Archaeal TFEα/β is a hybrid of TFIIE and the RNA polymerase III subcomplex hRPC62/39.
Archaeal TFEα/β is a hybrid of TFIIE and the RNA polymerase III subcomplex hRPC62/39.
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DOI：
10.7554/elife.08378
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发表时间：
2015-06-12
期刊：
影响因子：
7.7
通讯作者：
Werner F
中科院分区：
文献类型：
--
作者：
Blombach F;Salvadori E;Fouqueau T;Yan J;Reimann J;Sheppard C;Smollett KL;Albers SV;Kay CW;Thalassinos K;Werner F
古细菌RNA聚合酶（RNAP）和真核生物RNAPII的转录起始由保守的基础转录因子辅助。真核转录因子TFIIE由α和β亚基组成。在这里，我们已经鉴定并表征了古细菌中TFIIEβ同源物的功能，其在一级序列水平上与RNAPIII亚基hRPC 39相关。古细菌TFEβ和hRPC 39都含有一个立方烷4Fe-4S簇，这对TFEα/β的异二聚化及其与RNAP夹的接合至关重要。TFEα/β稳定前起始复合物，增强DNA解链，并刺激流产和生产性转录。这些活性严格依赖于β亚基和启动子序列。我们的研究结果表明，古细菌TFEα/β可能代表现存真核生物中TFIIE样因子的进化祖先。http://dx.doi.org/10.7554/eLife.08378.001地球上的生命通常分为三个领域：真核生物（包括植物，动物和真菌），细菌和一组不寻常的单细胞微生物，称为古生菌。但最近的一些发现表明，真核生物的起源是在古细菌领域。所有这些生物体的遗传物质都是由DNA组成的，DNA中的基因包含了制造其他生物分子的指令。制造这些分子首先需要通过一个称为转录的过程将这些指令复制到RNA分子中。生命的所有三个领域都使用称为RNA聚合酶（RNAP）的酶进行转录，并且所有RNAP都被认为起源于共同的祖先。酵母和细菌只有一种RNAP，而所有的真核生物至少有四种不同的RNAP。在古细菌中发现的RNAP与真核生物中的RNAP有许多共同的特征。在这两种情况下，区域国家行动方案都不是单独运作的。相反，一类被称为转录因子的蛋白质协助转录过程的第一步。其中一种真核RNAP称为RNAP II，与包含两个蛋白质亚基（称为TFIIEα和TFIIEβ）的转录因子一起工作。虽然TFIIEα的古细菌对应物（称为TFEα）是已知的，但TFIIEβ的对应物却不是。Blombach等人现在已经在一种名为Sulfolobus的古细菌中鉴定出TFIIEβ的古细菌对应物，并将其重新命名为TFEβ。硫化叶菌细胞在没有这种蛋白质的情况下无法生存，这种蛋白质以类似于TFIIEβ的方式协助RNAP启动转录。进一步的分析表明，TFEβ蛋白实际上与RNAP III所特有的蛋白亚基有关，RNAP III是另一种真核RNAP。这两种蛋白质都含有铁和硫的簇。Blombach等人还发现，这些铁硫簇使TFEβ能够与其TFEα伴侣结合，形成一种转录因子，该转录因子可以与RNAP相互作用，并帮助其进行转录。这些结果表明，在古细菌中发现的TFEα/β转录因子可能类似于在活的真核生物中发现的TFIIE转录因子的祖先。这一发现为古细菌和真核生物转录机制的进化史提供了新的见解。DOI：http://dx.doi.org/10.7554/eLife.08378.002网站
Transcription initiation of archaeal RNA polymerase (RNAP) and eukaryotic RNAPII is assisted by conserved basal transcription factors. The eukaryotic transcription factor TFIIE consists of α and β subunits. Here we have identified and characterised the function of the TFIIEβ homologue in archaea that on the primary sequence level is related to the RNAPIII subunit hRPC39. Both archaeal TFEβ and hRPC39 harbour a cubane 4Fe-4S cluster, which is crucial for heterodimerization of TFEα/β and its engagement with the RNAP clamp. TFEα/β stabilises the preinitiation complex, enhances DNA melting, and stimulates abortive and productive transcription. These activities are strictly dependent on the β subunit and the promoter sequence. Our results suggest that archaeal TFEα/β is likely to represent the evolutionary ancestor of TFIIE-like factors in extant eukaryotes. DOI: http://dx.doi.org/10.7554/eLife.08378.001 Life on Earth is often categorized into three domains: the eukaryotes (which include plants, animals and fungi), the bacteria and a group of unusual, single-celled microorganisms called the archaea. But several recent discoveries suggest that the origin of the eukaryotes lies within the archaeal domain. The genetic material of all of these living organisms is made up of DNA, and genes within DNA contain the instructions to make other biological molecules. Making these molecules involves first copying these instructions into a molecule of RNA via a process called transcription. All three domains of life use enzymes called RNA polymerases (RNAPs) for transcription, and all RNAPs are thought to have originated from a common ancestor. Archaea and bacteria have a single type of RNAP, whereas all eukaryotes have at least four different kinds of RNAP. The RNAPs found in archaea share many common features with their eukaryotic counterparts. In both cases, the RNAPs do not work alone. Instead, a class of proteins known as transcription factors assist in the first step of the transcription process. One of the eukarotyic RNAPs, termed RNAP II, works with a transcription factor that contains two protein subunits (called TFIIEα and TFIIEβ). While the archaeal counterpart for TFIIEα (called TFEα) is known, the counterpart for TFIIEβ is not. Blombach et al. have now identified the archaeal counterpart of TFIIEβ in a species of archaea called Sulfolobus and have renamed it TFEβ. Sulfolobus cells are unable to survive without this protein, which works in a similar way to TFIIEβ in assisting the RNAP to start transcription. Further analyses show that the TFEβ protein is actually related to a protein subunit that is unique to RNAP III, another eukarotyic RNAP. Both of these proteins contain clusters of iron and sulphur. Blombach et al. also found that these iron-sulphur clusters enable TFEβ to bind to its TFEα partner to form a transcription factor that can interact with the RNAP and help it to carry out transcription. These results suggest that the TFEα/β transcription factor found in archaea is likely to resemble the ancestor of the TFIIE transcription factors found in living eukaryotes. This discovery provides new insights in the evolutionary history of both the archaeal and the eukaryotic transcription machineries. DOI: http://dx.doi.org/10.7554/eLife.08378.002