Analysis of Carica papaya Telomeres and Telomere-Associated Proteins: Insights into the Evolution of Telomere Maintenance in Brassicales.
Analysis of Carica papaya Telomeres and Telomere-Associated Proteins: Insights into the Evolution of Telomere Maintenance in Brassicales.
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DOI：
10.1007/s12042-008-9018-x
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发表时间：
2008-12
影响因子：
2
通讯作者：
Shippen, D E
中科院分区：
文献类型：
--
作者：
Shakirov, E V;Salzberg, S L;Alam, M;Shippen, D E
端粒是真核生物线性染色体的末端区域，对基因组稳定性和细胞持续增殖至关重要。木瓜基因组的草案大会提供了一个机会，分析和比较端粒DNA序列组成和端粒维持机制的进化，在这个和其他生物的拟南芥目，其中包括拟南芥。在这里，我们调查端粒的大小和序列变异在番木瓜染色体末端。与大多数其他植物物种一样，木瓜端粒由TTTAGGG重复序列组成。然而，与密切相关的拟南芥科的成员相比，木瓜中的端粒长约10倍。序列分析表明，番木瓜中的许多近着丝粒端粒重复序列含有Gs和Ts的核苷酸替换和插入。相比之下，我们发现很少的N-到-C取代，甚至更少的情况下，核苷酸缺失，这表明一个六核苷酸端粒重复是不能很好地耐受。木瓜基因组编码参与端粒维持和染色体末端保护的几个基因的单拷贝序列同源物，包括端粒酶逆转录酶（TERT）和端粒保护（POT 1）。值得注意的是，与编码六种端粒重复序列结合因子样（TRFL）蛋白的拟南芥不同，木瓜似乎只编码两种这样的蛋白。因此，更精简的木瓜基因组将为植物端粒的比较和功能分析提供极好的资源。
Telomeres are terminal regions of linear eukaryotic chromosomes that are critical for genome stability and continued cell proliferation. The draft assembly of the papaya genome provides an opportunity to analyze and compare the evolution of telomeric DNA sequence composition and telomere maintenance machinery in this and other organisms of the Brassicales Order, which includes Arabidopsis. Here we investigate telomere size and sequence variation at papaya chromosome ends. As with most other plant species, papaya telomeres consist of TTTAGGG repeats. However, in contrast to members of the closely related Brassicaceae family, telomeres in papaya are ~10-fold longer. Sequence analysis reveals that many centromereproximal telomere repeats in papaya harbor nucleotide substitutions and insertions of Gs and Ts. In contrast, we found very few N-to-C substitutions, and even fewer instances of nucleotide deletion, suggesting that a six-nucleotide telomere repeat is not well tolerated. The papaya genome encodes single-copy sequence homologues of several genes involved in telomere maintenance and chromosome end protection, including the Telomerase Reverse Transcriptase (TERT) and Protection Of Telomeres (POT1). Notably, unlike Arabidopsis, which encodes six Telomere Repeat binding Factor-like (TRFL) proteins that bind double-stranded telomere DNA, papaya appears to encode only two such proteins. Thus, the more streamlined genome of papaya will provide an excellent resource for comparative and functional analysis of telomeres in plants.