Kinetochore assembly and heterochromatin formation occur autonomously in Schizosaccharomyces pombe
Kinetochore assembly and heterochromatin formation occur autonomously in Schizosaccharomyces pombe
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DOI：
10.1073/pnas.1216934111
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发表时间：
2014-02-04
影响因子：
11.1
通讯作者：
Loose, Matthew W.
中科院分区：
文献类型：
--
作者：
Brown, William R. A.;Thomas, Geraint;Loose, Matthew W.
多细胞真核生物中的动粒通常与异染色质有关。这种异染色质是否只是促进细胞分裂时染色体精确分离所必需的凝聚力，或者它是否也在动粒组装中起作用，目前还不清楚。粟酒裂殖酵母是研究着丝粒功能的重要实验系统，但以前对该物种的所有工作都利用了单个菌株或其衍生物。实验室菌株和大多数其他S.粟酒裂殖酵母菌株含有三条染色体，但最近发现的一种菌株CBS 2777含有四条染色体。我们发现CBS 2777的基因组与实验室菌株通过复杂的染色体重排相关。因此，CBS 2777中的两个着丝粒含有实验室菌株着丝粒中存在的中心核心序列，但缺乏相邻的异染色质。离这些重排的动粒最近的异染色质块类似于100 kb以外的新端粒。尽管缺乏大量的相邻异染色质，重排的动粒结合CENP-A（Cnp 1）和CENP-C-Cnp 3在类似的数量和类似的特异性作为实验室菌株。对这一结果最简单的解释是，组成性动粒组装和异染色质形成自主发生。
Kinetochores in multicellular eukaryotes are usually associated with heterochromatin. Whether this heterochromatin simply promotes the cohesion necessary for accurate chromosome segregation at cell division or whether it also has a role in kinetochore assembly is unclear. Schizosaccharomyces pombe is an important experimental system for investigating centromere function, but all of the previous work with this species has exploited a single strain or its derivatives. The laboratory strain and most other S. pombe strains contain three chromosomes, but one recently discovered strain, CBS 2777, contains four. We show that the genome of CBS 2777 is related to that of the laboratory strain by a complex chromosome rearrangement. As a result, two of the kinetochores in CBS 2777 contain the central core sequences present in the laboratory strain centromeres, but lack adjacent heterochromatin. The closest block of heterochromatin to these rearranged kinetochores is similar to 100 kb away at new telomeres. Despite lacking large amounts of adjacent heterochromatin, the rearranged kinetochores bind CENP-A(Cnp1) and CENP-C-Cnp3 in similar quantities and with similar specificities as those of the laboratory strain. The simplest interpretation of this result is that constitutive kinetochore assembly and heterochromatin formation occur autonomously.