From the Anhui Key Laboratory of Cellular Dynamics and Chemical Biology, Hefei National Center for Physical Sciences at the Microscale, University of Science and Technology of the China School of Life Sciences, Chinese Academy of Sciences Center of Excellence on Cell Sciences, Hefei 230027, China.
the Keck Center for Cellular Dynamics and Organoid Plasticity, Morehouse School of Medicine, Atlanta, Georgia 30310, and.
J Biol Chem. 2019 Jan 18;294(3):968-980. doi: 10.1074/jbc.RA118.004688. Epub 2018 Nov 20.
The centromere is an evolutionarily conserved eukaryotic protein machinery essential for precision segregation of the parental genome into two daughter cells during mitosis. Centromere protein A (CENP-A) organizes the functional centromere via a constitutive centromere-associated network composing the CENP-T complex. However, how CENP-T assembles onto the centromere remains elusive. Here we show that CENP-T binds directly to Holliday junction recognition protein (HJURP), an evolutionarily conserved chaperone involved in loading CENP-A. The binding interface of HJURP was mapped to the C terminus of CENP-T. Depletion of HJURP by CRISPR-elicited knockout minimized recruitment of CENP-T to the centromere, indicating the importance of HJURP in CEPN-T loading. Our immunofluorescence analyses indicate that HJURP recruits CENP-T to the centromere in S/G phase during the cell division cycle. Significantly, the HJURP binding-deficient mutant CENP-T failed to locate to the centromere. Importantly, CENP-T insufficiency resulted in chromosome misalignment, in particular chromosomes 15 and 18. Taken together, these data define a novel molecular mechanism underlying the assembly of CENP-T onto the centromere by a temporally regulated HJURP-CENP-T interaction.
着丝粒是一种进化上保守的真核蛋白机器,对于有丝分裂过程中亲本基因组精确分离到两个子细胞中至关重要。着丝粒蛋白 A (CENP-A) 通过组成 CENP-T 复合物的组成型着丝粒相关网络来组织功能着丝粒。然而,CENP-T 如何组装到着丝粒上仍然难以捉摸。在这里,我们表明 CENP-T 直接结合到 Holliday 连接识别蛋白 (HJURP),这是一种进化上保守的伴侣蛋白,参与 CENP-A 的加载。HJURP 的结合界面被映射到 CENP-T 的 C 端。通过 CRISPR 诱导的敲除耗尽 HJURP 最大限度地减少了 CENP-T 向着丝粒的募集,表明 HJURP 在 CENP-T 加载中的重要性。我们的免疫荧光分析表明,HJURP 在细胞分裂周期的 S/G 期将 CENP-T 招募到着丝粒。重要的是,缺乏 HJURP 结合能力的突变 CENP-T 无法定位到着丝粒。重要的是,CENP-T 不足会导致染色体错位,特别是 15 号和 18 号染色体。总之,这些数据定义了一个新的分子机制,即通过时空调节的 HJURP-CENP-T 相互作用将 CENP-T 组装到着丝粒上。