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Mutagenesis of a hepatitis B virus reverse transcriptase yields temperature-sensitive virus
C Seeger1, E H Leber, L K Wiens
1Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA. C Seeger@fccc.edu
Virology
|August 15, 1996
Summary
Hepadnavirus genome replication involves a pol protein with DNA polymerase and priming activities. Its amino-terminal (TP) domain is crucial for early viral DNA synthesis steps like protein priming.
Area of Science:
- Virology
- Molecular Biology
- Biochemistry
Background:
- Hepadnavirus genome replication relies on a unique pol protein, a multifunctional reverse transcriptase.
- This enzyme exhibits DNA polymerase, DNA priming, and strand transfer activities.
- A key feature is protein-primed RNA-directed DNA synthesis, differing from typical RNA priming.
Purpose of the Study:
- To investigate the structure-function relationship of the hepadnavirus pol protein.
- To elucidate the specific roles of the amino-terminal (TP) and reverse transcriptase (RT) domains.
- To identify key interactions in viral DNA synthesis and replication.
Main Methods:
- Analysis of 52 mutant pol proteins.
- In vitro assays for viral DNA replication.
- Studies in cultured cells to assess replication efficiency.
Main Results:
- The TP domain is essential for early viral DNA synthesis, including RNA packaging and protein priming.
- Both TP and RT domains are necessary for interaction with epsilon RNA, the priming template and packaging signal.
- A thermosensitive hepadnavirus variant was isolated for synchronized replication studies.
Conclusions:
- The TP domain plays a critical role in initiating hepadnavirus DNA replication.
- Coordinated function of TP and RT domains with epsilon RNA is vital for replication.
- The thermosensitive mutant offers a tool for detailed analysis of the viral replication cycle.