Li Ziyin, Lee Ju Huck, Chu Feixia, Burlingame Alma L, Günzl Arthur, Wang Ching C
Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America.
PLoS One. 2008 Jun 11;3(6):e2354. doi: 10.1371/journal.pone.0002354.
Aurora B kinase is a key component of the chromosomal passenger complex (CPC), which regulates chromosome segregation and cytokinesis. An ortholog of Aurora B was characterized in Trypanosoma brucei (TbAUK1), but other conserved components of the complex have not been found. Here we identified four novel TbAUK1 associated proteins by tandem affinity purification and mass spectrometry. Among these four proteins, TbKIN-A and TbKIN-B are novel kinesin homologs, whereas TbCPC1 and TbCPC2 are hypothetical proteins without any sequence similarity to those known CPC components from yeasts and metazoans. RNAi-mediated silencing of each of the four genes led to loss of spindle assembly, chromosome segregation and cytokinesis. TbKIN-A localizes to the mitotic spindle and TbKIN-B to the spindle midzone during mitosis, whereas TbCPC1, TbCPC2 and TbAUK1 display the dynamic localization pattern of a CPC. After mitosis, the CPC disappears from the central spindle and re-localizes at a dorsal mid-point of the mother cell, where the anterior tip of the daughter cell is tethered, to start cell division toward the posterior end, indicating a most unusual CPC-initiated cytokinesis in a eukaryote.
极光B激酶是染色体乘客复合体（CPC）的关键组成部分，该复合体调节染色体分离和胞质分裂。在布氏锥虫中鉴定出了极光B的一个直系同源物（TbAUK1），但尚未发现该复合体的其他保守成分。在这里，我们通过串联亲和纯化和质谱法鉴定了四种与TbAUK1相关的新蛋白。在这四种蛋白中，TbKIN-A和TbKIN-B是新的驱动蛋白同源物，而TbCPC1和TbCPC2是假设蛋白，与酵母和后生动物中已知的CPC成分没有任何序列相似性。RNA干扰介导的这四个基因中每个基因的沉默导致纺锤体组装、染色体分离和胞质分裂的丧失。在有丝分裂期间，TbKIN-A定位于有丝分裂纺锤体，TbKIN-B定位于纺锤体中区，而TbCPC1、TbCPC2和TbAUK1呈现CPC的动态定位模式。有丝分裂后，CPC从中央纺锤体消失，并重新定位于母细胞的背中点，子细胞的前端在此处被拴系，从而开始向后端进行细胞分裂，这表明在真核生物中存在一种非常特殊的由CPC启动的胞质分裂。
