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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Molecular cloning of the transcription factor TFIIB homolog from Sulfolobus shibatae.
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Molecular cloning of the transcription factor TFIIB homolog from Sulfolobus shibatae.

机译：来自Shibatolobus shibatae的转录因子TFILB同源物的分子克隆。

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摘要

The Archaea (archaebacteria) constitute a group of prokaryotes that are phylogenetically distinct from Eucarya (eukaryotes) and Bacteria (eubacteria). Although Archaea possess only one RNA polymerase, evidence suggests that their transcriptional apparatus is similar to that of Eucarya. For example, Archaea contain a homolog of the TATA-binding protein which interacts with the TATA-box like A-box sequence upstream of many archaeal genes. Here, we report the cloning of a Sulfolobus shibatae gene that encodes a protein (transcription factor TFB) with striking homology to the eukaryotic basal transcription factor TFIIB. We show by primer extension analysis that transcription of the S. shibatae TFB gene initiates 27 bp downstream from a consensus A-box element. Significantly, S. shibatae TFB contains an N-terminal putative metal-binding region and two imperfect direct repeats--structural features that are well conserved in eukaryotic TFIIBs. This suggests that TFB may perform analogous functions in Archaea and Eucarya. Consistent with this, we demonstrate that S. shibatae TFB promotes the binding of S. shibatae TBP to the A-box element of the Sulfolobus 16S/23S rRNA gene. Finally, we show that S. shibatae TFB is significantly more related to TFB of the archaeon Pyrococcus woesei than it is to eukaryotic TFIIBs. These data suggest that TFB arose in the common archaeal/eukaryotic ancestor and that the lineages leading to P. woesei and S. shibatae separated after the divergence of the archaeal and eukaryotic lines of descent.
机译：古细菌（古细菌）构成一组原核生物，在系统发育上不同于真核生物（真核生物）和细菌（真细菌）。尽管古细菌仅具有一种RNA聚合酶，但证据表明它们的转录装置与Eucarya相似。例如，古细菌包含TATA结合蛋白的同源物，其与许多古细菌基因上游的TATA-box类似A-box序列相互作用。在这里，我们报道了一种克隆的Shibatolo shibatae基因的克隆，该基因编码与真核基础转录因子TFIIB具有惊人同源性的蛋白质（转录因子TFB）。我们通过引物延伸分析表明，Shibatae TFB基因的转录起始于一个共有的A-box元件下游27 bp。重要的是，shibatae的SFB包含一个N端假定的金属结合区和两个不完美的直接重复序列，这些结构特征在真核TFIIBs中非常保守。这表明，TFB可能在古细菌和Eucarya中执行类似的功能。与此相符，我们证明了shibatae TFB促进了shibatae TBP与Sulfolobus 16S / 23S rRNA基因的A-box元件的结合。最后，我们表明，志贺链球菌TFB与古生火球菌TFB的关联远比其与真核TFIBB的关联更大。这些数据表明，TFB起源于常见的古细菌/真核生物祖先，而古细菌和真核假单胞菌的血统在古细菌和真核生物的后代分化之后就分离了。

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