TRF2 functions as a protein hub and regulates telomere maintenance by recognizing specific peptide motifs

TRF2 is a member of the telosome/shelterin complex, which helps maintain telomere integrity. Using an oriented peptide library based on a previously identified TRF2-interaction region to define a consensus sequence for binding, new proteins have been identified as TRF2 interactors and implicated in telomeric functions. This suggests that TRF2 acts as a hub for recruiting different proteins to the telomere via a distinct linear sequence. In mammalian cells, the telomeric repeat binding factor (TRF) homology (TRFH) domain–containing telomeric proteins TRF1 and TRF2 associate with a collection of molecules necessary for telomere maintenance and cell-cycle progression. However, the specificity and the mechanisms by which TRF2 communicates with different signaling pathways remain largely unknown. Using oriented peptide libraries, we demonstrate that the TRFH domain of human TRF2 recognizes [Y/F]XL peptides with the consensus motif YYHK Y R L SPL. Disrupting the interactions between the TRF2 TRFH domain and its targets resulted in telomeric DNA-damage responses. Furthermore, our genome-wide target analysis revealed phosphatase nuclear targeting subunit (PNUTS) and microcephalin 1 (MCPH1) as previously unreported telomere-associated proteins that directly interact with TRF2 via the [Y/F]XL motif. PNUTS and MCPH1 can regulate telomere length and the telomeric DNA-damage response, respectively. Our findings indicate that an array of TRF2 molecules functions as a protein hub and regulates telomeres by recruiting different signaling molecules via a linear sequence code.