Center for Plant Molecular Biology - Developmental Genetics, University of Tübingen, Tübingen, Germany.
Department of Plant Systems Biology, VIB, Ghent, Belgium.
EMBO Rep. 2018 Sep;19(9). doi: 10.15252/embr.201846085. Epub 2018 Jul 12.
Kinesins are versatile nano-machines that utilize variable non-motor domains to tune specific motor microtubule encounters. During plant cytokinesis, the kinesin-12 orthologs, PHRAGMOPLAST ORIENTING KINESIN (POK)1 and POK2, are essential for rapid centrifugal expansion of the cytokinetic apparatus, the phragmoplast, toward a pre-selected cell plate fusion site at the cell cortex. Here, we report on the spatio-temporal localization pattern of POK2, mediated by distinct protein domains. Functional dissection of POK2 domains revealed the association of POK2 with the site of the future cell division plane and with the phragmoplast during cytokinesis. Accumulation of POK2 at the phragmoplast midzone depends on its functional POK2 motor domain and is fine-tuned by its carboxy-terminal region that also directs POK2 to the division site. Furthermore, POK2 likely stabilizes the phragmoplast midzone via interaction with the conserved microtubule-associated protein MAP65-3/PLEIADE, a well-established microtubule cross-linker. Collectively, our results suggest that dual localized POK2 plays multiple roles during plant cell division.
驱动蛋白是多功能的纳米机器，利用可变的非马达结构域来调节特定的马达微管相互作用。在植物胞质分裂过程中，驱动蛋白-12 同源物 PHRAGMOPLAST ORIENTING KINESIN（POK）1 和 POK2 对于细胞质分裂器（phragmoplast）的快速向心性扩展至关重要，phragmoplast 朝着细胞皮层上预先选定的细胞板融合位点扩展。在这里，我们报告了 POK2 通过不同的蛋白质结构域介导的时空定位模式。POK2 结构域的功能分析揭示了 POK2 与未来细胞分裂平面的位置以及胞质分裂过程中的 phragmoplast 的关联。POK2 在 phragmoplast 中央带的积累依赖于其功能 POK2 马达结构域，并通过其羧基末端区域进行微调，该区域还将 POK2 引导至分裂位点。此外，POK2 可能通过与保守的微管相关蛋白 MAP65-3/PLEIADE 的相互作用稳定 phragmoplast 中央带，MAP65-3/PLEIADE 是一种成熟的微管交联剂。总之，我们的结果表明，双定位的 POK2 在植物细胞分裂过程中发挥多种作用。
