High-throughput screening of the Plasmodium falciparum cGMP-dependent protein kinase identified a thiazole scaffold which kills erythrocytic and sexual stage parasites

Maria Penzo,Laura De Las Heras-Dueña,Beatriz Diaz-Hernandez,Lydia Mata-Cantero,Elena Fernandez-Alvaro,David A Baker,Gerard Drewes,Sonja Ghidelli-Disse,Maria-Jesus Vazquez-Muñiz

doi:10.1038/s41598-019-42801-x

Maria Penzo, Laura De Las Heras-Dueña + Show 7 more

Open Access

PDF Available

https://doi.org/10.1038/s41598-019-42801-x

Copy DOI

Export

Save

Cite

Abstract
Highlights/Summary
Full-Text PDF
Similar Papers

Abstract

Listen

Antimalarial drug resistance compels the quest for new compounds that target alternative pathways to current drugs. The Plasmodium cyclic GMP-dependent protein kinase (PKG) has essential functions in all of the major life cycle developmental stages. An imidazopyridine PKG inhibitor scaffold was previously shown to clear P. falciparum infection in a rodent model in vivo and blocked transmission to mosquitoes providing proof of concept for this target. To find new classes of PKG inhibitors to serve as alternative chemical starting points, we performed a high-throughput screen of the GSK Full Diversity Collection using recombinant P. falciparum PKG. We developed a robust enzymatic assay in a 1536-well plate format. Promising compounds were then tested for activity against P. falciparum asexual blood stage growth, selectivity and cytotoxicity. By using a scoring system we selected the 66 most promising PKG inhibitors (comprising nine clusters and seven singletons). Among these, thiazoles were the most potent scaffold with mid-nanomolar activity on P. falciparum blood stage and gamete development. Using Kinobeads profiling we identified additional P. falciparum protein kinases targeted by the thiazoles that mediate a faster speed of the kill than PKG-selective compounds. This scaffold represents a promising starting point to develop a new antimalarial.

Highlights

Www.nature.com/scientificreports oocyst, where asexual replication takes place with thousands of sporozoites liberated that migrate to the salivary glands to be transmitted to a human host thereby completing the life cycle
The target-based approach has historically been disappointing for the discovery of new antimalarials, mainly because of the lack of strongly validated targets and the challenges to identify compounds where target-based activity correlates with cell-based activity
To identify new PKG inhibitor scaffolds, the 1.7 million GlaxoSmithKline Full Diversity collection was tested at a single final concentration of 10 μM against recombinant full length wild type (WT) PfPKG using a Kinase Glo-based assay (Promega)

Summary

Introduction

Www.nature.com/scientificreports oocyst, where asexual replication takes place with thousands of sporozoites liberated that migrate to the salivary glands to be transmitted to a human host thereby completing the life cycle. Several features of the malaria parasite PKG differ from mammalian PKGs, including the presence of two additional conserved cGMP-binding sequence motifs, where one of these does not bind cGMP but is essential for activity[23,24] Another peculiarity is the presence of a threonine residue in the so-called gatekeeper position. Substitution of the PfPKG gatekeeper threonine residue with glutamine (with a bulkier side chain), prevents access of the inhibitor to the hydrophobic gatekeeper pocket which adjoins the ATP-binding site[13] This chemical genetic approach proved an excellent tool to define off-target effects on parasites, as well as to study PKG-dependent processes in the parasite[13,16,18,19]

Methods

Results

Conclusion