Telomere maintenance without telomerase
Telomere maintenance without telomerase
复制标题
DOI：
10.1007/s004120050225
复制
发表时间：
1997-07-01
期刊：
影响因子：
1.6
通讯作者：
Mason, JM
中科院分区：
文献类型：
--
作者：
Biessmann, H;Mason, JM
端粒是真核生物染色体末端的核蛋白结构，具有多种重要功能。它们允许细胞区分自然染色体末端和染色体断裂，以延迟细胞周期和修复断裂的末端。端粒也弥补了DNA聚合酶无法完全复制染色体的缺陷。在大多数真核生物中，一种特殊的逆转录酶，端粒酶，利用内部RNA模板将端粒DNA重复序列添加到染色体末端。然而，越来越多的证据表明，在各种真核生物中存在替代的延伸机制。在通常使用端粒酶的酵母、酿酒酵母和人类中，当端粒酶失活或失活时，一种不同的机制可用于维持染色体长度。酵母显然利用重组来达到这个目的；人类的机制尚不清楚。另一方面，一些昆虫和植物物种不使用端粒酶作为维持染色体长度的主要机制。果蝇利用特定的逆转录转座子来实现这一目的，而其他双翅目动物则使用重组。我们在这里总结了这些备选端粒延伸机制的当前知识。
Telomeres are nucleoprotein structures at the ends of eukaryotic chromosomes that perform a number of vital functions. They allow a cell to distinguish between natural chromosome ends and chromosome breaks in order to delay the cell cycle and repair the broken end. Telomeres also compensate for the inability of DNA polymerase to replicate the chromosome completely. In most eukaryotes a special reverse transcriptase, telomerase, adds telomeric DNA repeats to the chromosome ends using an internal RNA template. However, evidence is accumulating for alternative elongation mechanisms in a variety of eukaryotes. In the yeast Saccharomyces cerevisiae, and possibly in humans, both of which normally use telomerase, a different mechanism can be used for chromosome length maintenance when telomerase is inactive or inactivated. Yeast apparently uses recombination for this purpose; the mechanism in humans is not known. Some insect and plant species, on the other hand, do not use telomerase as their primary mechanism for maintaining chromosome length. Drosophila makes use of specific retrotransposons for this purpose, while other dipterans use recombination. We summarize here the current knowledge of these alternative telomere elongation mechanisms.