Department of Life Sciences, Imperial College London, London SW7 2AZ, UK.
Nat Commun. 2013;4:1997. doi: 10.1038/ncomms2997.
Bacterial enhancer-dependent transcription systems support major adaptive responses and offer a singular paradigm in gene control analogous to complex eukaryotic systems. Here we report new mechanistic insights into the control of one-membrane stress-responsive bacterial enhancer-dependent system. Using millisecond single-molecule fluorescence microscopy of live cells we determine the localizations, two-dimensional diffusion dynamics and stoichiometries of complexes of the bacterial enhancer-binding ATPase PspF during its action at promoters as regulated by inner membrane interacting negative controller PspA. We establish that a stable repressive PspF-PspA complex is located in the nucleoid, transiently communicating with the inner membrane via PspA. The PspF as a hexamer stably binds only one of the two psp promoters at a time, suggesting that psp promoters will fire asynchronously and cooperative interactions of PspF with the basal transcription complex influence dynamics of the PspF hexamer-DNA complex and regulation of the psp promoters.
细菌增强子依赖型转录系统支持主要的适应性反应，并提供了一个类似于复杂真核系统的基因控制的独特范例。在这里，我们报告了对一种膜应激反应性细菌增强子依赖型系统控制的新的机制见解。我们使用活细胞的毫秒级单分子荧光显微镜，确定了在由内膜相互作用的负控制器 PspA 调节的启动子处，细菌增强子结合 ATP 酶 PspF 在其作用过程中的定位、二维扩散动力学和复合物的计量比。我们确定了一个稳定的抑制性 PspF-PspA 复合物位于核区，通过 PspA 与内膜瞬时通讯。作为六聚体的 PspF 一次只能稳定地结合两个 psp 启动子之一，这表明 psp 启动子将异步启动，并且 PspF 与基础转录复合物的合作相互作用会影响 PspF 六聚体-DNA 复合物的动力学和 psp 启动子的调节。
