裂殖酵母着丝粒的动粒和异染色质结构域。

Kinetochore and heterochromatin domains of the fission yeast centromere.

作者信息

Pidoux Alison L, Allshire Robin C

机构信息

Wellcome Trust Centre for Cell Biology, University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh, EH9 3JR, UK.

出版信息

Chromosome Res. 2004;12(6):521-34. doi: 10.1023/B:CHRO.0000036586.81775.8b.

Abstract

Fission yeast centromeres are composed of two distinctive chromatin domains. The central domain nucleosomes contain the histone H3-like protein CENP-A(Cnp1). In contrast, the flanking repeats are coated with silent chromatin in which Swi6 (HP1) binds histone H3 methylated on lysine 9 that is induced by the action of the RNA interference pathway on non-coding centromeric transcripts. The overall structure is similar to that of metazoan centromeres where the kinetochore is embedded in surrounding heterochromatin. Kinetochore specific proteins associate with the central domain and affect silencing in that region. The flanking heterochromatin is required to recruit cohesin and mediate tight physical cohesion between sister centromeres. The loss of silencing that accompanies defects in heterochromatin has been invaluable as a tool in the investigation of centromere function. Both the heterochromatin and kinetochore regions are required for the de novo assembly of a functional centromere on DNA constructs, suggesting that heterochromatin may provide an environment that promotes kinetochore assembly within the central domain. The process is clearly epigenetically regulated. Fission yeast kinetochores associate with 2-4 microtubules, and flanking heterochromatin may be required to promote the orientation of multiple microtubule binding sites on one kinetochore towards the same pole and thus prevent merotelic orientation.

摘要

裂殖酵母着丝粒由两个不同的染色质结构域组成。中央结构域核小体包含组蛋白H3样蛋白CENP - A(Cnp1)。相比之下,侧翼重复序列被沉默染色质覆盖,其中Swi6(HP1)与赖氨酸9位甲基化的组蛋白H3结合,这种甲基化是由RNA干扰途径对非编码着丝粒转录本的作用诱导产生的。整体结构类似于后生动物着丝粒,其中动粒嵌入周围的异染色质中。动粒特异性蛋白与中央结构域结合并影响该区域的沉默。侧翼异染色质对于募集黏连蛋白和介导姐妹着丝粒之间紧密的物理黏连是必需的。伴随异染色质缺陷的沉默丧失作为研究着丝粒功能的工具具有重要价值。异染色质和动粒区域对于在DNA构建体上从头组装功能性着丝粒都是必需的,这表明异染色质可能提供一种促进中央结构域内动粒组装的环境。这个过程显然是由表观遗传调控的。裂殖酵母动粒与2 - 4根微管结合,侧翼异染色质可能是促进一个动粒上多个微管结合位点朝向同一极的方向排列从而防止着丝粒错误定向所必需的。

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