PF3D7_1401500

PfPARE (PF3D7_1401500) is a functional P. falciparum esterase whose best-characterized role is the hydrolytic activation of esterified antimalarial prodrugs: recombinant enzyme de-esterifies pepstatin esters and MMV011438, and loss-of-function mutations selected in vitro block this activation to confer resistance (PMID:28106035). This prodrug-activating function generalizes across chemically distinct scaffolds—PfPARE is required to hydrolyze the benzoxaborole AN13762 to its active metabolite AN10248 (PMID:31992618) and to unmask the antimalarial activity of the sesquiterpenoid dimer chlorajaponilide C, with PfPARE mutations recovered in all resistant clones (PMID:32970404)—establishing PfPARE loss as a recurrent, low-level resistance mechanism to ester prodrugs. Its substrate specificity is distinct from the host-derived APEH esterase (PMID:40035755). Beyond xenobiotic hydrolysis, PfPARE is a membrane-associated enzyme concentrated at the parasite periphery that contributes redundantly to lysophosphatidylcholine catabolism: loss of PfPARE alone does not impair fatty acid scavenging, but combined loss with XL2 and XLH4 blocks choline and fatty acid scavenging from LPC (PMID:41043577). PfPARE is expressed throughout the intraerythrocytic developmental cycle, is highly conserved across strains, and is not essential for asexual replication (PMID:36189342).

1. 2017 High

   Established PfPARE as a catalytically active esterase and defined the paradigm that its hydrolytic activity is required to unmask ester prodrugs, so its inactivation drives resistance.

   Evidence In vitro resistance selection with whole-genome sequencing, recombinant enzyme hydrolysis assays on pepstatin esters and MMV011438, and synthesis of ester derivatives

   PMID:28106035

   Open questions at the time

   • No structural basis for catalysis or the active-site residues defined
   • Native physiological substrate not identified in this study
2. 2020 High

   Extended the prodrug-activation role to a chemically unrelated benzoxaborole and confirmed causality by genetic introduction of the mutations, showing PfPARE-dependent activation is scaffold-general.

   Evidence In vitro resistance selection, whole-genome sequencing, CRISPR introduction of PfPARE mutations, and recombinant enzyme hydrolysis of AN13762

   PMID:31992618

   Open questions at the time

   • Resistance conferred was only low-level, indicating additional activation routes exist
   • Kinetic parameters for AN13762 hydrolysis not reported
3. 2020 Medium

   Showed PfPARE also determines the potency of a natural-product scaffold (chlorajaponilide C) but only for a subset of related compounds, refining which chemotypes depend on PfPARE.

   Evidence In vitro resistance selection, whole-genome sequencing of clones, and structure-resistance relationship analysis across a compound series

   PMID:32970404

   Open questions at the time

   • No recombinant enzyme assay confirming direct hydrolysis of chlorajaponilide C
   • Chemical identity of the PfPARE-dependent step not resolved
4. 2022 Medium

   Defined the expression, dispensability, and conservation of the locus, establishing that PfPARE is non-essential for asexual growth despite constitutive intraerythrocytic expression.

   Evidence CRISPR reporter insertion at the pfpare locus, competitive fitness assays, and fluorescence microscopy across the intraerythrocytic cycle

   PMID:36189342

   Open questions at the time

   • Non-essentiality shown only in standard culture, not in LPC-limited conditions
   • Sexual-stage or in vivo requirement not assessed
5. 2025 Medium

   Assigned a native physiological function by localizing PfPARE to the parasite periphery and demonstrating its redundant contribution to lysophosphatidylcholine catabolism for lipid and choline scavenging.

   Evidence Genetic knockout of PARE alone and combined with XL2 and XLH4, growth assays in defined LPC media, and subcellular localization

   PMID:41043577

   Open questions at the time

   • Functional redundancy prevents attributing a specific reaction to PfPARE alone
   • Direct enzymatic hydrolysis of LPC by recombinant PfPARE not shown
6. 2025 Medium

   Distinguished PfPARE substrate specificity from the host APEH esterase, clarifying that PfPARE has its own catalytic profile relevant to prodrug design.

   Evidence Fluorogenic ester library screening and comparative biochemical structure-activity analysis of parasite versus host esterases

   PMID:40035755

   Open questions at the time

   • PfPARE was characterized secondarily to APEH in this study
   • No physiological substrate mapping from the fluorogenic profile

• The structural basis of PfPARE catalysis and the full endogenous substrate repertoire that explains its constitutive expression remain undefined.
• No crystal structure or catalytic-residue map
• Native substrate beyond LPC not comprehensively identified
• Contribution to drug metabolism in vivo untested