title: A conserved arginine residue in the terminal protein domain of hepatitis B virus polymerase is critical for RNA pre-genome encapsidation.
abstract: Hepadnaviruses, including human hepatitis B virus (HBV) and duck hepatitis B virus (DHBV), replicate their DNA genome through reverse transcription. Although hepadnaviral polymerase (Pol) is distantly related to retroviral reverse transcriptases, some of its features are distinct. In particular, in addition to the reverse transcriptase and RNase H domains, which are commonly encoded by retroviral reverse transcriptases, the N-terminally extended terminal protein (TP) domain confers unique features such as protein-priming capability. Importantly, the TP domain is also essential for encapsidation of the viral RNA pre-genome. To gain further insight into the TP domain, this study used clustered charged residue-to-alanine mutagenesis of HBV Pol. Of the 20 charged residues examined, only one arginine (R105) was critical for RNA encapsidation. This result contrasts with previous findings for DHBV Pol regarding the critical residue of the TP domain required for RNA binding. Firstly, R128 of DHBV Pol, which corresponds to R105 of HBV Pol, was reportedly tolerable to alanine substitution for RNA binding. Secondly, the C-terminal arginine residue of the DHBV Pol TP domain (R183) was shown to be critical for RNA binding, whereas alanine substitution of the corresponding arginine residue of the HBV Pol TP domain (R160) remained able to support RNA encapsidation. Together, these data highlight the divergence between avian and mammalian hepadnaviral Pols with respect to an arginine residue critical for RNA encapsidation.
authors.affiliation: Department of Biochemistry, Yonsei University, 262 Seongsanno, Seodaemungu, Seoul 120-749, Republic of Korea.
authors.forename: Youn-Chul
authors.initials: YC
authors.lastname: Shin
authors.affiliation: Department of Biochemistry, Yonsei University, 262 Seongsanno, Seodaemungu, Seoul 120-749, Republic of Korea.
authors.forename: Sunju
authors.initials: S
authors.lastname: Park
authors.affiliation: Department of Biochemistry, Yonsei University, 262 Seongsanno, Seodaemungu, Seoul 120-749, Republic of Korea.
authors.forename: Wang-Shick
authors.initials: WS
authors.lastname: Ryu
mesh_terms: D000595:Amino Acid Sequence; D001120:Arginine / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D017124:Conserved Sequence; D016679:Genome, Viral; D056945:Hep G2 Cells; D006515:Hepatitis B virus / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D006801:Humans; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D012367:RNA, Viral / Q000235:genetics* / Q000378:metabolism; D012194:RNA-Directed DNA Polymerase / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D019065:Virus Assembly
chemical_list: D012367:RNA, Viral; D014764:Viral Proteins; D001120:Arginine; D012194:RNA-Directed DNA Polymerase