title: Novel reactions involved in energy conservation by methanogenic archaea.
abstract: Methanogenic archaea of the order Methanosarcinales which utilize C(1) compounds such as methanol, methylamines or H(2)+CO(2), employ two novel membrane-bound electron transport systems generating an electrochemical proton gradient: the H(2):heterodisulfide oxidoreductase and the F(420)H(2):heterodisulfide oxidoreductase. The systems are composed of the heterodisulfide reductase and either a membrane-bound hydrogenase or a F(420)H(2) dehydrogenase which is functionally homologous to the proton-translocating NADH dehydrogenase. Cytochromes and the novel electron carrier methanophenazine are also involved. In addition, the methyl-H(4)MPT:HS-CoM methyltransferase is bioenergetically relevant. The enzyme couples methyl group transfer with the translocation of sodium ions and seems to be present in all methanogens. The proton-translocating systems with the participation of cytochromes and methanophenazine have been found so far only in the Methanosarcinales.
authors.affiliation: Institut für Mikrobiologie und Genetik, Georg-August-Universität, Grisebachstr. 8, 37077, Göttingen, Germany. udeppen@gwdg.de
authors.forename: U
authors.initials: U
authors.lastname: Deppenmeier
authors.forename: T
authors.initials: T
authors.lastname: Lienard
authors.forename: G
authors.initials: G
authors.lastname: Gottschalk
mesh_terms: D003580:Cytochromes / Q000378:metabolism; D004734:Energy Metabolism; D019605:Euryarchaeota / Q000737:chemistry / Q000145:classification / Q000378:metabolism*; D008780:Methyltransferases / Q000737:chemistry / Q000378:metabolism*; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D010619:Phenazines / Q000737:chemistry / Q000378:metabolism*
chemical_list: D003580:Cytochromes; D010619:Phenazines; C111939:methanophenazine; D010088:Oxidoreductases; C066352:coenzyme M-7-merceptoheptanoylthreonine-phosphate-heterodisulfide hydrogenase; D008780:Methyltransferases; C048755:tetrahydromethanopterin S-methyltransferase