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KIF1A 在受到阻碍的负载下,通过动力学调节成为一个超级结合的马达。

KIF1A is kinetically tuned to be a superengaging motor under hindering loads.

机构信息

The Pennsylvania Muscle Institute, Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104.

Center for Engineering Mechanobiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104.

出版信息

Proc Natl Acad Sci U S A. 2023 Jan 10;120(2):e2216903120. doi: 10.1073/pnas.2216903120. Epub 2023 Jan 4.

Abstract

KIF1A is a highly processive vesicle transport motor in the kinesin-3 family. Mutations in KIF1A lead to neurodegenerative diseases including hereditary spastic paraplegia. We applied optical tweezers to study the ability of KIF1A to generate and sustain force against hindering loads. We used both the three-bead assay, where force is oriented parallel to the microtubule, and the traditional single-bead assay, where force is directed along the radius of the bead, resulting in a vertical force component. The average force and attachment duration of KIF1A in the three-bead assay were substantially greater than those observed in the single-bead assay. Thus, vertical forces accelerate termination of force ramps of KIF1A. Average KIF1A termination forces were slightly lower than the kinesin-1 KIF5B, and the median attachment duration of KIF1A was >10-fold shorter than KIF5B under hindering loads. KIF1A rapidly reengages with microtubules after detachment, as observed previously. Strikingly, quantification enabled by the three-bead assay shows that reengagement largely occurs within 2 ms of detachment, indicating that KIF1A has a nearly 10-fold faster reengagement rate than KIF5B. We found that rapid microtubule reengagement is not due to KIF1A's positively charged loop-12; however, removal of charge from this loop diminished the unloaded run length at near physiological ionic strength. Both loop-12 and the microtubule nucleotide state have modulatory effects on reengagement under load, suggesting a role for the microtubule lattice in KIF1A reengagement. Our results reveal adaptations of KIF1A that lead to a model of superengaging transport under load.

摘要

KIF1A 是驱动蛋白-3 家族中一种具有高行进性的囊泡运输马达。KIF1A 的突变会导致包括遗传性痉挛性截瘫在内的神经退行性疾病。我们应用光镊研究了 KIF1A 产生和维持对抗阻碍负载的力的能力。我们既使用了力与微管平行的三珠测定法,也使用了传统的力沿珠子半径方向的单珠测定法,这会导致一个垂直的力分量。三珠测定法中 KIF1A 的平均力和附着持续时间明显大于单珠测定法中观察到的力和附着持续时间。因此,垂直力会加速 KIF1A 力斜坡的终止。KIF1A 的平均终止力略低于驱动蛋白-1 的 KIF5B,在阻碍负载下,KIF1A 的中位附着持续时间比 KIF5B 长>10 倍。KIF1A 在脱离后迅速与微管重新结合,这与之前的观察结果一致。引人注目的是,三珠测定法的量化结果表明,重新结合在脱离后约 2ms 内主要发生,这表明 KIF1A 的重新结合速度比 KIF5B 快近 10 倍。我们发现,快速的微管重新结合不是由于 KIF1A 的带正电荷的环 12;然而,从该环中去除电荷会在接近生理离子强度下减小空载运行长度。环 12 和微管核苷酸状态对负载下的重新结合都有调节作用,这表明微管晶格在 KIF1A 重新结合中起作用。我们的结果揭示了 KIF1A 的适应性,导致了在负载下超结合运输的模型。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/9b30/9926277/411744c5d1b0/pnas.2216903120fig01.jpg

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