Regulation and function of ferredoxin-linked versus cytochrome b-linked hydrogenase in electron transfer and energy metabolism of Methanosarcina barkeri MS |
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| Authors: | John M Kemner Gregory Zeikus |
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| Institution: | (1) Department of Microbiology and Public Health, Michigan State University, 48824 East Lansing, MI, USA;(2) Department of Microbiology and Public Health, Michigan State University, 48824 East Lansing, MI, USA;(3) Department of Biochemistry, Michigan State University, 48824 East Lansing, MI, USA;(4) Present address: Department of Microbiology SC-42, University of Washington, 98 195 Seattle, WA, USA;(5) Present address: Michigan Biotechnology Institute, 3900 Collins Road, 48910 Lansing, MI, USA |
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| Abstract: | Acetate-grown cells of Methanosarcina barkeri MS were found to form methane from H2:CO2 at the same rate as hydrogen-grown cells. Cells grown on acetate had similar levels of soluble F420-reactive hydrogenase I, and higher levels of cytochrome-linked hydrogenase II compared to hydrogen-grown cells. The hydrogenase I and II activities in the crude extract of acetate-grown cells were separated by differential binding properties to an immobilized Cu2+ column. Hydrogenase II did not react with ferredoxin or F420, whereas hydrogenase I coupled to both ferredoxin and F420. A reconstituted soluble protein system composed of purified CO dehydrogenase, F420-reactive hydrogenase I fraction, and ferredoxin produced H2 from CO oxidation at a rate of 2.5 nmol/min · mg protein. Membrane-bound hydrogenase II coupled H2 consumption to the reduction of CoM-S-S-HTP and the synthesis of ATP. The differential function of hydrogenase I and II is ascribed to ferredoxin-linked hydrogen production from CO and cytochrome b-linked H2 consumption coupled to methanogenesis and ATP synthesis, respectively. |
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| Keywords: | Methanosarcina barkeri Hydrogenase Regulation ATP synthesis Ferredoxin F420 |
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