Institute for Anatomy and Cell Biology, Ludwig Maximilian University of Munich, Schillerstr. 42, 80336 Munich, Germany.
Biochem Biophys Res Commun. 2013 Feb 15;431(3):490-5. doi: 10.1016/j.bbrc.2013.01.030. Epub 2013 Jan 16.
Kinesins are ATP-dependent molecular motors that mediate unidirectional intracellular transport along microtubules. Dictyostelium discoideum has 13 different kinesin isoforms including two members of the kinesin-7 family, Kif4 and Kif11. While Kif4 is structurally and functionally related to centromere-associated CENP-E proteins involved in the transport of chromosomes to the poles during mitosis, the function of the unusually short CENP-E variant Kif11 is unclear. Here we show that orthologs of short CENP-E variants are present in plants and fungi, and analyze functional properties of the Dictyostelium CENP-E version, Kif11. Gene knockout mutants reveal that Kif11 is not required for mitosis or development. Imaging of GFP-labeled Kif11 expressing Dictyostelium cells indicates that Kif11 is a plus-end directed motor that accumulates at microtubule plus ends. By multiple motor gliding assays, we show that Kif11 moves with an average velocity of 38nm/s, thus defining Kif11 as a very slow motor. The activity of the Kif11 motor appears to be modulated via interactions with the non-catalytic tail region. Our work highlights a subclass of kinesin-7-like motors that function outside of a role in mitosis.
驱动蛋白是一种依赖于 ATP 的分子马达，能够介导沿微管的单向细胞内运输。盘基网柄菌有 13 种不同的驱动蛋白同工型，包括驱动蛋白-7 家族的两个成员 Kif4 和 Kif11。虽然 Kif4 在结构和功能上与参与有丝分裂过程中染色体向两极运输的着丝粒相关的 CENP-E 蛋白有关，但异常短的 CENP-E 变体 Kif11 的功能尚不清楚。在这里，我们表明短 CENP-E 变体的同源物存在于植物和真菌中，并分析了盘基网柄菌 CENP-E 版本 Kif11 的功能特性。基因敲除突变体表明 Kif11 不是有丝分裂或发育所必需的。对 GFP 标记的 Kif11 表达的盘基网柄菌细胞的成像表明，Kif11 是一个指向微管正极的马达，在微管正极聚集。通过多次马达滑行实验，我们表明 Kif11 以 38nm/s 的平均速度移动，从而将 Kif11 定义为一个非常缓慢的马达。Kif11 马达的活性似乎通过与非催化尾部区域的相互作用而被调节。我们的工作强调了一类在有丝分裂中不起作用的驱动蛋白-7 样马达。
