Poster Presentation First Malaria World Congress 2018

A one-stop pH-based screen to identify inhibitors of H+ transporters on the P. falciparum plasma membrane (#498)

Xinxin Zhang 1
  1. Australian National University, Turner, ACT, Australia

The emergence and spread of drug-resistant P. falciparum has encouraged efforts to find novel compounds that kill the parasite via new mechanisms.  Two proteins that transport H+ (as well as an additional substrate) across the parasite plasma membrane, PfATP4 and PfFNT, have recently been validated as new drug targets.  Here we developed a one-stop assay to search for inhibitors of five plasma membrane H+ transport processes simultaneously:  H+ import via the Na+/H+ pump PfATP4, H+ transport via the lactate transporter PfFNT, H+ efflux via the V-type H+-ATPase, Cl--dependent H+ flux (via a transporter of unknown identity), and H+ influx via the H+-coupled pantothenate transporter.  The assay is performed in 96-well plates and entails measuring changes in cytosolic pH in saponin-isolated parasites suspended under varying conditions.  Inhibition of each of the different transporters gives rise to a unique ‘fingerprint’.  We validated the assay with known inhibitors of the different transport processes and screened the antimalarial compounds from the Medicines for Malaria Venture’s ‘Pathogen Box’.  We also tested an antimalarial clinical candidate for which a mutation in the V-type H+-ATPase has been implicated in resistance.  The results from these studies will be presented.