Domain rearrangement of SRP protein Ffh upon binding 4.5S RNA and the SRP receptor FtsY
Domain rearrangement of SRP protein Ffh upon binding 4.5S RNA and the SRP receptor FtsY
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DOI：
10.1261/rna.7242305
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发表时间：
2005-06-01
期刊：
影响因子：
4.5
通讯作者：
Wintermeyer, W
中科院分区：
文献类型：
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作者：
Buskiewicz, I;Kubarenko, A;Wintermeyer, W
信号识别颗粒（SRP）介导展示信号锚定序列的翻译核糖体的膜靶向。在大肠杆菌中，SRP由4.5S RNA和蛋白质Ffh组成，Ffh识别从核糖体出现的信号肽和膜上的SRP受体FtsY。在目前的工作中，我们研究了NG和M结构域之间的相互作用在Ffh和它们的重排后，与4.5S RNA和/或FtsY形成复合物。在游离Ffh中，NG和M结构域以允许G结构域中的位置231和M结构域中的位置377之间交联的取向彼此面对。两个结构域之间存在结合相互作用，因为分离的结构域形成强复合物。当Ffh与4.5S RNA结合时，结构域间的接触被破坏，消耗了4.5S RNA-Ffh结合的总结合能的一部分，该结合能大致相当于结构域彼此结合的自由能。在SRP颗粒中，NG结构域在与M结构域的结合位点相邻的区域中与4.5S RNA结合。Ffh与FtsY的结合也需要NG和M结构域的重定向。这些结果表明，在游离的Ffh，4.5S RNA和FtsY的结合位点被封闭的强烈的结构域-结构域的相互作用，必须被破坏的SRP或Ffh-FtsY复合物的形成。
The signal recognition particle (SRP) mediates membrane targeting of translating ribosomes displaying a signal-anchor sequence. in Escherichia coli, SRP consists of 4.5S RNA and a protein, Ffh, that recognizes the signal peptide emerging from the ribosome and the SRP receptor at the membrane, FtsY. In the present work, we studied the interactions between the NG and M domains in Ffh and their rearrangements upon complex formation with 4.5S RNA and/or FtsY. In free Ffh, the NG and M domains are facing one another in an orientation that allows cross-linking between positions 231 in the G domain and 377 in the M domain. There are binding interactions between the two domains, as the isolated domains form a strong complex. The interdomain contacts are disrupted upon binding of Ffh to 4.5S RNA, consuming a part of the total binding energy of 4.5S RNA-Ffh association that is roughly equivalent to the free energy of domain binding to each other. In the SRP particle, the NG domain binds to 4.5S RNA in a region adjacent to the binding site of the M domain. Ffh binding to FtsY also requires a reorientation of NG and M domains. These results suggest that in free Ffh, the binding sites for 4.5S RNA and FtsY are occluded by strong domain-domain interactions which must be disrupted for the formation of SRP or the Ffh-FtsY complex.