pH-tuneable binding of 2′-phospho-ADP-ribose to ketopantoate reductase: a structural and calorimetric study
- University Chemical Laboratory, Lensfield Road, Cambridge CB2 1EW (United Kingdom)
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA (United Kingdom)
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA (United Kingdom)
A combined crystallographic, calorimetric and mutagenic study has been used to show how changes in pH give rise to two distinct binding modes of 2′-phospho-ADP-ribose to ketopantoate reductase. The crystal structure of Escherichia coli ketopantoate reductase in complex with 2′-monophosphoadenosine 5′-diphosphoribose, a fragment of NADP{sup +} 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{sup +}, 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.
- OSTI ID:
- 22348008
- Journal Information:
- Acta Crystallographica. Section D: Biological Crystallography, Vol. 63, Issue Pt 2; Other Information: PMCID: PMC2483484; PMID: 17242510; PUBLISHER-ID: hv5073; OAI: oai:pubmedcentral.nih.gov:2483484; Copyright (c) International Union of Crystallography 2007; This is an open-access article distributed under the terms described at http://journals.iucr.org/services/termsofuse.html.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0907-4449
- Country of Publication:
- Denmark
- Language:
- English
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