title: Encapsidated hepatitis B virus reverse transcriptase is poised on an ordered RNA lattice.
abstract: Assembly of a hepatitis B virus (HBV) virion begins with the formation of an RNA-filled core composed of a symmetrical capsid (built of core protein), viral pregenomic RNA, and viral reverse transcriptase. To generate the circular dsDNA genome of HBV, reverse transcription requires multiple template switches within the confines of the capsid. To date, most anti-HBV therapeutics target this reverse transcription process. The detailed molecular mechanisms of this crucial process are poorly understood because of the lack of structural information. We hypothesized that capsid, RNA, and viral reverse transcriptase would need a precise geometric organization to accomplish reverse transcription. Here we present the asymmetric structure of authentic RNA-filled cores, determined to 14.5-Å resolution from cryo-EM data. Capsid and RNA are concentric. On the interior of the RNA, we see a distinct donut-like density, assigned to viral reverse transcriptase, which pins the viral pregenomic RNA to the capsid inner surface. The observation of a unique ordered structure inside the core suggests that assembly and the first steps of reverse transcription follow a single, determinate pathway and strongly suggests that all subsequent steps in DNA synthesis do as well.
authors.affiliation: Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405; and.
authors.forename: Joseph Che-Yen
authors.initials: JC
authors.lastname: Wang
authors.affiliation: Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405; and.
authors.forename: David G
authors.initials: DG
authors.lastname: Nickens
authors.affiliation: McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706.
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Lentz
authors.affiliation: McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706.
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Loeb
authors.affiliation: Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405; and azlotnic@indiana.edu.
authors.forename: Adam
authors.initials: A
authors.lastname: Zlotnick
mesh_terms: D002213:Capsid / Q000378:metabolism* / Q000648:ultrastructure; D045744:Cell Line, Tumor; D006515:Hepatitis B virus / Q000201:enzymology* / Q000235:genetics / Q000648:ultrastructure; D006801:Humans; D007091:Image Processing, Computer-Assisted; D012367:RNA, Viral / Q000737:chemistry* / Q000235:genetics*; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism; D048348:Reverse Transcription / Q000235:genetics
chemical_list: D012367:RNA, Viral; D012194:RNA-Directed DNA Polymerase
keywords: HBV intermediate; asymmetric reconstruction