EXP1 is critical for nutrient uptake across the parasitophorous vacuole membrane of malaria parasites

PLoS Biol. 2019 Sep 30;17(9):e3000473. doi: 10.1371/journal.pbio.3000473. eCollection 2019 Sep.

Abstract

Intracellular malaria parasites grow in a vacuole delimited by the parasitophorous vacuolar membrane (PVM). This membrane fulfils critical roles for survival of the parasite in its intracellular niche such as in protein export and nutrient acquisition. Using a conditional knockout (KO), we here demonstrate that the abundant integral PVM protein exported protein 1 (EXP1) is essential for parasite survival but that this is independent of its previously postulated function as a glutathione S-transferase (GST). Patch-clamp experiments indicated that EXP1 is critical for the nutrient-permeable channel activity at the PVM. Loss of EXP1 abolished the correct localisation of EXP2, a pore-forming protein required for the nutrient-permeable channel activity and protein export at the PVM. Unexpectedly, loss of EXP1 affected only the nutrient-permeable channel activity of the PVM but not protein export. Parasites with low levels of EXP1 became hypersensitive to low nutrient conditions, indicating that EXP1 indeed is needed for nutrient uptake and experimentally confirming the long-standing hypothesis that the channel activity measured at the PVM is required for parasite nutrient acquisition. Hence, EXP1 is specifically required for the functional expression of EXP2 as the nutrient-permeable channel and is critical for the metabolite supply of malaria parasites.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids / metabolism
  • Antigens, Protozoan / metabolism*
  • Erythrocytes / parasitology
  • Gene Knockout Techniques
  • Glutathione Transferase / metabolism
  • Host-Parasite Interactions
  • Nutrients / metabolism
  • Plasmodium falciparum / genetics
  • Plasmodium falciparum / metabolism*
  • Vacuoles / metabolism

Substances

  • Amino Acids
  • Antigens, Protozoan
  • QF116 antigen, Plasmodium falciparum
  • Glutathione Transferase

Grants and funding

This work was supported by the German Research Foundation (grant SP1209/4-1 to TS) (https://www.dfg.de/en/) and the Division of Intramural Research of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health (https://www.nichd.nih.gov/) to JZ. JS is supported by a fellowship of the Jürgen Manchot Stiftung (https://www.im.nrw/juergen-manchot-stiftung). INP was supported by a scholarship from Colciencias (https://www.colciencias.gov.co/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.