Structural insights into the intramolecular interactions of centromere protein CENP‐I
Structural insights into the intramolecular interactions of centromere protein CENP‐I
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DOI：
10.1002/jmr.2837
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发表时间：
2020-02
影响因子：
2.7
通讯作者：
Yu Zhang;Congcong Zhao;Beibei Cao;Jingjing Ye;Hao Huang;Liqiao Hu;W. Tian;Xiaojing He
中科院分区：
文献类型：
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作者：
Yu Zhang;Congcong Zhao;Beibei Cao;Jingjing Ye;Hao Huang;Liqiao Hu;W. Tian;Xiaojing He
在有丝分裂中，姐妹染色体的精确分离依赖于着丝粒，一种多亚基复合体组装在每个姐妹染色体的着丝粒上。CENP‐I作为内动粒的核心组分，在介导动粒组装和支持染色体可靠分离方面发挥重要作用。已分别报道了与CENP-H/K复合的CENP-I同系物的N-末端和C-末端的结构。不幸的是，CENP-I的分子内相互作用知之甚少，CENP-I如何与CENP-M相互作用仍然未知。在这里，我们验证了一个独特的螺旋α11，它与真菌CENP-I中的N-末端HEAT重复序列形成分子内相互作用。螺旋α11的缺失暴露了疏水表面，并导致真菌CENP-I的N-末端HEAT重复序列的体外蛋白质聚集。相应的螺旋及其分子内相互作用在人CENP-I中高度保守。人类CENP-I中相应螺旋的缺失显着降低了与CENP-H和CENP-M相互作用的功能活性。在HeLa细胞中，人CENP-I中螺旋上保守残基的突变显著减弱了与CENP-M的结合，而不是CENP-H。因此，我们的发现首次揭示了CENP‐I的保守螺旋，这对分子内相互作用和功能非常重要，并将有助于理解CENP‐I如何在细胞周期和有丝分裂期间介导动粒组装的结构基础。
In mitosis, the accurate segregation of sister chromosomes relies on kinetochore, a multiple subunits complex assembled on centromere of each sister chromosome. As a core component of inner kinetochore, CENP‐I plays important functions to mediate kinetochore assembly and supports the faithful chromosome segregation. The structures of the N‐terminus and C‐terminus of CENP‐I homologs in complex with CENP‐H/K have been reported, respectively. Unfortunately, the intramolecular interactions of CENP‐I are poorly understood, and how CENP‐I interacts with CENP‐M remains unknown. Here, we verified a unique helix α11, which forms the intramolecular interactions with N‐terminal HEAT repeats in fungal CENP‐I. Deletion of the helix α11 exposed the hydrophobic surface and resulted in the in vitro protein aggregation of N‐terminal HEAT repeats of fungal CENP‐I. The corresponding helix and its intramolecular interaction are highly conserved in human CENP‐I. Deletion of the corresponding helix in human CENP‐I dramatically reduced the functional activity to interact with CENP‐H and CENP‐M. Mutations of the conserved residues on the helix in human CENP‐I significantly weakened the binding to CENP‐M, but not CENP‐H, in HeLa cells. Therefore, our findings for the first time unveiled a conserved helix of CENP‐I, which is important for the intramolecular interaction and function, and would be helpful for understanding the structure basis of how CENP‐I mediates the kinetochore assembly during cell cycle and mitosis.