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Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1992 Nov 1;89(21):10046–10050. doi: 10.1073/pnas.89.21.10046

Hepatitis B virus capsid particles are assembled from core-protein dimer precursors.

S Zhou 1, D N Standring 1
PMCID: PMC50274  PMID: 1438193

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.

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Selected References

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