Determination of the crystal structure of EntA, a 2,3-dihydro-2,3-dihydroxybenzoic acid dehydrogenase from Escherichia coli

The Escherichia coli enterobactin synthetic cluster is composed of six proteins, EntA-EntF, that form the enterobactin molecule from three serine molecules and three molecules of 2,3-dihydroxybenzoic acid (DHB). EntC, EntB and EntA catalyze the three-step synthesis of DHB from chorismate. EntA is a member of the short-chain oxidoreductase (SCOR) family of proteins and catalyzes the final step in DHB synthesis, the NAD⁺-dependent oxidation of 2,3-­dihydro-2,3-dihydroxybenzoic acid to DHB. The structure of EntA has been determined by multi-wavelength anomalous dispersion methods. Here, the 2.0 Å crystal structure of EntA in the unliganded form is presented. Analysis of the structure in light of recent structural and bioinformatic analysis of other members of the SCOR family provides insight into the residues involved in cofactor and substrate binding.