終止子ATPase ρ依賴的轉錄終止機制
作者:
小柯機器人發布時間:2020/11/29 22:03:41
德國柏林自由大學Markus C. Wahl、美國俄亥俄州立大學Irina Artsimovitch研究組合作取得最新進展。他們揭示通過終止子ATPase ρ進行不依賴於轉運的RNA聚合酶失活的步驟。該項研究成果發表在2020年11月26日出版的《科學》雜誌上。
他們確定了一系列的冷凍電鏡結構,描繪了終止NusA / NusG修飾的延伸複合物的路徑上的六聚ATPase ρ。一個開放的ρ環接觸NusA、NusG和RNA聚合酶的多個區域,捕獲並局部打開近端上遊DNA。NusA楔入ρ環,最初隔離RNA。在RNA聚合酶Zinc結合結構域上方偏轉遠端上遊DNA後,NusA在一個加帽ρ亞基下方旋轉,隨後捕獲RNA。
在NusG脫離捕獲釋放後,RNA聚合酶失去了對RNA:DNA雜合體的控制並被滅活。他們的結構和功能分析表明,整個生命周期中的ρ和其他終止因子可能利用類似的策略以構象方式捕獲處於垂死狀態的轉錄複合物。
研究人員表示,依賴因子的轉錄終止機制了解甚少。
附:英文原文
Title: Steps toward translocation-independent RNA polymerase inactivation by terminator ATPase ρ
Author: Nelly Said, Tarek Hilal, Nicholas D. Sunday, Ajay Khatri, Jrg Bürger, Thorsten Mielke, Georgiy A. Belogurov, Bernhard Loll, Ranjan Sen, Irina Artsimovitch, Markus C. Wahl
Issue&Volume: 2020/11/26
Abstract: Factor-dependent transcription termination mechanisms are poorly understood. We determined a series of cryo-electron microscopy structures portraying the hexameric ATPase ρ on path to terminating NusA/NusG-modified elongation complexes. An open ρ ring contacts NusA, NusG, and multiple regions of RNA polymerase, trapping and locally unwinding proximal upstream DNA. NusA wedges into the ρ ring, initially sequestering RNA. Upon deflection of distal upstream DNA over the RNA polymerase Zinc-binding domain, NusA rotates underneath one capping ρ subunit, which subsequently captures RNA. Following detachment of NusG and clamp opening, RNA polymerase loses its grip on the RNA:DNA hybrid and is inactivated. Our structural and functional analyses suggest that ρ and other termination factors across life may utilize analogous strategies to allosterically trap transcription complexes in a moribund state.
DOI: 10.1126/science.abd1673
Source: https://science.sciencemag.org/content/early/2020/11/24/science.abd1673
Science:《科學》,創刊於1880年。隸屬於美國科學促進會,最新IF:41.037