Elucidating the path to Plasmodium prolyl-tRNA synthetase inhibitors that overcome halofuginone resistance
Mark A. Tye, N. Connor Payne, C. Johansson, Kritika Singh, Sofia A. Santos, Lọla Fagbami, Akansha Pant, Kayla Sylvester, Madeline R. Luth, Sofia Marques, Malcolm Whitman, Maria M. Mota, Elizabeth A. Winzeler, Amanda K. Lukens, Emily R. Derbyshire, Udo Oppermann, Dyann F. Wirth, Ralph Mazitschek
Abstract
The development of next-generation antimalarials that are efficacious against the human liver and asexual blood stages is recognized as one of the world's most pressing public health challenges. In recent years, aminoacyl-tRNA synthetases, including prolyl-tRNA synthetase, have emerged as attractive targets for malaria chemotherapy. We describe the development of a single-step biochemical assay for Plasmodium and human prolyl-tRNA synthetases that overcomes critical limitations of existing technologies and enables quantitative inhibitor profiling with high sensitivity and flexibility. Supported by this assay platform and co-crystal structures of representative inhibitor-target complexes, we develop a set of high-affinity prolyl-tRNA synthetase inhibitors, including previously elusive aminoacyl-tRNA synthetase triple-site ligands that simultaneously engage all three substrate-binding pockets. Several compounds exhibit potent dual-stage activity against Plasmodium parasites and display good cellular host selectivity. Our data inform the inhibitor requirements to overcome existing resistance mechanisms and establish a path for rational development of prolyl-tRNA synthetase-targeted anti-malarial therapies.