小柯机器人

美国圣裘德儿童研究医院Scott C. Blanchard课题组揭示核糖体早期易位事件的结构基础。相关论文于2021年7月7日在线发表在《自然》杂志上。

研究人员使用单分子荧光方法来指导捕获细菌核糖体上早期易位事件的结构。研究结果表明，细菌GTPase延伸因子G特异性地参与自发实现的核糖体构象，同时处于活跃的GTP结合构象来解锁和启动肽基-tRNA易位。这些发现表明，易位前核糖体复合物的内在过程可以调节蛋白质合成的速率，并且能量消耗在易位机制中的使用比先前提出的要晚。

据介绍，蛋白质合成过程中的肽链延伸需要连续的氨酰-tRNA选择和易位反应，这些反应在数千个循环中快速进行（每秒 2-20 次）并且错误率低（每步约10^-3到10^-5次）。核糖体划过mRNA模板的节奏和保真度是生物系统中运动的范式，这必须适用于不同生命领域的不同mRNA和tRNA底物。

附：英文原文

Title: Structural basis of early translocation events on the ribosome

Author: Emily J. Rundlet, Mikael Holm, Magdalena Schacherl, S. Kundhavai Natchiar, Roger B. Altman, Christian M. T. Spahn, Alexander G. Myasnikov, Scott C. Blanchard

Issue&Volume: 2021-07-07

Abstract: Peptide-chain elongation during protein synthesis entails sequential aminoacyl-tRNA selection and translocation reactions that proceed rapidly (2–20 per second) and with a low error rate (around 103 to 105 at each step) over thousands of cycles1. The cadence and fidelity of ribosome transit through mRNA templates in discrete codon increments is a paradigm for movement in biological systems that must hold for diverse mRNA and tRNA substrates across domains of life. Here we use single-molecule fluorescence methods to guide the capture of structures of early translocation events on the bacterial ribosome. Our findings reveal that the bacterial GTPase elongation factor G specifically engages spontaneously achieved ribosome conformations while in an active, GTP-bound conformation to unlock and initiate peptidyl-tRNA translocation. These findings suggest that processes intrinsic to the pre-translocation ribosome complex can regulate the rate of protein synthesis, and that energy expenditure is used later in the translocation mechanism than previously proposed.

DOI: 10.1038/s41586-021-03713-x

Source: https://www.nature.com/articles/s41586-021-03713-x

Nature：《自然》，创刊于1869年。隶属于施普林格·自然出版集团，最新IF：69.504
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