PF3D7_1252600

PfPARE (PF3D7_1252600) is a catalytically active serine esterase of P. falciparum that functions in both xenobiotic prodrug activation and host-lipid catabolism during the intraerythrocytic cycle (PMID:28106035, PMID:31772212). It is a membrane-associated enzyme with substantial presence at the parasite periphery/plasma membrane (PMID:41043577). Its best-defined activity is the hydrolytic de-esterification of chemically diverse esterified compounds: recombinant PfPARE hydrolyzes pepstatin esters and activates the prodrug MMV011438 (PMID:28106035), processes the benzoxaborole AN13762 to its active form AN10248 (PMID:31992618), and mediates the potency of the natural product chlorajaponilide C (PMID:32970404), with loss-of-function mutations in each case conferring resistance—establishing esterase-dependent prodrug activation as a resistance mechanism. Substrate profiling with a fluorogenic ester library shows PfPARE has distinct preferences relative to the imported erythrocyte enzyme APEH, notably differing toward substrates with alpha-carbon branching (PMID:40035755). Beyond prodrug activation, PfPARE contributes redundantly to catabolism of host lysophosphatidylcholine: PfPARE alone is dispensable for LPC-derived scavenging, but its combined knockdown with the lipases XL2 and XLH4 impairs both choline and fatty-acid scavenging and abolishes replication when LPC is the sole fatty-acid source (PMID:41043577). The gene is expressed throughout the asexual cycle, is highly conserved across strains, and is non-essential for asexual growth under standard conditions (PMID:36189342).

1. 2017 High

   Established that PF3D7_1252600 is a bona fide esterase whose catalytic activity is required to convert esterified prodrugs into their active forms, answering how certain antimalarial esters become active in parasites.

   Evidence Resistant mutant selection with whole-genome sequencing plus recombinant protein in vitro hydrolysis assays on pepstatin esters and MMV011438

   PMID:28106035

   Open questions at the time

   • No crystal structure or defined catalytic-residue geometry reported
   • Endogenous physiological substrate not identified in this study
2. 2019 Medium

   Confirmed that PfPARE is catalytically active in live asexual-stage parasites rather than only as a recombinant protein, validating in situ relevance of its serine hydrolase activity.

   Evidence Fluorophosphonate-based activity-based protein profiling coupled to mass spectrometry in erythrocytic-stage P. falciparum

   PMID:31772212

   Open questions at the time

   • Single method and single lab
   • Does not link in situ activity to a specific endogenous substrate
3. 2020 High

   Generalized the prodrug-activation role beyond the initial compounds by showing PfPARE activates the benzoxaborole AN13762 and that its mutation confers resistance, reinforcing esterase-dependent activation as a resistance liability.

   Evidence In vitro resistance selection, engineered introduction of PfPARE mutations, and recombinant PfPARE enzymatic assay

   PMID:31992618

   Open questions at the time

   • Resistance was only low-level, leaving other activation routes possible
   • Kinetics of AN13762 hydrolysis not quantified
4. 2020 Medium

   Extended the substrate range to a natural-product dimer (chlorajaponilide C) while showing structurally related dimers are not PfPARE-dependent, revealing that the enzyme has defined substrate specificity.

   Evidence In vitro resistance selection with whole-genome sequencing and structure-resistance relationship analysis

   PMID:32970404

   Open questions at the time

   • No direct in vitro enzymatic assay of PfPARE with chlorajaponilide C
   • Structural basis of the specificity difference among dimers unresolved
5. 2022 Medium

   Determined that PfPARE is expressed throughout the intraerythrocytic cycle and dispensable for asexual growth, framing it as a conditionally important enzyme whose loss is tolerated except under prodrug pressure.

   Evidence CRISPR disruption with mNeonGreen reporter insertion and fluorescence-based competitive growth assay in P. falciparum Dd2

   PMID:36189342

   Open questions at the time

   • Fitness assessed only under standard culture conditions
   • Endogenous function not addressed by disruption phenotype
6. 2023 Low

   Localized PfPARE to the plasma membrane in gametocytes and showed disruption does not impair gametocyte development or egress, extending its non-essentiality across stages.

   Evidence Fluorescence microscopy localization plus gene disruption with gametocyte development and egress assays

   PMID:38131156

   Open questions at the time

   • Study cites the locus as PF3D7_0709700, introducing possible locus ambiguity
   • Single-method localization in a single lab
   • No functional gametocyte-stage substrate identified
7. 2025 Medium

   Defined PfPARE's substrate preference relative to the imported host enzyme APEH, distinguishing the two esterases functionally and clarifying which ester chemistries PfPARE favors.

   Evidence Fluorogenic ester library structure-activity profiling and comparative enzymatic assay

   PMID:40035755

   Open questions at the time

   • Preferences defined with synthetic reporters, not endogenous substrates
   • Single study
8. 2025 Medium

   Assigned PfPARE an endogenous physiological role in lysophosphatidylcholine catabolism, showing it acts redundantly with the lipases XL2 and XLH4 to scavenge choline and fatty acids from LPC.

   Evidence Gene knockdown/knockout, subcellular localization microscopy, LPC scavenging assays in defined media, and competitive growth assays

   PMID:41043577

   Open questions at the time

   • PfPARE contribution alone is minor and only revealed by combined knockdown
   • Direct enzymatic hydrolysis of LPC by PfPARE not kinetically characterized
   • Molecular basis of functional redundancy with XL2/XLH4 unresolved

• The native structural and mechanistic determinants of PfPARE (catalytic-residue geometry, structure) and the full physiological substrate spectrum linking its prodrug and lipid-catabolic activities remain to be resolved.
• No structural model or defined active-site architecture in the corpus
• Whether the same active site handles both xenobiotic esters and LPC is untested
• Physiological trigger and regulation of PfPARE activity unknown