ATP synthesis coupled to electron transfer from H 2 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 H 2 with ATP formation. The rate of ATP synthesis was 1 nmol min 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 H 2. 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 H 2 to the heterodisulfide and ATP synthesis occurs via a transmembrane proton gradient.