Nagaki Kiyotaka, Cheng Zhukuan, Ouyang Shu, Talbert Paul B, Kim Mary, Jones Kristine M, Henikoff Steven, Buell C Robin, Jiang Jiming
Department of Horticulture, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Nat Genet. 2004 Feb;36(2):138-45. doi: 10.1038/ng1289. Epub 2004 Jan 11.
Centromeres are the last frontiers of complex eukaryotic genomes, consisting of highly repetitive sequences that resist mapping, cloning and sequencing. The centromere of rice Chromosome 8 (Cen8) has an unusually low abundance of highly repetitive satellite DNA, which allowed us to determine its sequence. A region of approximately 750 kb in Cen8 binds rice CENH3, the centromere-specific H3 histone. CENH3 binding is contained within a larger region that has abundant dimethylation of histone H3 at Lys9 (H3-Lys9), consistent with Cen8 being embedded in heterochromatin. Fourteen predicted and at least four active genes are interspersed in Cen8, along with CENH3 binding sites. The retrotransposons located in and outside of the CENH3 binding domain have similar ages and structural dynamics. These results suggest that Cen8 may represent an intermediate stage in the evolution of centromeres from genic regions, as in human neocentromeres, to fully mature centromeres that accumulate megabases of homogeneous satellite arrays.
着丝粒是复杂真核生物基因组的最后前沿领域，由高度重复序列组成，这些序列难以进行图谱绘制、克隆和测序。水稻第8号染色体（Cen8）的着丝粒中高度重复卫星DNA的丰度异常低，这使我们能够确定其序列。Cen8中大约750 kb的区域与水稻CENH3（着丝粒特异性H3组蛋白）结合。CENH3结合区域包含在一个更大的区域内，该区域组蛋白H3赖氨酸9（H3-Lys9）有丰富的二甲基化，这与Cen8嵌入异染色质一致。14个预测基因和至少4个活性基因散布在Cen8中，还有CENH3结合位点。位于CENH3结合域内外的逆转座子具有相似的年代和结构动态。这些结果表明，Cen8可能代表着丝粒从基因区域（如人类新着丝粒）进化到积累数百万碱基同源卫星阵列的完全成熟着丝粒的中间阶段。
