Hepatitis B virus: DNA polymerase activity of deletion mutants

• Published in: Biochemistry and molecular biology international 1999-02, Vol.47 (2), p.301-308
• Main Authors: Kim, Younhee, Hong, Young Bin, Jung, Guhung
• Format: Article
• Language: English
• Subjects: ATP-Binding Cassette Transporters; Carrier Proteins - genetics; DNA polymerase activity; DNA-Directed DNA Polymerase - genetics; domain; Electrophoresis, Polyacrylamide Gel; Escherichia coli Proteins; Hepatitis B Virus; Hepatitis B virus - enzymology; Hepatitis B virus - genetics; Maltose-Binding Proteins; Monosaccharide Transport Proteins; Mutation; mutational analysis; Recombinant Fusion Proteins - genetics; Ribonuclease H - genetics; Sequence Deletion; Viral Proteins - genetics
• ISSN: 1521-6543; 1039-9712; 1521-6551
• DOI: 10.1080/15216549900201323

The hepadnavirus P gene product is a multifunctional protein with priming, DNA‐and RNA‐dependent DNA polymerase, and RNase H activities. Nested N‐ or C‐terminal deletion mutations and deletions of domain(s) in human HBV polymerase have been made. Wild‐type and deletion forms of MBP‐fused HBV polymerase were expressed in E. coli, purified by amylose column chromatography, and the DNA‐dependent DNA polymerase activities of the purified proteins were compared. Deletion of the terminal protein or spacer regions reduced enzyme activity to 70%, respectively. However, deletion of the RNase H domain affected polymerase activity more than that of the terminal protein or spacer region. The polymerase domain alone or the N‐terminal deletion of the polymerase domain still exhibited enzymatic activity. In this report, it is demonstrated that the minimal domain for the polymerizing activity of the HBV polymerase is smaller than the polymerase domain.