Beck J, Nassal M
Department of Internal Medicine II/Molecular Biology, University Hospital Freiburg, D-79106 Freiburg, Germany.
Mol Cell Biol. 1998 Nov;18(11):6265-72. doi: 10.1128/MCB.18.11.6265.
The DNA genome of a hepatitis B virus is generated by reverse transcription of the RNA pregenome. Replication initiation does not involve a nucleic acid primer; instead, the hepadnavirus P protein binds to the structured RNA encapsidation signal epsilon, from which it copies a short DNA primer that becomes covalently linked to the enzyme. Using in vitro-translated duck hepatitis B virus (DHBV) P protein, we probed the secondary structure of the protein-bound DHBV epsilon RNA (Depsilon) and observed a marked conformational change compared to free Depsilon RNA. Several initiation-competent mutant RNAs with a different free-state structure were similarly altered, whereas a binding-competent but initiation-deficient variant was not, indicating the importance of the rearrangement for replication initiation and suggesting a mechanistic coupling to encapsidation.
乙型肝炎病毒的DNA基因组是通过RNA前基因组的逆转录产生的。复制起始不涉及核酸引物；相反，嗜肝DNA病毒P蛋白与结构化的RNA包装信号ε结合，从中复制出一段短的DNA引物，该引物与酶共价连接。我们使用体外翻译的鸭乙型肝炎病毒（DHBV）P蛋白，探测了与蛋白结合的DHBV ε RNA（Dε）的二级结构，发现与游离的Dε RNA相比，其构象发生了显著变化。几个具有不同自由状态结构的起始 competent 突变RNA也有类似的改变，而一个具有结合能力但起始缺陷的变体则没有，这表明这种重排对复制起始很重要，并暗示了与包装的机制耦合。 （注：“initiation-competent”可译为“具有起始能力的”，这里为保留原文表述未完全意译；“binding-competent”同理可译为“具有结合能力的” ）
