pH-tuneable binding of 2′-phospho-ADP-ribose to ketopantoate reductase: a structural and calorimetric study
✍ Scribed by Ciulli, Alessio ;Lobley, Carina M. C. ;Tuck, Kellie L. ;Smith, Alison G. ;Blundell, Tom L. ;Abell, Chris
- Book ID
- 104478289
- Publisher
- International Union of Crystallography
- Year
- 2007
- Tongue
- English
- Weight
- 729 KB
- Volume
- 63
- Category
- Article
- ISSN
- 0907-4449
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✦ Synopsis
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.