Phage display identifies macrocyclic peptides that bind the TRF2TRFH domain

Telomeric Repeat Binding Factor 2 (TRF2) is a subunit of the Shelterin protein complex that binds to telomeric DNA. TRF2 is a potential drug target for cancer therapy, as the genomic instability of cancer cells can result in telomeric fragility that is suppressed by overexpression of Shelterin proteins. In this study, we used phage display to screen for disulfide-cyclised peptides that bind the TRFH domain of TRF2, which is responsible for both homodimerisation and mediating the recruitment of accessory proteins. Enriched peptide sequences were resynthesised on standard solid-phase peptide synthesis and were shown to bind TRFH with micromolar affinity in biophysical assays. A macrocyclic analogue featuring a methylene crosslink between cysteine sidechains retained binding to TRFH. Sequence alignment and molecular modelling predicted that the bound poses of the enriched peptide sequences recapitulate the core binding motif found in TRFH-binding accessory proteins. This work demonstrates that phage display is a viable strategy for discovering novel peptide binders for TRF2, paving the way for screening and optimising modified peptides with greater functionality in future phage display campaigns.