Oxidation of Sulfur and Inorganic Sulfur Compounds in the Thermoacidophilic Archaeon Acidianus ambivalens²

嗜热嗜酸古菌 Acidianus ambivalens² 中硫和无机硫化合物的氧化

• 批准号: 223011195
• 负责人: Privatdozent Dr. Arnulf Kletzin
• 金额: --
• 依托单位: Arbeitsgruppe Sulfur Biochemistry and Microbial Bioenergetics
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/223011195?language=en
• 关键词: Oxidation; Sulfur; Inorganic; Compounds; Thermoacidophilic

The thermoacidophilic Archaeon Acidianus ambivalens oxidizes elemental sulfur to sulfuric acid as energy source when growing under oxygen atmosphere. The organism is an important model organ-ism of the chemolithoautotrophic lifestyle in volcanic hot springs and in bioleaching. A key enzyme in the sulfur oxidation pathway is a soluble sulfur oxygenase reductase (SOR), which dismutates ele-mental sulfur to sulfide and sulfite. We had determined the three-dimensional structure of the SOR of A. ambivalens and of the mesophilic bacterium Halothiobacillus neapolitanus. We had also conducted studies with SOR mutants, which resulted in a so far hypothetical reaction mechanism and a model of substrate and product pathways. The goals of this proposal are to reappraise our hypotheses experi-mentally and to elucidate the reaction mechanism of the SORs in more detail. We want to determine whether a redox change occurs at the active site iron during substrate turnover and why the ratio of oxidized and reduced reaction products changes with temperature, pH and mutants analyzed. We want to identify reaction intermediates and inhibitor adducts in the active site and to generate a map of indispensable residues of the enzyme(s). To achieve our goals, we will use a combination of additional mutagenesis trials, reduction potential determination, various spectroscopic techniques (Mößbauer, electron paramagnetic resonance, vibrational spectroscopy), computer simulations, rapid reaction kinetics, inhibitor studies, and X-ray crystallography of protein derivatives.

嗜热嗜酸菌Acidianus ambivalens在氧气环境下生长时，将元素硫氧化为硫酸作为能源。该生物是火山温泉化能自养生活方式和生物浸矿的重要模式生物。硫氧化途径中的关键酶是可溶性硫加氧酶还原酶（SOR），它将元素硫歧化为硫化物和亚硫酸盐。我们测定了A. ambivalens和嗜温细菌Halothiobacillusneapolitanus。我们还对SOR突变体进行了研究，得到了迄今为止假设的反应机制以及底物和产物途径的模型。本文的目的是从实验上重新评价我们的假设，并更详细地阐明SORs的反应机理。我们希望确定在底物周转期间活性位点铁是否发生氧化还原变化，以及氧化和还原反应产物的比例为何随温度、pH值和分析的突变体而变化。我们希望确定活性位点中的反应中间体和抑制剂加合物，并生成酶的不可缺少的残基的图谱。为了实现我们的目标，我们将使用额外的诱变试验，还原电位测定，各种光谱技术（穆斯堡尔，电子顺磁共振，振动光谱），计算机模拟，快速反应动力学，抑制剂研究和蛋白质衍生物的X射线晶体学的组合。