Department of Biology and Biochemistry, University of Houston, Houston, Texas, USA.
Biophys J. 2010 Nov 3;99(9):3002-9. doi: 10.1016/j.bpj.2010.08.037.
During protein biosynthesis the ribosome moves along mRNA in steps of precisely three nucleotides. The mechanism for this ribosome motion remains elusive. Using a classification algorithm to sort single-molecule fluorescence resonance energy transfer data into subpopulations, we found that the ribosome dynamics detected at the peptidyl transferase center are highly inhomogeneous. The pretranslocation complex has at least four subpopulations that sample two hybrid states, whereas the posttranslocation complex is mainly static. We observed transitions among the ribosome subpopulations under various conditions, including 1), in the presence of EF-G; 2), spontaneously; 3), in different buffers, and 4), bound to antibiotics. Therefore, these subpopulations represent biologically active ribosomes. One key observation indicates that the Hy2 hybrid state only exists in a fluctuating ribosome subpopulation, which prompts us to propose that ribosome dynamics are hierarchically arranged. This proposal may have important implications for the regulation of cellular translation rates.
在蛋白质生物合成过程中，核糖体沿着 mRNA 以精确的三个核苷酸为单位移动。这种核糖体运动的机制仍然难以捉摸。我们使用分类算法将单分子荧光共振能量转移数据分为亚群，发现肽基转移酶中心检测到的核糖体动力学高度不均匀。前移位复合物至少有四个亚群，它们分别采样两种杂交状态，而后移位复合物主要是静态的。我们观察到在各种条件下核糖体亚群之间的转变，包括 1）存在 EF-G 时；2）自发地；3）在不同的缓冲液中；4）与抗生素结合。因此，这些亚群代表具有生物活性的核糖体。一个关键的观察结果表明，Hy2 杂交状态仅存在于不断变化的核糖体亚群中，这促使我们提出核糖体动力学是按层次排列的。这一假设可能对细胞翻译速率的调节具有重要意义。
