X-Ray Crystal Structure of Escherichia Coli Taurine/Alpha-Ketoglutarate Dioxygenase Complexed to Ferrous Iron and Substrates

Taurine/α-ketoglutarate dioxygenase (TauD), a non-heme Fe(II) oxygenase, catalyses the conversion of taurine (2-aminoethanesulfonate) to sulfite and aminoacetaldehyde concurrent with the conversion of α-ketoglutarate (αKG) to succinate and CO2. The enzyme allows Escherichia coli to use taurine, widely available in the environment, as an alternative sulfur source. Here we describe the X-ray crystal structure of TauD complexed to Fe(II) and both substrates, αKG and taurine. The tertiary structure and fold of TauD are similar to those observed in other enzymes from the broad family of Fe(II)/αKG-dependent oxygenases, with closest structural similarity to clavaminate synthase. Using the TauD coordinates, a model was determined for the closely related enzyme 2,4-dichlorophenoxyacetate/αKG dioxygenase (TfdA), supporting predictions derived from site-directed mutagenesis and other studies of that biodegradative protein. The TauD structure and TfdA model define the metal ligands and the positions of nearby aromat...