Gene Center and Department of Biochemistry, Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany.
Mol Cell. 2010 Aug 27;39(4):583-94. doi: 10.1016/j.molcel.2010.07.028.
The eukaryotic RNA polymerases Pol I, II, and III use different promoters to transcribe different classes of genes. Promoter usage relies on initiation factors, including TFIIF and TFIIE, in the case of Pol II. Here, we show that the Pol I-specific subunits A49 and A34.5 form a subcomplex that binds DNA and is related to TFIIF and TFIIE. The N-terminal regions of A49 and A34.5 form a dimerization module that stimulates polymerase-intrinsic RNA cleavage and has a fold that resembles the TFIIF core. The C-terminal region of A49 forms a "tandem winged helix" (tWH) domain that binds DNA with a preference for the upstream promoter nontemplate strand and is predicted in TFIIE. Similar domains are predicted in Pol III-specific subunits. Thus, Pol I/III subunits that have no counterparts in Pol II are evolutionarily related to Pol II initiation factors and may have evolved to mediate promoter specificity and transcription processivity.
真核 RNA 聚合酶 Pol I、II 和 III 使用不同的启动子来转录不同类别的基因。启动子的使用依赖于起始因子，包括 Pol II 中的 TFIIF 和 TFIIE。在这里，我们表明 Pol I 特异性亚基 A49 和 A34.5 形成一个与 TFIIF 和 TFIIE 相关的亚复合物，该复合物结合 DNA。A49 和 A34.5 的 N 端区域形成一个二聚化模块，刺激聚合酶内在的 RNA 切割，其折叠类似于 TFIIF 核心。A49 的 C 端区域形成一个“串联翼状螺旋”（tWH）结构域，该结构域优先结合上游启动子非模板链，并且在 TFIIE 中被预测。Pol III 特异性亚基中也预测到了类似的结构域。因此，在 Pol II 中没有对应物的 Pol I/III 亚基与 Pol II 起始因子在进化上是相关的，它们可能是为了介导启动子特异性和转录持续性而进化的。
