On the evolution of the single-subunit RNA polymerases
On the evolution of the single-subunit RNA polymerases
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DOI：
10.1007/pl00006271
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发表时间：
1997-12-01
影响因子：
3.9
通讯作者：
Cedergren, R
中科院分区：
文献类型：
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作者：
Cermakian, N;Ikeda, TM;Cedergren, R
许多真核生物的核基因组和线粒体质粒都含有与噬菌体T7及其近亲的单亚基RNA聚合酶（ssRNAP）编码序列明显相似的基因。我们收集并整理了这些ssRNAP序列，并构建了无根系统发育树，证明ssRNAP分为三个定义明确且不重叠的簇（噬菌体编码、核编码和质粒编码）。我们的分析表明，这三个t7 -1样rnap亚家族具有共同的祖先；然而，这些群体分化的顺序无法从现有的数据中推断出来。根据结构相似性和突变数据，我们认为祖先的ssRNAP基因可能是通过DNA聚合酶或逆转录酶基因的复制和分化而产生的。考虑到目前ssRNAP序列的系统发育分布，我们进一步认为祖先ssRNAP基因的起源在时间上与线粒体通过真核细胞内共生引入真核细胞密切相关。
Many eukaryotic nuclear genomes as well as mitochondrial plasmids contain genes displaying evident sequence similarity to those encoding the single-subunit RNA polymerase (ssRNAP) of bacteriophage T7 and its relatives. We have collected and aligned these ssRNAP sequences and have constructed unrooted phylogenetic trees that demonstrate the separation of ssRNAPs into three well-defined and nonoverlapping clusters (phage-encoded, nucleus-encoded, and plasmid-encoded). Our analyses indicate that these three subfamiles of T7-1ike RNAPs shared a common ancestor; however, the order in which the groups diverged cannot be inferred from available data. On the basis of structural similarities and mutational data, we suggest that the ancestral ssRNAP gene may have arisen via duplication and divergence of a DNA polymerase or reverse transcriptase gene. Considering the current phylogenetic distribution of ssRNAP sequences, we further suggest that the origin of the ancestral ssRNAP gene closely paralleled in time the introduction of mitochondria into eukaryotic cells through a eubacterial endosymbiosis.