Graduate School of Agriculture, Utsunomiya University, 350 Minemachi, Utsunomiya, Tochigi 321-8505, Japan.
Graduate School of Agriculture, Utsunomiya University, 350 Minemachi, Utsunomiya, Tochigi 321-8505, Japan.
Biosens Bioelectron. 2015 May 15;67:309-14. doi: 10.1016/j.bios.2014.08.040. Epub 2014 Aug 23.
Transcriptional switches regulate gene expression in response to environmental changes surrounding cell. Many studies have focused on two fundamentally different models of transcriptional control by bacterial metalloregulatory protein. Distortion of the DNA fragment including cis-element, to which the trans-acting factor MerR binds, is accepted as the mechanism of gene expression regulation by Hg (II) while, in cases of the other trans-acting factors ArsR and CadC, events of association to and dissociation from cis-element are known to control transcription in response to As (III) and Cd (II), respectively. In this study, interactions between green-fluorescent-protein-tagged trans-acting factor and immobilized cis-element were analyzed on solid surface. Fluorescent measurements and surface plasmon resonance (SPR) responses revealed that although the equilibrium dissociation constant (KD) was much lower in MerR than in ArsR and CadC, the dissociation rate of MerR from DNA increased in response to Hg (II) at concentrations of 5-10(4) µg l(-1). These results firstly demonstrate an increase of KD between MerR and its recognition site in DNA by Hg (II), and possibility of rapid Hg (II) quantification with the low detection limit (5 µg l(-1)) and the high dynamic range (10(1)-10(4) µg l(-1)).
转录开关可响应细胞周围环境的变化来调节基因表达。许多研究都集中在两种截然不同的细菌金属调控蛋白的转录控制模型上。DNA 片段的扭曲，包括顺式元件，反式作用因子 MerR 结合的顺式元件，被认为是 Hg(II) 调控基因表达的机制，而在其他反式作用因子 ArsR 和 CadC 的情况下，与顺式元件的结合和解离事件被认为分别控制着对 As(III) 和 Cd(II)的转录。在这项研究中，在固体表面上分析了绿色荧光蛋白标记的反式作用因子与固定化顺式元件之间的相互作用。荧光测量和表面等离子体共振（SPR）响应表明，尽管 MerR 的平衡解离常数（KD）远低于 ArsR 和 CadC，但 MerR 从 DNA 上的解离速率在 5-10(4) µg l(-1)的 Hg(II)浓度下增加。这些结果首次证明了 Hg(II) 增加了 MerR 与其在 DNA 上的识别位点之间的 KD，并有可能通过低检测限（5 µg l(-1))和高动态范围（10(1)-10(4) µg l(-1))快速定量 Hg(II)。
