The complete plastid genome sequence of the parasitic green alga Helicosporidium sp is highly reduced and structured
The complete plastid genome sequence of the parasitic green alga Helicosporidium sp is highly reduced and structured
复制标题
DOI：
10.1186/1741-7007-4-12
复制
发表时间：
2006-04-21
期刊：
影响因子：
5.4
通讯作者：
Keeling, Patrick J.
中科院分区：
文献类型：
--
作者：
de Koning, Audrey P.;Keeling, Patrick J.
背景资料：光合作用的丧失已经独立地发生在几种植物和藻类谱系中，并且代表了对质体基因组的内容和结构具有潜在后果的主要代谢转变。要调查这样的变化，我们测序的完整的质体基因组的寄生，非光合作用的绿色昆虫，Helicosporidium.Results：Helicosporidium质体基因组是已知的最小的（37.5 kb），像其他质体从非光合作用的生物，它缺乏所有的基因蛋白质的光合作用。然而，它的缩小不仅仅是因为基因的丢失;它几乎没有非编码DNA，只有一个内含子和微小的基因间空间，没有反向重复（根本没有重复基因）。它精确地编码翻译通用遗传密码所需的最低限度的tRNA，并消除了所有多余的isoceptor。螺旋孢子虫质体基因组也是高度结构化的，每一半的环状基因组包含几乎所有的基因在一条链上。Helicosporidium是已知的是相关的trebouxiophyte绿色藻类，但基因组的结构和紧凑的方式更让人想起apicomplexan parasites.Conclusion的非光合质体：Helicosporidium有助于显着我们了解的质体DNA的进化，因为它说明了高度有序的减少，发生以下损失的主要代谢功能。螺旋孢子虫和顶复门的质体基因组结构的趋同提出了一种有趣的可能性，即在生物体失去光合作用后，有共同的力量塑造质体基因组。
Background: Loss of photosynthesis has occurred independently in several plant and algal lineages, and represents a major metabolic shift with potential consequences for the content and structure of plastid genomes. To investigate such changes, we sequenced the complete plastid genome of the parasitic, non-photosynthetic green alga, Helicosporidium.Results: The Helicosporidium plastid genome is among the smallest known ( 37.5 kb), and like other plastids from non-photosynthetic organisms it lacks all genes for proteins that function in photosynthesis. Its reduced size results from more than just loss of genes, however; it has little non-coding DNA, with only one intron and tiny intergenic spaces, and no inverted repeat ( no duplicated genes at all). It encodes precisely the minimal complement of tRNAs needed to translate the universal genetic code, and has eliminated all redundant isoacceptors. The Helicosporidium plastid genome is also highly structured, with each half of the circular genome containing nearly all genes on one strand. Helicosporidium is known to be related to trebouxiophyte green algae, but the genome is structured and compacted in a manner more reminiscent of the non-photosynthetic plastids of apicomplexan parasites.Conclusion: Helicosporidium contributes significantly to our understanding of the evolution of plastid DNA because it illustrates the highly ordered reduction that occurred following the loss of a major metabolic function. The convergence of plastid genome structure in Helicosporidium and the Apicomplexa raises the interesting possibility that there are common forces that shape plastid genomes, subsequent to the loss of photosynthesis in an organism.