Analysis of the G-overhang structures on plant telomeres: evidence for two distinct telomere architectures.
Analysis of the G-overhang structures on plant telomeres: evidence for two distinct telomere architectures.
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植物端粒上 G 突出结构的分析：两种不同端粒结构的证据。
DOI：
10.1046/j.1365-313x.2000.00831.x
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
D. Shippen
中科院分区：
文献类型：
--
作者：
K. Ríha;T. McKnight;J. Fajkus;B. Vyskot;D. Shippen
端粒是维持真核生物基因组完整性所必需的高度保守结构。在酵母、纤毛虫和哺乳动物中，端粒的富G链在染色体末端形成3'突出端。在这里，我们调查的结构，在双子叶植物的端粒宽叶蝇子草和拟南芥使用PENT（引物延伸/缺口翻译）检测。我们发现，拟南芥和Silene端粒携带G-突出超过20-30个核苷酸。然而，与酵母和纤毛虫端粒相反，只有一半的端粒在蝇子草幼苗具有可检测的G-突出。使用多种引物和反应条件的PENT反应揭示了Silene端粒的剩余部分不携带突出端或长度小于12个核苷酸的突出端。在缺乏端粒酶活性的蝇子草种子和叶片组织中观察到G-突出端。这些发现表明，滞后链的不完全DNA复制，而不是端粒酶的合成，是植物中G-突出端合成的主要机制。出乎意料的是，我们发现，可检测到的G-突出端的端粒的分数从幼苗中的50%下降到叶片中的35%。这种差异可能反映了成熟叶片中G-突出端对核酸酶攻击的敏感性增加，这一事件可能是伴随叶片衰老的分解代谢过程的前兆
Telomeres are highly conserved structures essential for maintaining the integrity of eukaryotic genomes. In yeast, ciliates and mammals, the G-rich strand of the telomere forms a 3' overhang on the chromosome terminus. Here we investigate the architecture of telomeres in the dicot plants Silene latifolia and Arabidopsis thaliana using the PENT (primer extension/nick translation) assay. We show that both Arabidopsis and Silene telomeres carry G-overhangs longer than 20-30 nucleotides. However, in contrast to yeast and ciliate telomeres, only half of the telomeres in Silene seedlings possess detectable G-overhangs. PENT reactions using a variety of primers and reaction conditions revealed that the remaining fraction of Silene telomeres carries either no overhangs or overhangs less than 12 nucleotides in length. G-overhangs were observed in Silene seeds and leaves, tissues that lack telomerase activity. These findings suggest that incomplete DNA replication of the lagging strand, rather than synthesis by telomerase, is the primary mechanism for G-overhang synthesis in plants. Unexpectedly, we found that the fraction of telomeres with detectable G-overhangs decreased from 50% in seedlings to 35% in leaves. The difference may reflect increased susceptibility of the G-overhangs to nuclease attack in adult leaves, an event that could act as a precursor for the catabolic processes accompanying leaf senescence
DOI：
10.1073/pnas.93.25.14422
发表时间：
1996-12-10
影响因子：
11.1
作者：
Fitzgerald, MS;McKnight, TD;Shippen, DE
通讯作者：
Shippen, DE
影响因子：
3.7
作者：
Wright, WE;Tesmer, VM;Shay, JW
通讯作者：
Shay, JW