RaPID Selection of Backbone Macrocyclic Peptides Targeting Akt2

Area of Science:

• Biochemistry
• Medicinal Chemistry
• Molecular Biology

Background:

• Backbone-cyclic peptides (BMPs) are prevalent in natural bioactive products.
• Conventional mRNA display and ribosomal synthesis methods are unsuitable for BMPs due to genotype-phenotype linkage issues.

Purpose of the Study:

• To develop a novel strategy for linking BMPs to mRNA for display selection.
• To construct and apply a library of BMPs fused to cognate mRNAs for ligand discovery.
• To identify BMP ligands targeting Akt2, a protein implicated in cancer pathogenesis.

Main Methods:

• A new strategy was devised involving a sidechain-to-S-mainchain bond formation via an S-to-N acyl-shift.
• This method connects BMPs to the C-terminal peptide fragment linked to mRNA.
• A library of BMPs fused to cognate mRNAs was constructed and utilized for selection.

Main Results:

• The developed system successfully constructed a library of BMPs fused to cognate mRNAs.
• BMP ligands targeting Akt2 were identified from this library.
• The most potent inhibitor, BMPakti-3, demonstrated a dissociation constant of 1.3 nM and an IC50 of 34 nM.

Conclusions:

• The novel strategy enables the de novo discovery of backbone-cyclic peptides fused to mRNA.
• This platform facilitates the identification of bioactive BMP ligands against various protein targets.
• The findings present a unique approach for developing novel therapeutics, particularly for cancer targets like Akt2.