The complete chloroplast genome sequence of the chlorophycean green alga Scenedesmus obliquus reveals a compact gene organization and a biased distribution of genes on the two DNA strands.
The complete chloroplast genome sequence of the chlorophycean green alga Scenedesmus obliquus reveals a compact gene organization and a biased distribution of genes on the two DNA strands.
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DOI：
10.1186/1471-2148-6-37
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发表时间：
2006-04-25
影响因子：
3.4
通讯作者：
Turmel M
中科院分区：
文献类型：
--
作者：
de Cambiaire JC;Otis C;Lemieux C;Turmel M
绿藻门包含了绿藻的大部分，分为四个纲。虽然绿藻亚科的基本位置已经确定，但绿藻亚科、银藻亚科和绿藻亚科(UTC)的分化顺序仍然不确定。目前获得的五个完整的叶绿体DNA(CpDNA)序列在总体结构、基因含量、基因密度、内含子含量和基因顺序上显示出相当大的差异性。在这些基因组中，绿藻衣藻的基因组保留了最少的祖先特征。这两个被大的反向重复(IR)隔开的单复制区具有相似的大小，而不是不相等的大小，并且相对于原生植物和绿藻cpDNA的单复制区，它们在基因内容和基因组织上都有根本的不同。为了深入了解叶绿素绿藻进化过程中叶绿体基因组的各种变化，我们对斜生栅藻的cpDNA进行了测序，斜生栅藻是一个独特的叶绿素家族成员。Scenedesmus基因组包含161,452bp的IR区，具有相似大小的单拷贝区域，编码96个基因，即相对于其衣藻同源物仅增加两个基因(infA和rpl12)，并包含七个第一组内含子和两个第二组内含子。它明显比迄今检测到的四种UTC藻类cpDNA更紧凑，在这些藻类中显示出最低的短重复比例，并且与衣藻cpDNA相比，它在同一DNA链上的基因聚集方面表现出更强的偏向。与后者的基因组一样，栅栏藻cpDNA只显示了几个祖先的基因簇。这两个叶绿素类植物基因组共有11个基因簇，这些基因簇是以前测得的树芽和绿藻cpDNA中没有的，也有一些基因具有不同的结构；然而，它们的单复制区在基因含量上有很大的差异。我们的结果强调了叶绿体基因组的显著可塑性。由于这种可塑性，只能为栅藻和衣藻的最后共同祖先的叶绿体基因组画出一幅粗略的肖像。
The phylum Chlorophyta contains the majority of the green algae and is divided into four classes. While the basal position of the Prasinophyceae is well established, the divergence order of the Ulvophyceae, Trebouxiophyceae and Chlorophyceae (UTC) remains uncertain. The five complete chloroplast DNA (cpDNA) sequences currently available for representatives of these classes display considerable variability in overall structure, gene content, gene density, intron content and gene order. Among these genomes, that of the chlorophycean green alga Chlamydomonas reinhardtii has retained the least ancestral features. The two single-copy regions, which are separated from one another by the large inverted repeat (IR), have similar sizes, rather than unequal sizes, and differ radically in both gene contents and gene organizations relative to the single-copy regions of prasinophyte and ulvophyte cpDNAs. To gain insights into the various changes that underwent the chloroplast genome during the evolution of chlorophycean green algae, we have sequenced the cpDNA of Scenedesmus obliquus, a member of a distinct chlorophycean lineage. The 161,452 bp IR-containing genome of Scenedesmus features single-copy regions of similar sizes, encodes 96 genes, i.e. only two additional genes (infA and rpl12) relative to its Chlamydomonas homologue and contains seven group I and two group II introns. It is clearly more compact than the four UTC algal cpDNAs that have been examined so far, displays the lowest proportion of short repeats among these algae and shows a stronger bias in clustering of genes on the same DNA strand compared to Chlamydomonas cpDNA. Like the latter genome, Scenedesmus cpDNA displays only a few ancestral gene clusters. The two chlorophycean genomes share 11 gene clusters that are not found in previously sequenced trebouxiophyte and ulvophyte cpDNAs as well as a few genes that have an unusual structure; however, their single-copy regions differ considerably in gene content. Our results underscore the remarkable plasticity of the chlorophycean chloroplast genome. Owing to this plasticity, only a sketchy portrait could be drawn for the chloroplast genome of the last common ancestor of Scenedesmus and Chlamydomonas.
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影响因子：
2.5
作者：
Besendahl, A;Qiu, YL;Bhattacharya, D
通讯作者：
Bhattacharya, D
影响因子：
5.1
作者：
BOUDREAU, E;OTIS, C;TURMEL, M
通讯作者：
TURMEL, M
影响因子：
3.9
作者：
Bhattacharya, D;Weber, K;Berning-Koch, W
通讯作者：
Berning-Koch, W
影响因子：
56.9
作者：
Karol, KG;McCourt, RM;Delwiche, CF
通讯作者：
Delwiche, CF
影响因子：
5.1
作者：
BOUDREAU, E;TURMEL, M
通讯作者：
TURMEL, M