title: A mechanism of covalent substrate binding in the x-ray structure of subunit K of the Escherichia coli dihydroxyacetone kinase.
abstract: Dihydroxyacetone (Dha) kinases are homologous proteins that use different phosphoryl donors, a multiphosphoryl protein of the phosphoenolpyruvate-dependent carbohydrate:phosphotransferase system in bacteria, ATP in animals, plants, and some bacteria. The Dha kinase of Escherichia coli consists of three subunits, DhaK and DhaL, which are colinear to the ATP-dependent Dha kinases of eukaryotes, and the multiphosphoryl protein DhaM. Here we show the crystal structure of the DhaK subunit in complex with Dha at 1.75 A resolution. DhaK is a homodimer with a fold consisting of two six-stranded mixed beta-sheets surrounded by nine alpha-helices and a beta-ribbon covering the exposed edge strand of one sheet. The core of the N-terminal domain has an alpha/beta fold common to subunits of carbohydrate transporters and transcription regulators of the phosphoenolpyruvate-dependent carbohydrate:phosphotransferase system. The core of the C-terminal domain has a fold similar to the C-terminal domain of the cell-division protein FtsZ. A molecule of Dha is covalently bound in hemiaminal linkage to the N epsilon 2 of His-230. The hemiaminal does not participate in covalent catalysis but is the chemical basis for discrimination between short-chain carbonyl compounds and polyols. Paralogs of Dha kinases occur in association with transcription regulators of the TetR/QacR and the SorC families, pointing to their biological role as sensors in signaling.
authors.affiliation: Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Siebold
authors.forename: Luis Fernando
authors.initials: LF
authors.lastname: García-Alles
authors.forename: Bernhard
authors.initials: B
authors.lastname: Erni
authors.forename: Ulrich
authors.initials: U
authors.lastname: Baumann
mesh_terms: D000595:Amino Acid Sequence; D001419:Bacteria / Q000201:enzymology; D001426:Bacterial Proteins / Q000737:chemistry; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D021122:Protein Subunits; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; D017853:Phosphotransferases (Alcohol Group Acceptor); C023132:glycerone kinase