• Open Access

Using a Fragment-Based Approach To Target Protein–Protein Interactions

Authors

  • Dr. Duncan E. Scott,

    1. Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW (UK)
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  • Dr. Matthias T. Ehebauer,

    1. Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Old Addenbrooke's Site, Cambridge, CB2 1GA (UK)
    2. Current address: EMBL Hamburg c/o DESY, Building 25A, Notkestrasse 85, 22603 Hamburg (Germany)
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  • Dr. Tara Pukala,

    1. Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW (UK)
    2. Current Address: School of Chemistry and Physics, University of Adelaide, North Tce, Adelaide, 5005 (Australia)
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  • Dr. May Marsh,

    1. Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Old Addenbrooke's Site, Cambridge, CB2 1GA (UK)
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  • Prof. Sir Tom L. Blundell,

    1. Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Old Addenbrooke's Site, Cambridge, CB2 1GA (UK)
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  • Prof. Ashok R. Venkitaraman,

    1. Hutchison/MRC Research Centre, University of Cambridge, Hills Road, Cambridge, CB2 0XZ (UK)
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  • Prof. Chris Abell,

    1. Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW (UK)
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  • Dr. Marko Hyvönen

    Corresponding author
    1. Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Old Addenbrooke's Site, Cambridge, CB2 1GA (UK)
    • Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Old Addenbrooke's Site, Cambridge, CB2 1GA (UK)
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Abstract

The ability to identify inhibitors of protein–protein interactions represents a major challenge in modern drug discovery and in the development of tools for chemical biology. In recent years, fragment-based approaches have emerged as a new methodology in drug discovery; however, few examples of small molecules that are active against chemotherapeutic targets have been published. Herein, we describe the fragment-based approach of targeting the interaction between the tumour suppressor BRCA2 and the recombination enzyme RAD51; it makes use of a screening pipeline of biophysical techniques that we expect to be more generally applicable to similar targets. Disruption of this interaction in vivo is hypothesised to give rise to cellular hypersensitivity to radiation and genotoxic drugs. We have used protein engineering to create a monomeric form of RAD51 by humanising a thermostable archaeal orthologue, RadA, and used this protein for fragment screening. The initial fragment hits were thoroughly validated biophysically by isothermal titration calorimetry (ITC) and NMR techniques and observed by X-ray crystallography to bind in a shallow surface pocket that is occupied in the native complex by the side chain of a phenylalanine from the conserved FxxA interaction motif found in BRCA2. This represents the first report of fragments or any small molecule binding at this protein–protein interaction site.

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