Electronic circular dichroism and nuclear magnetic resonance studies of peptides derived from the FKBP52‐interacting β‐turn of the hERα ligand‐binding domain

Abstract

When located at the surface of proteins, turns containing a Pro‐Gly (PG) motif are often involved in protein/protein interactions and may participate in intracellular signaling cascades. As such, conformationally constrained short protein‐derived turn peptides offer promising perspectives for the development of drug candidates in the context of interfering with protein/protein interactions. From X‐ray crystal structures of the human estrogen receptor α ligand‐binding domain (hERα‐LBD), we have identified a short peptide motif (residues 363‐367, sequence: RVPGF) that adopts a type II β‐turn and which is a substrate of the FK1 peptidyl‐prolyl cis‐trans isomerase (PPIase or rotamase) catalytic site of the immunophilin FKBP52, when synthesized independently from the protein. Using ECD and NMR spectroscopy in combination with molecular dynamics simulations, we have embarked on a conformational study of peptides derived from this sequence, and we have explored the effects resulting from N‐ and C‐termini chemical modifications, cyclization, as well as from the replacement of both the proline and its preceding residue by various natural and non‐natural amino acids. All peptides are found to explore several conformational states in aqueous solution, differing by the conformation of the peptide bond preceding the proline residue of the central VPG segment. Trans isomers are characterized by a conformational equilibrium between a type II β‐turn around PG and an extended conformation, while cis isomers adopt a type VIb β‐turn centered on the Xaa‐Pro segment. We show here how limited chemical modifications can deeply influence the turn conformation of this FKBP52‐interacting peptide.

TAT-RasGAP317-326kills cells by targeting inner-leaflet–enriched phospholipids

“…The latter is more pronounced for the wild-type peptide, e.g., in PB and in the presence of lyso-phosphatidylcholine. This correlates with the expected higher rigidity of the backbone around tryptophan residue in this sequence and resembles the CD signals often observed in tryptophan-containing small cyclic peptides (22)(23)(24)(25).…”

Bioinspired Hybrid Fluorescent Ligands for the FK1 Domain of FKBP52

“…While the K d values remained weak, this study also supports the notion of the FK1 domain/active site pocket as a PPIase-independent platform of recognition between nuclear receptors and FKBP52, and thus as a potential target for protein–protein inhibition . A second structural study investigated the effects on the folding of these peptides into tight turns (type II and/or type VI), and a preference for certain turns by the FK1 domain based on their similarity to high affinity ligands . The aim of the current study was to generate a small library of water-soluble, fluorescent reporter molecules capable of binding the FKBP52 FK1 domain.…”

“…20 A second structural study investigated the effects on the folding of these peptides into tight turns (type II and/or type VI), and a preference for certain turns by the FK1 domain based on their similarity to high affinity ligands. 22 The aim of the current study was to generate a small library of water-soluble, fluorescent reporter molecules capable of binding the FKBP52 FK1 domain. These compounds had substantial peptide character to emulate natural substrates.…”

CX3CL1 homo-oligomerization drives cell-to-cell adherence

“…188 inter-proton distance restraints (71 intraresidual, 85 sequential, 32 medium-range) were derived from NOESY cross-peak intensities and 43 dihedral angle restraints (22 φ, 21 ψ) were obtained from the analysis of 1 Hα CSDs. Structures were calculated using Amber 14 program 51 and ff14SB force field 52 , as described 53 .…”