Abstract
The two major envelope proteins (large [L] and small [S]) of duck hepatitis B virus are encoded by the pre-S/S open reading frame. The L protein is initiated from the AUG at position 801 in the pre-S region of the pre-S/S coding sequence, yielding an N-terminal consensus sequence for myristylation. Western immunoblots of the L protein often reveal a doublet at 36 and 35 kDa, with the latter attributed to the use of one of the three internal initiation codons. However, metabolic labelling with [3H]myristic acid results in labelling of both P35 and P36, indicating that both species must be initiated from the same start codon. Using metabolic labelling with 32P and digestion with residue-specific phosphatases, we demonstrate that L protein heterogeneity is due to phosphorylation of threonine and/or serine residues within the pre-S domain. We propose that at least one possible phosphorylation site is located at a novel (S/T)PPL motif which is conserved near the carboxyl end of the pre-S1 domain in all hepadnavirus sequences. Two to three additional (S/T)P motifs are also present in the carboxyl half of the pre-S1 (but not pre-S2 or S) domain of all hepadnaviruses. L protein in serum-derived particles is resistant to phosphatase digestion in the absence of detergents, reflecting an internal disposition of the phosphorylated pre-S domain and suggesting a role for dephosphorylation in the topological shift within L during morphogenesis (P. Ostapchuk, P. Hearing, and D. Ganem, EMBO J. 13:1048-1057, 1994). Furthermore, we observe that the relative amount of the phosphorylated form of L increases with time in the viral growth cycle. These findings imply that phosphorylation-dephosphorylation of the L protein is an important, regulated mechanism necessary for correct virion morphogenesis.
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- Bishop N., Civitico G., Wang Y. Y., Guo K. J., Birch C., Gust I., Locarnini S. Antiviral strategies in chronic hepatitis B virus infection: I. Establishment of an in vitro system using the duck hepatitis B virus model. J Med Virol. 1990 Jun;31(2):82–89. doi: 10.1002/jmv.1890310204. [DOI] [PubMed] [Google Scholar]
- Borovec S. V., Anderson D. A. Synthesis and assembly of hepatitis A virus-specific proteins in BS-C-1 cells. J Virol. 1993 Jun;67(6):3095–3102. doi: 10.1128/jvi.67.6.3095-3102.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bruss V., Lu X., Thomssen R., Gerlich W. H. Post-translational alterations in transmembrane topology of the hepatitis B virus large envelope protein. EMBO J. 1994 May 15;13(10):2273–2279. doi: 10.1002/j.1460-2075.1994.tb06509.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bruss V., Thomssen R. Mapping a region of the large envelope protein required for hepatitis B virion maturation. J Virol. 1994 Mar;68(3):1643–1650. doi: 10.1128/jvi.68.3.1643-1650.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Büscher M., Reiser W., Will H., Schaller H. Transcripts and the putative RNA pregenome of duck hepatitis B virus: implications for reverse transcription. Cell. 1985 Mar;40(3):717–724. doi: 10.1016/0092-8674(85)90220-x. [DOI] [PubMed] [Google Scholar]
- Cheung R. C., Robinson W. S., Marion P. L., Greenberg H. B. Epitope mapping of neutralizing monoclonal antibodies against duck hepatitis B virus. J Virol. 1989 Jun;63(6):2445–2451. doi: 10.1128/jvi.63.6.2445-2451.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Civitico G., Wang Y. Y., Luscombe C., Bishop N., Tachedjian G., Gust I., Locarnini S. Antiviral strategies in chronic hepatitis B virus infection: II. Inhibition of duck hepatitis B virus in vitro using conventional antiviral agents and supercoiled-DNA active compounds. J Med Virol. 1990 Jun;31(2):90–97. doi: 10.1002/jmv.1890310205. [DOI] [PubMed] [Google Scholar]
- Fernholz D., Galle P. R., Stemler M., Brunetto M., Bonino F., Will H. Infectious hepatitis B virus variant defective in pre-S2 protein expression in a chronic carrier. Virology. 1993 May;194(1):137–148. doi: 10.1006/viro.1993.1243. [DOI] [PubMed] [Google Scholar]
- Freiman J. S., Cossart Y. E. Natural duck hepatitis B virus infection in Australia. Aust J Exp Biol Med Sci. 1986 Oct;64(Pt 5):477–484. doi: 10.1038/icb.1986.51. [DOI] [PubMed] [Google Scholar]
