REGULATION AND STRUCTURE OF THE MER OPERON

我们将在分子水平上描述这一机制。 无处不在的细菌质粒编码的汞基因座 抗性(MER)。这是非常常见的，但从生化角度来看 不同寻常的，排毒系统在 汞化合物的微生物循环，包括神经毒性 化合物甲基汞，在自然界中。Mer操纵子包括一个 汞(II)运输系统，将有毒阴离子输送到 胞浆酶汞(II)还原酶(HR)。人力资源，在结构上 在机制上与谷胱甘肽还原酶有关，减少 汞(II)对挥发性汞(O)，相对无毒。而当 人力资源机制是比较被理解的， 汞(II)转运系统尚未阐明。《歌剧集》 处于Merr基因的正转录控制下，该基因 其本身是负自动调节的；然而， 诱导物和操纵子控制的分子细节不是 为人所知。首先，将使用遗传和生化技术 检测转录的起始和终止， 降解，以及翻译调控在操纵子中的作用 表情。其次，将对运输过程进行研究 强调他们的内在兴趣，也是因为 了解操纵子表达的调控依赖于知道 汞(II)在存在和不存在时如何进入细胞 当然是梅尔。所有Mer基因中的特定位点或功能突变将 通过各种体外和体内方法寻找。最后， 几种遗传方法将被用来发现 宿主细菌细胞在MER功能的表达中发挥作用。

We will describe at a molecular level the mechanism of the ubiquitous bacterial plasmid-encoded locus conferring mercury resistance (mer). This very commonly found, but biochemically unusual, detoxification system plays a significant role in the microbial cycling of mercury compounds, including the neurotoxic compound methyl mercury, in nature. The mer operon includes a Hg(II) transport system which delivers the toxic anion to the cytosolic enzyme Hg(II) reductase (HR). HR, which is structurally and mechanistically related to glutathione reductase, reduces Hg(II) to volatile Hg(O) which is comparatively non-toxic. While the HR mechanism is relatively well-understood, the mechanism of the Hg(II) transport system has not been elucidated. The operon is under positive transcriptional control of the merR gene which itself is negatively autoregulated; however, the precise nature of the inducer and the molecular details of operon control are not known. Firstly, genetic and biochemical techniques will be used to examine transcription initiation and termination, mRNA degradation, and the role of translational regulation in operon expression. Secondly, studies of the transport process will be emphasized for their intrinsic interest but also because understanding regulation of operon expression depends on knowing how Hg(II) enters the cell both in the presence and in the absence of mer. Site- or function-specific mutants in all mer genes will be sought by a variety of in vitro and in vivo methods. Finally, several genetic approaches will be used to discover what role the host bacterial cell plays in the expression of mer functions.