Isolation and characterization of methanophenazine and function of phenazines in membrane-bound electron transport of Methanosarcina mazei Gö1
| Autor: | Sebastian Bäumer, Hans-Jörg Abken, Uwe Beifuss, Jens Brodersen, Mario Tietze, Uwe Deppenmeier |
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| Rok vydání: | 1998 |
| Předmět: |
Hydrogenase
Physiology and Metabolism Coenzyme M Flavin group Biology Methanofuran Microbiology Mass Spectrometry Substrate Specificity Electron Transport 03 medical and health sciences chemistry.chemical_compound Oxidoreductase Molecular Biology Nuclear Magnetic Resonance Biomolecular Chromatography High Pressure Liquid 030304 developmental biology chemistry.chemical_classification Flavin adenine dinucleotide 0303 health sciences Molecular Structure 030306 microbiology Cell Membrane Tetrahydromethanopterin Electron acceptor Kinetics chemistry Biochemistry Models Chemical Methanosarcina Phenazines Oxidoreductases |
| Zdroj: | Journal of bacteriology. 180(8) |
| ISSN: | 0021-9193 |
| Popis: | The formation of methane from H2 + CO2, formate, methanol, methylamines, or acetate is the characteristic feature of methanogenic archaea. The metabolic pathways leading to the generation of CH4 are unique and involve novel enzymes and coenzymes such as tetrahydromethanopterin, methanofuran, coenzyme M (CoM-SH), and CoB-SH. Methyl-S-CoM is the central intermediate in all methanogenic pathways and is reductively demethylated to methane catalyzed by the methyl-CoM reductase. The two electrons required for the reduction derive from CoB-SH, resulting in the formation of a heterodisulfide (CoB-S-S-CoM) of CoM-SH and CoB-SH (10, 25). An energy-conserving step in the metabolism of methylotrophic methanogens is the reduction of CoB-S-S-CoM with either hydrogen or reduced F420 (8). In recent years, the membrane-bound electron transfer of Methanosarcina mazei Go1 has been analyzed in detail, resulting in the discovery of two proton-translocating systems referred to as H2:heterodisulfide oxidoreductase and F420H2:heterodisulfide oxidoreductase (4, 5). It has been shown that a membrane-bound, F420-nonreducing hydrogenase, cytochromes, and the heterodisulfide reductase are involved in the first of these electron transport systems. Electron transport from F420H2 to CoB-S-S-CoM is mediated by an F420H2 dehydrogenase which channels electrons via unknown electron carriers to the heterodisulfide reductase. Recently, the F420H2 dehydrogenase from M. mazei Go1 was purified (1). The native enzyme (115 kDa) contains iron-sulfur clusters and flavin adenine dinucleotide and is composed of five different subunits with molecular masses of 40, 37, 22, 20, and 17 kDa. Different compounds such as methylviologen, flavins, and quinones could act as electron acceptors. The most interesting question concerns the nature of the electron carriers which are responsible for electron transfer from F420H2 dehydrogenase to the heterodisulfide reductase. In this publication, we report on the identification of a small hydrophobic component referred to as methanophenazine which was extracted from the cytoplasmic membrane of M. mazei Go1. Furthermore, it is shown that phenazine derivatives are able to interact with enzymes which are involved in membrane-bound electron transport. |
| Databáze: | OpenAIRE |
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