ATP-getriebener Elektronentransport der Benzoyl-CoA Reduktase

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The iron-sulfur-enzyme benzoyl-CoA reductase catalyzes the reduction of benzoyl-CoA to a non-aromatic cyclic diene; this reaction is driven by the hydrolysis of 2 ATP. ATP hydrolysis results in the energetization of an electron and is accompanied by a switch from S = 1/2 to S = 7/2 high-spin EPR signals of the reduced enzyme. In parallel it induces the reversible magnetic interaction of two [4Fe-4S] clusters. We postulate consecutive one-electron transfer and protonation steps in the dearomatization process (Birch reduction). ATP hydrolysis would be coupled to electron activation which is required to overcome the high redox barrier (E'o = -1.9 V) for the first electron transfer to the aromatic ring. Our approaches in getting deeper insights in the structure/function relationships of benzoyl-CoA reductase include spectroscopical (EPR-, Mössbauer-, MCD-spectroscopy), crystallographical/X-ray analytical and molecular biological techniques (heterologous expression of part-activities containing subunits) as well as substrate binding studies. It is possible to investigate the ATP-dependent electron activation separately from the electron transfer to the aromatic ring. We attempt to understand how an enzyme with relatively simple redox modules transfers the energy of ATP hydrolysis into the redox energy required for the dearomatization process.