Yamada Moé, Tanaka-Takiguchi Yohko, Hayashi Masahito, Nishina Momoko, Goshima Gohta
Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan.
Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
J Cell Biol. 2017 Jun 5;216(6):1705-1714. doi: 10.1083/jcb.201610065. Epub 2017 Apr 25.
Minus end-directed cargo transport along microtubules (MTs) is exclusively driven by the molecular motor dynein in a wide variety of cell types. Interestingly, during evolution, plants have lost the genes encoding dynein; the MT motors that compensate for dynein function are unknown. Here, we show that two members of the kinesin-14 family drive minus end-directed transport in plants. Gene knockout analyses of the moss revealed that the plant-specific class VI kinesin-14, KCBP, is required for minus end-directed transport of the nucleus and chloroplasts. Purified KCBP directly bound to acidic phospholipids and unidirectionally transported phospholipid liposomes along MTs in vitro. Thus, minus end-directed transport of membranous cargoes might be driven by their direct interaction with this motor protein. Newly nucleated cytoplasmic MTs represent another known cargo exhibiting minus end-directed motility, and we identified the conserved class I kinesin-14 (ATK) as the motor involved. These results suggest that kinesin-14 motors were duplicated and developed as alternative MT-based minus end-directed transporters in land plants.
沿微管（MTs）的负端定向货物运输在多种细胞类型中完全由分子马达动力蛋白驱动。有趣的是，在进化过程中，植物失去了编码动力蛋白的基因；补偿动力蛋白功能的MT马达尚不清楚。在这里，我们表明驱动蛋白-14家族的两个成员在植物中驱动负端定向运输。对苔藓的基因敲除分析表明，植物特有的VI类驱动蛋白-14，即KCBP，是细胞核和叶绿体负端定向运输所必需的。纯化的KCBP直接结合酸性磷脂，并在体外沿MT单向运输磷脂脂质体。因此，膜性货物的负端定向运输可能是由它们与这种马达蛋白的直接相互作用驱动的。新形成的胞质MTs代表另一种已知的表现出负端定向运动性的货物，我们确定保守的I类驱动蛋白-14（ATK）为相关马达。这些结果表明，驱动蛋白-14马达在陆地植物中被复制并发展成为基于MT的替代负端定向转运体。
