Abstract
Our studies on the assembly of hepatitis B virus capsids or core particles in Xenopus oocytes have demonstrated that unassembled p21.5 core proteins ("free p21.5") provide a pool of low-molecular-mass precursors for core-particle assembly. Here we have characterized this material. Free p21.5 sedimented through gradients of 3-25% sucrose (wt/vol) as a single protein species of approximately 40 kDa, corresponding to a p21.5 dimer. On nonreducing SDS/polyacrylamide gels, free p21.5 migrated as disulfide-linked p21.5 dimeric species of 35 and 37 kDa. Truncated core proteins lacking most or all of the 36-amino acid protamine region at the p21.5 carboxyl terminus were also found to behave as disulfide-linked dimers with appropriately reduced molecular masses. Our experiments failed to reveal monomeric core proteins or stable intermediates between dimers and capsids along the assembly pathway. We conclude that hepatitis B virus core particles are most likely assembled by aggregating 90 (or possibly 180) disulfide-linked p21.5 dimers. We discuss similarities between the assembly of hepatitis B virus capsids and simple T = 3 plant virus and bacteriophage structures.
Full text
PDF




Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Beckett D., Uhlenbeck O. C. Ribonucleoprotein complexes of R17 coat protein and a translational operator analog. J Mol Biol. 1988 Dec 20;204(4):927–938. doi: 10.1016/0022-2836(88)90052-6. [DOI] [PubMed] [Google Scholar]
- Birnbaum F., Nassal M. Hepatitis B virus nucleocapsid assembly: primary structure requirements in the core protein. J Virol. 1990 Jul;64(7):3319–3330. doi: 10.1128/jvi.64.7.3319-3330.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gallina A., Bonelli F., Zentilin L., Rindi G., Muttini M., Milanesi G. A recombinant hepatitis B core antigen polypeptide with the protamine-like domain deleted self-assembles into capsid particles but fails to bind nucleic acids. J Virol. 1989 Nov;63(11):4645–4652. doi: 10.1128/jvi.63.11.4645-4652.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jeng K. S., Hu C. P., Chang C. M. Differential formation of disulfide linkages in the core antigen of extracellular and intracellular hepatitis B virus core particles. J Virol. 1991 Jul;65(7):3924–3927. doi: 10.1128/jvi.65.7.3924-3927.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Onodera S., Ohori H., Yamaki M., Ishida N. Electron microscopy of human hepatitis B virus cores by negative staining-carbon film technique. J Med Virol. 1982;10(2):147–155. doi: 10.1002/jmv.1890100209. [DOI] [PubMed] [Google Scholar]
- Petit M. A., Pillot J. HBc and HBe antigenicity and DNA-binding activity of major core protein P22 in hepatitis B virus core particles isolated from the cytoplasm of human liver cells. J Virol. 1985 Feb;53(2):543–551. doi: 10.1128/jvi.53.2.543-551.1985. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rossmann M. G., Johnson J. E. Icosahedral RNA virus structure. Annu Rev Biochem. 1989;58:533–573. doi: 10.1146/annurev.bi.58.070189.002533. [DOI] [PubMed] [Google Scholar]
- Salunke D. M., Caspar D. L., Garcea R. L. Self-assembly of purified polyomavirus capsid protein VP1. Cell. 1986 Sep 12;46(6):895–904. doi: 10.1016/0092-8674(86)90071-1. [DOI] [PubMed] [Google Scholar]
- Standring D. N., Ou J. H., Masiarz F. R., Rutter W. J. A signal peptide encoded within the precore region of hepatitis B virus directs the secretion of a heterogeneous population of e antigens in Xenopus oocytes. Proc Natl Acad Sci U S A. 1988 Nov;85(22):8405–8409. doi: 10.1073/pnas.85.22.8405. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Standring D. N., Ou J. H., Rutter W. J. Assembly of viral particles in Xenopus oocytes: pre-surface-antigens regulate secretion of the hepatitis B viral surface envelope particle. Proc Natl Acad Sci U S A. 1986 Dec;83(24):9338–9342. doi: 10.1073/pnas.83.24.9338. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Takahashi K., Akahane Y., Gotanda T., Mishiro T., Imai M., Miyakawa Y., Mayumi M. Demonstration of hepatitis B e antigen in the core of Dane particles. J Immunol. 1979 Jan;122(1):275–279. [PubMed] [Google Scholar]
- Zhou S. L., Standring D. N. Production of hepatitis B virus nucleocapsidlike core particles in Xenopus oocytes: assembly occurs mainly in the cytoplasm and does not require the nucleus. J Virol. 1991 Oct;65(10):5457–5464. doi: 10.1128/jvi.65.10.5457-5464.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zhou S., Standring D. N. Cys residues of the hepatitis B virus capsid protein are not essential for the assembly of viral core particles but can influence their stability. J Virol. 1992 Sep;66(9):5393–5398. doi: 10.1128/jvi.66.9.5393-5398.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zhou S., Yang S. Q., Standring D. N. Characterization of hepatitis B virus capsid particle assembly in Xenopus oocytes. J Virol. 1992 May;66(5):3086–3092. doi: 10.1128/jvi.66.5.3086-3092.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]