title: Structural organization of pregenomic RNA and the carboxy-terminal domain of the capsid protein of hepatitis B virus.
abstract: The Hepatitis B Virus (HBV) double-stranded DNA genome is reverse transcribed from its RNA pregenome (pgRNA) within the virus core (or capsid). Phosphorylation of the arginine-rich carboxy-terminal domain (CTD) of the HBV capsid protein (Cp183) is essential for pgRNA encapsidation and reverse transcription. However, the structure of the CTD remains poorly defined. Here we report sub-nanometer resolution cryo-EM structures of in vitro assembled empty and pgRNA-filled Cp183 capsids in unphosphorylated and phosphorylation-mimic states. In empty capsids, we found unexpected evidence of surface accessible CTD density partially occluding pores in the capsid surface. We also observed that CTD organization changed substantively as a function of phosphorylation. In RNA-filled capsids, unphosphorylated CTDs favored thick ropes of RNA, while the phosphorylation-mimic favored a mesh of thin, high-density strands suggestive of single stranded RNA. These results demonstrate that the CTD can regulate nucleic acid structure, supporting the hypothesis that the HBV capsid has a functional role as a nucleic acid chaperone.
authors.affiliation: Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana, USA.
authors.forename: Joseph C-Y
authors.initials: JC
authors.lastname: Wang
authors.forename: Mary S
authors.initials: MS
authors.lastname: Dhason
authors.forename: Adam
authors.initials: A
authors.lastname: Zlotnick
mesh_terms: D002213:Capsid / Q000378:metabolism / Q000648:ultrastructure*; D036022:Capsid Proteins / Q000737:chemistry* / Q000378:metabolism*; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism; D016679:Genome, Viral; D006515:Hepatitis B virus / Q000737:chemistry* / Q000235:genetics* / Q000648:ultrastructure; D018832:Molecular Chaperones; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism*; D019065:Virus Assembly
chemical_list: D036022:Capsid Proteins; D004279:DNA, Viral; D018832:Molecular Chaperones; D012367:RNA, Viral