Investigating the Origins of Membrane Phospholipid Biosynthesis Genes Using Outgroup-Free Rooting
Investigating the Origins of Membrane Phospholipid Biosynthesis Genes Using Outgroup-Free Rooting
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DOI：
10.1093/gbe/evz034
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发表时间：
2019-03-01
影响因子：
3.3
通讯作者：
Williams, Tom A.
中科院分区：
文献类型：
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作者：
Coleman, Gareth A.;Pancost, Richard D.;Williams, Tom A.
细菌和古生菌的关键区别之一是它们的典型膜磷脂，它们是通过不同的生物合成途径与非同源酶合成的。这种“脂分裂”对于细胞的早期进化和在最后一个世界共同祖先中存在的膜磷脂的类型具有重要的意义。膜进化研究中的主要挑战之一是，关键的生物合成基因是古老的，它们的进化史没有得到很好的解决。这对传统的生根方法提出了重大挑战，因为唯一可用的外群是遥远的亲缘关系。在这里，我们通过使用最好的单基因树替代模型来解决这个问题，通过将我们的分析扩展到最近由环境基因组学揭示的未培养原核生物的多样性，并通过使用两种不依赖于外群的互补方法来生根。与以前的一些分析一致，我们的根基基因树支持膜磷脂生物合成基因的广泛跨域水平转移，主要是从古生菌到细菌。他们还提出，在最后一个世界共同祖先中，已经存在制造古生型膜磷脂的能力。
One of the key differences between Bacteria and Archaea is their canonical membrane phospholipids, which are synthesized by distinct biosynthetic pathways with nonhomologous enzymes. This "lipid divide" has important implications for the early evolution of cells and the type of membrane phospholipids present in the last universal common ancestor. One of the main challenges in studies of membrane evolution is that the key biosynthetic genes are ancient and their evolutionary histories are poorly resolved. This poses major challenges for traditional rooting methods because the only available outgroups are distantly related. Here, we address this issue by using the best available substitution models for single-gene trees, by expanding our analyses to the diversity of uncultivated prokaryotes recently revealed by environmental genomics, and by using two complementary approaches to rooting that do not depend on outgroups. Consistent with some previous analyses, our rooted gene trees support extensive interdomain horizontal transfer of membrane phospholipid biosynthetic genes, primarily from Archaea to Bacteria. They also suggest that the capacity to make archaeal-type membrane phospholipids was already present in last universal common ancestor.