STRUCTURE AND ENZYMATIC CATALYSIS OF THE ORGANOMERCURIAL LYASE MERB

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 汞污染是一个极其重要的环境问题，在剧毒的甲基汞(MeHg)集中的沉积物中尤其危险。通过物理或化学补救方法清理受汞污染的沉积物的努力因这些程序昂贵且破坏环境的事实而受到阻碍。因此，开发一种生物修复系统来处理汞污染一直是人们关注的焦点。从有机汞污染场所分离的细菌已经开发出一种由两种酶(MERA和MerB)组成的系统，使它们能够有效地将离子汞和有机汞化合物转化为毒性较低的元素汞。目前使用的许多生物修复系统都试图利用MERA和MERB的独特性质来清除汞污染。我们的目标是对MerB是如何将有机汞化合物降解为离子汞的结构和机理有一个详细的了解。作为第一步，我们建议收集在各种筛选条件下生长的MerB晶体的最高分辨率数据。在第二系列实验中，我们将把适当的有机汞试剂浸入汞B晶体中，以确定汞的结合位置(S)和随之而来的结构变化(如果有的话)。MerB对有机汞的亲和力很强，使我们能够在低浓度(&lt；10 mM)下工作。在与天然晶体同构较好的情况下，将单一波长采集的有机汞导数数据作为重原子，基于同构和反常差分求解MerB结构。在大量不同构象的情况下，我们计划利用异常汞信号收集MAD数据，并求解与有机汞结合的MerB结构。我们的目标是详细描述MerB上的汞结合部位。

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. Mercury contamination is an extremely important environmental problem, and it is particularly hazardous in sediments where the highly toxic methyl mercury (MeHg) concentrates. Attempts to clean up mercury-contaminated sediments by either physical or chemical remediation have been hampered by the fact that these procedures are expensive and environmentally destructive. As a result, there has been a great deal of focus to develop a bioremediation system to deal with mercury contamination. Bacteria isolated from organic mercury-contaminated sites have developed a system of two enzymes (MerA and MerB) that allows them to efficiently convert both ionic and organic mercury compounds to the less toxic elemental mercury. Many of the currently used bioremediation systems attempt to take advantage of the unique properties of MerA and MerB to clean up mercury contamination. Our objective is to gain a detailed structural and mechanistic understanding of how MerB are able to degrade organomercurial compounds to ionic mercury. We propose as a first step to collect highest resolution data on MerB crystals grown under a variety of screening conditions. In a second series of experiments, we will soak into MerB crystals appropriate organic mercurial agents to identify the mercury binding site(s) and accompanying structural changes if any. The avidity of MerB for organomercurials is substantial and will allow us to work at low concentrations (< 10mM). In case of good isomorphism with native crystals, the organomercurial derivative data collected at a single wavelength will be used as a heavy atom to solve the MerB structure based on isomorphous and anomalous differences. In case of substantial non-isomorphism, we plan to collect MAD data using the anomalous mercury signal and solve the MerB structure bound with the organomercurial. Our objective being a detailed description of the mercury binding site on MerB.