Effects of yeast DNA topoisomerase III on telomere structure.
Effects of yeast DNA topoisomerase III on telomere structure.
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酵母DNA拓扑异构酶III对端粒结构的影响。
DOI：
10.1073/pnas.92.7.2667
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发表时间：
1995
影响因子：
11.1
通讯作者：
Wang,JC
中科院分区：
文献类型：
--
作者：
Kim,RA;Caron,PR;Wang,JC
酵母的TOP3基因编码DNA拓扑异构酶III， EST1基因编码一种假定的端粒酶，这两个起始密码子在12号染色体上头接头，两个起始密码子相隔258 bp。这种排列表明，这两个基因可能具有共同的上游调控序列，它们的产物可能在功能上相关。酵母TOP3+和delta TOP3的等基因对比较表明，delta TOP3细胞的G1-3T重复序列轨迹明显缩短，约为150 bp。缺乏拓扑异构酶III的细胞在亚端粒区域也显示出更高的序列流动性。在delta top3细胞中，由两个或多个Y′元素组成的簇由于元素的丢失或分散而有很高的消失趋势；同样，嵌入在靠近染色体尖端的Y'元件中的URA3标记，相对于TOP3+细胞，其丢失率要高得多。这些结果表明酵母DNA拓扑异构酶III可能影响端粒稳定性，并讨论了可能的机制。
The yeast TOP3 gene, encoding DNA topoisomerase III, and EST1 gene, encoding a putative telomerase, are shown to be abutted head-to-head on chromosome XII, with the two initiation codons separated by 258 bp. This arrangement suggests that the two genes might share common upstream regulatory sequences and that their products might be functionally related. A comparison of isogenic pairs of yeast TOP3+ and delta top3 strains indicates that the G1-3T repetitive sequence tracks in delta top3 cells are significantly shortened, by about 150 bp. Cells lacking topoisomerase III also show a much higher sequence fluidity in the subtelomeric regions. In delta top3 cells, clusters of two or more copies of tandemly arranged Y' elements have a high tendency of disappearing due to the loss or dispersion of the elements; similarly, a URA3 marker embedded in a Y' element close to the chromosomal tip shows a much higher rate of being lost relative to that in TOP3+ cells. These results suggest that yeast DNA topoisomerase III might affect telomere stability, and plausible mechanisms are discussed.