ppGpp Binding to a Site at the RNAP-DksA Interface Accounts for Its Dramatic Effects on Transcription Initiation during the Stringent Response.
ppGpp Binding to a Site at the RNAP-DksA Interface Accounts for Its Dramatic Effects on Transcription Initiation during the Stringent Response.
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DOI：
10.1016/j.molcel.2016.04.029
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发表时间：
2016-06-16
期刊：
影响因子：
16
通讯作者：
Gourse RL
中科院分区：
文献类型：
--
作者：
Ross W;Sanchez-Vazquez P;Chen AY;Lee JH;Burgos HL;Gourse RL
在整个细菌领域，警报素ppGpp在营养受限后会极大地重新编程转录过程。这种“严谨反应”对生存和抗生素耐受性至关重要，并且是小分子配体调控转录的一个范例。我们报道ppGpp结合在大肠杆菌RNA聚合酶（RNAP）上相距60埃的两个不同位点，一个位点（位点1）之前已有描述，另一个位点（位点2）在此处被确定位于RNAP和转录因子DksA的界面。位点2的位置及其不寻常的三方性质解释了DksA - ppGpp的协同作用，并提示了ppGpp增强DksA对RNAP影响的机制。位点2的结合导致了ppGpp在体外和体内对转录起始的大部分影响，并且缺乏位点2的菌株在营养转变后的生长受到严重损害。在不同的ppGpp浓度下两个位点的填充将扩大细胞对ppGpp水平变化的动态反应范围。
Throughout the bacterial domain, the alarmone ppGpp dramatically reprograms transcription following nutrient limitation. This “stringent response” is critical for survival and antibiotic-tolerance and is a model for transcriptional regulation by small ligands. We report that ppGpp binds to two distinct sites 60 angstroms apart on E. coli RNA polymerase (RNAP), one characterized previously (Site 1) and a second identified here at an interface of RNAP and the transcription factor DksA (Site 2). The location and unusual tripartite nature of Site 2 account for the DksA-ppGpp synergism and suggest mechanisms for ppGpp enhancement of DksA’s effects on RNAP. Site 2 binding results in the majority of ppGpp’s effects on transcription initiation in vitro and in vivo, and strains lacking Site 2 are severely impaired for growth following nutritional shifts. Filling of the two sites at different ppGpp concentrations would expand the dynamic range of cellular responses to changes in ppGpp levels.