PPII Helical Peptidomimetics Templated by Cation-π Interactions.

Area of Science:

• Biochemistry
• Structural Biology
• Medicinal Chemistry

Background:

• Poly-proline II (PPII) helices are crucial for protein-protein interactions in cellular signaling.
• Existing methods for stabilizing protein secondary structures (alpha-helices, beta-strands) lack analogous PPII helix strategies.
• PXXP motifs, which adopt PPII conformations, are vital recognition elements in many biological processes.

Purpose of the Study:

• To develop a novel strategy for enforcing PPII helical secondary structure.
• To create stable and chemically diverse PPII helical scaffolds.
• To enable the discovery of new peptidomimetic inhibitors targeting PXXP-mediated interactions.

Main Methods:

• Designed and synthesized a 19-residue TrpPlexus miniature protein.
• Employed sequence variation to identify key residues and interactions.
• Investigated the role of cation-π interactions in stabilizing PPII conformations.
• Utilized both peptide and N-substituted glycine peptoid residues.

Main Results:

• Successfully enforced PPII helical secondary structure in the TrpPlexus miniature protein.
• Demonstrated that a network of cation-π interactions drives PPII helix formation.
• Confirmed the ability to generate chemically diverse PPII helical scaffolds.
• Showcased the applicability to both peptide and peptoid residues.

Conclusions:

• A novel strategy for generating PPII helical structures has been established.
• Cation-π interactions are key drivers for PPII helix stabilization.
• The developed scaffolds offer a promising platform for designing PXXP-motif-targeting peptidomimetics.
• This work opens new avenues for inhibiting critical protein-protein interactions in cellular signaling.