Trigger factor binds to ribosome-signal-recognition particle (SRP) complexes and is excluded by binding of the SRP receptor
Trigger factor binds to ribosome-signal-recognition particle (SRP) complexes and is excluded by binding of the SRP receptor
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DOI：
10.1073/pnas.0402231101
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发表时间：
2004-05-25
影响因子：
11.1
通讯作者：
Wintermeyer, W
中科院分区：
文献类型：
--
作者：
Buskiewicz, I;Deuerling, E;Wintermeyer, W
触发因子（TF）和信号识别颗粒（SRP）结合到细菌核糖体上，并在肽出口处与蛋白质L23交联，在那里它们与新生的肽链相互作用。目前还不清楚TF和SRP是否从它们的核糖体结合位点相互排斥。在这里，我们表明，SRP和TF可以同时结合到核糖体或核糖体新生链复合物暴露的SRP特异性信号序列。基于交联模式的变化和使用荧光标记的SRP通过荧光测量获得的结果，TF结合诱导核糖体-SRP复合物的结构变化。此外，我们表明，结合的SRP受体，FtsY，核糖体结合SRP排除TF从核糖体。这些结果表明，TF和SRP样本新生的核糖体上的链在一个非排他性的方式。暴露信号序列的核糖体新生链复合物进入SIRP依赖性膜靶向的决定似乎是由SRP的结合决定的，SRP的结合通过信号序列识别来稳定，并且由于SRP受体与核糖体结合的SRP的结合而通过TF的排除来促进。
Trigger factor (TF) and signal recognition particle (SRP) bind to the bacterial ribosome and are both crosslinked to protein L23 at the peptide exit, where they interact with emerging nascent peptide chains. It is unclear whether TF and SRP exclude one another from their ribosomal binding site(s). Here we show that SRP and TF can bind simultaneously to ribosomes or ribosome nascent-chain complexes exposing a SRP-specific signal sequence. Based on changes of the crosslinking pattern and on results obtained by fluorescence measurements using fluorescence-labeled SRP, TF binding induces structural changes in the ribosome-SRP complex. Furthermore, we show that binding of the SRP receptor, FtsY, to ribosome-bound SRP excludes TF from the ribosome. These results suggest that TF and SRP sample nascent chains on the ribosome in a nonexclusive fashion. The decision for ribosome nascent-chain complexes exposing a signal sequence to enter SIRP-dependent membrane targeting seems to be determined by the binding of SRP, which is stabilized by signal sequence recognition, and promoted by the exclusion of TF due to the binding of the SRP receptor to ribosome-bound SRP.