1uoe
From Proteopedia
Crystal structure of the dihydroxyacetone kinase from E. coli in complex with glyceraldehyde
Structural highlights
FunctionDHAK_ECOLI Dihydroxyacetone binding subunit of the dihydroxyacetone kinase, which is responsible for phosphorylating dihydroxyacetone. Binds covalently dihydroxyacetone in hemiaminal linkage. Acts also as a corepressor of DhaR by binding to its sensor domain, in the absence of dihydroxyacetone. 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 PubMedDihydroxyacetone (Dha) kinases are a sequence-conserved family of enzymes, which utilize two different phosphoryldonors, ATP in animals, plants, and some bacteria, and a multiphosphoprotein of the phosphoenolpyruvate carbohydrate phosphotransferase system (PTS) in most bacteria. Here, we compare the PTS-dependent kinase of Escherichia coli and the ATP-dependent kinase of Citrobacter freundii. They display 30% sequence identity. The binding constants of the E. coli kinase for eleven short-chain carbonyl compounds were determined by acetone precipitation of the enzyme-substrate complexes. They are 3.4 microM for Dha, 780 microM for Dha-phosphate (DhaP), 50 microM for D,L-glyceraldehyde (GA), and 90 microM for D,L-glyceraldehyde-3-phosphate. The k(cat) for Dha of the PTS-dependent kinase is 290 min(-1), and that of the ATP-dependent kinase is 1050 min(-1). The Km for Dha of both kinases is <6 microM. The X-ray structures of the enzyme-GA and the enzyme-DhaP complex show that substrates as well as products are bound in hemiaminal linkage to an active-site histidine. Quantum-mechanical calculations offer no indication for activation of the reacting hydroxyl group by the formation of the hemiaminal. However, the formation of the hemiaminal bond allows selection for short-chain carbonyl compounds and discrimination against structurally similar polyols. The Dha kinase remains fully active in the presence of 2 M glycerol, and phosphorylates trace impurities of carbonyl compounds present in glycerol. Phosphoenolpyruvate- and ATP-dependent dihydroxyacetone kinases: covalent substrate-binding and kinetic mechanism.,Garcia-Alles LF, Siebold C, Nyffeler TL, Flukiger-Bruhwiler K, Schneider P, Burgi HB, Baumann U, Erni B Biochemistry. 2004 Oct 19;43(41):13037-45. PMID:15476397[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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