Clarke L, Baum M P
Department of Biological Sciences, University of California, Santa Barbara 93106.
Mol Cell Biol. 1990 May;10(5):1863-72. doi: 10.1128/mcb.10.5.1863-1872.1990.
A circular minichromosome carrying functional centromere sequences (cen2) from Schizosaccharomyces pombe chromosome II behaves as a stable, independent genetic linkage group in S. pombe. The cen2 region was found to be organized into four large tandemly repeated sequence units which span over 80 kilobase pairs (kb) of untranscribed DNA. Two of these units occurred in a 31-kb inverted repeat that flanked a 7-kb central core of nonhomology. The inverted repeat region had centromere function, but neither the central core alone nor one arm of the inverted repeat was functional. Deletion of a portion of the repeated sequences that flank the central core had no effect on mitotic segregation functions or on meiotic segregation of a minichromosome to two of the four haploid progeny, but drastically impaired centromere-mediated maintenance of sister chromatid attachment in meiosis I. This requirement for centromere-specific repeated sequences could not be satisfied by introduction of random DNA sequences. These observations suggest a function for the heterochromatic repeated DNA sequences found in the centromere regions of higher eucaryotes.
携带粟酒裂殖酵母二号染色体功能性着丝粒序列（cen2）的环状微型染色体在粟酒裂殖酵母中表现为一个稳定、独立的遗传连锁群。发现cen2区域由四个大的串联重复序列单元组成，这些单元跨越超过80千碱基对（kb）的非转录DNA。其中两个单元存在于一个31 kb的反向重复序列中，该反向重复序列侧翼是一个7 kb的非同源中央核心序列。反向重复序列区域具有着丝粒功能，但单独的中央核心序列或反向重复序列的一个臂均无功能。删除中央核心序列侧翼的部分重复序列对有丝分裂分离功能或微型染色体在减数分裂时向四个单倍体后代中的两个进行分离没有影响，但严重损害了减数分裂I中着丝粒介导的姐妹染色单体附着的维持。引入随机DNA序列无法满足对着丝粒特异性重复序列的这一要求。这些观察结果提示了在高等真核生物着丝粒区域发现的异染色质重复DNA序列的一种功能。
