TY - JOUR T1 - Target identification for small-molecule discovery in the FOXO3a tumor-suppressor pathway using a biodiverse peptide library. JF - Cell Chem Biol Y1 - 2021 A1 - Emery, Amy A1 - Hardwick, Bryn S A1 - Crooks, Alex T A1 - Milech, Nadia A1 - Watt, Paul M A1 - Mithra, Chandan A1 - Kumar, Vikrant A1 - Giridharan, Saranya A1 - Sadasivam, Gayathri A1 - Mathivanan, Subashini A1 - Sudhakar, Sneha A1 - Bairy, Sneha A1 - Bharatham, Kavitha A1 - Hurakadli, Manjunath A A1 - Prasad, Thazhe K A1 - Kamariah, Neelagandan A1 - Muellner, Markus A1 - Coelho, Miguel A1 - Torrance, Christopher J A1 - McKenzie, Grahame J A1 - Venkitaraman, Ashok R AB -

Genetic screening technologies to identify and validate macromolecular interactions (MMIs) essential for complex pathways remain an important unmet need for systems biology and therapeutics development. Here, we use a library of peptides from diverse prokaryal genomes to screen MMIs promoting the nuclear relocalization of Forkhead Box O3 (FOXO3a), a tumor suppressor more frequently inactivated by post-translational modification than mutation. A hit peptide engages the 14-3-3 family of signal regulators through a phosphorylation-dependent interaction, modulates FOXO3a-mediated transcription, and suppresses cancer cell growth. In a crystal structure, the hit peptide occupies the phosphopeptide-binding groove of 14-3-3ε in a conformation distinct from its natural peptide substrates. A biophysical screen identifies drug-like small molecules that displace the hit peptide from 14-3-3ε, providing starting points for structure-guided development. Our findings exemplify "protein interference," an approach using evolutionarily diverse, natural peptides to rapidly identify, validate, and develop chemical probes against MMIs essential for complex cellular phenotypes.

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