Williams B C, Murphy T D, Goldberg M L, Karpen G H
Section of Genetics and Development, Cornell University, Ithaca, New York 14853, USA.
Nat Genet. 1998 Jan;18(1):30-7. doi: 10.1038/ng0198-30.
Chromosome fragments that lack centromeric DNA (structurally acentric chromosomes) are usually not inherited in mitosis and meiosis. We previously described the isolation, after irradiation of a Drosophila melanogaster mini-chromosome, of structurally acentric mini-chromosomes that display efficient mitotic and meiotic transmission despite their small size (under 300 kb) and lack of centromeric DNA. Here we report that these acentric mini-chromosomes bind the centromere-specific protein ZW10 and associate with the spindle poles in anaphase. The sequences in these acentric mini-chromosomes were derived from the tip of the X chromosome, which does not display centromere activity or localize ZW10, even when separated from the rest of the X. We conclude that the normally non-centromeric DNAs present in these acentric mini-chromosomes have acquired centromere function, and suggest that this example of 'neocentromere' formation involves appropriation of a self-propagating centromeric chromatin structure. The potential relevance of these observations to the identity, propagation and function of normal centromeres is discussed.
缺乏着丝粒DNA的染色体片段（结构上无着丝粒的染色体）通常在有丝分裂和减数分裂中不会遗传。我们之前描述过，在对黑腹果蝇的一条小染色体进行辐射后，分离出了结构上无着丝粒的小染色体，尽管它们体积小（小于300 kb）且缺乏着丝粒DNA，但仍表现出高效的有丝分裂和减数分裂传递。在此我们报告，这些无着丝粒小染色体结合着丝粒特异性蛋白ZW10，并在后期与纺锤体极相关联。这些无着丝粒小染色体中的序列源自X染色体的末端，即使与X染色体的其余部分分离，该末端也不显示着丝粒活性或定位ZW10。我们得出结论，这些无着丝粒小染色体中存在的通常非着丝粒DNA已获得着丝粒功能，并表明这种“新着丝粒”形成的例子涉及对一种自我传播的着丝粒染色质结构的挪用。我们还讨论了这些观察结果与正常着丝粒的身份、传播和功能的潜在相关性。
