title: Esterase mutation is a mechanism of resistance to antimalarial compounds.
abstract: Pepstatin is a potent peptidyl inhibitor of various malarial aspartic proteases, and also has parasiticidal activity. Activity of pepstatin against cultured Plasmodium falciparum is highly variable depending on the commercial source. Here we identify a minor contaminant (pepstatin butyl ester) as the active anti-parasitic principle. We synthesize a series of derivatives and characterize an analogue (pepstatin hexyl ester) with low nanomolar activity. By selecting resistant parasite mutants, we find that a parasite esterase, PfPARE (P. falciparum Prodrug Activation and Resistance Esterase) is required for activation of esterified pepstatin. Parasites with esterase mutations are resistant to pepstatin esters and to an open source antimalarial compound, MMV011438. Recombinant PfPARE hydrolyses pepstatin esters and de-esterifies MMV011438. We conclude that (1) pepstatin is a potent but poorly bioavailable antimalarial; (2) PfPARE is a functional esterase that is capable of activating prodrugs; (3) Mutations in PfPARE constitute a mechanism of antimalarial resistance.
authors.affiliation: Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri 63110, USA.|Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri 63110, USA.
authors.forename: Eva S
authors.initials: ES
authors.lastname: Istvan
authors.affiliation: Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri 63110, USA.|Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri 63110, USA.
authors.forename: Jeremy P
authors.initials: JP
authors.lastname: Mallari
authors.affiliation: Department of Pediatrics, School of Medicine, University of California San Diego School of Medicine, La Jolla, California 92093, USA.
authors.forename: Victoria C
authors.initials: VC
authors.lastname: Corey
authors.affiliation: Department of Pediatrics, School of Medicine, University of California San Diego School of Medicine, La Jolla, California 92093, USA.
authors.forename: Neekesh V
authors.initials: NV
authors.lastname: Dharia
authors.affiliation: Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, Missouri 63110, USA.
authors.forename: Garland R
authors.initials: GR
authors.lastname: Marshall
authors.affiliation: Department of Pediatrics, School of Medicine, University of California San Diego School of Medicine, La Jolla, California 92093, USA.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Winzeler
authors.affiliation: Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri 63110, USA.|Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri 63110, USA.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Goldberg
mesh_terms: D000962:Antimalarials / Q000494:pharmacology*; D004351:Drug Resistance; D004950:Esterases / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D010436:Pepstatins / Q000494:pharmacology*; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D011355:Prodrugs / Q000494:pharmacology; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism
chemical_list: D000962:Antimalarials; D010436:Pepstatins; D011355:Prodrugs; D015800:Protozoan Proteins; D004950:Esterases; C031375:pepstatin