MOLECULAR MECHANISMS OF THE MERCURY RESISTANCE SYSTEM

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 子项目的主要研究者可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 表示子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 我们建议使用X射线吸收光谱来研究由Tn 501 mer操纵子编码的细菌抗汞系统对重金属解毒的分子机制。mer系统采用金属转运蛋白、将汞物质转化和还原为元素挥发性Hg（0）的酶以及一个典型的金属调节系统（基于MerR），所有这些都表现出对Hg的特异性。在一般情况下，我们有兴趣在阐明所涉及的分子机制，并在调查工程这一系统处理其他重金属（镉，Au等）的潜力。用于生物修复。该特定程序有两个主要目标：（a）MerR，其与merO/P和/或RNA聚合酶的相互作用，以及MerD的作用，其似乎参与缓解MerR活化;（B）MerA（汞还原酶）和变体，其现在已显示也催化Au（III）还原为Au（I），最终沉淀形成Au（0）胶体。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. We propose to use X-ray absorption spectroscopy to study the molecular mechanisms of heavy metal detoxification by the bacterial mercury resistance system, encoded by the Tn501 mer operon. The mer system employs metal transport proteins, enzymes for transformation and reduction of mercury species to elemental volatile Hg(0), and a paradigmatic metalloregulatory system (based on MerR), all of which demonstrate specificity for Hg. In general, we are interested in elucidating the molecular mechanisms involved and in investigating the potential for engineering this system to handle other heavy metals (Cd, Au, etc.) for bioremediation. This particular program has two major targets: (a) MerR, its interactions with merO/P and/or RNA polymerase, and the role of MerD which appears to be involved in relieving MerR activation; (b) MerA (mercuric reductase) and variants that have now been shown to also catalyze the reduction of Au(III) to Au(I), with eventual disproportionation to form Au(0) colloids.