the 3′ end of the pgRNA, was introduced at that location. Within this 72-nt region, we uncovered two new cis -acting sequences, which flank the acceptor site. We show that one of these sequences, named ω and located 3′ of the acceptor site, base pairs with φ to contribute to the synthesis of minus-strand DNA. Thus, base pairing between three cis -acting elements (5′ half of the upper stem of ε, φ, and ω) are necessary for the synthesis of HBV minus-strand DNA. We propose that this topology of pgRNA facilitates first-strand template switch and/or the initiation of synthesis of minus-strand DNA.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2007
    detail.hit.zdb_id: 1495529-5
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  • 2
    Online Resource
    Online Resource
    American Society for Microbiology ; 2006
    In:  Journal of Virology Vol. 80, No. 9 ( 2006-05), p. 4380-4387
    In: Journal of Virology, American Society for Microbiology, Vol. 80, No. 9 ( 2006-05), p. 4380-4387
    Abstract: Synthesis of minus-strand DNA of human hepatitis B virus (HBV) can be divided into three phases: initiation of DNA synthesis, the template switch, and elongation of minus-strand DNA. Although much is known about minus-strand DNA synthesis, the mechanism(s) by which this occurs has not been completely elucidated. Through a deletion analysis, we have identified a cis -acting element involved in minus-strand DNA synthesis that lies within a 27-nucleotide region between DR2 and the 3′ copy of DR1. A subset of this region (termed Φ) has been hypothesized to base pair with the 5′ half of ε (H. Tang and A. McLachlan, Virology, 303: 199-210, 2002). To test the proposed model, we used a genetic approach in which multiple sets of variants that disrupted and then restored putative base pairing between the 5′ half of ε and Φ were analyzed. Primer extension analysis, using two primers simultaneously, was performed to measure encapsidated pregenomic RNA (pgRNA) and minus-strand DNA synthesized in cell culture. The efficiency of minus-strand DNA synthesis was defined as the amount of minus-strand DNA synthesized per encapsidation event. Our results indicate that base pairing between Φ and the 5′ half of ε contributes to efficient minus-strand DNA synthesis. Additional results are consistent with the idea that the primary sequence of Φ and/or ε also contributes to function. How base pairing between Φ and ε contributes to minus-strand DNA synthesis is not known, but a simple speculation is that Φ base pairs with the 5′ half of ε to juxtapose the donor and acceptor sites to facilitate the first-strand template switch.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2006
    detail.hit.zdb_id: 1495529-5
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
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