Design and NMR Studies of Cyclic Peptides Targeting the N-Terminal Domain of the Protein Tyrosine Phosphatase YopH

We report on the design and evaluation of novel cyclic peptides targeting the N-terminal domain of the protein tyrosine phosphatase YopH from Yersinia. Cyclic peptides have been designed based on a short sequence from the protein SKAP-HOM [DE(hal)DDPF (pY = phosphotyrosine)], and they all contain the motif DEZXDPfK (where Z is a phosphotyrosine or a non-hydrolyzable phosphotyrosine mimetic, X is an aspartic acid or a leucine and f is a d-phenylalanine). These peptides present a ‘head to tail’ architecture, enabling cyclization through formation of an amide bond in between the side chains of the first aspartic acid and the lysine residues. Chemical shift perturbation studies have been carried out to monitor the binding of these peptides to the N-terminal domain of YopH. Peptides containing a phosphotyrosine moiety exhibit binding affinities in the low micromolar range; substitution of the phosphotyrosine with one of its non-hydrolyzable derivatives dramatically reduces the binding affinities. These preliminary studies may pave the way for the discovery of more potent and selective peptidebased ligands of the YopH N-terminal domain which could be further investigated for their ability to inhibit Yersiniae infections.