1gth | pdb_00001gth
DIHYDROPYRIMIDINE DEHYDROGENASE (DPD) FROM PIG, TERNARY COMPLEX WITH NADPH AND 5-IODOURACIL
Structural highlights
Function[DPYD_PIG] Involved in pyrimidine base degradation. Catalyzes the reduction of uracil and thymine.[1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedDihydroprymidine dehydrogenase catalyzes the first and rate-limiting step in pyrimidine degradation by converting pyrimidines to the corresponding 5,6- dihydro compounds. The three-dimensional structures of a binary complex with the inhibitor 5-iodouracil and two ternary complexes with NADPH and the inhibitors 5-iodouracil and uracil-4-acetic acid were determined by x-ray crystallography. In the ternary complexes, NADPH is bound in a catalytically competent fashion, with the nicotinamide ring in a position suitable for hydride transfer to FAD. The structures provide a complete picture of the electron transfer chain from NADPH to the substrate, 5-iodouracil, spanning a distance of 56 A and involving FAD, four [Fe-S] clusters, and FMN as cofactors. The crystallographic analysis further reveals that pyrimidine binding triggers a conformational change of a flexible active-site loop in the alpha/beta-barrel domain, resulting in placement of a catalytically crucial cysteine close to the bound substrate. Loop closure requires physiological pH, which is also necessary for correct binding of NADPH. Binding of the voluminous competitive inhibitor uracil-4-acetic acid prevents loop closure due to steric hindrance. The three-dimensional structure of the ternary complex enzyme-NADPH-5-iodouracil supports the proposal that this compound acts as a mechanism-based inhibitor, covalently modifying the active-site residue Cys-671, resulting in S-(hexahydro-2,4-dioxo-5-pyrimidinyl)cysteine. Crystal structure of the productive ternary complex of dihydropyrimidine dehydrogenase with NADPH and 5-iodouracil. Implications for mechanism of inhibition and electron transfer.,Dobritzsch D, Ricagno S, Schneider G, Schnackerz KD, Lindqvist Y J Biol Chem. 2002 Apr 12;277(15):13155-66. Epub 2002 Jan 16. PMID:11796730[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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