Microtubule-Associated Kinase-like Protein RUNKEL Needed for Cell Plate Expansion in Arabidopsis Cytokinesis
Microtubule-Associated Kinase-like Protein RUNKEL Needed for Cell Plate Expansion in Arabidopsis Cytokinesis
复制标题
DOI：
10.1016/j.cub.2009.02.021
复制
发表时间：
2009-03-24
期刊：
影响因子：
9.2
通讯作者：
Juergens, Gerd
中科院分区：
文献类型：
--
作者：
Krupnova, Tamara;Sasabe, Michiko;Juergens, Gerd
胞质分裂将分裂的真核细胞的细胞质分隔开。在高等植物中，动态微管阵列-成膜体-以离心方式介导分隔膜-细胞板的形成[1，2]。这种成膜体动力学涉及微管相关蛋白[3-7]。拟南芥新基因伦克尔（RUK）的突变导致细胞质分裂缺陷，这是由成膜体组织异常和细胞板扩展受阻引起的。RUK编码一个必需的细胞周期调节的152 kDa的蛋白质与一个假定的丝氨酸/苏氨酸激酶结构域和一个大的微管结合结构域，这两个在很大程度上是保守的未表征的蛋白质从原生动物，植物和动物。RUK在体外直接与微管结合，在体内与有丝分裂前前期带、纺锤体和成膜体共定位。一个工程RUK融合蛋白，在末期前降解没有拯救的ruk突变体表型，证明RUK细胞质分裂过程中的行动。微管结合结构域和推定的激酶结构域是必不可少的RUK功能。令人惊讶的是，RUK在体外没有表现出激酶活性，转基因表达的“激酶死亡”RUK拯救了RUK突变体的幼苗致死性。我们的研究结果表明，RUK起着调节作用，而不是催化，在成膜体微管组织在胞质分裂的细胞板扩张。
Cytokinesis partitions the cytoplasm of dividing eukaryotic cells. In higher plants, a dynamic microtubule array-phragmoplast-mediates the formation of the partitioning membrane-cell plate-in a centrifugal fashion [1, 2]. This phragmoplast dynamic involves microtubule-associated proteins [3-7]. Mutations in a novel Arabidopsis gene RUNKEL (RUK) result in cytokinesis defects caused by abnormal phragmoplast organization and arrested cell plate expansion. RUK encodes an essential cell-cycle-regulated 152 kDa protein with a putative serine/threonine kinase domain and a large microtubule-binding domain, both of which are largely conserved in uncharacterized proteins from protozoa, plants, and animals. RUK directly bound to microtubules in vitro and colocalized with mitotic preprophase band, spindle, and phragmoplast in vivo. An engineered RUK fusion protein that was degraded before telophase did not rescue the ruk mutant phenotype, demonstrating RUK action during cytokinesis. Both microtubule-binding domain and putative kinase domain were essential for RUK function. Surprisingly, RUK did not show kinase activity in vitro, and transgenically expressed "kinase-dead" RUK rescued the seedling lethality of ruk mutants. Our results suggest that RUK plays a regulatory, rather than catalytic, role in phragmoplast microtubule organization during cell plate expansion in cytokinesis.