Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York, United States of America ; State Key Lab of Reproductive Medicine, College of Basic Medicine, Nanjing Medical University, Nanjing, Jiangsu, China.
PLoS One. 2013 Aug 28;8(8):e73075. doi: 10.1371/journal.pone.0073075. eCollection 2013.
Kinesin-13s are microtubule (MT) depolymerases different from most other kinesins that move along MTs. Like other kinesins, they have a motor or head domain (HD) containing a tubulin and an ATP binding site. Interestingly, kinesin-13s have an additional binding site (Kin-Tub-2) on the opposite side of the HD that contains several family conserved positively charged residues. The role of this site in kinesin-13 function is not clear. To address this issue, we investigated the in-vitro and in-vivo effects of mutating Kin-Tub-2 family conserved residues on the Drosophila melanogaster kinesin-13, KLP10A. We show that the Kin-Tub-2 site enhances tubulin cross-linking and MT bundling properties of KLP10A in-vitro. Disruption of the Kin-Tub-2 site, despite not having a deleterious effect on MT depolymerization, results in abnormal mitotic spindles and lagging chromosomes during mitosis in Drosophila S2 cells. The results suggest that the additional Kin-Tub-2 tubulin biding site plays a direct MT attachment role in-vivo.
驱动蛋白-13 是微管 (MT) 解聚酶，与大多数沿 MT 运动的其他驱动蛋白不同。与其他驱动蛋白一样，它们具有马达或头部结构域 (HD)，其中包含一个微管蛋白和一个 ATP 结合位点。有趣的是，驱动蛋白-13 在 HD 的另一侧有一个额外的结合位点 (Kin-Tub-2)，其中包含几个家族保守的带正电荷残基。该位点在驱动蛋白-13 功能中的作用尚不清楚。为了解决这个问题，我们研究了突变果蝇驱动蛋白-13，KLP10A 的 Kin-Tub-2 家族保守残基对其在体外和体内的影响。我们表明，Kin-Tub-2 位点增强了 KLP10A 在体外的微管交联和 MT 成束特性。尽管破坏 Kin-Tub-2 位点对 MT 解聚没有不利影响，但会导致果蝇 S2 细胞有丝分裂过程中异常的有丝分裂纺锤体和滞后染色体。结果表明，额外的 Kin-Tub-2 微管结合位点在体内发挥直接的 MT 附着作用。
