The reported point centromeres of Scheffersomyces stipitis are retrotransposon long terminal repeats
The reported point centromeres of Scheffersomyces stipitis are retrotransposon long terminal repeats
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DOI：
10.1002/yea.3375
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发表时间：
2019-05-01
期刊：
影响因子：
2.6
通讯作者：
Wolfe, Kenneth H.
中科院分区：
文献类型：
--
作者：
Coughlan, Aisling Y.;Wolfe, Kenneth H.
点着丝粒存在于一些子囊菌酵母（例如酿酒酵母）中，其结构与其他真核生物的着丝粒有很大不同。它们很小且不重复，仅包含两个短的保守序列基序。直到最近，点着丝粒还被认为具有单一的进化起源，即芽殖酵母家族。该家族以外的大多数酵母都具有数千碱基大小的着丝粒。有些具有由大的反向重复序列组成的着丝粒，其他具有逆转录转座子的着丝粒簇，而包括白色念珠菌在内的第三组具有没有保守序列特征的着丝粒。最近有报道称，树干树干酵母（Scheffersomyces stipitis）的点着丝粒具有高度保守的 125 bp 核心序列，这是出乎意料的，因为树干酵母仅与已知的点着丝粒物种有远缘关系。我们在这里表明，125 bp 核心序列实际上是 Ty5 样逆转录转座子 Tps5 的长末端重复序列 (LTR) 的一部分，它在每个树干树干染色体的着丝粒区域形成一个簇。因此，当着丝粒相关的逆转录转座子克隆到质粒中时，LTR 赋予着丝粒样有丝分裂稳定性。 S. stipitis 的着丝粒区域包含三种类型的 Tps5 元件（Tps5a、Tps5b 和 Tps5c）和非编码非自主大型逆转录转座子衍生物。
Point centromeres, found in some ascomycete yeasts such Saccharomyces cerevisiae, are very different in structure from the centromeres of other eukaryotes. They are tiny and nonrepetitive and contain only two short conserved sequence motifs. Until recently, point centromeres were thought to have a single evolutionary origin, in the budding yeast family Saccharomycetaceae. Most yeasts outside this family have centromeres that are many kilobases in size. Some have centromeres consisting of a large inverted repeat sequence, others have centromeric clusters of retrotransposons, and a third group including Candida albicans has centromeres with no conserved sequence features. It was recently reported that Scheffersomyces stipitis has point centromeres with a strongly conserved 125-bp core sequence, which is unexpected because S. stipitis is only distantly related to the known point-centromere species. We show here that the 125-bp core sequence is actually part of the long terminal repeat (LTR) of the Ty5-like retrotransposon Tps5, which forms a cluster in the centromeric region of each S. stipitis chromosome. Thus, the LTR of a centromere-associated retrotransposon confers centromere-like mitotic stability when cloned into a plasmid. The centromeric regions of S. stipitis contain three types of Tps5 element (Tps5a, Tps5b, and Tps5c) and a noncoding nonautonomous large retrotransposon derivative.