The mitochondrial genome of the gymnosperm Cycas taitungensis contains a novel family of short interspersed elements, Bpu sequences, and abundant RNA editing sites
The mitochondrial genome of the gymnosperm Cycas taitungensis contains a novel family of short interspersed elements, Bpu sequences, and abundant RNA editing sites
复制标题
DOI：
10.1093/molbev/msn009
复制
发表时间：
2008-03-01
影响因子：
10.7
通讯作者：
Chou, The-Yuan
中科院分区：
文献类型：
--
作者：
Chaw, Shu-Miaw;Shih, Arthur Chun-Chieh;Chou, The-Yuan
台东苏铁的mtDNA是一个414，903 bp的环状分子，比轮藻和苔藓植物的mtDNA大2- 6倍，但与7种被子植物mtDNA的平均值相似。它的特点是丰富的RNA编辑位点（1，084），是被子植物mtDNA中发现的数量的两倍多。苏铁线粒体DNA的A + T含量为53.1%，是已知陆生植物中最低的。苏铁线粒体DNA中约有5%的序列由一个新的移动的元件家族组成，我们将其命名为“Bpu序列”。它们共有36 bp的共有序列，具有2个末端直接重复序列（AAGG）和Bpu 10 I限制性内切酶（CCTGAAGC）的识别位点。苏铁mtDNA与其他植物mtDNA的比较揭示了许多陆地植物mtDNA生物学和进化的新见解。例如，随着陆地植物的进化，线粒体DNA中的非编码序列急剧增加，在芽生植物中突然增加，然后在种子植物中出现。因此，种子植物mtDNA的基因组组织远不如其他植物紧密。此外，苏铁mtDNA似乎已从被子植物mtDNA中观察到的频繁的基因丢失中豁免。与被子植物相似，苏铁的3个基因nad 1、nad 2和nad 5被5个II组内含子序列破坏，这使基因进入反式剪接排列。对苏铁线粒体DNA中Bpu序列的进化起源和入侵/复制机制进行了推测和讨论。
The mtDNA of Cycas taitungensis is a circular molecule of 414,903 bp, making it 2- to 6-fold larger than the known mtDNAs of charophytes and bryophytes, but similar to the average of 7 elucidated angiosperm mtDNAs. It is characterized by abundant RNA editing sites (1,084), more than twice the number found in the angiosperm mtDNAs. The A + T content of Cycas mtDNA is 53.1%, the lowest among known land plants. About 5% of the Cycas mtDNA is composed of a novel family of mobile elements, which we designated as "Bpu sequences.'' They share a consensus sequence of 36 bp with 2 terminal direct repeats (AAGG) and a recognition site for the Bpu 10I restriction endonuclease (CCTGAAGC). Comparison of the Cycas mtDNA with other plant mtDNAs revealed many new insights into the biology and evolution of land plant mtDNAs. For example, the noncoding sequences in mtDNAs have drastically expanded as land plants have evolved, with abrupt increases appearing in the bryophytes, and then in the seed plants. As a result, the genomic organizations of seed plant mtDNAs are much less compact than in other plants. Also, the Cycas mtDNA appears to have been exempted from the frequent gene loss observed in angiosperm mtDNAs. Similar to the angiosperms, the 3 Cycas genes nad1, nad2, and nad5 are disrupted by 5 group II intron squences, which have brought the genes into trans-splicing arrangements. The evolutionary origin and invasion/duplication mechanism of the Bpu sequences in Cycas mtDNA are hypothesized and discussed.