Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA.
Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, USA.
J Cell Biol. 2023 Jul 3;222(7). doi: 10.1083/jcb.202107027. Epub 2023 May 15.
Cytoplasmic linker-associated proteins (CLASPs) regulate microtubules in fundamental cellular processes. CLASPs stabilize dynamic microtubules by suppressing microtubule catastrophe and promoting rescue, the switch-like transitions between growth and shrinkage. How CLASPs specifically modulate microtubule transitions is not understood. Here, we investigate the effects of CLASPs on the pre-catastrophe intermediate state of microtubule dynamics, employing distinct microtubule substrates to mimic the intermediate state. Surprisingly, we find that CLASP1 promotes the depolymerization of stabilized microtubules in the presence of GTP, but not in the absence of nucleotide. This activity is also observed for CLASP2 family members and a minimal TOG2-domain construct. Conversely, we find that CLASP1 stabilizes unstable microtubules upon tubulin dilution in the presence of GTP. Strikingly, our results reveal that CLASP1 drives microtubule substrates with vastly different inherent stabilities into the same slowly depolymerizing state in a nucleotide-dependent manner. We interpret this state as the pre-catastrophe intermediate state. Therefore, we conclude that CLASPs suppress microtubule catastrophe by stabilizing the intermediate state between growth and shrinkage.
细胞质连接蛋白（CLASPs）在基本的细胞过程中调节微管。CLASPs 通过抑制微管崩解和促进救援来稳定动态微管，救援是指微管生长和收缩之间的开关样转变。CLASPs 如何特异性地调节微管转变尚不清楚。在这里，我们研究了 CLASPs 对微管动力学的预崩解中间状态的影响，使用不同的微管底物来模拟中间状态。令人惊讶的是，我们发现 CLASP1 在 GTP 存在的情况下促进稳定微管的解聚，但在没有核苷酸的情况下则不促进。CLASP2 家族成员和最小的 TOG2 结构域构建体也观察到了这种活性。相反，我们发现 CLASP1 在 GTP 存在的情况下稳定不稳定微管在微管蛋白稀释时。引人注目的是，我们的结果表明，CLASP1 以核苷酸依赖性的方式将具有截然不同固有稳定性的微管底物驱动到相同的缓慢解聚状态。我们将这种状态解释为预崩解中间状态。因此，我们得出结论，CLASPs 通过稳定生长和收缩之间的中间状态来抑制微管崩解。
