Ferredoxin requirement for electron transport from the carbon monoxide dehydrogenase complex to a membrane-bound hydrogenase in acetate-grown Methanosarcina thermophila |
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Authors: | K C Terlesky J G Ferry |
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Affiliation: | Department of Anaerobic Microbiology, Virginia Polytechnic Institute and State University, Blacksburg 24061. |
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Abstract: | Cell extracts from acetate-grown Methanosarcina thermophila contained CO-oxidizing:H2-evolving activity 16-fold greater than extracts from methanol-grown cells. Following fractionation of cell extracts into soluble and membrane components, CO-dependent H2 evolution and CO-dependent methyl-coenzyme M methylreductase activities were only present in the soluble fraction, but addition of the membrane fraction enhanced both activities. A b-type cytochrome(s), present in the membrane fraction, was linked to a membrane-bound hydrogenase. CO-oxidizing:H2-evolving activity was reconstituted with: (i) CO dehydrogenase complex, (ii) a ferredoxin, and (iii) purified membranes with associated hydrogenase. The ferredoxin was a direct electron acceptor for the CO dehydrogenase complex. The ferredoxin also coupled CO oxidation by CO dehydrogenase complex to metronidazole reduction. |
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