RNA polymerase stalls in a post-translocated register and can hyper-translocate.
RNA polymerase stalls in a post-translocated register and can hyper-translocate.
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DOI：
10.4161/trns.22307
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发表时间：
2012-09
期刊：
影响因子：
--
通讯作者：
Burton ZF
中科院分区：
文献类型：
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作者：
Nedialkov YA;Nudler E;Burton ZF
外切核酸酶（Exo）III用于探测RNA聚合酶（RNAP）三元延伸复合物（TEC）的易位状态。大肠杆菌RNAP主要在易位后寄存器中停滞，该寄存器相对缓慢地漂移到超易位状态或易位前状态。Tagetitoxin（TGT）强烈抑制超易位和抑制回溯，因此，如Exo III映射所示，TGT似乎稳定RNAP的前和可能部分易位后状态。因为在许多模板位置处，从易位前到易位后的转变是缓慢的，所以这些研究似乎与RNAP使其频繁和快速的模型不一致（即，毫秒相位）在易位前和易位后状态之间的振荡。9个核苷酸（9-nt）和10-nt TEC以及具有较长新生RNA的TEC具有与9-10 nt RNA/DNA杂合体一致的独特易位性质。鉴定了桥螺旋和触发环中抑制或刺激正向和反向易位的RNAP突变蛋白。
Exonuclease (Exo) III was used to probe translocation states of RNA polymerase (RNAP) ternary elongation complexes (TECs). Escherichia coli RNAP stalls primarily in a post-translocation register that makes relatively slow excursions to a hyper-translocated state or to a pre-translocated state. Tagetitoxin (TGT) strongly inhibits hyper-translocation and inhibits backtracking, so, as indicated by Exo III mapping, TGT appears to stabilize both the pre- and probably a partially post-translocation state of RNAP. Because the pre-translocated to post-translocated transition is slow at many template positions, these studies appear inconsistent with a model in which RNAP makes frequent and rapid (i.e., millisecond phase) oscillations between pre- and post-translocation states. Nine nucleotides (9-nt) and 10-nt TECs, and TECs with longer nascent RNAs, have distinct translocation properties consistent with a 9–10 nt RNA/DNA hybrid. RNAP mutant proteins in the bridge helix and trigger loop are identified that inhibit or stimulate forward and backward translocation.