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Assessment of Biological Role and Insight into Druggability of the Plasmodium falciparum Protease Plasmepsin V

Authors
  • Polino, Alexander J.1
  • Nasamu, Armiyaw S.1
  • Niles, Jacquin C.2
  • Goldberg, Daniel E.1
  • 1 Washington University School of Medicine, United States , (United States)
  • 2 Massachusetts Institute of Technology, United States , (United States)
Type
Published Article
Journal
ACS Infectious Diseases
Publisher
American Chemical Society
Publication Date
Feb 18, 2020
Volume
6
Issue
4
Pages
738–746
Identifiers
DOI: 10.1021/acsinfecdis.9b00460
PMID: 32069391
PMCID: PMC7155168
Source
PubMed Central
Keywords
Disciplines
  • Article
License
Unknown

Abstract

Upon infecting a red blood cell (RBC), the malaria parasite Plasmodium falciparum drastically remodels its host by exporting hundreds of proteins into the RBC cytosol. This protein export program is essential for parasite survival. Hence export-related proteins could be potential drug targets. One essential enzyme in this pathway is plasmepsin V (PMV), an aspartic protease that processes export-destined proteins in the parasite endoplasmic reticulum (ER) at the Plasmodium export element (PEXEL) motif. Despite long-standing interest in this enzyme, functional studies have been hindered by the inability of previous technologies to produce a regulatable lethal depletion of PMV. To overcome this technical barrier, we designed a system for stringent post-transcriptional regulation allowing a tightly controlled, tunable knockdown of PMV. Using this system, we found that PMV must be dramatically depleted to affect parasite growth, suggesting the parasite maintains this enzyme in substantial excess. Surprisingly, depletion of PMV arrested parasite growth immediately after RBC invasion, significantly before the death from exported protein deficit that has previously been described. The data suggest that PMV inhibitors can halt parasite growth at two distinct points in the parasite life cycle. However, overcoming the functional excess of PMV in the parasite may require inhibitor concentrations far beyond the enzyme’s IC50.

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