Localization of the Q beta replicase recognition site in MDV-1 RNA.
Localization of the Q beta replicase recognition site in MDV-1 RNA.
复制标题
MDV-1 RNA 中 Q β 复制酶识别位点的定位。
DOI：
10.1093/jb/93.3.669
复制
发表时间：
1983
影响因子：
2.7
通讯作者：
Kramer,FR
中科院分区：
文献类型：
--
作者：
Nishihara,T;Mills,DR;Kramer,FR
在 5• Œ 末端或 3• Œ 末端缺失核苷酸的 MDV-1 RNA 片段（Q 复制酶的一种天然存在的小模板）仍然能够与 Q 复制酶形成复合物。通过测定不同长度片段的结合能力，确定 QfÀ 复制酶的结合位点是由位于 MDV-1 RNA 中部附近的核苷酸序列决定的。 5• Œ 末端缺失核苷酸的片段能够作为合成互补链的模板，但 3• Œ 末端缺失核苷酸的片段没有活性，表明模板的 3• Œ 末端区域是 RNA 合成起始所必需的。 MDV-1(+) RNA 3• Œ 末端和中央结合区的核苷酸序列与 Q/(-) RNA 3• Œ 末端和内部区域的序列几乎相同。Q/3 复制酶是一种高度选择性的 RNA 指导的 RNA 聚合酶 (1)。它促进噬菌体 QfÀ 和密切相关的 III 族 RNA 噬菌体 (2) 基因组 RNA 的自催化合成，但它不能复制其他病毒 RNA，也不能复制任何大肠杆菌 RNA。韦斯曼和他的同事探索了这种模板特异性的基础。他们表明 Q (i 复制酶与 Q 的 4,220 核苷酸序列内的特定内部识别位点结合
Fragments of MDV-1 RNA (a small, naturally occurring template for QƒÀ replicase) that were missing nucleotides at either their 5• Œ end or their 3• Œ end were still able to form a complex with QƒÀ replicase. By assaying the binding ability of fragments of different length, it was established that the binding site for QƒÀ replicase is determined by nucleotide sequences that are located near the middle of MDV-1 RNA. Frag ments missing nucleotides at their 5• Œ end were able to serve as templates for the synthesis of complementary strands, but fragments missing nucleotides at their 3• Œ end were inactive, indicating that the 3• Œ-terminal region of the template is required for the initiation of RNA synthesis. The nucleotide sequences of both the 3• Œ termi nus and the central binding region of MDV-1(+) RNA are almost identical to sequences at the 3• Œ terminus and at an internal region of Q/(-) RNA.Q/3 replicase is a highly selective RNA-directed RNA polymerase(1). It promotes the autocata lytic synthesis of the genomic RNA of bacterio phage QƒÀ and the closely related group III RNA bacteriophages(2), but it cannot replicate other viral RNAs, nor any Escherichia coli RNA. Weissmann and his colleagues explored the basis of this template specificity. They showed that Q (i replicase binds to a specific internal recognition site within the 4,220-nucleotide sequence of Q