Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute for Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
Proc Natl Acad Sci U S A. 2011 Aug 2;108(31):12687-92. doi: 10.1073/pnas.1104978108. Epub 2011 Jul 18.
The centromeres of budding yeast are ~120 bp in size and contain three functional elements: an AT-rich region flanked by binding sites for Cbf1 and CBF3. A specialized nucleosome containing the H3 variant Cse4 (CenH3) is formed at the centromere. Our genome-wide paired-end sequencing of nucleosomal DNA reveals that the centromeric nucleosome contains a micrococcal nuclease-resistant kernel of 123-135 bp, depending on the centromere, and is therefore significantly shorter than the canonical nucleosome. Unlike canonical nucleosomes, the centromeric nucleosome is essentially perfectly positioned. The entire centromere is included, together with at least 1 bp of DNA upstream of the Cbf1 site and at least 4 bp downstream of the CBF3 site. The fact that the binding sites for Cbf1 and CBF3 are included within the centromeric nucleosome has important implications for models of the centromeric nucleosome and for kinetochore function.
芽殖酵母的着丝粒大小约为 120bp,包含三个功能元件:富含 AT 的区域,两侧是 Cbf1 和 CBF3 结合位点。在着丝粒处形成含有 H3 变体 Cse4(CenH3)的特殊核小体。我们对核小体 DNA 的全基因组配对末端测序表明,着丝粒核小体含有 123-135bp 的微球菌核酸酶抗性核心,具体取决于着丝粒,因此明显短于典型核小体。与典型核小体不同,着丝粒核小体的位置几乎是完美的。整个着丝粒都包含在内,至少包括 Cbf1 位点上游的 1bpDNA 和 CBF3 位点下游的至少 4bpDNA。Cbf1 和 CBF3 结合位点包含在着丝粒核小体中的事实,对着丝粒核小体模型和动粒功能具有重要意义。