A protein-targeting strategy used to develop a selective inhibitor of the E17K point mutation in the PH domain of Akt1

Ligands that can bind selectively to proteins with single amino-acid point mutations offer the potential to detect or treat an abnormal protein in the presence of the wild type (WT). However, it is difficult to develop a selective ligand if the point mutation is not associated with an addressable location, such as a binding pocket. Here we report an all-chemical synthetic epitope-targeting strategy that we used to discover a 5-mer peptide with selectivity for the E17K-transforming point mutation in the pleckstrin homology domain of the Akt1 oncoprotein. A fragment of Akt1 that contained the E17K mutation and an I19[propargylglycine] substitution was synthesized to form an addressable synthetic epitope. Azide-presenting peptides that clicked covalently onto this alkyne-presenting epitope were selected from a library using in situ screening. One peptide exhibits a 10:1 in vitro selectivity for the oncoprotein relative to the WT, with a similar selectivity in cells. This 5-mer peptide was expanded into a larger ligand that selectively blocks the E17K Akt1 interaction with its PIP3 (phosphatidylinositol (3,4,5)-trisphosphate) substrate.

K. M. Deyle, B. Farrow, Y. Q. Hee, J. Work, M. Wong, B. Lai, A. Umeda, S. W. Millward, A. Nag, Samir Das, and J. R. Heath
Nature Chemistry
Volume: 7
Pages: 455–462
Date: April, 2015
ICB Affiliated Authors: James R Heath