title: Discovery and characterization of a nonphosphorylated cyclic peptide inhibitor of the peptidylprolyl isomerase, Pin1.
abstract: Phage panning led to the discovery of a disulfide-cyclized peptide CRYPEVEIC that inhibits Pin1 activity with a K(I) of 0.5 μM. NMR chemical shift perturbation experiments show that cyclic CRYPEVEIC binds to the active site of Pin1. Pin1 residues K63 and R68, which bind the phosphate of substrate peptides, do not show a significant chemical shift change in response to binding of cyclic CRYPEVEIC, consistent with absence of phosphate on the peptide. Cyclic CRYPEVEIC adopts a stable conformation with the side chains of the Y, P, V, and I residues packed together on one side of the ring. Cyclic CRYPEVEIC in solution exists as a mixture of two species, with a 1:4 cis/trans ratio for the Y-P bond. This mixture is stabilized to a single conformation when bound to Pin1. The constrained structure of cyclic CRYPEVEIC apparently facilitates high affinity binding without the presence of a phosphate group.
authors.affiliation: Department of Biochemistry, The University of Western Ontario , London, Ontario N6A 5C1, Canada.
authors.forename: Kelly E
authors.initials: KE
authors.lastname: Duncan
authors.forename: Brian R
authors.initials: BR
authors.lastname: Dempsey
authors.forename: Lauren E
authors.initials: LE
authors.lastname: Killip
authors.forename: Jarrett
authors.initials: J
authors.lastname: Adams
authors.forename: Melanie L
authors.initials: ML
authors.lastname: Bailey
authors.forename: Gilles A
authors.initials: GA
authors.lastname: Lajoie
authors.forename: David W
authors.initials: DW
authors.lastname: Litchfield
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Brandl
authors.forename: Gary S
authors.initials: GS
authors.lastname: Shaw
authors.forename: Brian H
authors.initials: BH
authors.lastname: Shilton
mesh_terms: D001665:Binding Sites; D020134:Catalytic Domain; D055808:Drug Discovery; D004791:Enzyme Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D015394:Molecular Structure; D058990:Molecular Targeted Therapy; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D019151:Peptide Library; D010456:Peptides, Cyclic / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D019696:Peptidylprolyl Isomerase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation; D013379:Substrate Specificity
chemical_list: D004791:Enzyme Inhibitors; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D019151:Peptide Library; D010456:Peptides, Cyclic; C560298:cysteinyl-arginyl-tyrosyl-prolyl-glutamyl-valyl-glutamyl-isoleucyl-cysteine (1-9) disulfide; D019696:Peptidylprolyl Isomerase