Functional mapping of a trypanosome centromere by chromosome fragmentation identifies a 16-kb GC-rich transcriptional "strand-switch"' domain as a major feature
Functional mapping of a trypanosome centromere by chromosome fragmentation identifies a 16-kb GC-rich transcriptional "strand-switch"' domain as a major feature
复制标题
DOI：
10.1101/gr.2895105
复制
发表时间：
2005-01-01
期刊：
影响因子：
7
通讯作者：
Kelly, JM
中科院分区：
文献类型：
--
作者：
Obado, SO;Taylor, MC;Kelly, JM
锥虫是一个古老的家族，在进化早期就与主要的真核生物谱系分离，表现出一些独特的基因组织和表达特征。尽管基因组测序现已完成，但这些和其他寄生原生动物中着丝粒的性质尚未得到解决。在这里，我们报告了美洲锥虫（Trypanosoma cruzi）中着丝粒的功能图谱，这种寄生虫具有不寻常的遗传交换机制，涉及通过核杂交产生非整性。使用端粒相关的染色体断裂方法，我们发现3号染色体有丝分裂稳定性所需的区域包含由16kb富含GC的岛构成的转录“链开关”结构域。该结构域包含几个简并的逆转录转座子样插入，但非典型地缺乏通常与着丝粒区域相关的卫星重复序列。这种不寻常的组织类型可能代表了克氏锥虫和其他原始真核生物着丝粒的范例。
Trypanosomatids are an ancient family that diverged from the main eukaryotic lineage early in evolution, which display several unique features of gene organization and expression. Although genome sequencing is now complete, the nature of centromeres in these and other parasitic protozoa has not been resolved. Here, we report the functional mapping of a centromere in the American trypanosome, Trypanosoma cruzi, a parasite with an unusual mechanism of genetic exchange that involves the generation of aneupioidy by nuclear hybridization. Using a telomere-associated chromosome fragmentation approach, we show that the region required for the mitotic stability of chromosome 3 encompasses a transcriptional "strand-switch" domain constituted by a 16-kb GC-rich island. The domain contains several degenerate retrotransposon-like insertions, but atypically, lacks the arrays of satellite repeats normally associated with centromeric regions. This unusual type of organization may represent a paradigm for centromeres in T. cruzi and other primitive eukaryotes.