title: pH-tuneable binding of 2'-phospho-ADP-ribose to ketopantoate reductase: a structural and calorimetric study.
abstract: The crystal structure of Escherichia coli ketopantoate reductase in complex with 2'-monophosphoadenosine 5'-diphosphoribose, a fragment of NADP+ that lacks the nicotinamide ring, is reported. The ligand is bound at the enzyme active site in the opposite orientation to that observed for NADP+, with the adenine ring occupying the lipophilic nicotinamide pocket. Isothermal titration calorimetry with R31A and N98A mutants of the enzyme is used to show that the unusual ;reversed binding mode' observed in the crystal is triggered by changes in the protonation of binding groups at low pH. This research has important implications for fragment-based approaches to drug design, namely that the crystallization conditions and the chemical modification of ligands can have unexpected effects on the binding modes.
authors.affiliation: University Chemical Laboratory, Lensfield Road, Cambridge CB2 1EW, England.
authors.forename: Alessio
authors.initials: A
authors.lastname: Ciulli
authors.forename: Carina M C
authors.initials: CM
authors.lastname: Lobley
authors.forename: Kellie L
authors.initials: KL
authors.lastname: Tuck
authors.forename: Alison G
authors.initials: AG
authors.lastname: Smith
authors.forename: Tom L
authors.initials: TL
authors.lastname: Blundell
authors.forename: Chris
authors.initials: C
authors.lastname: Abell
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D000429:Alcohol Oxidoreductases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002151:Calorimetry; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D020125:Mutation, Missense; D009249:NADP; D011485:Protein Binding
chemical_list: D029968:Escherichia coli Proteins; D008024:Ligands; C020857:phosphoadenosine diphosphoribose; D000246:Adenosine Diphosphate Ribose; D009249:NADP; D000429:Alcohol Oxidoreductases; C021934:2-dehydropantoate 2-reductase