Delta mu Na+ drives the synthesis of ATP via an delta mu Na(+)-translocating F1F0-ATP synthase in membrane vesicles of the archaeon Methanosarcina mazei Gö1.
Methanosarcina mazei Gö1 couples the methyl transfer from methyl-tetrahydromethanopterin to 2-mercaptoethanesulfonate (coenzyme M) with the generation of an electrochemical sodium ion gradient (delta mu Na+) and the reduction of the heterodisulfide of coenzyme M and 7-mercaptoheptanoylthreoninephosphate with the generation of an electrochemical proton gradient (delta muH+). Experiments with washed inverted vesicles were performed to investigate whether both ion gradients are used directly for the synthesis of ATP. delta mu Na+ and delta mu H+ were both able to drive the synthesis of ATP in the vesicular system. ATP synthesis driven by heterodisulfide reduction (delta mu H+) or an artificial delta pH was inhibited by the protonophore SF6847 but not by the sodium ionophore ETH157, whereas ETH157 but not SF6847 inhibited ATP synthesis driven by a chemical sodium ion gradient (delta pNa) as well as the methyl transfer reaction (delta mu Na+). Inhibition of the Na+/H+ antiporter led to a stimulation of ATP synthesis driven by the methyl transfer reaction (delta mu Na+), as well as by delta pNa. These experiments indicate that delta mu Na+ and delta mu H+ drive the synthesis of ATP via an Na(+)- and an H(+)-translocating ATP synthase, respectively. Inhibitor studies were performed to elucidate the nature of the ATP synthase(s) involved. delta pH-driven ATP synthesis was specifically inhibited by bafilomycin A1, whereas delta pNa-driven ATP synthesis was exclusively inhibited by 7-chloro-4-nitro-2-oxa-1,3-diazole, azide, and venturicidin. These results are evidence for the presence of an F(1)F(0)-ATP synthase in addition to the A(1)A(0)-ATP synthase in membranes of M. Mazei Gö1 and suggest that the F(1)F(0)-type enzyme is an Na+-translocating ATP synthase, whereas the A(1)A(0)-ATP synthase uses H+ as the coupling ion.
Becher
B
B
Institut für Mikrobiologie, Georg-August-Universität, Göttingen, Germany.
Müller
V
V
D000081:Acetamides / Q000494:pharmacology; D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000096:biosynthesis*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000935:Antifungal Agents / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D018942:Macrolides; D008564:Membrane Potentials; D015080:Mesna / Q000378:metabolism; D017020:Methanosarcina / Q000201:enzymology*; D008780:Methyltransferases / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D010769:Phosphothreonine / Q000031:analogs & derivatives / Q000378:metabolism; D011522:Protons; D012964:Sodium / Q000378:metabolism*
D000081:Acetamides; D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D018942:Macrolides; D009570:Nitriles; D011522:Protons; C049349:7-mercaptoheptanoylthreonine phosphate; D010769:Phosphothreonine; C001784:SF 6847; C087007:ETH 157; C040929:bafilomycin A1; D000255:Adenosine Triphosphate; D012964:Sodium; D008780:Methyltransferases; D000251:Adenosine Triphosphatases; D015080:Mesna