title: Inhibition of Plasmepsin V activity demonstrates its essential role in protein export, PfEMP1 display, and survival of malaria parasites.
abstract: The malaria parasite Plasmodium falciparum exports several hundred proteins into the infected erythrocyte that are involved in cellular remodeling and severe virulence. The export mechanism involves the Plasmodium export element (PEXEL), which is a cleavage site for the parasite protease, Plasmepsin V (PMV). The PMV gene is refractory to deletion, suggesting it is essential, but definitive proof is lacking. Here, we generated a PEXEL-mimetic inhibitor that potently blocks the activity of PMV isolated from P. falciparum and Plasmodium vivax. Assessment of PMV activity in P. falciparum revealed PEXEL cleavage occurs cotranslationaly, similar to signal peptidase. Treatment of P. falciparum-infected erythrocytes with the inhibitor caused dose-dependent inhibition of PEXEL processing as well as protein export, including impaired display of the major virulence adhesin, PfEMP1, on the erythrocyte surface, and cytoadherence. The inhibitor killed parasites at the trophozoite stage and knockdown of PMV enhanced sensitivity to the inhibitor, while overexpression of PMV increased resistance. This provides the first direct evidence that PMV activity is essential for protein export in Plasmodium spp. and for parasite survival in human erythrocytes and validates PMV as an antimalarial drug target.
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Brad E
authors.initials: BE
authors.lastname: Sleebs
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.
authors.forename: Sash
authors.initials: S
authors.lastname: Lopaticki
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Danushka S
authors.initials: DS
authors.lastname: Marapana
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: O'Neill
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Pravin
authors.initials: P
authors.lastname: Rajasekaran
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Michelle
authors.initials: M
authors.lastname: Gazdik
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.
authors.forename: Svenja
authors.initials: S
authors.lastname: Günther
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Lachlan W
authors.initials: LW
authors.lastname: Whitehead
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Kym N
authors.initials: KN
authors.lastname: Lowes
authors.affiliation: University of Copenhagen and Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
authors.forename: Lea
authors.initials: L
authors.lastname: Barfod
authors.affiliation: University of Copenhagen and Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
authors.forename: Lars
authors.initials: L
authors.lastname: Hviid
authors.affiliation: National Center for Genetic Engineering and Biotechnology (BIOTEC), Pathum Thani, Thailand.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Shaw
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Anthony N
authors.initials: AN
authors.lastname: Hodder
authors.affiliation: Department of Chemistry, La Trobe University, Victoria, Australia.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Smith
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Alan F
authors.initials: AF
authors.lastname: Cowman
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Justin A
authors.initials: JA
authors.lastname: Boddey
mesh_terms: D016282:Aspartic Acid Endopeptidases / Q000037:antagonists & inhibitors*; D057055:Aspartic Acid Proteases / Q000037:antagonists & inhibitors*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004912:Erythrocytes / Q000469:parasitology; D006801:Humans; D009842:Oligopeptides / Q000494:pharmacology*; D021381:Protein Transport / Q000187:drug effects; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology*
chemical_list: D009842:Oligopeptides; D015800:Protozoan Proteins; D013449:Sulfonamides; C000595444:WEHI-916; C085731:erythrocyte membrane protein 1, Plasmodium falciparum; D057055:Aspartic Acid Proteases; D016282:Aspartic Acid Endopeptidases; C089643:plasmepsin