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One-megadalton metalloenzyme complex in Geobacter metallireducens involved in benzene ring reduction beyond the biological redox window
- Source :
- ISSN: 0027-8424
- Publication Year :
- 2019
-
Abstract
- Reversible biological electron transfer usually occurs between redox couples at standard redox potentials ranging from +0.8 to −0.5 V. Dearomatizing benzoyl-CoA reductases (BCRs), key enzymes of the globally relevant microbial degradation of aromatic compounds at anoxic sites, catalyze a biological Birch reduction beyond the negative limit of this redox window. The structurally characterized BamBC subunits of class II BCRs accomplish benzene ring reduction at an active-site tungsten cofactor; however, the mechanism and components involved in the energetic coupling of endergonic benzene ring reduction have remained hypothetical. We present a 1-MDa, membrane-associated, Bam[(BC)2DEFGHI]2 complex from the anaerobic bacterium Geobacter metallireducens harboring 4 tungsten, 4 zinc, 2 selenocysteines, 6 FAD, and >50 FeS cofactors. The results suggest that class II BCRs catalyze electron transfer to the aromatic ring, yielding a cyclic 1,5-dienoyl-CoA via two flavin-based electron bifurcation events. This work expands our knowledge of energetic couplings in biology by high-molecular-mass electron bifurcating machineries.
Details
- Database :
- OAIster
- Journal :
- ISSN: 0027-8424
- Notes :
- ISSN: 0027-8424, Proceedings of the National Academy of Sciences of the United States of America 116 (6);; 2259 - 2264, English
- Publication Type :
- Electronic Resource
- Accession number :
- edsoai.on1406010991
- Document Type :
- Electronic Resource