Cooperative assembly of CYK-4/MgcRacGAP and ZEN-4/MKLP1 to form the centralspindlin complex
Cooperative assembly of CYK-4/MgcRacGAP and ZEN-4/MKLP1 to form the centralspindlin complex
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DOI：
10.1091/mbc.e07-05-0468
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发表时间：
2007-12-01
影响因子：
3.3
通讯作者：
Glotzer, Michael
中科院分区：
文献类型：
--
作者：
Pavicic-Kaltenbrunner, Visnja;Mishima, Masanori;Glotzer, Michael
后生动物细胞的胞质分裂需要一组反平行的微管，这些微管在分裂后期开始时成束，形成一种称为中央纺锤体的结构。这些微管的捆绑需要一种蛋白质复合物centralspindlin，它由CYK-4/MgcRacGAP Rho家族GTP酶激活蛋白和ZEN-4/MKLP 1驱动蛋白-6马达蛋白组成。Centralspindlin，而不是它的单个亚基，足以在体外捆绑微管。在这里，我们提出了一个生化和遗传解剖centralspindlin。我们发现，每一个centralspindlin的两个亚基通过一个平行的卷曲螺旋二聚化。两个同源二聚体通过两个低亲和力相互作用组装成高亲和力异源四聚体复合物。介导复合物组装的区域中的条件突变可以容易地被相互作用区域中的许多第二位点突变抑制。这种意想不到的可塑性解释了这种重要蛋白质-蛋白质相互作用关键区域的一级序列保守性的缺乏。
Cytokinesis in metazoan cells requires a set of antiparallel microtubules that become bundled upon anaphase onset to form a structure known as the central spindle. Bundling of these microtubules requires a protein complex, centralspindlin, that consists of the CYK-4/MgcRacGAP Rho-family GTPase-activating protein and the ZEN-4/MKLP1 kinesin-6 motor protein. Centralspindlin, but not its individual subunits, is sufficient to bundle microtubules in vitro. Here, we present a biochemical and genetic dissection of centralspindlin. We show that each of the two subunits of centralspindlin dimerize via a parallel coiled coil. The two homodimers assemble into a high-affinity heterotetrameric complex by virtue of two low-affinity interactions. Conditional mutations in the regions that mediate complex assembly can be readily suppressed by numerous second site mutations in the interacting regions. This unexpected plasticity explains the lack of primary sequence conservation of the regions critical for this essential protein-protein interaction.