Forward translocation is the natural pathway of RNA release at an intrinsic terminator
Forward translocation is the natural pathway of RNA release at an intrinsic terminator
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DOI：
10.1016/s1097-2765(04)00154-6
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发表时间：
2004-04-09
期刊：
影响因子：
16
通讯作者：
Roberts, JW
中科院分区：
文献类型：
--
作者：
Santangelo, TJ;Roberts, JW
细菌核糖核酸聚合酶的内在终止子是包含二联体对称性的小序列，该序列编码∼中的发夹，紧随其后的是紧随其后的富含尿苷的5-9个核苷酸片段。RNA发夹的形成破坏了延伸复合体的稳定，导致转录本的释放。我们测试了一个模型，在这个模型中，发夹的形成驱动RNA聚合酶和融化的DNA气泡下游，而不是转录延长，从而将转录作为RNA/DNA杂交从酶内的封闭区域释放出来。我们发现，阻止RNAP下游易位和阻止下游DNA解离都会抑制转录释放。我们认为，RNA聚合酶的易位是必不可少的，气泡的易位刺激了RNA的释放，但不是必需的；我们得出结论，正向易位是RNA在内在终止子处释放的自然途径。
Intrinsic terminators of bacterial RNA polymerase are small < ∼30 bp) sequences containing a dyad symmetry that encodes a hairpin in the RNA, followed immediately by a uridine-rich stretch of 5-9 nucleotides just before the site of RNA release. Formation of the RNA hairpin destabilizes the elongation complex, leading to transcript release. We test a model in which hairpin formation drives RNA polymerase and the melted DNA bubble downstream without transcript elongation, thus releasing the transcript from its enclosure within the enzyme as an RNA/DNA hybrid. We show that blocking downstream translocation of RNAP and preventing downstream DNA unwinding both inhibit transcript release. We argue that translocation of RNA polymerase is essential and that translocation of the bubble stimulates, but is not required, for RNA release; we conclude that forward translocation is the natural pathway of RNA release at an intrinsic terminator.