Department of Biological Sciences, Virginia Tech, Blacksburg, VA, 24061, USA.
Nat Commun. 2020 Sep 9;11(1):4506. doi: 10.1038/s41467-020-18281-3.
Bacteriophages play critical roles in the biosphere, but their vast genomic diversity has obscured their evolutionary origins, and phylogenetic analyses have traditionally been hindered by their lack of universal phylogenetic marker genes. In this study we mine metagenomic data and identify a clade of Caudovirales that encodes the β and β' subunits of multi-subunit RNA polymerase (RNAP), a high-resolution phylogenetic marker which enables detailed evolutionary analyses. Our RNAP phylogeny revealed that the Caudovirales RNAP forms a clade distinct from cellular homologs, suggesting an ancient acquisition of this enzyme. Within these multimeric RNAP-encoding Caudovirales (mReC), we find that the similarity of major capsid proteins and terminase large subunits further suggests they form a distinct clade with common evolutionary origin. Our study characterizes a clade of RNAP-encoding Caudovirales and suggests the ancient origin of this enzyme in this group, underscoring the important role of viruses in the early evolution of life on Earth.
噬菌体在生物圈中发挥着关键作用，但它们巨大的基因组多样性掩盖了它们的进化起源，传统的系统发育分析也受到缺乏通用系统发育标记基因的阻碍。在这项研究中，我们挖掘了宏基因组数据，并鉴定出一个包含多亚基 RNA 聚合酶（RNAP）β 和 β'亚基的尾病毒目（Caudovirales）分支，这是一个高分辨率的系统发育标记，可实现详细的进化分析。我们的 RNAP 系统发育表明，尾病毒目 RNAP 形成了一个与细胞同源物不同的分支，这表明这种酶是古老的获得的。在这些编码多亚基 RNA 聚合酶的尾病毒目（mReC）中，我们发现主要衣壳蛋白和末端酶大亚基的相似性进一步表明它们形成了一个具有共同进化起源的独特分支。我们的研究描述了一个编码多亚基 RNA 聚合酶的尾病毒目分支，并提出了这种酶在该组中的古老起源，强调了病毒在地球生命早期进化中的重要作用。
