Allosteric vs. spontaneous exit-site (E-site) tRNA dissociation early in protein synthesis
Allosteric vs. spontaneous exit-site (E-site) tRNA dissociation early in protein synthesis
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DOI：
10.1073/pnas.1106999108
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发表时间：
2011-10-11
影响因子：
11.1
通讯作者：
Goldman, Yale E.
中科院分区：
文献类型：
--
作者：
Chen, Chunlai;Stevens, Benjamin;Goldman, Yale E.
在蛋白质合成期间，脱酰化的转移RNA在mRNA易位后经由出口（E）位点离开核糖体。核糖体如何调节tRNA解离以及氨酰基（A）和E位点之间的功能性连接是否调节蛋白质合成的动力学一直存在争议。使用单分子荧光共振能量转移实验，我们发现，在蛋白质延伸的早期周期中，tRNA通常被保持在E位点，直到下一个氨酰tRNA结合到A位点时被变构释放。这一过程是由新生肽的长度和序列，并通过构象状态，检测到的tRNA接近，易位之前。在以后的循环中，E位点tRNA自发解离。我们的研究结果表明，在每个延伸周期内通过核糖体中的远距离子域之间的通信，前易位tRNA状态和后易位途径的分布是相关的，但延伸周期中间体之间的这种相关性不会持续到后续周期。
During protein synthesis, deacylated transfer RNAs leave the ribosome via an exit (E) site after mRNA translocation. How the ribosome regulates tRNA dissociation and whether functional linkages between the aminoacyl (A) and E sites modulate the dynamics of protein synthesis have long been debated. Using single molecule fluorescence resonance energy transfer experiments, we find that, during early cycles of protein elongation, tRNAs are often held in the E site until being allosterically released when the next aminoacyl tRNA binds to the A site. This process is regulated by the length and sequence of the nascent peptide and by the conformational state, detected by tRNA proximity, prior to translocation. In later cycles, E-site tRNA dissociates spontaneously. Our results suggest that the distribution of pretranslocation tRNA states and posttranslocation pathways are correlated within each elongation cycle via communication between distant subdomains in the ribosome, but that this correlation between elongation cycle intermediates does not persist into succeeding cycles.