title: On the benefit of bivalency in peptide ligand/pin1 interactions.
abstract: The human peptidyl prolyl cis/trans isomerase (PPIase) Pin1 has a key role in developmental processes and cell proliferation. Pin1 consists of an N-terminal WW domain and a C-terminal catalytic PPIase domain both targeted specifically to Ser(PO(3)H(2))/Thr(PO(3)H(2))-Pro sequences. Here, we report the enhanced affinity originating from bivalent binding of ligands toward Pin1 compared to monovalent binding. We developed composite peptides where an N-terminal segment represents a catalytic site-directed motif and a C-terminal segment exhibits a predominant affinity to the WW domain of Pin1 tethered by polyproline linkers of different chain length. We used NMR shift perturbation experiments to obtain information on the specific interaction of a bivalent ligand to both targeted sites of Pin1. The bivalent ligands allowed a considerable range of thermodynamic investigations using isothermal titration calorimetry and PPIase activity assays. They expressed up to 350-fold improved affinity toward Pin1 in the nanomolar range in comparison to the monovalent peptides. The distance between the two binding motifs was highly relevant for affinity. The optimum in affinity manifested by a linker length of five prolyl residues between active site- and WW domain-directed peptide fragments suggests that the corresponding domains in Pin1 are allowed to adopt preferred spatial arrangement upon ligand binding.
authors.affiliation: Max Planck Research Unit for Enzymology of Protein Folding, Weinbergweg 22, 06120 Halle/Saale, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Daum
authors.forename: Christian
authors.initials: C
authors.lastname: Lücke
authors.forename: Dirk
authors.initials: D
authors.lastname: Wildemann
authors.forename: Cordelia
authors.initials: C
authors.lastname: Schiene-Fischer
mesh_terms: D001665:Binding Sites; D020134:Catalytic Domain; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D010446:Peptide Fragments / Q000737:chemistry*; D019696:Peptidylprolyl Isomerase / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D015398:Signal Transduction
chemical_list: D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D010446:Peptide Fragments; C000606846:PIN1 protein, human; D019696:Peptidylprolyl Isomerase