RNA 聚合酶 III 特异性通用转录因子 IIIC 包含一个类似于 TFIIF Rap30/Rap74 的异二聚体。
RNA polymerase III-specific general transcription factor IIIC contains a heterodimer resembling TFIIF Rap30/Rap74.
机构信息
European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany and UJF-EMBL-CNRS UMI 3265, Unit of Virus Host-Cell Interactions, 38042 Grenoble Cedex 9, France.
出版信息
Nucleic Acids Res. 2013 Oct;41(19):9183-96. doi: 10.1093/nar/gkt664. Epub 2013 Aug 5.
Transcription of tRNA-encoding genes by RNA polymerase (Pol) III requires the six-subunit general transcription factor IIIC that uses subcomplexes τA and τB to recognize two gene-internal promoter elements named A- and B-box. The Schizosaccharomyces pombe τA subcomplex comprises subunits Sfc1, Sfc4 and Sfc7. The crystal structure of the Sfc1/Sfc7 heterodimer reveals similar domains and overall domain architecture to the Pol II-specific general transcription factor TFIIF Rap30/Rap74. The N-terminal Sfc1/Sfc7 dimerization module consists of a triple β-barrel similar to the N-terminal TFIIF Rap30/Rap74 dimerization module, whereas the C-terminal Sfc1 DNA-binding domain contains a winged-helix domain most similar to the TFIIF Rap30 C-terminal winged-helix domain. Sfc1 DNA-binding domain recognizes single and double-stranded DNA by an unknown mechanism. Several features observed for A-box recognition by τA resemble the recognition of promoters by bacterial RNA polymerase, where σ factor unfolds double-stranded DNA and stabilizes the non-coding DNA strand in an open conformation. Such a function has also been proposed for TFIIF, suggesting that the observed structural similarity between Sfc1/Sfc7 and TFIIF Rap30/Rap74 might also reflect similar functions.
RNA 聚合酶 (Pol) III 转录 tRNA 编码基因需要由六个亚基组成的通用转录因子 IIIC,该因子利用亚基 τA 和 τB 识别两个内部基因启动子元件,分别命名为 A- 和 B-盒。裂殖酵母的 τA 亚基由 Sfc1、Sfc4 和 Sfc7 三个亚基组成。Sfc1/Sfc7 异源二聚体的晶体结构揭示了与 Pol II 特异性通用转录因子 TFIIF Rap30/Rap74 相似的结构域和整体结构架构。N 端 Sfc1/Sfc7 二聚化模块由一个类似于 N 端 TFIIF Rap30/Rap74 二聚化模块的三链 β-桶组成,而 C 端 Sfc1 DNA 结合域包含一个具有翼状螺旋结构域的结构域,与 TFIIF Rap30 C 端的具有翼状螺旋结构域最相似。Sfc1 DNA 结合域通过未知机制识别单链和双链 DNA。观察到的 τA 识别 A 盒的几个特征类似于细菌 RNA 聚合酶识别启动子的特征,其中 σ 因子展开双链 DNA 并以开放构象稳定非编码 DNA 链。同样的功能也被提出用于 TFIIF,这表明观察到的 Sfc1/Sfc7 和 TFIIF Rap30/Rap74 之间的结构相似性可能也反映了类似的功能。