Characterization of the Membrane-Associated Electron-Bifurcating Flavoenzyme EtfABCX from the Hyperthermophilic Bacterium Thermotoga maritima.

ABSTRACT: Electron bifurcation is an energy-conservation mechanism in which a single enzyme couples an exergonic reaction with an endergonic one. Heterotetrameric EtfABCX drives the reduction of low-potential ferredoxin (E°' ∼ -450 mV) by oxidation of the midpotential NADH (E°' = -320 mV) by simultaneously coupling the reaction to reduction of the high-potential menaquinone (E°' = -74 mV). Electron bifurcation occurs at the NADH-oxidizing bifurcating-flavin adenine dinucleotide (BF-FAD) in EtfA, which has extremely crossed half-potentials and passes the first, high-potential electron to an electron-transferring FAD and via two iron-sulfur clusters eventually to menaquinone. The low-potential electron on the BF-FAD semiquinone simultaneously reduces ferredoxin. We have expressed

SUBMITTER: Ge X 

PROVIDER: S-EPMC10734219 | biostudies-literature | 2023 Dec

REPOSITORIES: biostudies-literature