Gene duplication and exon shuffling by helitron-like transposons generate intraspecies diversity in maize
Gene duplication and exon shuffling by helitron-like transposons generate intraspecies diversity in maize
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DOI：
10.1038/ng1615
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发表时间：
2005-09-01
期刊：
影响因子：
30.8
通讯作者：
Rafalski, A
中科院分区：
文献类型：
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作者：
Morgante, M;Brunner, S;Rafalski, A
我们报告了一个全基因组比较基因内容的等位基因BAC重叠群从两个玉米自交系。基因含量多态性涉及多达10，000个序列，主要由DNA插入产生。我们分析的九个基因插入中的八个的末端共享helitron滚环转座子的结构特征（1-3）。由helitron末端定义的DNA片段包含多个基因衍生的片段，并具有非自主helitron样转座子的典型结构。在多个基因组位置发现了密切相关的插入。其中一些产生了包含不同基因片段的转录本，支持这些转座事件在外显子改组和新蛋白质进化中发挥作用的观点。我们确定了假定的自主helitron元素，并找到了他们的转录证据。玉米中的Helitrons似乎不断产生新的非自主元件，这些元件负责将基因片段重复插入到新的位置和前所未有的基因多样性。玉米基因组是在不断变化的，因为转座因子继续改变基因组的基因和非基因部分，深刻地影响遗传多样性。
We report a whole- genome comparison of gene content in allelic BAC contigs from two maize inbred lines. Genic content polymorphisms involve as many as 10,000 sequences and are mainly generated by DNA insertions. The termini of eight of the nine genic insertions that we analyzed shared the structural hallmarks of helitron rolling- circle transposons(1-3). DNA segments defined by helitron termini contained multiple gene- derived fragments and had a structure typical of nonautonomous helitron- like transposons. Closely related insertions were found in multiple genomic locations. Some of these produced transcripts containing segments of different genes, supporting the idea that these transposition events have a role in exon shuffling and the evolution of new proteins. We identified putative autonomous helitron elements and found evidence for their transcription. Helitrons in maize seem to continually produce new nonautonomous elements responsible for the duplicative insertion of gene segments into new locations and for the unprecedented genic diversity. The maize genome is in constant flux, as transposable elements continue to change both the genic and nongenic fractions of the genome, profoundly affecting genetic diversity.