Ancient dynamin segments capture early stages of host-mitochondrial integration
Ancient dynamin segments capture early stages of host-mitochondrial integration
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DOI：
10.1073/pnas.1407163112
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发表时间：
2015-03-03
影响因子：
11.1
通讯作者：
Thattai, Mukund
中科院分区：
文献类型：
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作者：
Purkanti, Ramya;Thattai, Mukund
真核细胞使用动力素-机械化学GTP酶-来驱动内共生细胞器的分裂。在这里，我们探索线粒体和叶绿体内共生的早期步骤，通过跟踪动力蛋白的进化。我们开发了一种基于简约的系统发育方法，用于蛋白质序列重建，具有深时间分辨率。利用这一点，我们表明，动力通过间断的二级结构元件的规模上的序列片段的转换多样化。我们发现了一些片段的例子，这些片段从18亿年前的最后一个真核生物共同祖先到现在基本上保持不变。将这些缝合在一起，我们重建了三个祖先的发动蛋白：第一个是几乎相同的无处不在的线粒体分裂发动蛋白的现存真核生物，第二个是部分保存在粘病毒抗性样的后生动物的发动蛋白，第三个引起的细胞动力学的变形虫和植物和叶绿体分裂发动蛋白。重建的序列，结合进化模型和已发表的功能数据，表明祖先的线粒体分裂动力蛋白也介导囊泡断裂。这种双功能蛋白复制成专门的线粒体和囊泡变体至少三个独立的时间-在肺泡，绿色藻类，真菌和后生动物的祖先-伴随着古老的原核线粒体分裂蛋白FtsZ的损失。值得注意的是，许多保留FtsZ的现存物种也保留了预测的祖先双功能发动蛋白。包括变形虫、红藻和层状藻在内的这些生物的线粒体分裂装置似乎以接近原始的形式保存下来。
Eukaryotic cells use dynamins-mechano-chemical GTPases-to drive the division of endosymbiotic organelles. Here we probe early steps of mitochondrial and chloroplast endosymbiosis by tracing the evolution of dynamins. We develop a parsimony-based phylogenetic method for protein sequence reconstruction, with deep time resolution. Using this, we demonstrate that dynamins diversify through the punctuated transformation of sequence segments on the scale of secondary-structural elements. We find examples of segments that have remained essentially unchanged from the 1.8-billion-y-old last eukaryotic common ancestor to the present day. Stitching these together, we reconstruct three ancestral dynamins: The first is nearly identical to the ubiquitous mitochondrial division dynamins of extant eukaryotes, the second is partially preserved in the myxovirus-resistance-like dynamins of metazoans, and the third gives rise to the cytokinetic dynamins of amoebozoans and plants and to chloroplast division dynamins. The reconstructed sequences, combined with evolutionary models and published functional data, suggest that the ancestral mitochondrial division dynamin also mediated vesicle scission. This bifunctional protein duplicated into specialized mitochondrial and vesicle variants at least three independent times-in alveolates, green algae, and the ancestor of fungi and metazoans-accompanied by the loss of the ancient prokaryotic mitochondrial division protein FtsZ. Remarkably, many extant species that retain FtsZ also retain the predicted ancestral bifunctional dynamin. The mitochondrial division apparatus of such organisms, including amoebozoans, red algae, and stramenopiles, seems preserved in a nearprimordial form.