MERISTEM DISORGANIZATION1 Encodes TEN1, an Essential Telomere Protein That Modulates Telomerase Processivity in Arabidopsis
MERISTEM DISORGANIZATION1 Encodes TEN1, an Essential Telomere Protein That Modulates Telomerase Processivity in Arabidopsis
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DOI：
10.1105/tpc.112.107425
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发表时间：
2013-04-01
期刊：
影响因子：
11.6
通讯作者：
Shippen, Dorothy E.
中科院分区：
文献类型：
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作者：
Leehy, Katherine A.;Lee, Jung Ro;Shippen, Dorothy E.
端粒可以保护染色体末端不被识别为 DNA 损伤，并且促进线性染色体的完整复制。 CST [CTC1(Cdc13)/STN1/TEN1] 是一种三聚体染色体末端结合复合物，涉及端粒功能的两个方面。在这里，我们表征了开花植物拟南芥中的 TEN1。我们报告说，TEN1（与 Stn1 相关的端粒通路，Stn1 代表 cdc 13 的抑制子）是由先前表征的基因 MERISTEM DISORGANIZATION1 (MDO1) 编码的。 MDO1 的点突变 mdo1-1/ten1-3 (G77E) 可触发干细胞分化和死亡以及组成型 DNA 损伤反应。我们提供的生化和遗传学证据表明 ten1-3 很可能是无效突变。与 ctc1 和 stn1 无效突变体一样，ten1-3 中的端粒束比野生型更短且更异质。突变体还表现出频繁的端粒融合、单链端粒 DNA 和端粒环的增加。然而，与 stn1 或 ctc1 突变体不同，ten1-3 突变体中的端粒酶活性由于重复添加过程能力的增加而升高。此外，检测到的 TEN1 端粒部分明显小于 CTC1。这些数据表明 TEN1 对于端粒稳定性至关重要，并且在调节端粒酶活性方面也发挥着意想不到的作用。
Telomeres protect chromosome ends from being recognized as DNA damage, and they facilitate the complete replication of linear chromosomes. CST [for CTC1(Cdc13)/STN1/TEN1] is a trimeric chromosome end binding complex implicated in both aspects of telomere function. Here, we characterize TEN1 in the flowering plant Arabidopsis thaliana. We report that TEN1 (for telomeric pathways in association with Stn1, which stands for suppressor of cdc thirteen) is encoded by a previously characterized gene, MERISTEM DISORGANIZATION1 (MDO1). A point mutation in MDO1, mdo1-1/ten1-3 (G77E), triggers stem cell differentiation and death as well as a constitutive DNA damage response. We provide biochemical and genetic evidence that ten1-3 is likely to be a null mutation. As with ctc1 and stn1 null mutants, telomere tracts in ten1-3 are shorter and more heterogeneous than the wild type. Mutants also exhibit frequent telomere fusions, increased single-strand telomeric DNA, and telomeric circles. However, unlike stn1 or ctc1 mutants, telomerase enzyme activity is elevated in ten1-3 mutants due to an increase in repeat addition processivity. In addition, TEN1 is detected at a significantly smaller fraction of telomeres than CTC1. These data indicate that TEN1 is critical for telomere stability and also plays an unexpected role in modulating telomerase enzyme activity.