Diatom centromeres suggest a mechanism for nuclear DNA acquisition
Diatom centromeres suggest a mechanism for nuclear DNA acquisition
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DOI：
10.1073/pnas.1700764114
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发表时间：
2017-07-18
影响因子：
11.1
通讯作者：
Weyman, Philip D.
中科院分区：
文献类型：
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作者：
Diner, Rachel E.;Nodding, Chari M.;Weyman, Philip D.
着丝粒对于所有真核生物的细胞分裂和生长都是必不可少的，并且它们的序列和结构的知识指导了用于功能细胞生物学研究的人工染色体的开发。着丝粒蛋白在真核生物中是保守的;然而，着丝粒DNA序列是高度可变的。我们结合正向和反向遗传学的方法与染色质免疫沉淀，以确定模式硅藻三角褐指藻的着丝粒。我们观察到25个独特的着丝粒序列，通常每个染色体出现一次，这一发现有助于解决核基因组组织，并表明单着丝粒区域着丝粒。硅藻着丝粒序列含有低GC含量的区域，但缺乏重复或其他保守的序列特征。具有与三角褐指藻着丝粒相似的GC含量的天然和外源序列可以维持附加体并募集硅藻着丝粒组蛋白CENH 3，这表明非天然序列也可以作为硅藻着丝粒起作用。因此，简单的序列要求可能使来自外源的DNA作为染色体外附加体在细胞核中持续存在，揭示了细胞器和外源DNA获取的潜在机制。
Centromeres are essential for cell division and growth in all eukaryotes, and knowledge of their sequence and structure guides the development of artificial chromosomes for functional cellular biology studies. Centromeric proteins are conserved among eukaryotes; however, centromeric DNA sequences are highly variable. We combined forward and reverse genetic approaches with chromatin immunoprecipitation to identify centromeres of the model diatom Phaeodactylum tricornutum. We observed 25 unique centromere sequences typically occurring once per chromosome, a finding that helps to resolve nuclear genome organization and indicates monocentric regional centromeres. Diatom centromere sequences contain low-GC content regions but lack repeats or other conserved sequence features. Native and foreign sequences with similar GC content to P. tricornutum centromeres can maintain episomes and recruit the diatom centromeric histone protein CENH3, suggesting nonnative sequences can also function as diatom centromeres. Thus, simple sequence requirements may enable DNA from foreign sources to persist in the nucleus as extrachromosomal episomes, revealing a potential mechanism for organellar and foreign DNA acquisition.