Biochemistry and Functional Genomics of Methanococcus Jannaschii

产甲烷的古生菌将简单的碳化合物转化为甲烷气体。由于生物产生的甲烷既是一种具有商业吸引力的能源，也是一种温室气体，因此人们希望找到控制甲烷生成的方法。该项目利用比较基因组学、分析生物化学、酶纯化、蛋白质化学和分子遗传学，在研究最多的产甲烷菌之一--简氏甲烷球菌的全基因组序列中确定生长和形成甲烷所需的新基因。这种自养生物利用氢气将二氧化碳还原为甲烷，并从大洋中部热液喷口释放的气体和矿物中产生生长所需的所有有机化合物。为了催化这些反应，Jannaschii需要至少19种有机辅酶，其中包括7种对甲烷形成至关重要的辅酶。该项目将鉴定和表征雅纳什分枝杆菌辅酶和氨基酸的生物合成所需的酶，但尚未从该生物体的完整基因组序列中鉴定出来。这些“看不见的”酶是设计特定的甲烷生成抑制剂的有吸引力的目标。Jannaschii产生的两种辅酶，核黄素和去氮核黄素辅酶F420，来自共同的前体。虽然古菌和真核生物通过相同的途径生物合成这一前体，但古菌使用不同的酶来催化几个反应，包括GTP环水解酶和嘧啶脱氨酶步骤。除了研究这些独特的酶，该项目还将表征辅酶F420生物合成后续步骤中涉及的蛋白质，包括COFC、COFD、COFE、COFG和COFH蛋白。这项研究还研究了生物合成4-氨基苯甲酸(用于生产甲烷蝶呤辅酶)所需的新型酶。最后，该项目将识别催化脯氨酸、半胱氨酸和蛋氨酸氨基酸生物合成、3-脱氢奎尼酸生物合成(芳香族氨基酸的前体)和嘌呤核苷酸生物合成的“隐形”酶。微生物詹纳斯基甲烷球菌生长在大洋中部的热液喷口，利用氢气和二氧化碳制造甲烷气体。该项目使用分子遗传学、生化和计算技术，在詹纳斯基分枝杆菌的完整基因组序列中确定生长和形成甲烷所需的新基因。这项研究的结果将有助于解释产甲烷生物是如何进化来产生甲烷的，并提出了有益于调节生物甲烷形成的分子靶标，有助于生产燃料或减少温室气体排放。

The methanogenic archaea convert simple carbon compounds into methane gas. Because biologically produced methane is both a commercially attractive energy source and a greenhouse gas, it is desirable to find methods to regulate methanogenesis. This project uses comparative genomics, analytical biochemistry, enzyme purification, protein chemistry and molecular genetics to identify new genes that are required for growth and methane formation in the complete genome sequence of one of the best-studied methanogens, Methanococcus jannaschii. This autolithotrophic organism uses hydrogen to reduce carbon dioxide to methane and produces all the organic compounds that it requires for growth from gases and minerals released from mid-ocean hydrothermal vent fluids. To catalyze these reactions, M. jannaschii requires at least 19 organic coenzymes including seven coenzymes that are essential for methane formation. This project will identify and characterize enzymes from M. jannaschii that are required for the biosynthesis of coenzymes and amino acids, but have not yet been identified from that organism's complete genome sequence. These "invisible" enzymes are attractive targets for designing specific inhibitors of methanogenesis. Two coenzymes produced by M. jannaschii, riboflavin and the deaza-riboflavin coenzyme F420, are derived from a common precursor. Although both archaea and eukaryotes biosynthesize this precursor by the same pathway, the archaea use different enzymes to catalyze several reactions including the GTP cyclohydrolase and pyrimidine deaminase steps. In addition to studying these unique enzymes, this project will characterize proteins involved in subsequent steps of coenzyme F420 biosynthesis, including the CofC, CofD,CofE, CofG and CofH proteins. This research also studies novel enzymes required for the biosynthesis of 4-aminobenzoic acid (used to produce the methanopterin coenzyme). Finally, this project will identify "invisible" enzymes that catalyze proline, cysteine and methionine amino acid biosyntheses, 3-dehydroquinate biosynthesis (a precursor of aromatic amino acids) and purine nucleotide biosynthesis.The microorganism Methanococcus jannaschii grows in mid-ocean hydro thermal vents, using hydrogen and carbon dioxide to make methane gas. This project uses molecular genetic, biochemical and computational techniques to identify new genes in the complete genome sequence of M. jannaschii that are required for growth and methane formation. Results from this research will help explain how methanogenic organisms have evolved to produce methane and suggest molecular targets for the beneficial regulation of biological methane formation, useful to produce fuel or to reduce greenhouse gas emissions.