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Humboldt-Universitaet zu Berlin - Structural Biology / Biochemistry

Humboldt-Universitaet zu Berlin | Department of Biology | Structural Biology / Biochemistry | Publications | Crystal structure of 4-hydroxybutyryl-CoA dehydratase: radical catalysis involving a [4Fe-4S] cluster and flavin

Berta M Martins, Holger Dobbek, Irfan Cinkaya, Wolfgang Buckel, and Albrecht Messerschmidt (2004)

Crystal structure of 4-hydroxybutyryl-CoA dehydratase: radical catalysis involving a [4Fe-4S] cluster and flavin

Proceedings of the National Academy of Sciences US, 101(44):15645–15649.

Dehydratases catalyze the breakage of a carbon-oxygen bond leading to unsaturated products via the elimination of water. The 1.6-A resolution crystal structure of 4-hydroxybutyryl-CoA dehydratase from the gamma-aminobutyrate-fermenting Clostridium aminobutyricum represents a new class of dehydratases with an unprecedented active site architecture. A [4Fe-4S](2+) cluster, coordinated by three cysteine and one histidine residues, is located 7 A from the Re-side of a flavin adenine dinucleotide (FAD) moiety. The structure provides insight into the function of these ubiquitous prosthetic groups in the chemically nonfacile, radical-mediated dehydration of 4-hydroxybutyryl-CoA. The substrate can be bound between the [4Fe-4S](2+) cluster and the FAD with both cofactors contributing to its radical activation and catalytic conversion. Our results raise interesting questions regarding the mechanism of acyl-CoA dehydrogenases, which are involved in fatty acid oxidation, and address the divergent evolution of the ancestral common gene.