InterPro domain: IPR010960

This entry describes a family of redox proteins related to the succinate dehydrogenases and fumarate reductases (FRDs) of Escherichia coli, mitochondria, and other well-characterised systems. A member of this family from Shewanella frigidimarina (strain NCIMB 400) is characterised as a water-soluble periplasmic protein with four haem groups, a non-covalently bound FAD, and essentially unidirectional fumarate reductase activity. At least seven distinct members of this family are found in Shewanella oneidensis, a species able to use a wide variety of pathways for respiration, whose physiological reductant is unknown. Proteins with the FRD-like domain architecture are widely distributed among various bacteria that comprise a new type of water-soluble NADH:fumarate oxidoreductases. NADH:fumarate oxidoreductase (or FRD) from Klebsiella pneumoniae catalyses the anaerobic reduction of fumarate to succinate using NADH as the inherent electron donor [ 1 ]. This entry includes Urocanate reductase (urdA) from Shewanella oneidensis, which catalyses the two-electron reduction of urocanate to dihydrourocanate and contains a FAD‐binding domain homologous to the FAD‐binding domains of succinate dehydrogenase and periplasmic fumarate reductase [ 2 ].

1. A new water-soluble bacterial NADH: fumarate oxidoreductase. FEMS Microbiol Lett 367
2. Urocanate reductase: identification of a novel anaerobic respiratory pathway in Shewanella oneidensis MR-1. Mol Microbiol 86, 1452-63