δ 亚基和 NTPase HelD 构成了 RNA 聚合酶回收的双管齐下的机制。
The δ subunit and NTPase HelD institute a two-pronged mechanism for RNA polymerase recycling.
机构信息
Laboratory of Structural Biochemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraβe 6, 14195, Berlin, Germany.
Institute of Chemistry and Biochemistry, Research Center of Electron Microscopy and Core Facility BioSupraMol, Freie Universität Berlin, Fabeckstr. 36a, 14195, Berlin, Germany.
出版信息
Nat Commun. 2020 Dec 18;11(1):6418. doi: 10.1038/s41467-020-20159-3.
Cellular RNA polymerases (RNAPs) can become trapped on DNA or RNA, threatening genome stability and limiting free enzyme pools, but how RNAP recycling into active states is achieved remains elusive. In Bacillus subtilis, the RNAP δ subunit and NTPase HelD have been implicated in RNAP recycling. We structurally analyzed Bacillus subtilis RNAP-δ-HelD complexes. HelD has two long arms: a Gre cleavage factor-like coiled-coil inserts deep into the RNAP secondary channel, dismantling the active site and displacing RNA, while a unique helical protrusion inserts into the main channel, prying the β and β' subunits apart and, aided by δ, dislodging DNA. RNAP is recycled when, after releasing trapped nucleic acids, HelD dissociates from the enzyme in an ATP-dependent manner. HelD abundance during slow growth and a dimeric (RNAP-δ-HelD) structure that resembles hibernating eukaryotic RNAP I suggest that HelD might also modulate active enzyme pools in response to cellular cues.
细胞 RNA 聚合酶（RNAP）可滞留在 DNA 或 RNA 上，从而威胁基因组稳定性并限制游离酶库，但 RNAP 如何重新循环进入活跃状态仍不清楚。在枯草芽孢杆菌中，RNAP δ 亚基和 NTPase HelD 与 RNAP 循环回收有关。我们对枯草芽孢杆菌 RNAP-δ-HelD 复合物进行了结构分析。HelD 有两个长臂：一个 Gre 切割因子样卷曲螺旋深入到 RNAP 二级通道，破坏活性位点并驱逐 RNA，而一个独特的螺旋突出物插入主通道，将β和β'亚基分开，并在 δ 的帮助下，将 DNA 逐出。当 HelD 以 ATP 依赖的方式从酶上解离时，释放出被困的核酸后，RNAP 就会被回收。在缓慢生长过程中 HelD 的丰度和类似于休眠真核生物 RNAP I 的二聚体（RNAP-δ-HelD）结构表明，HelD 可能还会根据细胞信号来调节活性酶库。
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