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Crystal structure of 1,6-APD (2-ANIMOPHENOL-1,6-DIOXYGENASE) complexed with intermediate products
Structural highlights
FunctionAMNA_COMTE Component of the 2-aminophenol 1,6-dioxygenase (APD) complex that catalyzes the ring fission of 2-aminophenol to produce 2-aminomuconic semialdehyde. CnbCa may have a role in the stability of the complex. The complex is also active on other substrates such as 2-amino-5-chlorophenol (68% activity), protocatechuate (33% activity) and catechol (5% activity). Both 2-aminophenol and 2-amino-5-cholorophenol are likely native substrates for this dioxygenase which is involved in the reductive degradation pathway of both nitrobenzene (NB) and 4-chloronitrobenzene (4-CNB), allowing C.testosteroni strain CNB-1 to grow on these compounds as sole source of carbon, nitrogen, and energy.[1] [2] Publication Abstract from PubMedDioxygen activation by nonhaem Fe(II) enzymes containing the 2-His-1-carboxylate facial triad has been extensively studied in recent years. Here, crystal structures of 2-aminophenol 1,6-dioxygenase, an enzyme that represents a minor group of extradiol dioxygenases and that catalyses the ring opening of 2-aminophenol, in complex with the lactone intermediate (4Z,6Z)-3-iminooxepin-2(3H)-one and the product 2-aminomuconic 6-semialdehyde and in complex with the suicide inhibitor 4-nitrocatechol are reported. The Fe-ligand binding schemes observed in these structures revealed some common geometrical characteristics that are shared by the published structures of extradiol dioxygenases, suggesting that enzymes that catalyse the oxidation of noncatecholic compounds are very likely to utilize a similar strategy for dioxygen activation and the fission of aromatic rings as the canonical mechanism. The Fe-ligation arrangement, however, is strikingly enantiomeric to that of all other 2-His-1-carboxylate enzymes apart from protocatechuate 4,5-dioxygenase. This structural variance leads to the generation of an uncommon O(-)-Fe(2+)-O(-) species prior to O(2) binding, which probably forms the structural basis on which APD distinguishes its specific substrate and inhibitor, which share an analogous molecular structure. Structures of aminophenol dioxygenase in complex with intermediate, product and inhibitor.,Li de F, Zhang JY, Hou YJ, Liu L, Hu Y, Liu SJ, Wang da C, Liu W Acta Crystallogr D Biol Crystallogr. 2013 Jan;69(Pt 1):32-43. doi:, 10.1107/S0907444912042072. Epub 2012 Dec 20. PMID:23275161[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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