A1 Refereed original research article in a scientific journal

High-throughput amenable fluorescence-assays to screen for calmodulin-inhibitors




AuthorsManoharan G.B., Kopra K., Eskonen V., Härmä H., Abankwa D.

PublisherACADEMIC PRESS INC ELSEVIER SCIENCE

Publication year2019

JournalAnalytical Biochemistry

Journal name in sourceANALYTICAL BIOCHEMISTRY

Journal acronymANAL BIOCHEM

Volume572

First page 25

Last page32

Number of pages8

ISSN0003-2697

DOIhttps://doi.org/10.1016/j.ab.2019.02.015


Abstract
The KRAS gene is highly mutated in human cancers and the focus of current Ras drug development efforts. Recently the interface between the C-terminus of K-Ras and calmodulin (CaM) was proposed as a target site to block K-Ras driven cancer cell sternness. We therefore aimed at developing a high-throughput amenable screening assay to identify novel CaM-inhibitors as potential K-Ras sternness-signaling disruptors.A modulated time-resolved Forster resonance energy transfer (mTR-FRET)-assay was developed and bench-marked against an identically designed fluorescence anisotropy (FA)-assay. In both assays, two CaM-binding peptides were labeled with Eu(III)-chelate or fluorescein and used as single-label reporter probes that were displaced from CaM upon competitor binding. Thus, peptidic and small molecule competitors with nanomolar to micromolar affinities to CaM could be detected, including a peptide that was derived from the C-terminus of K-Ras.In order to detect CaM-residue specific covalent inhibitors, a cell lysate-based Forster resonance energy transfer (FRET)-assay was furthermore established. This assay enabled us to measure the slow, residue-specific, covalent inhibition by ophiobolin A in the presence of other endogenous proteins. In conclusion, we have developed a panel of fluorescence-assays that allows identification of conventional and covalent CaM-inhibitors as potential disruptors of K-Ras driven cancer cell sternness.



Last updated on 2024-26-11 at 16:32