Eukaryotic and eubacterial contributions tothe establishment of plastid proteomeestimated by large-scale phylogeneticanalyses
Eukaryotic and eubacterial contributions tothe establishment of plastid proteomeestimated by large-scale phylogeneticanalyses
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通过大规模系统发育分析估计真核和真细菌对质体蛋白质组建立的贡献
DOI：
10.1093/molbev/msp273
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
SY
中科院分区：
文献类型：
--
作者：
Suzuki K. & Miyagishima;SY
包括叶绿体在内的叶绿体来自蓝藻内共生体，并保留了自己的基因组，但其大小已减少到不到原始细菌基因组的十分之一。随着时间的推移，对叶绿体功能至关重要的基因已经从祖先的叶绿体基因组转移到细胞核，基因产物现在从宿主细胞质转移到叶绿体中。然而，系统发育分析表明，内共生菌基因组编码的某些原始蛋白质的功能已被非蓝藻起源的核编码蛋白质所取代，并添加了几种新的蛋白质来维持和控制质体。为了评估有助于建立叶绿体蛋白质组的非蓝藻蛋白质的比例和来源，我们对红藻蓝藻(455个蛋白质)和拟南芥(744个蛋白质)共有的叶绿体靶标蛋白质进行了系统发育分析。我们的结果表明，红藻和绿色植物共有的大约40%的叶绿体蛋白质组来自于祖先真核宿主和蓝藻以外的各种细菌(真细菌)的基因。除了光合作用的光反应以及叶绿体中蛋白质的翻译和降解外，大多数叶绿体的功能都经常观察到成分的替换或添加。这些结果表明，在红藻和绿藻分裂之前，相当数量的细菌元基因组物质以及寄主和内共生体的基因组对叶绿体的建立做出了贡献。
Plastids including chloroplasts arose from a cyanobacterial endosymbiont and have retained their own genome, but the size has been reduced to less than one-tenth of the original bacterial genome. Over time, genes essential to plastid function have been transferred from the ancestral plastid genome to the nucleus, and the gene products are now targeted into the plastid from the host cytosol. However, phylogenetic analyses have suggested that the functions of certain original proteins encoded by the endosymbiont genome have been replaced by nucleus-encoded proteins of noncyanobacterial origin and that several proteins have been newly added to maintain and control plastids. In order to evaluate the rate and origin of noncyanobacterial proteins that have contributed to the establishment of the plastid proteome, we performed phylogenetic analyses of plastid-targeted proteins that are shared by the red algaCyanidioschyzon merolae(455 proteins) and the ViridiplantaArabidopsis thaliana(744 proteins). Our results show that approximately 40% of the plastid proteome common to red algae and green plants originated from genes of both the ancestral eukaryotic host and various lineages of bacteria (eubacteria) other than cyanobacteria. The replacement or addition of components was frequently observed for most of the plastid functions except for the light reaction of photosynthesis and the translation and degradation of proteins in the plastid. These results suggest that a considerable amount of bacterial metagenomic material, as well as the genomes of the host and the endosymbiont, has contributed to the establishment of the plastid before the split of the red and green algae.