Balancing Acts of Two HEAT Subunits of Condensin I Support Dynamic Assembly of Chromosome Axes
Balancing Acts of Two HEAT Subunits of Condensin I Support Dynamic Assembly of Chromosome Axes
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DOI：
10.1016/j.devcel.2015.01.034
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发表时间：
2015-04-06
影响因子：
11.8
通讯作者：
Hirano, Tatsuya
中科院分区：
文献类型：
--
作者：
Kinoshita, Kazuhisa;Kobayashi, Tetsuya J.;Hirano, Tatsuya
凝聚素I是一种五亚基蛋白复合物，在真核生物有丝分裂染色体组装和分离中起着重要作用。为了剖析其作用机制，我们重组野生型和突变体复合物的重组亚基，并测试他们的能力，组装染色体在非洲爪蟾卵细胞无提取物耗尽内源性凝聚素。我们发现，ATP的结合和SMC亚基水解有不同的贡献，缩合素I的行动和连续的ATP水解所需的结构维持的染色体。突变体复合物缺乏两个热亚基之一产生异常染色体具有高度特征性的缺陷，并与野生型复合物的染色体轴预组装的对比结构的影响。我们建议，两个热亚基的平衡行为支持SMC ATP酶循环控制下的染色体轴的动态组装，从而管理真核细胞中杆状染色体的构建。
Condensin I is a five-subunit protein complex that plays a central role in mitotic chromosome assembly and segregation in eukaryotes. To dissect its mechanism of action, we reconstituted wild-type and mutant complexes from recombinant subunits and tested their abilities to assemble chromosomes in Xenopus egg cell-free extracts depleted of endogenous condensins. We find that ATP binding and hydrolysis by SMC subunits have distinct contributions to the action of condensin I and that continuous ATP hydrolysis is required for structural-maintenance of chromosomes. Mutant complexes lacking either one of two HEAT subunits produce abnormal chromosomes with highly characteristic defects and have contrasting structural effects on chromosome axes preassembled with the wild-type complex. We propose that balancing acts of the two HEAT subunits support dynamic assembly of chromosome axes under the control of the SMC ATPase cycle, thereby governing construction of rod-shaped chromosomes in eukaryotic cells.