title: A protein-targeting strategy used to develop a selective inhibitor of the E17K point mutation in the PH domain of Akt1.
abstract: 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.
authors.affiliation: Department of Chemistry, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Kaycie M
authors.initials: KM
authors.lastname: Deyle
authors.affiliation: Department of Applied Physics and Materials Science, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Blake
authors.identifier: 0000000210077111
authors.initials: B
authors.lastname: Farrow
authors.affiliation: Department of Chemistry, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Qiao Hee
authors.affiliation: Department of Chemistry, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Work
authors.affiliation: Department of Chemistry, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Michelle
authors.initials: M
authors.lastname: Wong
authors.affiliation: Indi Molecular, Culver City, California 90230. USA.
authors.forename: Bert
authors.initials: B
authors.lastname: Lai
authors.affiliation: Department of Chemistry, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Aiko
authors.initials: A
authors.lastname: Umeda
authors.affiliation: Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.
authors.forename: Steven W
authors.initials: SW
authors.lastname: Millward
authors.affiliation: Department of Chemistry, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Arundhati
authors.initials: A
authors.lastname: Nag
authors.affiliation: Department of Chemistry, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Samir
authors.initials: S
authors.lastname: Das
authors.affiliation: Department of Chemistry, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: James R
authors.initials: JR
authors.lastname: Heath
mesh_terms: D000595:Amino Acid Sequence; D000939:Epitopes / Q000737:chemistry; D008024:Ligands; D008969:Molecular Sequence Data; D017354:Point Mutation; D011485:Protein Binding; D051057:Proto-Oncogene Proteins c-akt / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D000939:Epitopes; D008024:Ligands; C494918:AKT1 protein, human; D051057:Proto-Oncogene Proteins c-akt