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Publication Abstract from PubMed

Uronate dehydrogenase from Agrobacterium tumefaciens (AtUdh) belongs to the short-chain dehydrogenase/reductase (SDR) superfamily and catalyzes the oxidation of D-galacturonic and D-glucuronic acid with NAD+ as a cofactor. We have determined the crystal structures of an apo form of AtUdh, a ternary form in complex with NADH and product (substrate soaked structure) and an inactive Tyr136Ala mutant in complex with NAD+. The crystal structures suggested AtUdh to be a homo-hexamer, which has also been observed to be the major form in solution. The monomer contains a Rossmann fold, essential for nucleotide binding and a common feature of the sort-chain dehydrogenase (SDR) -family enzymes. The ternary complex structure revealed a product, D-galactaro-1,5-lactone, which is bound above the nicotinamide ring. This product rearranges in solution to D-galactaro-1,4-lactone as verified by mass spectrometry analysis, which agrees with our previous NMR study. The crystal structure of the catalytic residue Tyr136 mutant to alanine showed changes in the position of the residues Ile74 and Ser75. This probably altered the binding of the nicotinamide end of NAD+, which was not visible in the electron density map. The structures presented provide novel insights into the cofactor and substrate binding and the reaction mechanism of AtUdh. This information can be applied in the for design of efficient microbial conversion of D-galacturonic acid-based waste materials.

Crystal structure of uronate dehydrogenase from Agrobacterium tumefaciens.,Parkkinen T, Boer H, Janis J, Andberg M, Penttila M, Koivula A, Rouvinen J J Biol Chem. 2011 Jun 15. PMID:21676870^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.