Département de biologie Université d'Ottawa, Ottawa, Ontario, Canada.
Mol Biol Evol. 2010 May;27(5):1035-43. doi: 10.1093/molbev/msp316. Epub 2009 Dec 21.
The number of subunits of RNA polymerases (RNAPs) increases during evolution from 5 in eubacteria to 12 in archaea. In eukaryotes, which have at least three RNAPs, the number of subunits has expanded from 12 in RNA polymerase II (RNAPII) to 14 in RNA polymerase I (RNAPI) and to 17 in RNA polymerase III (RNAPIII). It was recently demonstrated that the two additional subunits found in RNAPI relative to RNAPII are homologous to TFIIF, a dimeric general transcription factor of RNAPII. Here, we extend this finding by demonstrating that four of the five RNAPIII-specific subunits are also homologous to transcription factors of RNAPII. We use the available evidence to propose an evolutionary history of the eukaryotic RNAPs and argue that the increases in the number of subunits that occurred in RNAPs I and III are due to the permanent recruitment of preexisting transcription factors.
RNA 聚合酶 (RNAP) 的亚基数量在从细菌到古菌的进化过程中增加，从 5 个增加到 12 个。在至少具有三种 RNAP 的真核生物中，亚基数量从 RNA 聚合酶 II (RNAPII) 的 12 个增加到 RNA 聚合酶 I (RNAPI) 的 14 个，再增加到 RNA 聚合酶 III (RNAPIII) 的 17 个。最近的研究表明，与 RNAPII 相比，在 RNAPI 中发现的两个额外亚基与 TFIIF 同源，TFIIF 是 RNAPII 的二聚体通用转录因子。在这里，我们通过证明 RNAPIII 的五个特异性亚基中的四个也与 RNAPII 的转录因子同源来扩展这一发现。我们利用现有证据提出了真核生物 RNAP 的进化历史，并认为在 RNAP I 和 III 中发生的亚基数量增加是由于预先存在的转录因子的永久招募。
