title: Enantioselective oxidation of galactitol 1-phosphate by galactitol-1-phosphate 5-dehydrogenase from Escherichia coli.
abstract: Galactitol-1-phosphate 5-dehydrogenase (GPDH) is a polyol dehydrogenase that belongs to the medium-chain dehydrogenase/reductase (MDR) superfamily. It catalyses the Zn(2+)- and NAD(+)-dependent stereoselective dehydrogenation of L-galactitol 1-phosphate to D-tagatose 6-phosphate. Here, three crystal structures of GPDH from Escherichia coli are reported: that of the open state of GPDH with Zn(2+) in the catalytic site and those of the closed state in complex with the polyols Tris and glycerol, respectively. The closed state of GPDH reveals no bound cofactor, which is at variance with the conformational transition of the prototypical mammalian liver alcohol dehydrogenase. The main intersubunit-contacting interface within the GPDH homodimer presents a large internal cavity that probably facilitates the relative movement between the subunits. The substrate analogue glycerol bound within the active site partially mimics the catalytically relevant backbone of galactitol 1-phosphate. The glycerol binding mode reveals, for the first time in the polyol dehydrogenases, a pentacoordinated zinc ion in complex with a polyol and also a strong hydrogen bond between the primary hydroxyl group and the conserved Glu144, an interaction originally proposed more than thirty years ago that supports a catalytic role for this acidic residue.
authors.affiliation: Department of Crystallography and Structural Biology, Institute of Physical Chemistry Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain.
authors.forename: Rocío
authors.initials: R
authors.lastname: Benavente
authors.affiliation: Laboratory of Bacterial Biotechnology, Institute of Food Science and Technology and Nutrition (ICTAN), CSIC, Juan de la Cierva 3, 28006 Madrid, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Esteban-Torres
authors.affiliation: Microbiology, Saarland University, Campus Gebäude A1.5, 66123 Saarbruecken, Germany.
authors.forename: Gert-Wieland
authors.initials: GW
authors.lastname: Kohring
authors.affiliation: Department of Biomedical Sciences, School of Medicine and Health Sciences, University of Alcalá, 28871 Alcalá de Henares, Spain.
authors.forename: Álvaro
authors.initials: Á
authors.lastname: Cortés-Cabrera
authors.affiliation: Department of Biomedical Sciences, School of Medicine and Health Sciences, University of Alcalá, 28871 Alcalá de Henares, Spain.
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Sánchez-Murcia
authors.affiliation: Department of Biomedical Sciences, School of Medicine and Health Sciences, University of Alcalá, 28871 Alcalá de Henares, Spain.
authors.forename: Federico
authors.initials: F
authors.lastname: Gago
authors.affiliation: Department of Crystallography and Structural Biology, Institute of Physical Chemistry Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain.
authors.forename: Iván
authors.initials: I
authors.lastname: Acebrón
authors.affiliation: Laboratory of Bacterial Biotechnology, Institute of Food Science and Technology and Nutrition (ICTAN), CSIC, Juan de la Cierva 3, 28006 Madrid, Spain.
authors.forename: Blanca
authors.initials: B
authors.lastname: de las Rivas
authors.affiliation: Laboratory of Bacterial Biotechnology, Institute of Food Science and Technology and Nutrition (ICTAN), CSIC, Juan de la Cierva 3, 28006 Madrid, Spain.
authors.forename: Rosario
authors.initials: R
authors.lastname: Muñoz
authors.affiliation: Department of Crystallography and Structural Biology, Institute of Physical Chemistry Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain.
authors.forename: José M
authors.initials: JM
authors.lastname: Mancheño
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D002413:Cations, Divalent / Q000378:metabolism; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000737:chemistry* / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism*; D005990:Glycerol / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009243:NAD / Q000378:metabolism; D064430:NAD (+) and NADP (+) Dependent Alcohol Oxidoreductases / Q000737:chemistry* / Q000378:metabolism*; D010084:Oxidation-Reduction; D011487:Protein Conformation; D016415:Sequence Alignment; D013237:Stereoisomerism; D014325:Tromethamine / Q000378:metabolism; D015032:Zinc / Q000378:metabolism
chemical_list: D002413:Cations, Divalent; D029968:Escherichia coli Proteins; D014325:Tromethamine; D009243:NAD; D064430:NAD (+) and NADP (+) Dependent Alcohol Oxidoreductases; C000606716:galactitol-1-phosphate 5-dehydrogenase, E coli; D015032:Zinc; D005990:Glycerol
keywords: catalytic mechanism; crystal structure; dehydrogenase; enantioselectivity; galactitol phosphate; galactitol-1-phosphate 5-dehydrogenase; metal binding; metal coordination