Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.26.4 (RNase H)
 2,751 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human Hepatitis B Virus (HBV) replication is accomplished by its own polymerase. The HBV RNase H domain of HBV polymerase has been expressed in Escherichia coli and purified by affinity column chromatography. The MBP-RNase H fusion protein (43 kDa MBP plus 17 kDa HBV RNase H domain) was proved to be RNase H by in vitro activity assay, inhibitor studies, and mutagenesis. The HBV RNase H domain represented the optimal RNase H activity in the presence of either 8 mM MgCl2 or 16 mM MnCl2. In Tris-Cl buffer, the optimum pH for MBP-RNase H fusion protein is between 7.7 and 8.2. The MBP-RNase H fusion protein required 40 mM monovalent cation for its enzyme activity, whereas it showed lower activity at a salt concentration of more than 100 mM. Ribonucleoside Vanadyl complex (RAV) and 2'-deoxyadenosine 5'-monophosphate (dAMP) inhibited the RNase H activity. Moreover, the mutation of highly conserved amino acids in the HBV RNase H domain diminished the RNase H activity. These results clearly suggest that the RNase H activity is separable from viral HBV polymerase enzymatic activities.
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PMID:RNase H activity of human hepatitis B virus polymerase expressed in Escherichia coli. 914 47

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.
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PMID:Hepatitis B virus: DNA polymerase activity of deletion mutants. 1020 76