Function of fumarate reductase in methanogenic bacteria (Methanobacterium) |
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Authors: | Georg Fuchs Erhard Stupperich Rudolf K. Thauer |
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Affiliation: | (1) Fachbereich Biologie-Mikrobiologie der Philipps-Universität, Lahnberge, D-3550 Marburg, Federal Republic of Germany |
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Abstract: | Methanogenic bacteria contain high activities of fumarate reductase. An interesting hypothesis has recently been advanced that this enzyme, in cooperation with a succinate dehydrogenase, functions in a fumarate-succinate cycle for ATP synthesis. This hypothesis was tested by determining whether [2, 3-3H] succinate loses3H when taken up by growing cells.Methanobacterium thermoautotrophicum was grown on H2 plus CO2 in the presence of [U-14C, 2,3-3H] succinate. The double labelled dicarboxylic acid was found to be incorporated into cell material with the loss of only 30% of tritium. Neither was3H released into H2O in significant amounts. This finding excludes a catabolic oxidation of succinate to fumarate in the growing cells and thus the operation of a fumaratesuccinate cycle. It is shown that the function of fumarate reductase inM. thermoautotrophicum is to provide the cells with succinate for the synthesis of -ketoglutarate, an intermediate in glutamate, arginine and proline synthesis. |
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Keywords: | Methanobacterium thermoautotrophicum ATP synthesis Funtarate reductase Menaquinone Cytochromeb Succinate dehydrogenase /content/k188546072677kvv/xxlarge945.gif" alt=" agr" align=" BASELINE" BORDER=" 0" >-Ketoglutarate synthesis Succinate incorporation Fumarate incorporation |
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