Article

Fidelity of hepatitis���B virus polymerase

School of Biological Science, Seoul National University, Seoul, Korea.
European Journal of Biochemistry (Impact Factor: 3.58). 07/2003; 270(14):2929-36. DOI: 10.1046/j.1432-1033.2003.03650.x
Source: PubMed

ABSTRACT Although efficient vaccines are available, chronic hepatitis B (HBV) infection poses a major health problem worldwide, and prolonged treatment of chronically infected HBV patients with nucleoside analogs often results in drug-resistant HBV variants. Therefore, it is critical to evaluate the contribution of the HBV polymerase to mutations. FLAG-tagged wild-type (FPolE) and mutant (FPolE/D551A) HBV polymerases have been expressed in insect cells and purified. The purified FPolE showed DNA polymerase activity, but FPolE/D551A did not, implying that the activity was derived from FPolE. No 3'-->5'exonuclease activity was detected in FPolE. The fidelity of FPolE was investigated and compared with that of HIV-1 RT, which is highly error-prone. The fidelity of HBV polymerase seems to be achieved by increasing the Km for the dNTP being misinserted. The nucleotide misinsertion efficiency of FPolE and HIV-1 RT ranged from 3.59 x 10-4 (C : T) to 1.51 x 10-3 (G : T) and from 1.75 x 10-4 (C : T) to 1.62 x 10-3 (G : T), respectively, and the overall misinsertion efficiency of HIV-1 RT was just 1.04-fold higher than that of FPolE, implying that HBV polymerase is fairly error-prone. Though HBV genetic mutation rate in replication is thought to be between those in RNA and DNA viruses, our data shows that the rate of mutation by HBV polymerase is higher than the rate of genetic mutation in vivo. This may be a result from more overlapping HBV genes in the HBV genome than that of other retroviruses.

Download full-text

Full-text

Available from: Younhee Kim, Sep 05, 2015
0 Followers
 · 
141 Views
 · 
59 Downloads
  • Source
    • "The hepatitis B virus (HBV) particle contains a partially double stranded DNA genome of about 3200 base pairs [1], [2] with four partially overlapping reading frames encoding the C, S and X proteins and the error-prone viral reverse transcriptase or polymerase [3], [4]. Besides human HBV, the subfamily of Orthohepadnaviridae includes similar virus strains isolated from gorilla, orangutan, chimpanzee, gibbon, woolly monkey, chuck and squirrel species. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Orthohepadnavirus (mammalian hosts) and avihepadnavirus (avian hosts) constitute the family of Hepadnaviridae and differ by their capability and inability for expression of protein X, respectively. Origin and functions of X are unclear. The evolutionary analysis at issue of X indicates that present strains of orthohepadnavirus started to diverge about 25,000 years ago, simultaneously with the onset of avihepadnavirus diversification. These evolutionary events were preceded by a much longer period during which orthohepadnavirus developed a functional protein X while avihepadnavirus evolved without X. An in silico generated 3D-model of orthohepadnaviral X protein displayed considerable similarity to the tertiary structure of DNA glycosylases (key enzymes of base excision DNA repair pathways). Similarity is confined to the central domain of MUG proteins with the typical DNA-binding facilities but without the capability of DNA glycosylase enzymatic activity. The hypothetical translation product of a vestigial X reading frame in the genome of duck hepadnavirus could also been folded into a DNA glycosylase-like 3D-structure. In conclusion, the most recent common ancestor of ortho- and avihepadnavirus carried an X sequence with orthology to the central domain of DNA glycosylase.
    PLoS ONE 08/2011; 6(8):e23392. DOI:10.1371/journal.pone.0023392 · 3.23 Impact Factor
  • Source
    • "The hepatitis B virus (HBV) envelope contains a capsid with a partially double stranded DNA genome of about 3200 base pairs (Summers et al., 1975; Delius et al., 1983). Mutations are introduced during nucleotide polymerization by the error-prone viral reverse transcriptase or polymerase (Park et al., 2003). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Surface protein and polymerase of hepatitis B virus provide a striking example of gene overlap. Inclusion of more coding constraints in the phylogenetic analysis forces the tree toward accepted topology. Three-dimensional protein modeling demonstrates that participation in local protein function underlies the observed mosaic patterns of amino acid conservation and variability. Conserved amino acid residues of polymerase were typically clustered at the catalytic core marked by the YMDD motif. The proposed tertiary structure of surface protein displayed the expected transmembrane helices in a 2-domain constellation. Conserved amino acids like, for instance, cysteine residues are involved in the spatial orientation of the two domains, the exposed location of the a-determinant and the dimer formation of surface protein. By means of computational alanine replacement scanning, we demonstrated that the interfaces between domains in monomeric surface protein, between the monomers in dimeric surface protein and in a capsid-surface protein complex mainly consist of relatively well-conserved amino acid residues.
    Virology 02/2008; 370(2):362-72. DOI:10.1016/j.virol.2007.08.036 · 3.28 Impact Factor
  • Source
Show more