Wellinger R J, Zakian V A
Fred Hutchinson Cancer Research Center, Seattle, WA 98104.
Proc Natl Acad Sci U S A. 1989 Feb;86(3):973-7. doi: 10.1073/pnas.86.3.973.
In the yeast Saccharomyces cerevisiae, origins of replication (autonomously replicating sequences; ARSs), centromeres, and telomeres have been isolated and characterized. The identification of these structures allows the construction of artificial chromosomes in which the architecture of eukaryotic chromosomes may be studied. A common feature of most, and possibly all, natural yeast chromosomes is that they have an ARS within 2 kilobases of their physical ends. To study the effects of such telomeric ARSs on chromosome maintenance, we introduced artificial chromosomes of approximately 15 and 60 kilobases into yeast cells and analyzed the requirements for telomeric ARSs and the effects of ARS-free chromosomal arms on the stability of these molecules. We find that terminal blocks of telomeric repeats are sufficient to be recognized as telomeres. Moreover, artificial chromosomes containing telomere-associated Y' sequences and telomeric ARSs were no more stable during both mitosis and meiosis than artificial chromosomes lacking terminal ARSs, indicating that yeast-specific blocks of telomeric sequences are the only cis-acting requirement for a functional telomere during both mitotic growth and meiosis. The results also show that there is no requirement for an origin of replication on each arm of the artificial chromosomes, indicating that a replication fork may efficiently move through a functional centromere region.
在酿酒酵母中，复制起点（自主复制序列；ARSs）、着丝粒和端粒已被分离并进行了表征。这些结构的鉴定使得人工染色体的构建成为可能，通过人工染色体可以研究真核染色体的结构。大多数（可能所有）天然酵母染色体的一个共同特征是，它们在物理末端的2千碱基范围内有一个ARS。为了研究这种端粒ARS对染色体维持的影响，我们将大约15和60千碱基的人工染色体导入酵母细胞，并分析了对端粒ARS的需求以及无ARS染色体臂对这些分子稳定性的影响。我们发现端粒重复序列的末端片段足以被识别为端粒。此外，含有端粒相关Y'序列和端粒ARS的人工染色体在有丝分裂和减数分裂过程中并不比缺乏末端ARS的人工染色体更稳定，这表明酵母特异性的端粒序列片段是有丝分裂生长和减数分裂过程中功能性端粒唯一的顺式作用要求。结果还表明，人工染色体的每条臂上并不需要复制起点，这表明复制叉可以有效地穿过功能性着丝粒区域。
