Guo Wenhan, Gao Yuan, Du Dan, Sanchez Jason E, Li Yupeng, Qiu Weihong, Li Lin
Department of Physics, University of Texas at El Paso, 500 W University Ave, El Paso, TX 79968, United States.
Department of Physics, Oregon State University, 1500 Jefferson Way, Corvallis, OR 97330, United States.
Brief Bioinform. 2025 Mar 4;26(2). doi: 10.1093/bib/bbaf144.
Kinesin-5 s are bipolar motor proteins that contribute to cell division by crosslinking and sliding apart antiparallel microtubules inside the mitotic spindle. However, the mechanism underlying the interactions between kinesin-5 and the microtubule remains poorly understood. In this study, we investigated the binding of BimC, a kinesin-5 motor from Aspergillus nidulans, to the microtubule using a combination of total internal reflection fluorescence (TIRF) microscopy and molecular dynamics (MD) simulations. TIRF microscopy experiments revealed that increasing the concentration of KCl in the motility buffer from 0 mM to 150 mM completely abolishes the ability of BimC to bind to the microtubule. Consistent with this experimental finding, MD simulations demonstrated a significant reduction in the strength of electrostatic interactions between BimC and microtubules at 150 mM KCl compared to 0 mM KCl. Furthermore, we identified several salt bridges at the BimC-microtubule interface, with positively charged residues on BimC interacting with negatively charged residues on the tubulin heterodimer. These results provide mechanistic insights into the role of electrostatic interactions in kinesin-5-microtubule binding, advancing our understanding of the molecular underpinnings of kinesin-5 motility.
驱动蛋白-5是一种双极运动蛋白，通过交联和分离有丝分裂纺锤体内的反平行微管来促进细胞分裂。然而，驱动蛋白-5与微管之间相互作用的潜在机制仍知之甚少。在本研究中，我们结合全内反射荧光（TIRF）显微镜和分子动力学（MD）模拟，研究了构巢曲霉的驱动蛋白-5运动蛋白BimC与微管的结合。TIRF显微镜实验表明，将运动缓冲液中KCl的浓度从0 mM增加到150 mM会完全消除BimC与微管结合的能力。与这一实验结果一致，MD模拟表明，与0 mM KCl相比，在150 mM KCl时，BimC与微管之间的静电相互作用强度显著降低。此外，我们在BimC-微管界面鉴定了几个盐桥，BimC上带正电的残基与微管蛋白异二聚体上带负电的残基相互作用。这些结果为静电相互作用在驱动蛋白-5与微管结合中的作用提供了机制上的见解，增进了我们对驱动蛋白-5运动分子基础的理解。
