Affinage · Toxoplasma gondii

BFD1

Myb family DNA-binding domain-containing protein · UniProt S8GIB3

Annotated
2026-09-10
32 papers in source corpus 3 papers cited in narrative 3 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

BFD1 is a Myb-like transcription factor that serves as the master regulator of tachyzoite-to-bradyzoite differentiation in Toxoplasma gondii (PMID:31955846). It accumulates under stress, and its ectopic expression is sufficient to drive differentiation while its loss blocks stage conversion, establishing it as both necessary and sufficient for the switch; it acts by binding the promoters of many stage-specific bradyzoite genes to activate their expression (PMID:31955846). Within the differentiation pathway BFD1 lies downstream of the chromatin modifiers MORC and HDAC3, and it controls only a subset of bradyzoite genes (e.g., BCLA) while others (e.g., BSM) are regulated independently, indicating multilayered transcriptional control of stage conversion (PMID:40389644). BFD1 abundance is itself constrained post-transcriptionally: a GID/CTLH-type E3 ubiquitin ligase complex (TgGID) mediates translational repression of BFD1 through its 3' UTR, coupling glucose-sensing and ubiquitination-dependent proteostasis to the differentiation decision (PMID:40766703).

Mechanistic history

Synthesis pass · year-by-year structured walk · 3 steps
  1. 2020 High

    Whether a single dedicated regulator governs the tachyzoite-to-bradyzoite switch was unknown; identifying BFD1 as necessary and sufficient established a master transcriptional switch for differentiation.

    Evidence Cas9 genetic screen, single-cell transcriptional profiling, ectopic gain-of-function expression, ChIP promoter binding, and loss-of-function in culture and in mice

    PMID:31955846

    Open questions at the time
    • Direct DNA-binding sequence specificity and full regulon not resolved
    • Upstream signals triggering BFD1 accumulation during stress not defined
    • Whether BFD1 acts alone or requires cofactors at target promoters not established
  2. 2025 Medium

    How BFD1 integrates with upstream epigenetic control was unclear; epistasis placed BFD1 downstream of MORC and HDAC3 and revealed a BFD1-independent branch of bradyzoite gene regulation.

    Evidence Genetic epistasis with double mutants/knockdowns of MORC, HDAC3 and BFD1 plus expression profiling of BFD1-dependent vs. -independent genes

    PMID:40389644

    Open questions at the time
    • Molecular mechanism by which MORC/HDAC3 chromatin state controls BFD1 not detailed
    • Identity of the regulator(s) driving the BFD1-independent bradyzoite gene subset unknown
  3. 2025 Medium

    The mechanism restraining BFD1 protein levels was unknown; a GID/CTLH E3 ubiquitin ligase complex acting through the BFD1 3' UTR links glucose availability and proteostasis to the differentiation decision.

    Evidence CRISPR screen for differentiation-deficient mutants under glucose limitation, TgGID complex characterization, and 3' UTR reporter assays (preprint)

    PMID:40766703

    Open questions at the time
    • Not yet peer-reviewed
    • Direct ubiquitination substrate(s) and how 3' UTR couples to the ligase complex not fully defined
    • Physiological glucose thresholds triggering the response not established

Open questions

Synthesis pass · forward-looking unresolved questions
  • The upstream stress and nutrient signals that converge on BFD1 accumulation, and the full BFD1 target regulon, remain to be defined.
  • Signaling pathway connecting stress sensing to BFD1 accumulation unknown
  • Complete set of BFD1 direct promoter targets not mapped

Mechanism profile

Synthesis pass · controlled-vocabulary classification
Partners
HDAC3 (EPISTATIC UPSTREAM REGULATOR)MORC (EPISTATIC UPSTREAM REGULATOR)TGGID GID/CTLH E3 UBIQUITIN LIGASE COMPLEX (POST-TRANSCRIPTIONAL REGULATOR VIA 3' UTR)

Evidence

Reading pass · 3 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2020 BFD1 is a Myb-like transcription factor that is necessary and sufficient for tachyzoite-to-bradyzoite differentiation in Toxoplasma gondii. BFD1 accumulates during stress conditions, its synthetic (ectopic) expression is sufficient to drive differentiation, and it binds the promoters of many stage-specific bradyzoite genes, acting as a master transcriptional regulator of differentiation. Cas9-mediated genetic screen, single-cell transcriptional profiling, ectopic expression (gain-of-function), chromatin immunoprecipitation (promoter binding), loss-of-function in cell culture and in mice Cell High 31955846
2025 The chromatin modifiers MORC and HDAC3 epistatically regulate BFD1, placing BFD1 downstream of these epigenetic regulators in the bradyzoite differentiation pathway. BFD1 controls expression of a subset of bradyzoite genes (e.g., BCLA) while a distinct subset of bradyzoite genes (e.g., BSM) is regulated independently of BFD1, indicating multilayered transcriptional control of stage conversion. Genetic epistasis analysis (double mutants/knockdowns of MORC, HDAC3, and BFD1), gene expression profiling of BFD1-dependent vs. BFD1-independent bradyzoite genes EMBO molecular medicine Medium 40389644
2025 A GID/CTLH-type E3 ubiquitin ligase complex (TgGID) regulates translational repression of BFD1 through its 3' UTR, linking glucose-sensing and ubiquitination-dependent proteostasis to control of the key differentiation transcription factor BFD1. CRISPR screen for differentiation-deficient mutants under glucose-limiting conditions, functional characterization of TgGID complex, 3' UTR reporter assays bioRxivpreprint Medium 40766703

