Fumarate respiration of Wolinella succinogenes:: enzymology, energetics and coupling mechanism

Wolinella succinogenes performs oxidative phosphorylation with fumarate instead of O-2 as terminal electron acceptor and H-2 or formate as electron donors. Fumarate reduction by these donors ('fumarate respiration') is catalyzed by an electron transport chain in the bacterial membrane, and is coupled to the generation of an electrochemical proton potential (Deltap) across the bacterial membrane. The experimental evidence concerning the electron transport and its coupling to Deltap generation is reviewed in this article. The electron transport chain consists of fumarate reductase, menaquinone (MK) and either hydrogenase or formate dehydrogenase. Measurements indicate that the Deltap is generated exclusively by MK reduction with H-2 or formate; MKH2 oxidation by fumarate appears to be an electroneutral process. However, evidence derived from the crystal structure of fumarate reductase suggests an electrogenic mechanism for the latter process. (C) 2002 Elsevier Science B.V. All rights reserved.