Abstract

In this work we assume that the ribosome propels itself during the translocation step of the translation process of protein synthesis by running a cycle of stochastically generated conformational changes involving its two subunits. This cycle includes only two experimentally found ribosome shape changes. The main result is an analytic expression for ribosome’s average swimming speed on a polysome, where the ribosome is in the presence of other ribosomes. Relevant geometric parameters of ribosome deformations are calculated first by solving a deterministic problem where the ribosome runs a cycle of prescribed conformational changes. The method of reflections and pairwise additivity are used to obtain the stresses and forces needed to apply the multiparticle reciprocal theorem. Ribosome’s average velocity when it runs the corresponding stochastic cycle of deformations is calculated assuming independence among the conformational cycles of different ribosomes on the polysome. The results obtained show that swimming in tandem on the polysome allows the ribosome to reach any typical subcellular speed with deformations whose amplitude is of a smaller size than when it swims alone in the fluid. Also, the flow organized by its swimming stroke becomes more determinant for its motion than random diffusion, compared to the solitary ribosome.

Graphic abstract

中文翻译：

---

多核糖体上核糖体运动的随机微游泳模型

摘要

在这项工作中，我们假设核糖体在蛋白质合成翻译过程的易位步骤中通过运行涉及其两个亚基的随机生成的构象变化循环来推动自身。这个循环只包括两个实验发现的核糖体形状变化。主要结果是核糖体在多核糖体上的平均游泳速度的分析表达式，其中核糖体存在其他核糖体。核糖体变形的相关几何参数首先通过解决确定性问题来计算，其中核糖体运行规定的构象变化周期。反射和成对可加性的方法用于获得应用多粒子互易定理所需的应力和力。假设多核糖体上不同核糖体的构象循环之间的独立性，计算核糖体在运行相应的随机变形循环时的平均速度。获得的结果表明，在多核糖体上串联游泳允许核糖体达到任何典型的亚细胞速度，变形的幅度比它在流体中单独游泳时的幅度要小。此外，与孤立的核糖体相比，由游泳运动组织的流动比随机扩散更能决定其运动。获得的结果表明，在多核糖体上串联游泳允许核糖体达到任何典型的亚细胞速度，变形的幅度比它在流体中单独游泳时的幅度要小。此外，与孤立的核糖体相比，由游泳运动组织的流动比随机扩散更能决定其运动。获得的结果表明，在多核糖体上串联游泳允许核糖体达到任何典型的亚细胞速度，变形的幅度比它在流体中单独游泳时的幅度要小。此外，与孤立的核糖体相比，由游泳运动组织的流动比随机扩散更能决定其运动。

图形摘要