Sulfide Metabolism and Toxicity in Chlorobaculum Tepidum

硫化氢是已知的硫还原程度最高的物种，是全球硫循环中的重要中间体，也是对人类有效的毒素和信号分子。这项由这笔赠款支持的研究将增加我们对一种关键酶的了解，该酶氧化硫化物作为能量代谢的关键部分，并用于解毒：苯醌氧化还原酶(SQR)。编码SQR同源物的基因在生命的三个领域都有发现，从小基因组的细菌、古生物到人类，但这个酶家族的成员很少被详细研究。这项研究将利用一个模型系统，被盖绿杆菌，这是唯一已知的包含三个编码SQR同源物基因的生物。初步数据表明，这三个基因都得到了表达，其中两个基因编码了活性SQR，而第三个基因产物的活性仍然未知。赤霉菌是一种产氧、光养细菌，利用硫化物和其他还原硫化合物作为电子供体，在厌氧条件下进行光合作用。硫氧化菌等厌氧硫氧化菌有助于维持沉积物和热液系统等厌氧环境的低硫化物通量，从而有助于维持好氧生物圈。这项研究的具体目标是了解被盖隐翅虫SQR同源物在该生物体生物学背景下的作用，并帮助确定SQR家族中序列和功能多样性之间的特定关系。这三个同源物都来自SQR分支，以前没有对其进行过详细的生化研究。另外两株绿色硫磺细菌的SQR也将被检查，这两株细菌被认为代表了相对于毛滴虫的低硫化物和高硫化物适应生态型。更广泛的影响。本课程将结合电化学、生化和分子遗传学技术，为相关的本科生和研究生提供高度跨学科的培训。该实验室有非常成功的指导本科生的历史，这些本科生在全国会议上提交数据，并作为已发表论文的合著者。还制定了计划，通过特拉华大学的许多正在进行的外联计划，向普通公众和K-12教育工作者传播信息。这些活动包括帮助公众建造自己的微生物花园，并在相差显微镜上观察样本，以及为将微生物学纳入K-12科学课程提供材料和实验。

Hydrogen sulfide, the most reduced species of sulfur known, is an important intermediate in the global sulfur cycle, and is also both a potent toxin to and signaling molecule for humans. The research that will be supported by this grant will increase our understanding of a key enzyme that oxidizes sulfide either as a key part of energy metabolism and for detoxification, sulfide:quinone oxidoreductase (SQR). Genes encoding homologs of SQR are found in organisms from all three domains of life ranging from small genome size bacteria and archaea to humans, but few members of this enzyme family have been studied in molecular detail. This study will utilize a model system, Chlorobaculum tepidum, which is the only organism known to contain three genes that encode SQR homologs. Prelimary data indicate that all three genes are expressed and that two of these genes encode active SQRs while the activity of the third gene product remains cryptic. C. tepidum is an anoxygenic, phototrophic bacterium that utilizes sulfide and other reduced sulfur compounds as electron donors for photosynthesis under anaerobic conditions. Anaerobic sulfur oxidizers like C. tepidum help to maintain low sulfide fluxes from anaerobic environments like sediments and hydrothermal systems thereby helping to maintain the aerobic biosphere. The specific goals of this research are to understand the roles of the C. tepidum SQR homologs in the context of the biology of this organism and help to define specific relationships between sequence and functional diversity in the SQR family. All three of the homologs are from clades of SQR that have not previously been studied in biochemical detail. SQRs from two other strains of green sulfur bacteria that are thought to represent low sulfide and high sulfide adapted ecotypes relative to C. tepidum will also be examined. Broader Impacts. A powerful combination of electrochemical, biochemical, and molecular genetic techniques will be employed in the course of this program that will provide highly interdisciplinary training for the undergraduate and graduate students involved. The laboratory has a very successful history of mentoring undergraduates who present data at national meetings and serve as co-authors on published papers. Plans are also in place to disseminate information to the general public and to K-12 educators through numerous ongoing outreach programs at the University of Delaware. These activities include helping the public construct their own microbial gardens and view samples on a phase contrast microscope and providing materials and experiments for incorporating microbiology into K-12 science curriculum.