ATP synthesis coupled to electron transfer from H2 to the heterodisulfide of 2‐mercaptoethanesulfonate and 7‐mercaptoheptanoylthreonine phosphate in vesicle preparations of the methanogenic bacterium strain Gö1

Abstract

Crude vesicle preparations of the methanogenic strain Gol were able to couple the reduction of the heterodisulfide of 2‐mercaptoethanesulfonate and 7‐mercaptoheptanoylthreonine phosphate (CoM‐S‐S‐HTP) by H₂ with ATP formation. The rate of ATP synthesis was 1 mg protein. ATP synthesis and disulfide reduction were only observed with CoM‐S‐S‐HTP, but not with CoM‐S‐S‐CoM or HTP‐S‐S‐HTP. The methylreductase inhibitor 2‐bromoethanesulfonic acid had no effect on ATP synthesis induced by CoM‐S‐S‐HTP reduction with H₂. ATP synthesis was completely inhibited by the uncoupler SF 6847 whereas the concomitant CoM‐S‐S‐HTP reduction was stimulated. The ATP synthase inhibitors DCCD and DES also inhibited ATP formation completely and decreased the CoM‐S‐S‐HTP reduction rate to 35% of the control. These inhibitory effects were abolished by addition of the uncoupler. From these results it is concluded that energy coupling between the electron transfer from H₂ to the heterodisulfide and ATP synthesis occurs via a transmembrane proton gradient.