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Membrane-bound F420H2-dependent heterodisulfide reduction in methanococcus voltae
Brodersen1, Gottschalk, Deppenmeier
1Institut fur Mikrobiologie und Genetik, Georg-August-Universitat, Grisebachstrasse 8, D-37077 Gottingen, Germany.
Archives of Microbiology
|January 23, 1999
Summary
Methanococcus voltae membranes oxidize coenzyme F420H2 using a heterodisulfide reductase. This activity is linked to a membrane-associated F420-reducing hydrogenase, identified by its molecular mass and subunit composition.
Area of Science:
- Microbiology
- Biochemistry
- Bioenergetics
Background:
- Methanogens utilize heterodisulfide reductase for methanogenesis.
- Coenzyme F420H2 is a key electron carrier in some archaea.
- Understanding electron transfer pathways is crucial for microbial metabolism.
Purpose of the Study:
- To identify the enzyme responsible for coenzyme F420H2 oxidation in Methanococcus voltae.
- To characterize the purified F420H2-oxidizing enzyme.
- To investigate the role of hydrogenase in methanogenic electron transport.
Main Methods:
- Cellular membrane preparation and washing.
- Enzyme solubilization using detergents.
- Protein purification via sucrose density centrifugation, anion-exchange chromatography, and gel filtration.
- Enzyme activity assays (H2-dependent reduction of methyl viologen and F420).
Main Results:
- Membranes catalyzed oxidation of coenzyme F420H2 and reduction of the heterodisulfide (CoB-S-S-CoM).
- Purified enzyme demonstrated F420-reducing hydrogenase activity.
- The enzyme's molecular mass and subunit composition (43, 37, 27 kDa) matched known F420-reducing hydrogenase.
- N-terminal sequence of the 37-kDa subunit aligned with the fruG gene product.
Conclusions:
- F420H2 oxidation in M. voltae is catalyzed by a membrane-associated F420-reducing hydrogenase.
- This hydrogenase plays a role in the terminal steps of methanogenic electron transfer.
- M. voltae lacks a distinct F420H2 dehydrogenase found in methylotrophic methanogens.