Bloom Kerry S
Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599-3280; email:
Annu Rev Genet. 2014;48:457-84. doi: 10.1146/annurev-genet-120213-092033. Epub 2014 Sep 18.
Centromeres are specialized domains of heterochromatin that provide the foundation for the kinetochore. Centromeric heterochromatin is characterized by specific histone modifications, a centromere-specific histone H3 variant (CENP-A), and the enrichment of cohesin, condensin, and topoisomerase II. Centromere DNA varies orders of magnitude in size from 125 bp (budding yeast) to several megabases (human). In metaphase, sister kinetochores on the surface of replicated chromosomes face away from each other, where they establish microtubule attachment and bi-orientation. Despite the disparity in centromere size, the distance between separated sister kinetochores is remarkably conserved (approximately 1 μm) throughout phylogeny. The centromere functions as a molecular spring that resists microtubule-based extensional forces in mitosis. This review explores the physical properties of DNA in order to understand how the molecular spring is built and how it contributes to the fidelity of chromosome segregation.
着丝粒是异染色质的特殊结构域，为动粒提供基础。着丝粒异染色质的特征在于特定的组蛋白修饰、着丝粒特异性组蛋白H3变体（CENP - A）以及黏连蛋白、凝聚素和拓扑异构酶II的富集。着丝粒DNA的大小在数量级上差异很大，从125 bp（芽殖酵母）到几兆碱基（人类）不等。在中期，复制染色体表面的姐妹动粒彼此相对，在那里它们建立微管附着和双定向。尽管着丝粒大小存在差异，但在整个系统发育过程中，分离的姐妹动粒之间的距离显著保守（约1μm）。着丝粒在有丝分裂中起到分子弹簧的作用，抵抗基于微管的拉伸力。本综述探讨了DNA的物理性质，以了解分子弹簧是如何构建的以及它如何有助于染色体分离的保真度。
