title: Translation of the first upstream ORF in the hepatitis B virus pregenomic RNA modulates translation at the core and polymerase initiation codons.
abstract: The human hepatitis B virus (HBV) has a compact genome encoding four major overlapping coding regions: the core, polymerase, surface and X. The polymerase initiation codon is preceded by the partially overlapping core and four or more upstream initiation codons. There is evidence that several mechanisms are used to enable the synthesis of the polymerase protein, including leaky scanning and ribosome reinitiation. We have examined the first AUG in the pregenomic RNA, it precedes that of the core. It initiates an uncharacterized short upstream open reading frame (uORF), highly conserved in all HBV subtypes, we designated the C0 ORF. This arrangement suggested that expression of the core and polymerase may be affected by this uORF. Initiation at the C0 ORF was confirmed in reporter constructs in transfected cells. The C0 ORF had an inhibitory role in downstream expression from the core initiation site in HepG2 cells and in vitro, but also stimulated reinitiation at the polymerase start when in an optimal context. Our results indicate that the C0 ORF is a determinant in balancing the synthesis of the core and polymerase proteins.
authors.affiliation: Biochemistry Department, University of Otago Dunedin, New Zealand.
authors.forename: Augustine
authors.initials: A
authors.lastname: Chen
authors.forename: Y F
authors.initials: YF
authors.lastname: Kao
authors.forename: Chris M
authors.initials: CM
authors.lastname: Brown
mesh_terms: D020121:5' Untranslated Regions; D001483:Base Sequence; D045744:Cell Line, Tumor; D018387:Codon, Initiator; D017124:Conserved Sequence; D015967:Gene Expression Regulation, Viral; D015684:Gene Products, pol / Q000235:genetics*; D017930:Genes, Reporter; D016679:Genome, Viral; D006512:Hepatitis B Core Antigens / Q000235:genetics*; D006515:Hepatitis B virus / Q000145:classification / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010442:Peptide Chain Initiation, Translational; D012367:RNA, Viral / Q000737:chemistry*
chemical_list: D020121:5' Untranslated Regions; D018387:Codon, Initiator; D015684:Gene Products, pol; D006512:Hepatitis B Core Antigens; C066027:P protein, Hepatitis B virus; D012367:RNA, Viral
references.citation: Microbiol Mol Biol Rev. 2000 Mar;64(1):51-68
references.pmid: 10704474
references.citation: J Gen Virol. 1999 Jul;80 ( Pt 7):1769-76
references.pmid: 10423146
references.citation: Mol Cell Biol. 2000 Dec;20(23):8635-42
references.pmid: 11073965
references.citation: Gene. 2000 Dec 30;261(1):85-91
references.pmid: 11164040
references.citation: Bioinformatics. 2001 Oct;17(10):890-900
references.pmid: 11673233
references.citation: Trends Genet. 2001 Dec;17(12):685-7
references.pmid: 11718907
references.citation: J Biomol Struct Dyn. 2002 Feb;19(4):627-36
references.pmid: 11843624
references.citation: Mamm Genome. 2002 Aug;13(8):401-10
references.pmid: 12226704
references.citation: Science. 2002 Sep 13;297(5588):1864-7
references.pmid: 12228716
references.citation: Genes Dev. 2002 Nov 15;16(22):2906-22
references.pmid: 12435632
references.citation: Gene. 2002 Oct 16;299(1-2):1-34
references.pmid: 12459250
references.citation: Nucleic Acids Res. 2003 Jun 15;31(12):3174-84
references.pmid: 12799445
references.citation: Rev Med Virol. 2003 Jul-Aug;13(4):255-72
references.pmid: 12820187
references.citation: Mol Microbiol. 2003 Aug;49(4):859-67
references.pmid: 12890013
references.citation: Hepatology. 2003 Sep;38(3):545-53
references.pmid: 12939579
references.citation: Genes Dev. 2004 Jan 1;18(1):62-75
references.pmid: 14701882
references.citation: Nucleic Acids Res. 2004;32(4):1382-91
references.pmid: 14990743
references.citation: Biochem Soc Trans. 2004 Aug;32(Pt 4):592-6
references.pmid: 15270684
references.citation: Proc Natl Acad Sci U S A. 2004 Aug 3;101(31):11269-74
references.pmid: 15277680
references.citation: J Virol. 2004 Nov;78(21):11751-7
references.pmid: 15479816
references.citation: Cell. 1986 Jan 31;44(2):283-92
references.pmid: 3943125
references.citation: J Mol Biol. 1986 Jul 5;190(1):45-57
references.pmid: 3023636
references.citation: Annu Rev Biochem. 1987;56:651-93
references.pmid: 3039907
references.citation: Cell. 1989 Jan 13;56(1):85-92
references.pmid: 2463093
references.citation: J Cell Biol. 1989 Feb;108(2):229-41
references.pmid: 2645293
references.citation: J Biol Chem. 1989 Mar 25;264(9):5031-5
references.pmid: 2538469
references.citation: Proc Natl Acad Sci U S A. 1990 Jul;87(13):5158-62
references.pmid: 1695011
references.citation: J Virol. 1990 Sep;64(9):4578-81
references.pmid: 2384923
references.citation: Cell. 1990 Dec 21;63(6):1357-63
references.pmid: 2261646
references.citation: Virology. 1992 May;188(1):342-52
references.pmid: 1566578
references.citation: Gene Expr. 1991 May;1(2):117-25
references.pmid: 1820209
references.citation: J Virol. 1993 Aug;67(8):4886-95
references.pmid: 7687304
references.citation: J Bacteriol. 1994 Nov;176(22):7115-7
references.pmid: 7961481
references.citation: J Gen Virol. 1996 Jun;77 ( Pt 6):1123-7
references.pmid: 8683196
references.citation: Curr Biol. 1996 Mar 1;6(3):315-24
references.pmid: 8805248
references.citation: J Gen Virol. 1998 Sep;79 ( Pt 9):2181-9
references.pmid: 9747727
references.citation: Gene. 1999 Jul 8;234(2):187-208
references.pmid: 10395892
references.citation: Microbiol Mol Biol Rev. 2000 Jun;64(2):239-80
references.pmid: 10839817