Luo Jie, Hall Benjamin D
Department of Biology, University of Washington, Seattle, WA 98195, USA.
J Mol Evol. 2007 Jan;64(1):101-12. doi: 10.1007/s00239-006-0093-z. Epub 2006 Dec 9.
Since their discovery in Metazoa, the three nuclear RNA polymerases (RNAPs) have been found in fungi, plants, and diverse protists. In all eukaryotes studied to date, RNAPs I, II, and III collectively transcribe all major RNAs made in the nucleus. We have found genes for the largest subunit (RPD1/RPE1) of a new DNA-dependent RNAP, RNAP IV, in all major land plant taxa and in closely related green algae. Genes for the second-largest subunit (RPD2) of this enzyme were found in all land plants. Phylogenetic study indicates that RNAP IV genes are sister to the corresponding RNAP II genes. Our results show the genesis of RNAP IV to be a multistep process in which the largest and second-largest subunit genes evolved by independent duplication events in the ancestors of Charales and land plants. These findings provide insights into evolutionary mechanisms that can explain the origin of multiple RNAPs in the eukaryotic nucleus.
自从在后生动物中被发现以来，三种核RNA聚合酶（RNAPs）已在真菌、植物和多种原生生物中被发现。在迄今研究的所有真核生物中，RNAP I、II和III共同转录细胞核中产生的所有主要RNA。我们在所有主要陆地植物类群以及与之亲缘关系较近的绿藻中发现了一种新的依赖DNA的RNAP即RNAP IV最大亚基（RPD1/RPE1）的基因。在所有陆地植物中都发现了这种酶第二大亚基（RPD2）的基因。系统发育研究表明，RNAP IV基因是相应RNAP II基因的姐妹基因。我们的结果表明，RNAP IV的起源是一个多步骤过程，其中最大和第二大亚基基因通过轮藻和陆地植物祖先中的独立复制事件而进化。这些发现为进化机制提供了见解，这些机制可以解释真核细胞核中多种RNAP的起源。
