Liao C, Rovira C, He H, Edström J E
Department of Genetics, Lund University, Sölvegatan 29 S-22362 Lund, Sweden.
J Mol Biol. 1998 Jul 31;280(5):811-21. doi: 10.1006/jmbi.1998.1896.
A SINE-like dispersed element, Cp1, from the dipteran Chironomus pallidivittatus was found to show site-specific insertion into two different centromeric tandem repeats. The insertions result in identical target site duplications of nine base-pairs. In contrast, extracentromeric Cp1 elements, which are polymorphic and degenerate, are previously known to be surrounded by different target site duplications. The intracentromeric Cp1 is uniform in structure and contains a single pol III unit, upstream of which 87 bp arms of a palindrome surround a 103 bp unique sequence. The numbers of Cp1 elements per centromere were determined in microdissected material and were found to be in the range of five to ten units per centromere. The well-defined insertion properties, correlated to chromosomal localization, suggest that Cp1 is likely to be a component of importance for the centromere. Similarities of Cp1 and its parts to functionally identified centromeres in Saccharomyces cerevisiae and Schizosaccharomyces pombe are discussed.
在双翅目昆虫苍白摇蚊中发现了一种类似SINE的分散元件Cp1，它能位点特异性插入到两种不同的着丝粒串联重复序列中。这些插入导致了相同的9个碱基对的靶位点重复。相比之下，着丝粒外的Cp1元件具有多态性且已退化，此前已知其周围有不同的靶位点重复序列。着丝粒内的Cp1结构一致，包含一个单一的聚合酶III单元，在其上游，一个回文结构的87 bp臂围绕着一个103 bp的独特序列。通过显微切割材料确定了每个着丝粒中Cp1元件的数量，发现每个着丝粒中Cp1元件的数量在5到10个单位之间。与染色体定位相关的明确插入特性表明，Cp1可能是着丝粒的重要组成部分。文中还讨论了Cp1及其部分与酿酒酵母和粟酒裂殖酵母中功能已明确的着丝粒的相似性。