Source papers

Stage 0 corpus · 32 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
1989 Direct and sensitive detection of a pathogenic protozoan, Toxoplasma gondii, by polymerase chain reaction. Journal of clinical microbiology 645 2768467
2000 Identification of a 200- to 300-fold repetitive 529 bp DNA fragment in Toxoplasma gondii, and its use for diagnostic and quantitative PCR. International journal for parasitology 585 10675747
1997 A plastid of probable green algal origin in Apicomplexan parasites. Science (New York, N.Y.) 542 9045615
2015 Diagnosis of toxoplasmosis and typing of Toxoplasma gondii. Parasites & vectors 322 26017718
2003 Comparison of two DNA targets for the diagnosis of Toxoplasmosis by real-time PCR using fluorescence resonance energy transfer hybridization probes. BMC infectious diseases 271 12729464
2011 Toxoplasma gondii triggers release of human and mouse neutrophil extracellular traps. Infection and immunity 220 22104111
2020 Identification of a Master Regulator of Differentiation in Toxoplasma. Cell 196 31955846
1997 Diagnosis of AIDS-related focal brain lesions: a decision-making analysis based on clinical and neuroradiologic characteristics combined with polymerase chain reaction assays in CSF. Neurology 180 9065549
2013 Combined action of nucleic acid-sensing Toll-like receptors and TLR11/TLR12 heterodimers imparts resistance to Toxoplasma gondii in mice. Cell host & microbe 159 23290966
2001 Defining the cell cycle for the tachyzoite stage of Toxoplasma gondii. Molecular and biochemical parasitology 152 11420103
2006 Real-time PCR targeting a 529-bp repeat element for diagnosis of toxoplasmosis. Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases 136 16441450
2000 Comparison of PCR detection methods for B1, P30, and 18S rDNA genes of T. gondii in aqueous humor. Investigative ophthalmology & visual science 136 10711675
1990 Polymerase chain reaction for detection of Toxoplasma gondii. Journal of medical microbiology 116 2342084
2014 Toxoplasma gondii infection reduces predator aversion in rats through epigenetic modulation in the host medial amygdala. Molecular ecology 102 25142402
1993 Detection of Toxoplasma gondii by competitive DNA amplification of bronchoalveolar lavage samples. The Journal of infectious diseases 102 8245552
2002 Prevalence of Toxoplasma gondii in commercial meat products as monitored by polymerase chain reaction--food for thought? International journal for parasitology 100 12117502
1984 Determination of nuclear DNA of five eucoccidian parasites, Isospora (Toxoplasma) gondii, Sarcocystis cruzi, Eimeria tenella, E. acervulina and Plasmodium berghei, with special reference to gamontogenesis and meiosis in I. (T.) gondii. Parasitology 88 6204268
2008 Evaluation of loop-mediated isothermal amplification for detection of Toxoplasma gondii in water samples and comparative findings by polymerase chain reaction and immunofluorescence test (IFT). Diagnostic microbiology and infectious disease 83 18715739
2003 Molecular evidence for multiple Toxoplasma gondii infections in individual patients in England and Wales: public health implications. International journal for parasitology 78 12547351
2002 Ocular toxoplasmosis after the fifth decade. American journal of ophthalmology 78 11931784
1971 False-positive anti-Toxoplasma fluorescent-antibody tests in patients with antinuclear antibodies. Applied microbiology 74 4940868
2012 Loop-mediated isothermal amplification (LAMP): early detection of Toxoplasma gondii infection in mice. Parasites & vectors 73 22214421
2007 Diagnosis of Sarcocystis cruzi, Neospora caninum, and Toxoplasma gondii infections in cattle. Parasitology research 73 18066600
2005 Evolution of plant-like crystalline storage polysaccharide in the protozoan parasite Toxoplasma gondii argues for a red alga ancestry. Journal of molecular evolution 73 15785854
1993 Comparison of two gene amplification methods for the detection of Toxoplasma gondii in experimentally infected sheep. Journal of medical microbiology 72 8487293
2011 The first detection of Toxoplasma gondii DNA in environmental fruits and vegetables samples. European journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology 69 21948336
2020 Economic and public health importance of Toxoplasma gondii infections in sheep: 2009-2020. Veterinary parasitology 65 32979682
2009 Toxoplasma gondii: sensitive and rapid detection of infection by loop-mediated isothermal amplification (LAMP) method. Experimental parasitology 65 19545521
1999 The genus Hammondia is paraphyletic. Parasitology 65 10340325
1992 Detection of Toxoplasma gondii in cerebrospinal fluid from AIDS patients by polymerase chain reaction. Journal of clinical microbiology 64 1452673
2025 Uncovering biomarkers for chronic toxoplasmosis detection highlights alternative pathways shaping parasite dormancy. EMBO molecular medicine 3 40389644
2025 Differentiation of Toxoplasma into latent forms is linked to central carbon metabolism and requires a GID/CTLH-type E3 ubiquitin ligase. bioRxiv : the preprint server for biology 2 40766703