Phylogeny of endocytic components yields insight into the process of nonendosymbiotic organelle evolution
Phylogeny of endocytic components yields insight into the process of nonendosymbiotic organelle evolution
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DOI：
10.1073/pnas.0707318105
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发表时间：
2008-01-15
影响因子：
11.1
通讯作者：
Field, Mark C.
中科院分区：
文献类型：
--
作者：
Dacks, Joel B.;Poon, Pak P.;Field, Mark C.
一些真核细胞器，例如内膜系统，在没有内共生输入的情况下进化的过程仍然知之甚少。这个问题的出现主要是因为许多主要的细胞系统早于最后一个共同的真核生物祖先（LCEA），因此没有提供正在进行的细胞器发生的例子。一个模型正在出现，即基因复制和分歧的多个“特异性”或“身份”编码蛋白质的各种内膜细胞器产生的多样性nonendosybiotically衍生的细胞室存在于现代真核生物。为了解决这种可能性，我们分析了内吞膜运输机制的三个分子组成部分。系统发育分析的enclocytic突触融合蛋白，拉布5，和β-adaptins各自揭示了一种模式的祖先，未分化的enclocytic同源物中的LCEA。随后，这些未分化的祖细胞在广泛不同的谱系中独立地复制，会聚地产生具有类似包合作用的组分，例如，β 1和β 2-适应素。相比之下，β 3、β 4和所有其他适应素复合物亚基，以及突触融合蛋白和Rab的旁系同源物，都是在LCEA之前进化出来的。因此，该过程引起的分化细胞器的包合系统似乎已被中断的主要物种形成事件，产生现存的真核细胞谱系。这些结果表明，虽然许多encocytic组件LCEA之前演变，其他主要功能独立和收敛后，多样化的主要真核生物超群。这一发现提供了一个例子，一个基本的细胞系统，是简单的LCEA比许多现存的真核生物，并产生洞察非内共生细胞器的进化。
The process by which some eukaryotic organelles, for example the endomembrane system, evolved without endosymbiotic input remains poorly understood. This problem largely arises because many major cellular systems predate the last common eukaryotic,ancestor (LCEA) and thus do not provide examples of organellogenesis in progress. A model is emerging whereby gene duplication and divergence of multiple "specificity-" or "identity-" encoding proteins for the various endomembranous organelles produced the diversity of nonendosymbiotically derived cellular compartments present in modern eukaryotes. To address this possibility, we analyzed three molecular components of the endocytic membrane-trafficking machinery. Phylogenetic analyses of the enclocytic syntaxins, Rab 5, and the beta-adaptins each reveal a pattern of ancestral, undifferentiated enclocytic homologues in the LCEA. Subsequently, these undifferentiated progenitors independently duplicated in widely divergent lineages, convergently producing components with similar enclocytic roles, e.g., beta 1 and beta 2-adaptin. In contrast, beta 3, beta 4, and all other adaptin complex subunits, as well as paralogues of the syntaxins and Rabs specific for the other membrane-trafficking organelles, all evolved before the LCEA. Thus, the process giving rise to the differentiated organelles of the enclocytic system appears to have been interrupted by the major speciation event that produced the extant eukaryotic lineages. These results suggest that although many enclocytic components evolved before the LCEA, other major features evolved independently and convergently after diversification into the primary eukaryotic supergroups. This finding provides an example of a basic cellular system that was simpler in the LCEA than in many extant eukaryotes and yields insight into nonendosymbiotic organelle evolution.