Abstract
The morphogenesis of Hepatitis B Virus (HBV) viral particles is nucleated by the oligomerization of HBc protein molecules, resulting in the formation of an icosahedral capsid shell containing the replication-competent nucleoprotein complex made of the viral polymerase and the pre-genomic RNA (pgRNA). HBc is a phospho-protein containing two distinct domains acting together throughout the viral replication cycle. The N-terminal domain, (residues 1–140), shown to self-assemble, is linked by a short flexible domain to the basic C-terminal domain (residues 150–183) that interacts with nucleic acids (NAs). In addition, the C-terminal domain contains a series of phospho-acceptor residues that undergo partial phosphorylation and de-phosphorylation during virus replication. This highly dynamic process governs the homeostatic charge that is essential for capsid stability, pgRNA packaging and to expose the C-terminal domain at the surface of the particles for cell trafficking. In this review, we discuss the roles of the N-terminal and C-terminal domains of HBc protein during HBV morphogenesis, focusing on how the C-terminal domain phosphorylation dynamics regulate its interaction with nucleic acids throughout the assembly and maturation of HBV particles.
Highlights
A potent HBV (Hepatitis B Virus) vaccine is available, about 300 million people experienceHBV infection, causing ~900,000 annual deaths due to liver-associated diseases, such as cirrhosis and hepatocellular carcinoma [1]
UP-HBV core protein (HBc) capsids purified from E. coli are un-phosphorylated due to the absence of cognate kinases and being full of E. coli RNAs [42,45,49], while P-HBc capsids from insect and mammalian cells are empty of RNAs if they are incompetent for pre-genomic RNA (pgRNA) packaging [15]
Y63F mutant DNA polymerase and containing only pgRNA, were mainly hypo-phosphorylated [62]. These results suggest that, during the pre-assembly process, phosphorylation most probably causes a decrease in the affinity of capsids for cellular RNAs, and once assembly is kickstarted by the formation of the pgRNA–Pol complex, de-phosphorylation occurs in order to increase the
Summary
A potent HBV (Hepatitis B Virus) vaccine is available, about 300 million people experience. A series of residues mapping in the groove between the spikes andspikes at the contains 20 facets (triangle) with the threefold axes going through the center of the opposite face, base of the spike was shown to be essential for the core to interact with L during the envelopment of the twelve fivefold axes (pentagon) going through the opposed vertices and fifteen twofold axes (oval) capsid [36,38]. C–D HBc dimers viral cycle and, is the target of an intense research for compounds endowing antiviral oriented to form the T = 4 capsid These structures were obtained from the PDB, file 1QGT, and colored activity reviews,. HBc–NTD is essential at several stages of the viral cycle and, is the target of an intense research for compounds endowing antiviral activity (for reviews, [19,20])
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