title: ATP synthesis in Methanobacterium thermoautotrophicum coupled to CH4 formation from H2 and CO2 in the apparent absence of an electrochemical proton potential across the cytoplasmic membrane.
abstract: Methanogenic bacteria are considered to couple methane formation with the synthesis of ATP by a chemiosmotic mechanism. This hypothesis was tested with Methanobacterium thermoautotrophicum. Methane formation from H2 and CO2 (2.5 - 3 mumol X min-1 X mg cells-1) by cell suspensions of this organism resulted in the formation of an electrochemical proton potential (delta mu H +) across the cytoplasmic membrane of 230 mV (inside negative) and in the synthesis of ATP up to an intracellular concentration of 5 - 7 nmol/mg. The addition of ionophores at concentrations which completely dissipated delta mu H + without inhibiting methane formation did not result in an inhibition of ATP synthesis. It thus appears that delta mu H + across the cytoplasmic membrane is not the driving force for the synthesis of ATP in M. thermoautotrophicum.
authors.forename: P
authors.initials: P
authors.lastname: Schönheit
authors.forename: D B
authors.initials: DB
authors.lastname: Beimborn
mesh_terms: D000255:Adenosine Triphosphate / Q000096:biosynthesis*; D002245:Carbon Dioxide / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D004563:Electrochemistry; D019605:Euryarchaeota / Q000378:metabolism*; D006859:Hydrogen / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007476:Ionophores / Q000494:pharmacology; D008564:Membrane Potentials; D008697:Methane / Q000096:biosynthesis*; D011188:Potassium / Q000494:pharmacology; D011522:Protons; D014634:Valinomycin / Q000494:pharmacology
chemical_list: D007476:Ionophores; D011522:Protons; D002245:Carbon Dioxide; D014634:Valinomycin; D006859:Hydrogen; D000255:Adenosine Triphosphate; D008697:Methane; D011188:Potassium