Xie Ping
Key Laboratory of Soft Matter Physics and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Biochem Biophys Rep. 2015 Jun 9;2:87-93. doi: 10.1016/j.bbrep.2015.05.004. eCollection 2015 Jul.
The ribosomal translocation involves both intersubunit rotations between the small 30S and large 50S subunits and the intrasubunit rotations of the 30S head relative to the 30S body. However, the detailed molecular mechanism on how the intersubunit and intrasubunit rotations are related to the translocation remains unclear. Here, based on available structural data a model is proposed for the ribosomal translocation, into which both the intersubunit and intrasubunit rotations are incorporated. With the model, we provide quantitative explanations of in vitro experimental data showing the biphasic character in the fluorescence change associated with the mRNA translocation and the character of a rapid increase that is followed by a slow single-exponential decrease in the fluorescence change associated with the 30S head rotation. The calculated translation rate is also consistent with the in vitro single-molecule experimental data.
核糖体易位涉及小亚基（30S）和大亚基（50S）之间的亚基间旋转以及30S头部相对于30S主体的亚基内旋转。然而，亚基间和亚基内旋转如何与易位相关的详细分子机制仍不清楚。在此，基于现有的结构数据，提出了一个核糖体易位模型，该模型纳入了亚基间和亚基内旋转。利用该模型，我们对体外实验数据进行了定量解释，这些数据显示了与mRNA易位相关的荧光变化具有双相特征，以及与30S头部旋转相关的荧光变化呈现快速增加后缓慢单指数下降的特征。计算得到的翻译速率也与体外单分子实验数据一致。
