Periodic Reporting for period 1 - TaGFrag (Stabilising Protein-Protein Interactions: A Target-Guided Fragment-Based Approach)
Reporting period: 2016-10-01 to 2018-09-30
Early results prompted a change in focus to the 14-3-3σ – p53 PPI which was also of great pharmaceutical interest because of its potential as a drug target for cancer treatment. FBDD screening led to the identification of novel fragment compounds binding to the 14-3-3σ – p53 PPI interface, a crucial first step toward functional molecules. The development of new bioorthogonal chemistry approaches led to the discovery of fusicoccin A (FC-A) as the first small molecule stabiliser of this PPI thus providing an important starting point for rational drug design. During the project it was also observed that different length peptides used to mimic the p53 binding motif had very different binding properties. This had significant fundamental implications for how PPI stabilisation is studied in vitro and so was also pursued as a research avenue.
Early development of the biorthogonal chemistry-based discovery approaches led to the unexpected observation that the natural product fusicoccin A (FC-A) stabilises the 14-3-3σ - p53 PPI. This project element therefore evolved into a systematic investigation into the molecular basis for this finding. These results have been published: Doveston et al., FEBS Lett. 2017, 591, 2449.
As part of this study it was discovered that the length of peptide (used to mimic the p53 binding partner) had a dramatic effect on binding affinity. This result had significant implications for the planned biorthogonal chemistry research elements as well as the reliability of other assays in development. In order to establish a thorough rational for these observations this also became the focus of a systematic study the outcomes of which are the subject of a manuscript in preparation for publication.