Phosphorus Metabolism in Methanogenic Bacteria

获资助的研究重点是两种主要的磷化合物在热自养甲烷菌和黄热甲烷菌中的作用。这些嗜热产甲烷菌的最佳生长温度分别为65℃和84℃。主要的焦点是环2,3-二磷酸甘油酸酯（环DPG）的合成和功能，从生物或非生物来源的环状焦磷酸盐的第一个例子。环状DPG水平在热自养M.中为70 mM，在fervidus中为300 mM，表明其在热适应中起主要作用。放射性磷示踪实验将提供环DPG转化的重要信息，并表明它是否可能在中温产甲烷菌的能量流动中起作用，以及在嗜热产甲烷菌中的双重作用。最近，本实验室在热自养m.c ortrophicum中发现了一个大的（36mm）长链多磷酸池；这个池的半衰期不到10分钟，表明它在能量流动中起着重要作用。主要目标是鉴定和表征环DPG和多磷酸途径中的酶，特别关注环DPG酶作为热传感系统的可能作用。这些途径的阐明将有助于我们对产甲烷菌生物化学的认识，并对产甲烷菌在生物技术中的应用产生重大影响。* * * / /

The funded research focuses on the role of two major phosphorus compounds in Methanobacterium thermoautotrophicum and Methanothermus fervidus. These thermophilic methanogens have optimal growth temperatures of 65 and 84 C, respectively. The major focus is on the synthesis and function of cyclic 2,3- diphosphoglycerate (cyclic DPG), the first example of a cyclic pyrophosphate from either biological or nonbiological origins. Cyclic DPG levels range from 70 mM in M. thermoautotrophicum to 300 mM in M. fervidus, indicating a major role in thermal adaptation. Tracer experiments with radioactive phosphorus will provide important information on the turnover of cyclic DPG and indicate whether it might have a role in energy flow in mesophilic methanogens and a dual role in thermophilic methanogens. Recently this lab has discovered a large (36 mM) long-chain polyphosphate pool in M. thermoautotrophicum; this pool has a half-life under 10 minutes, indicating a major role in energy flow. The main goal is the identification and characterization of the enzymes in the cyclic DPG and polyphosphate pathways, with special attention to the possible role of the cyclic DPG enzymes as a thermal sensing system. Elucidation of these pathways will contribute significantly to our understanding of the biochemistry of methanogens and could have significant impact on the application of methanogens in biotechnology.*** //