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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Direct substitution and assisted dissociation pathways for turning off transcription by a MerR-family metalloregulator
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Direct substitution and assisted dissociation pathways for turning off transcription by a MerR-family metalloregulator

机译:通过MerR家族金属调节剂关闭转录的直接取代和辅助解离途径

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摘要

Metalloregulators regulate transcription in response to metal ions. Many studies have provided insights into how transcription is activated upon metal binding by MerR-family metalloregulators. In contrast, how transcription is turned off after activation is unclear. Turning off transcription promptly is important, however, as the cells would not want to continue expressing metal resistance genes and thus waste energy after metal stress is relieved. Using single-molecule FRET measurements we studied the dynamic interactions of the copper efflux regulator (CueR), a Cu~+-responsive MerR-family metalloregulator, with DNA. Besides quantifying its DNA binding and unbinding kinetics, we discovered that CueR spontaneously flips its binding orientation at the recognition site. CueR also has two different binding modes, corresponding to interactions with specific and nonspecific DNA sequences, which would facilitate recognition localization. Most strikingly, a CueR molecule coming from solution can directly substitute for a DNA-bound CueR or assist the dissociation of the incumbent CueR, both of which are unique examples for any DNA-binding protein. The kinetics of the direct protein substitution and assisted dissociation reactions indicate that these two unique processes can provide efficient pathways to replace a DNA-bound holo-CueR with apo-CueR, thus turning off transcription promptly and facilely.
机译:金属调节剂响应金属离子调节转录。许多研究提供了有关MerR系列金属调节剂在金属结合后如何激活转录的见解。相反,激活后如何关闭转录尚不清楚。但是,迅速关闭转录很重要,因为细胞不希望继续表达金属抗性基因,因此在缓解金属胁迫后浪费了能量。使用单分子FRET测量,我们研究了铜外排调节剂(CueR),Cu〜+响应的MerR系列金属调节剂与DNA的动态相互作用。除了量化其DNA结合和解结合动力学,我们还发现CueR在识别位点自发翻转其结合方向。 CueR还具有两种不同的结合模式,分别对应于与特定和非特定DNA序列的相互作用,这将有助于识别定位。最引人注目的是,来自溶液的CueR分子可以直接替代与DNA结合的CueR或协助现有CueR的解离,这两者都是任何DNA结合蛋白的独特实例。直接蛋白质取代和辅助解离反应的动力学表明,这两个独特的过程可以提供有效的途径,以apo-CueR取代DNA结合的holo-CueR,从而迅速而轻松地关闭转录。

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