- Heermann K. H., Goldmann U., Schwartz W., Seyffarth T., Baumgarten H., Gerlich W. H. Large surface proteins of hepatitis B virus containing the pre-s sequence. J Virol. 1984 Nov;52(2):396–402. doi: 10.1128/jvi.52.2.396-402.1984. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jilbert A. R., Freiman J. S., Gowans E. J., Holmes M., Cossart Y. E., Burrell C. J. Duck hepatitis B virus DNA in liver, spleen, and pancreas: analysis by in situ and Southern blot hybridization. Virology. 1987 Jun;158(2):330–338. doi: 10.1016/0042-6822(87)90205-4. [DOI] [PubMed] [Google Scholar]
- Kann M., Thomssen R., Köchel H. G., Gerlich W. H. Characterization of the endogenous protein kinase activity of the hepatitis B virus. Arch Virol Suppl. 1993;8:53–62. doi: 10.1007/978-3-7091-9312-9_6. [DOI] [PubMed] [Google Scholar]
- Macrae D. R., Bruss V., Ganem D. Myristylation of a duck hepatitis B virus envelope protein is essential for infectivity but not for virus assembly. Virology. 1991 Mar;181(1):359–363. doi: 10.1016/0042-6822(91)90503-4. [DOI] [PubMed] [Google Scholar]
- Mandart E., Kay A., Galibert F. Nucleotide sequence of a cloned duck hepatitis B virus genome: comparison with woodchuck and human hepatitis B virus sequences. J Virol. 1984 Mar;49(3):782–792. doi: 10.1128/jvi.49.3.782-792.1984. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ostapchuk P., Hearing P., Ganem D. A dramatic shift in the transmembrane topology of a viral envelope glycoprotein accompanies hepatitis B viral morphogenesis. EMBO J. 1994 Mar 1;13(5):1048–1057. doi: 10.1002/j.1460-2075.1994.tb06353.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Persing D. H., Varmus H. E., Ganem D. The preS1 protein of hepatitis B virus is acylated at its amino terminus with myristic acid. J Virol. 1987 May;61(5):1672–1677. doi: 10.1128/jvi.61.5.1672-1677.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pugh J. C., Sninsky J. J., Summers J. W., Schaeffer E. Characterization of a pre-S polypeptide on the surfaces of infectious avian hepadnavirus particles. J Virol. 1987 May;61(5):1384–1390. doi: 10.1128/jvi.61.5.1384-1390.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pugh J., Zweidler A., Summers J. Characterization of the major duck hepatitis B virus core particle protein. J Virol. 1989 Mar;63(3):1371–1376. doi: 10.1128/jvi.63.3.1371-1376.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Roossinck M. J., Siddiqui A. In vivo phosphorylation and protein analysis of hepatitis B virus core antigen. J Virol. 1987 Apr;61(4):955–961. doi: 10.1128/jvi.61.4.955-961.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schlicht H. J., Bartenschlager R., Schaller H. The duck hepatitis B virus core protein contains a highly phosphorylated C terminus that is essential for replication but not for RNA packaging. J Virol. 1989 Jul;63(7):2995–3000. doi: 10.1128/jvi.63.7.2995-3000.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schlicht H. J., Kuhn C., Guhr B., Mattaliano R. J., Schaller H. Biochemical and immunological characterization of the duck hepatitis B virus envelope proteins. J Virol. 1987 Jul;61(7):2280–2285. doi: 10.1128/jvi.61.7.2280-2285.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Summers J., Smith P. M., Huang M. J., Yu M. S. Morphogenetic and regulatory effects of mutations in the envelope proteins of an avian hepadnavirus. J Virol. 1991 Mar;65(3):1310–1317. doi: 10.1128/jvi.65.3.1310-1317.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tuttleman J. S., Pugh J. C., Summers J. W. In vitro experimental infection of primary duck hepatocyte cultures with duck hepatitis B virus. J Virol. 1986 Apr;58(1):17–25. doi: 10.1128/jvi.58.1.17-25.1986. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Yokosuka O., Omata M., Ito Y. Expression of pre-S1, pre-S2, and C proteins in duck hepatitis B virus infection. Virology. 1988 Nov;167(1):82–86. doi: 10.1016/0042-6822(88)90056-6. [DOI] [PubMed] [Google Scholar]
- Yu M., Summers J. Multiple functions of capsid protein phosphorylation in duck hepatitis B virus replication. J Virol. 1994 Jul;68(7):4341–4348. doi: 10.1128/jvi.68.7.4341-4348.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Yu M., Summers J. Phosphorylation of the duck hepatitis B virus capsid protein associated with conformational changes in the C terminus. J Virol. 1994 May;68(5):2965–2969. doi: 10.1128/jvi.68.5.2965-2969.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]