The membrane-bound electron transport system of Methanosarcina species.
Members of the genus Methanosarcina are strictly anaerobic archaea that derive their metabolic energy from the conversion of a restricted number of substrates to methane. H2 + CO2 are converted to CH4 via the CO2-reducing pathway, while methanol and methylamines are metabolized by the methylotrophic pathway. Two novel electron transport systems are involved in the process of methanogenesis. Both systems are able to use a heterodisulfide as electron acceptor and either H2 or F420H2 as electron acceptors and generate a proton-motive force by redox potential-driven H(+)-translocation. The H2:heterodisulfide oxidoreductase is composed of an F420-nonreducing hydrogenase and the heterodisulfide reductase. The latter protein is also part of the F420H2:heterodisulfide oxidoreductase system. The second component of this system is referred to as F420H2 dehydrogenase. The archaeal protein is a homologue of complex I of the respiratory chain from bacteria and mitochondria. This review focuses on the biochemical and genetic characteristics of the three energy-transducing enzymes and on the mechanisms of ion translocation.
Deppenmeier
Uwe
U
Department of Biological Sciences, University of Wisconsin-Milwaukee, PO Box 413, Milwaukee, Wisconsin 53201, USA. udeppen@uwm.edu
D000693:Anaerobiosis / Q000502:physiology; D019843:Archaeal Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D004579:Electron Transport / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism*; D008697:Methane / Q000378:metabolism*; D017018:Methanomicrobiales / Q000378:metabolism*; D010088:Oxidoreductases / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
D019843:Archaeal Proteins; D008565:Membrane Proteins; C072742:F420H2 dehydrogenase; D010088:Oxidoreductases; C087171:heterodisulfide reductase; D008697:Methane