Sulfide Oxidation and Signaling

膳食纤维与蛋白质摄入量、微生物发酵和蛋白质摄入量的三方交互作用 宿主细胞代谢，显示在结肠上皮细胞经常暴露于 高浓度的呼吸道毒素，硫化氢(硫化氢)。硫化氢也是有益的；它 用于通过过硫化(一种翻译后修饰)传递信号，是 电子转移链，生成三磷酸腺苷。硫代硫酸盐是#年硫化氢氧化的主要产物。 结肠及其合成涉及三种线粒体酶：硫代苯醌氧化还原酶 (SQR)、一个过硫化物双加氧酶(PDO)和一个硫磺转移酶。我们发现根尖的 这三种酶在结肠隐窝中的定位受有无的影响 微生物区系，这些酶在结肠癌中显著过度表达。我们现在 寻求从我们最初关注的人类硫化物氧化酶的酶学扩展到 硫化氢和丁酸盐的氧化途径之间的相互联系，这是首选的 克隆细胞的燃料，由微生物新陈代谢提供。我们假设硫化氢的优先顺序 过度丁酸氧化(避免中毒)，是通过辅酶A过硫化物(CoASSH)实现的 由SQR生产，由PDO氧化。CoASSH抑制丁酰辅酶A脱氢酶 (ACADS)，解释了为什么天然ACADS长期以来被纯化为一种“绿色”酶，因为 CoASSH和黄素辅因子之间的抑制性电荷转移复合体。为了测试这一点 假设，我们将确定CoASSH合成的动力学及其对AADS的抑制。 在体外，SQR或PDO表达正常或被消融的细胞中的丁酸氧化作用。我们会 还测定了人SQR和PDO的结构(带有紧密结合的抑制物)以告知 我们的动力学和细胞研究，并将评估SQR和复合体之间的竞争 II用于有限的辅酶Q库。使用蛋白质组学方法，我们已经鉴定了&gt；1800 过硫化物靶标，我们将研究硫化氢信号在调节代谢中的作用。 非恶性和恶性结肠上皮细胞。为此，我们将使用放射性标记跟踪和 代谢组学分析评估硫化物对中枢碳、核苷酸和脂质的影响 代谢，评估硫磺转移酶在蛋白质靶标催化过硫化中的作用， 评估肠道微生物区系和饲料对宿主硫化物代谢的影响。网络的影响 我们对硫化物介导的信号和信号的挑战性研究的广泛和严格的攻击 代谢调节，由强大的持续合作支持(与内科科学家， 癌细胞生物学家、微生物学家和物理化学家)，将从根本上提供 在相对未被探索的宿主-微生物组界面上的重要生物学见解。

The tripartite interaction between dietary fiber and protein intake, microbial fermentation and host cell metabolism, is on display in the colon where epithelial cells are routinely exposed to high concentrations of the respiratory poison, hydrogen sulfide (H2S). H2S is also beneficent; it is used for signaling via persulfidation, a posttranslational modification, and is a substrate for the electron transfer chain, generating ATP. Thiosulfate is the primary product of H2S oxidation in colon and its synthesis involves three mitochondrial enzymes: sulfide quinone oxidoreductase (SQR), a persulfide dioxygenase (PDO), and a sulfurtransferase. We have found that the apical localization of all three enzymes in colonic crypts is influenced by the presence or absence of microbiota and that these enzymes are significantly overexpressed in colon cancer. We now seek to expand from our initial focus on the enzymology of human sulfide oxidation enzymes to the interconnection between the oxidation pathways for H2S and butyrate, which is the preferred fuel for colonocytes and is furnished by microbial metabolism. We posit that prioritization of H2S over butyrate oxidation (to avert poisoning), is achieved via coenzyme A persulfide (CoASSH) produced by SQR and oxidized by PDO. CoASSH inhibits butyryl-CoA dehydrogenase (ACADS), explaining why native ACADS has long been purified as a “green” enzyme due to an inhibitory charge transfer complex between CoASSH and the flavin cofactor. To test this hypothesis, we will determine the kinetics of CoASSH synthesis and its inhibition of ACADS in vitro and of butyrate oxidation in cells with normal or ablated SQR or PDO expression. We will also determine the structures of human SQR and PDO (with a tightly bound inhibitor) to inform our kinetic and cellular studies and will assess the competition between SQR and complexes I and II for a limited coenzyme Q pool. Using a proteomic method, we have identified >1800 persulfide targets and we will investigate the role of H2S signaling in modulating metabolism in nonmalignant and malignant colon epithelial cells. For this, we will use radiolabel tracing and metabolomics analyses to assess the influence of sulfide on central carbon, nucleotide and lipid metabolism, evaluate the role of a sulfurtransferase in catalytic persulfidation of protein targets, and assess the influence of gut microbiota and diet on host sulfide metabolism. The impact of our broad and rigorous attack on the challenging study of sulfide-mediated signaling and metabolic modulation, supported by strong ongoing collaborations (with a physician scientist, cancer cell biologists, a microbiologist and physical chemists), will be to provide fundamentally important biological insights at the relatively unexplored host-microbiome interface.