HPPU-MonoTag
Small-molecule ligand-protein binding pairs are invaluable tools in the field of biology. However, discovering such binding pairs from natural products remains challenging. Here, we report the development of a novel ligand-protein pair using a de novo approach. We first designed 1-(4-hydroxyphenyl)-3-phenylurea (HPPU) as the target ligand and used TRAP display to select an HPPU-binding monobody. Through an initial selection and affinity maturation, we obtained a monobody (Mb-P') with a single-nanomolar dissociation constant against HPPU (KD = 8.5 nM).