MECHANISM OF AUTOTROPHIC GROWTH WITH CO OR CO2 AND H2

CO 或 CO2 和 H2 的自养生长机制

• 批准号: 3272649
• 负责人: HARLAND G. WOOD
• 金额: $ 15.35万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1978
• 资助国家: 美国
• 起止时间: 1978-04-01 至 1991-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3272649
• 关键词: Clostridium; Mossbauer spectrometry; acetates; acetyl coA; bioenergetics; carbon dioxide; carbon monoxide; chemical binding; circular dichroism; coenzyme A; electron nuclear double resonance spectroscopy; electron spin resonance spectroscopy; enzyme structure; hydrogen; methyl group; methyltransferase; microorganism metabolism; molecular cloning; nuclear magnetic resonance spectroscopy; tetrahydrofolates

These investigations have as the ultimate objective elucidation of the pathway by which certain bacteria grow with CO or CO2 and H2 as the source of carbon and energy. This is a pathway of autotrophic growth which differs from any previously described. It involves reduction of CO2 to methyltetrahydrofolate, then combination of this methyl group with CO and CoASH to form acetyl-CoA which is then used as the source of carbon for anabolic growth. The synthesis of acetyl-CoA from methyltetrahydrofolate, CO and CoASH is the unique portion of this pathway. Homogeneous proteins have been isolated from Clostridium thermoaceticum which catalyze this synthesis. They are CO dehydrogenase methyltransferase, a corrinoid enzyme, ferredoxin, and disulfide reductase. The CO dehydrogenase is the master enzyme of this pathway. It forms the C1 intermediate from CO or CO2 that is the precursor of the carbonyl group of acetyl-CoA, is the acceptor of the methyl from the methyl corrinoid enzyme and through the action of the CO dehydrogenase reductase combines with CoA. It then catalyzes the condensation of these three groups to acetyl-CoA. Our main objective is to elucidate how CO dehydrogenase catalyzes this condensation. We will use electron spin resonance (ESR), electron-nuclear double resonance, Mossbauer, and magnetic circular dichroism techniques to characterize the geometry and redox state of the Ni-Fe-S center of the CO dehydrogenase. We will investigate the mechanism of transfer of the methyl group from the methylated corrinoid protein to CO dehydrogenase with formation of an acetyl intermediate. We hope to detect this methyl-CO dehydrogenase complex using ESR techniques and chemically identify the amino acid sequence at the binding site. Likewise, the sequence near the linkage of CoASH to the enzyme, presumed to be by a disulfide bond, will be investigated. The monomers of the Alpha3Beta3 enzyme will be isolated, their metal content determined and genes for these proteins will be cloned and sequenced. The properties of CO dehydrogenase from certain methanogenic bacteria will be tested for their ability to synthesize acetyl-CoA to determine whether they may use a pathway of acetyl-CoA synthesis similar to that of C. thermoaceticum.

这些调查是最终的客观阐明 某些细菌用CO或CO2和H2作为源生长的途径 碳和能量。 这是一种自养生长的途径 与先前描述的任何不同之处。 它涉及将二氧化碳减少到 甲基四氢叶酸，然后该甲基与CO和CO和 加油形成乙酰辅酶A，然后用作碳来源 合成代谢生长。 从甲基四氢叶酸的乙酰辅酶A合成， Co和Coash是该路径的独特部分。 均质蛋白 已从热乙酰梭状芽胞杆菌中分离出来，这使它催化 合成。 它们是CO脱氢酶甲基转移酶，一种类氧 酶，铁蛋白和二硫键还原酶。 CO脱氢酶是 该途径的主酶。 它从CO或CO2形成C1中间体 那是乙酰辅酶A的羰基的前体，是受体 从甲基类酶的甲基和通过 CO脱氢酶还原酶与COA结合。 然后催化 这三组与乙酰辅酶A的缩合。 我们的主要目标是 阐明CO脱氢酶如何催化这种冷凝。 我们将使用 电子自旋共振（ESR），电子核双共振， Mossbauer和磁性圆二色性技术来表征 CO脱氢酶的Ni-FE-S中心的几何形状和氧化还原状态。 我们 将研究甲基从 与形成 乙酰中间体。 我们希望检测到这种甲基-CO脱氢酶 使用ESR技术的复合物并化学识别氨基酸 结合位点的序列。 同样，接近链接的序列 将酶涂到酶，被认为是二硫键，将是 调查。 将分离出α3Beta3酶的单体， 它们确定的金属含量和这些蛋白质的基因将被克隆 并测序。 CO脱氢酶的特性 将测试甲烷基细菌的合成能力 乙酰辅酶A确定它们是否可以使用乙酰辅酶A的途径 合成类似于热乙酰梭菌的合成。