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.*** //
