Affinage · Toxoplasma gondii

CYP450mt

cytochrome p450 superfamily protein · UniProt S8EQL7

Annotated
2026-09-08
2 papers in source corpus 1 papers cited in narrative 5 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

TgCYP450mt is a mitochondrion-localized, type I cytochrome P450 oxidase in Toxoplasma gondii that drives parasite steroidogenesis and is essential for viability (PMID:37651449). It physically associates in situ with TgMAPR, a MAPR-family heme-binding protein bearing a cytochrome b5 domain, forming a partnership analogous to the mammalian mitochondrial steroidogenic system (PMID:37651449). Functionally, TgCYP450mt is required for the conversion of steroid precursors into hydroxypregnenolone species, deoxycorticosterone, and dehydroepiandrosterone, as conditional knockout (iΔTgCYP450mt) parasites show markedly reduced levels of these metabolites (PMID:37651449). Loss of this steroidogenic function impairs parasite growth in culture and attenuates virulence in mice, linking mitochondrial steroid biosynthesis to pathogenesis (PMID:37651449). Beyond these findings, the enzyme's precise catalytic reactions, substrate-binding determinants, and structural organization have not been characterized in the available corpus.

Mechanistic history

Synthesis pass · year-by-year structured walk · 3 steps
  1. 2023 Medium

    Establishing where the enzyme acts and what it partners with was needed to place TgCYP450mt in a specific biosynthetic context; localization and interaction data situated it in the mitochondrion alongside a heme-binding cytochrome b5-domain partner.

    Evidence Direct subcellular localization plus in situ proximity ligation assay with TgMAPR in Toxoplasma gondii

    PMID:37651449

    Open questions at the time
    • TgMAPR interaction rests on a single method (proximity ligation) without reciprocal biochemical validation
    • Stoichiometry and functional consequence of the TgCYP450mt-TgMAPR interaction not resolved
    • Electron donor/redox partner supplying the P450 not identified
  2. 2023 High

    Whether TgCYP450mt was dispensable and what pathway it served were open; conditional ablation combined with metabolomics showed it is essential and required for steroid metabolite production, defining a mitochondrial steroidogenic role.

    Evidence Conditional knockout (iΔTgCYP450mt), growth assays, and LC-MS targeted lipidomics in Toxoplasma gondii

    PMID:37651449

    Open questions at the time
    • Specific enzymatic reactions and direct substrates catalyzed by TgCYP450mt not defined in vitro
    • Whether reduced steroids are a direct or downstream consequence of ablation not distinguished
    • No structural or active-site characterization
  3. 2023 Medium

    It was unknown whether the steroidogenic function mattered in vivo; conditional loss reduced virulence in mice, tying mitochondrial steroidogenesis to pathogenesis.

    Evidence Mouse virulence assay with conditional knockout parasites

    PMID:37651449

    Open questions at the time
    • Mechanism linking steroid depletion to attenuated virulence not established
    • Host cell processes affected by parasite-derived steroids not identified

Open questions

Synthesis pass · forward-looking unresolved questions
  • The catalytic mechanism, direct substrates and products, redox partners, and structural basis of TgCYP450mt activity remain undefined.
  • No in vitro reconstitution of the P450 reaction
  • Electron-transfer partner and heme utilization not characterized
  • No structural model of substrate binding or the TgMAPR complex

Mechanism profile

Synthesis pass · controlled-vocabulary classification
Partners
TGMAPR
Complex memberships
TgCYP450mt-TgMAPR (cytochrome b5-domain heme-binding partner)

Evidence

Reading pass · 5 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2023 TgCYP450mt (a type I cytochrome P450 oxidase) localizes to the mitochondrion of Toxoplasma gondii, as demonstrated by direct localization experiments. Subcellular localization (direct imaging/fractionation) PLoS pathogens Medium 37651449
2023 TgCYP450mt physically interacts with TgMAPR (a MAPR family heme-binding protein with a cytochrome b5 domain) in situ, as demonstrated by proximity ligation assays, analogous to the mammalian mitochondrial steroidogenesis system. In situ proximity ligation assay PLoS pathogens Medium 37651449
2023 TgCYP450mt is essential for Toxoplasma viability; genetic ablation of cyp450mt is not tolerated, and a conditional knockout (iΔTgCYP450mt) shows growth impairment in cultured cells and reduced steroid metabolite levels, establishing its role in parasite steroidogenesis. Conditional knockout (iΔTgCYP450mt), growth assays, metabolomics (LC-MS) PLoS pathogens High 37651449
2023 TgCYP450mt is required for synthesis of steroid metabolites (hydroxypregnenolone species, deoxycorticosterone, dehydroepiandrosterone) in Toxoplasma, as iΔTgCYP450mt mutants have reduced levels of these steroids detected by LC-MS targeted lipidomics. LC-MS targeted lipidomics/metabolomics on conditional knockout parasites PLoS pathogens High 37651449
2023 Conditional loss of TgCYP450mt results in reduced virulence in mice, establishing that the mitochondrial steroidogenic function of TgCYP450mt contributes to parasite pathogenesis in vivo. Mouse virulence assay with conditional knockout parasites PLoS pathogens Medium 37651449

Source papers

Stage 0 corpus · 2 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2023 Function and regulation of a steroidogenic CYP450 enzyme in the mitochondrion of Toxoplasma gondii. PLoS pathogens 5 37651449
2026 Toxoplasma gondii as a Direct Cause of Reproductive Dysfunction: Dual Threats to Male and Female Fertility. Veterinary sciences 0 42188900