Important role of the tetraloop region of 4.5S RNA in SRP binding to its receptor FtsY
Important role of the tetraloop region of 4.5S RNA in SRP binding to its receptor FtsY
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DOI：
10.1017/s1355838201002205
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发表时间：
2001-02-01
期刊：
影响因子：
4.5
通讯作者：
Wintermeyer, W
中科院分区：
文献类型：
--
作者：
Jagath, JR;Matassova, NB;Wintermeyer, W
大肠杆菌信号识别颗粒 (SRP) 与其受体 FtsY 的结合需要 4.5S RNA 的存在，但单独的 FtsY 不与 4.5S RNA 相互作用。在这项研究中，我们报告说，根据凝胶阻滞和膜靶向实验确定，将 4.5S RNA 结构域 IV 中的 GGAA 四环序列替换为 UUCG 消除了 SRP-FtsY 相互作用，而用其他 GNRA 型四环序列替换则没有效果。四环序列中的许多其他碱基交换具有较小或中等的抑制作用。邻近四环的茎中的碱基对破坏或用 G-C 替换闭合的 C-G 碱基对部分恢复了原本失活的 UUCG 突变体的功能。通过羟基自由基裂解 4.5S RNA 变体进行的化学探测表明，在四环序列中用 UUCG 替换 GGAA 会导致四环内和相邻茎中的结构变化；这些结果表明，SRP-FtsY 相互作用受到 SRP RNA 四环区域结构（特别是四环茎）的强烈影响，并表明 SRP RNA 和 Ffh 经历相互结构适应，形成在与受体 FtsY 相互作用中发挥功能的 SRP。
Binding of Escherichia coli signal recognition particle (SRP) to its receptor, FtsY, requires the presence of 4.5S RNA, although FtsY alone does not interact with 4.5S RNA. In this study, we report that the exchange of the GGAA tetraloop sequence in domain IV of 4.5S RNA for UUCG abolishes SRP-FtsY interaction, as determined by gel retardation and membrane targeting experiments, whereas replacements with other GNRA-type tetraloops have no effect. A number of other base exchanges in the tetraloop sequence have minor or intermediate inhibitory effects. Base pair disruptions in the stem adjacent to the tetraloop or replacement of the closing C-G base pair with G-C partially restored function of the otherwise inactive UUCG mutant. Chemical probing by hydroxyl radical cleavage of 4.5S RNA variants show that replacing GGAA with UUCG in the tetraloop sequence leads to structural changes both within the tetraloop and in the adjacent stem; the latter change is reversed upon reverting the C-G closing base pair to G-C, These results show that the SRP-FtsY interaction is strongly influenced by the structure of the tetraloop region of SRP RNA, in particular the tetraloop stem, and suggest that both SRP RNA and Ffh undergo mutual structural adaptation to form SRP that is functional in the interaction with the receptor, FtsY.