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A structural model for maturation of the hepatitis B virus core
Alan M Roseman1, John A Berriman, Samantha A Wynne
1MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, United Kingdom.
Summary
Hepatitis B virus (HBV) core structure changes during maturation from RNA-containing to DNA-containing forms. These structural shifts, observed via cryomicroscopy, may control HBV envelopment and infectivity.
Area of Science:
- Virology
- Structural Biology
- Molecular Biology
Background:
- Hepatitis B virus (HBV) is a major human pathogen replicating via reverse transcription.
- HBV virions comprise an inner core (nucleocapsid) within a lipid envelope containing surface proteins.
Purpose of the Study:
- To compare the structures of RNA-containing and mature DNA-containing HBV core particles.
- To investigate potential structural changes signaling HBV maturation and controlling envelopment.
Main Methods:
- Electron cryomicroscopy was used to determine the structures of bacterially expressed RNA-containing core particles and mature DNA-containing core particles from virions.
- Structural comparisons focused on differences between the two core particle types.
Main Results:
- Both RNA- and DNA-containing cores adopt a T=4 icosahedral arrangement with 240 subunits.
- Significant structural differences were identified between RNA- and DNA-containing cores, including alterations in a hydrophobic pocket.
- Mutations in this pocket correlate with abnormal HBV secretion.
Conclusions:
- Structural changes in the HBV core particle accompany maturation from RNA- to DNA-containing states.
- These structural alterations, particularly in the hydrophobic pocket, likely play a role in regulating HBV envelopment.
- A mechanism for triggering these changes, linked to viral DNA synthesis, is proposed.