Lermontova Inna, Schubert Veit, Fuchs Joerg, Klatte Sabina, Macas Jiri, Schubert Ingo
Leibniz Institute of Plant Genetics and Crop Plant Research, D-06466 Gatersleben, Germany.
Plant Cell. 2006 Oct;18(10):2443-51. doi: 10.1105/tpc.106.043174. Epub 2006 Oct 6.
The centromeric histone H3 (CENH3) substitutes histone H3 within the nucleosomes of active centromeres in all eukaryotes. CENH3 deposition at centromeres is needed to assemble the kinetochore, a complex of conserved proteins responsible for correct chromosome segregation during nuclear division. Histones of regular nucleosomes are loaded during replication in S phase, while CENH3 deposition deviates from this pattern in yeast, human, and Drosophila melanogaster cells. Little is known about when and how CENH3 targets centromeric loci. Therefore, we determined the location and quantity of recombinant enhanced yellow fluorescent protein (EYFP)-CENH3 in mitotic root and endopolyploid leaf nuclei of transgenic Arabidopsis thaliana cells. Our data indicate significant loading of A. thaliana CENH3 during G2 (before splitting into sister kinetochores) rather than during the S or M phase of the cell cycle. The histone fold domain of the C-terminal part of CENH3 is sufficient to target A. thaliana centromeres. A. thaliana EYFP-CENH3 can recognize and target three different centromeric repeats of Arabidopsis lyrata but not field bean (Vicia faba) centromeres.
着丝粒组蛋白H3（CENH3）在所有真核生物的活跃着丝粒核小体中替代组蛋白H3。着丝粒处CENH3的沉积是组装动粒所必需的，动粒是一种保守蛋白质复合体，负责核分裂期间染色体的正确分离。常规核小体的组蛋白在S期复制时加载，而在酵母、人类和果蝇细胞中，CENH3的沉积偏离了这种模式。关于CENH3何时以及如何靶向着丝粒位点知之甚少。因此，我们确定了转基因拟南芥细胞有丝分裂根细胞核和多倍体叶细胞核中重组增强型黄色荧光蛋白（EYFP）-CENH3的位置和数量。我们的数据表明，拟南芥CENH3在G2期（分裂成姐妹动粒之前）大量加载，而不是在细胞周期的S期或M期。CENH3 C末端部分的组蛋白折叠结构域足以靶向拟南芥着丝粒。拟南芥EYFP-CENH3可以识别并靶向琴叶拟南芥的三种不同着丝粒重复序列，但不能识别蚕豆着丝粒。
