title: Three novel cis-acting elements required for efficient plus-strand DNA synthesis of the hepatitis B virus genome.
abstract: Synthesis of the relaxed-circular (RC) DNA genomes of hepadnaviruses by reverse transcriptase involves two template switches during plus-strand DNA synthesis. These template switches require repeat sequences (so-called donor and acceptor sites) between which a complementary strand of nucleic acid is transferred. To determine cis-acting elements apart from the donor and acceptor sites that are required for plus-strand RC DNA synthesis by hepatitis B virus (HBV), a series of mutants bearing a small deletion were made and analyzed for their impact on the viral genome synthesis. We found three novel cis-acting elements in the HBV genome: one element, located in the middle of the minus strand, is indispensable, whereas the other two elements, located near either end of the minus strand, contribute modestly to the plus-strand RC DNA synthesis. The data indicated that the first element facilitates plus-strand RNA primer translocation or subsequent elongation during plus-strand RC DNA synthesis, while the last two elements, although distantly located on the minus strand, act at multiple steps to promote plus-strand RC DNA synthesis. The necessity of multiple cis-acting elements on the minus-strand template reflects the complex nature of hepadnavirus reverse transcription.
authors.affiliation: Department of Biochemistry, Yonsei University, Seoul 120-749, Korea.
authors.forename: Jehan
authors.initials: J
authors.lastname: Lee
authors.forename: Myeong-Kyun
authors.initials: MK
authors.lastname: Shin
authors.forename: Hye-Jin
authors.initials: HJ
authors.lastname: Lee
authors.forename: Gyesoon
authors.initials: G
authors.lastname: Yoon
authors.forename: Wang-Shick
authors.initials: WS
authors.lastname: Ryu
mesh_terms: D002460:Cell Line; D004270:DNA, Circular / Q000096:biosynthesis* / Q000235:genetics; D004279:DNA, Viral / Q000096:biosynthesis* / Q000235:genetics; D004742:Enhancer Elements, Genetic; D016679:Genome, Viral; D006515:Hepatitis B virus / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D006801:Humans; D009154:Mutation
chemical_list: D004270:DNA, Circular; D004279:DNA, Viral