Ma Rui, Hendel Nathan L, Marshall Wallace F, Qin Hongmin
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut.
Department of Biochemistry and Biophysics, University of California, San Francisco, California; Bioinformatics Graduate Group, University of California, San Francisco, California.
Biophys J. 2020 Jun 2;118(11):2790-2800. doi: 10.1016/j.bpj.2020.03.034. Epub 2020 Apr 22.
Flagellar length control in Chlamydomonas is a tractable model system for studying the general question of organelle size regulation. We have previously proposed that the diffusive return of the kinesin motor that powers intraflagellar transport can play a key role in length regulation. Here, we explore how the motor speed and diffusion coefficient for the return of kinesin-2 affect flagellar growth kinetics. We find that the system can exist in two distinct regimes, one dominated by motor speed and one by diffusion coefficient. Depending on length, a flagellum can switch between these regimes. Our results indicate that mutations can affect the length in distinct ways. We discuss our theory's implication for flagellar growth influenced by beating and provide possible explanations for the experimental observation that a beating flagellum is usually longer than its immotile mutant. These results demonstrate how our simple model can suggest explanations for mutant phenotypes.
衣藻鞭毛长度控制是研究细胞器大小调控这一普遍问题的一个易于处理的模型系统。我们之前提出，驱动鞭毛内运输的驱动蛋白的扩散返回在长度调控中可能起关键作用。在此，我们探讨驱动蛋白-2返回的运动速度和扩散系数如何影响鞭毛生长动力学。我们发现该系统可以存在于两种不同的状态，一种由运动速度主导，另一种由扩散系数主导。根据长度不同，鞭毛可以在这些状态之间切换。我们的结果表明，突变可以以不同方式影响长度。我们讨论了我们的理论对受摆动影响的鞭毛生长的意义，并为摆动的鞭毛通常比其不能运动的突变体长这一实验观察结果提供了可能的解释。这些结果证明了我们的简单模型如何能够为突变体表型提出解释。
