EM TOMOGRAPHY OF KINETOCHORE FORMATION

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。最近的研究强调着丝粒特异性组蛋白H3样蛋白(CENP-A)在着丝粒功能中的重要性。我们发现果蝇CID和人CENP-A在中期以三维结构出现，缺乏组蛋白H3。然而，CID/CENP-A和H3核小体的区块线性散布在延伸的染色质纤维上，CID在多核小体制剂中接近H3核小体。当CID被RNAi耗尽时，它被H3取代，表现出着丝粒染色质组织的灵活性。最后，与H3和CID/CENP-A核小体在S期不同时间复制的模型相反，我们证明了散布的H3和CID/CENP-A染色质在人和苍蝇的S期同时复制。我们认为，CID/CENP-A和H3核小体的独特结构安排使凝聚的有丝分裂染色体的极向面呈现着丝粒染色质。该项目的结果如下：鼓风机医学博士，沙利文BA，卡尔本GH。(2002)在苍蝇和人类中保守着丝粒染色质的组织。Dev细胞。2(3)：319-30。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Recent studies have highlighted the importance of centromere-specific histone H3-like (CENP-A) proteins in centromere function. We show that Drosophila CID and human CENP-A appear at metaphase as a three-dimensional structure that lacks histone H3. However, blocks of CID/CENP-A and H3 nucleosomes are linearly interspersed on extended chromatin fibers, and CID is close to H3 nucleosomes in polynucleosomal preparations. When CID is depleted by RNAi, it is replaced by H3, demonstrating flexibility of centromeric chromatin organization. Finally, contrary to models proposing that H3 and CID/CENP-A nucleosomes are replicated at different times in S phase, we show that interspersed H3 and CID/CENP-A chromatin are replicated concurrently during S phase in humans and flies. We propose that the unique structural arrangement of CID/CENP-A and H3 nucleosomes presents centromeric chromatin to the poleward face of the condensing mitotic chromosome. This project resulted in the following publication: Blower MD, Sullivan BA, Karpen GH. (2002) Conserved organization of centromeric chromatin in flies and humans. Dev Cell. 2(3): 319-30.