Despite their essentiality for chromosome segregation, centromeres are diverse among eukaryotes and embody two main configurations: mono- and holocentromeres, referring respectively to a localized or unrestricted distribution of centromeric activity. Previous studies revealed that holocentricity in many insects coincides with the loss of the otherwise essential centromere component CenH3 (CENP-A), suggesting a molecular link between the two events. In this study, we leveraged recently-identified centromere components to map and characterize the centromeres of Bombyx mori. This uncovered a robust correlation between centromere profiles and regions of low chromatin dynamics. Transcriptional perturbation experiments showed that low chromatin activity is crucial for centromere formation in B. mori. Our study points to a novel mechanism of centromere formation that occurs in a manner recessive to the chromosome-wide chromatin landscape. Based on similar profiles in additional Lepidoptera, we propose an evolutionarily conserved mechanism that underlies the establishment of holocentromeres through loss of centromere specificity.

中文翻译：

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鳞翅目中CenH3缺陷型全着丝粒的分子结构取决于转录和染色质动力学

尽管着丝粒对染色体分离至关重要，但在真核生物中着丝粒却是多种多样的，并具有两个主要构型：单着丝粒和全着丝粒，分别指着丝粒活性的局部或不受限制的分布。先前的研究表明，许多昆虫的整体中心性与原本必不可少的着丝粒成分CenH3（CENP-A）的丢失相吻合，表明这两个事件之间存在分子联系。在这项研究中，我们利用最近确定的着丝粒成分来绘制和鉴定家蚕的着丝粒。这揭示了着丝粒概况和低染色质动力学区域之间的强相关性。转录扰动实验表明，低染色质活性对于桑蚕中着丝粒的形成至关重要。我们的研究指出了一种着丝粒形成的新机制，这种机制以隐性方式出现在整个染色体上的染色质景观中。基于其他鳞翅目中的相似概况，我们提出了一种进化保守的机制，该机制是通过着丝粒特异性丧失而建立整体着丝粒的基础。