bims-toxgon Biomed News
on Toxoplasma gondii metabolism
Issue of 2026–06–07
twelve papers selected by
Lakesh Kumar, BITS Pilani
  1. Fragmented rRNAs and lineage-specific RNA-binding proteins define myzozoan mitoribosomes.
  2. TGIF is a Golgin-like protein required for Golgi structural maintenance and function in Toxoplasma gondii.
  3. Enhanced Vaccine Design Strategies for Toxoplasmosis: A Computational Analysis of Toxoplasma gondii Rhoptry Protein 13 (ROP13).
  4. Is heme metabolism a promising drug target in Toxoplasma gondii?
  5. Multi-epitope mRNA vaccine and protein vaccine protect mice against Toxoplasma gondii.
  6. Protein arginine methyltransferase 5 is essential for virulence in Toxoplasma gondii.
  7. Identification of a Putative Metal Transporter in the Apicoplast of Malaria Parasites.
  8. ATAD3 megadalton complex in Plasmodium falciparum is essential for mitochondrial and cellular viability.
  9. Lead Optimization of TgCDPK1 Inhibitors for the Treatment of Toxoplasmosis.
  10. Mitochondrial copper stabilizes lipoylated TCA cycle proteins to sustain metabolism and proliferation.
  11. The bromodomain protein Bdf3 is sufficient to activate expression of a procyclin gene in bloodstream stage African trypanosomes.
  12. Characterization of ovine abortion in Uruguay reveals extensive non-clonal diversity and multiple evolutionary origins of Toxoplasma gondii.
  1. Trends Parasitol. 2026 May 30. pii: S1471-4922(26)00131-5. [Epub ahead of print]
    Fragmented rRNAs and lineage-specific RNA-binding proteins define myzozoan mitoribosomes.
    Chaoyue Wang, Sari Kassem, Xun Suo, Dominique Soldati-Favre, Yonggen Jia.
      Myzozoa, a clade of alveolate protists including Apicomplexa, Chromerida, Perkinsozoa, and dinoflagellates, possesses the most reduced mitochondrial genomes among eukaryotes. Apicomplexan parasites, such as Toxoplasma gondii and Plasmodium spp., retain mitochondrial genomes encoding only three proteins and highly fragmented rRNAs. Despite this reduction, recent structural studies show that T. gondii mitoribosome incorporates lineage-specific RNA-binding proteins as integral components to maintain a functional complex composed of over 50 rRNA fragments. The conservation of rRNA fragmentation and protein repertoire observed among Apicomplexa suggests a shared evolution within the phylum. This radical divergence from all other currently investigated cytoplasmic and mitochondrial ribosomes highlights evolutionary plasticity and common ancestry, providing a model for studying mitochondrial evolution and potential antiparasitic drug discovery.
    Keywords:  Apicomplexa; Myzozoa; Plasmodium falciparum; Toxoplasma gondii; fragmented mitochondrial rRNA; mitoribosome
    DOI:  https://doi.org/10.1016/j.pt.2026.05.008
  2. bioRxiv. 2026 May 24. pii: 2026.05.21.726867. [Epub ahead of print]
    TGIF is a Golgin-like protein required for Golgi structural maintenance and function in Toxoplasma gondii.
    Camille Pearce, Aoife T Heaslip.
      The Golgi is an essential organelle that serves as a central hub for endomembrane trafficking. In the protozoan parasite Toxoplasma gondii , a single Golgi stack is essential for parasite survival; however, the molecular determinants governing Golgi structure and function remain poorly understood. Here, we characterize a Golgi-associated protein that is required for Golgi integrity and function, which we named Toxoplasma Golgi Integrity Factor (TGIF). Loss of TGIF disrupts parasite replication and natural egress and is lethal to the parasite. To investigate the impact of TGIF depletion on secretory protein trafficking, we adapted a fluorescence-based pulse-chase assay to monitor the synthesis and trafficking of microneme and rhoptry proteins. We found that loss of TGIF significantly impaired the synthesis and trafficking of microneme and rhoptry neck proteins, whereas trafficking of rhoptry bulb proteins was minimally affected. These findings suggest that rhoptry bulb proteins may traffic independently of canonical Golgi-dependent pathways. Collectively, our study provides new insight into the mechanisms of Golgi-mediated trafficking in T. gondii and identifies TGIF as a critical regulator of parasite secretory pathway organization and function.
    DOI:  https://doi.org/10.64898/2026.05.21.726867
  3. Arch Razi Inst. 2025 Sep;80(5): 1301-1320
    Enhanced Vaccine Design Strategies for Toxoplasmosis: A Computational Analysis of Toxoplasma gondii Rhoptry Protein 13 (ROP13).
    Zaki Leila, Vafae Eslahi Aida, Foroutan Masoud, Pirestani Majid, Hatam-Nahavandi Kareem, Karimipour-Saryazdi Amir, Ghaffari Cherati Mohammad, Diaz Daniel, Badri Milad.
       Introduction: Toxoplasma gondii, an intracellular parasite, utilizes a variety of rhoptry proteins (ROPs) to facilitate invasion and interaction with host cells. Among these ROPs, rhoptry protein 13 (ROP13) stands out for its expression in both bradyzoite and tachyzoite forms of T. gondii and its ability to engage with various host cytoplasmic compartments.
    Materials & Methods: In this bioinformatics study, we employed a range of tools to predict the fundamental characteristics of the ROP13 protein.
    Results: Our analysis revealed that the ROP13 protein consists of 400 amino acid residues with an average molecular weight (MW) of 44,714.15 daltons. The grand average of hydropathicity (GRAVY) was determined to be -0.311, indicating the protein's hydrophilic nature, while the aliphatic index scored 84.40, highlighting its hydrophobic character. Furthermore, we identified 43 post-translationally modified sites within the ROP13 sequence. When examining the secondary structure, the ROP13 protein was predicted to have a composition of 40% alpha helix, 9.25% extended strand, and 50.75% random coil using the GOR4 method, suggesting a diverse structural organization that may contribute to its functional versatility. Additionally, our analysis identified several potential B- and T-cell epitopes within the ROP13 sequence, indicating regions that could be targeted for immune responses.
    Conclusion: The bioinformatics analysis of ROP13 provides valuable insights into its structural, immunogenic, and antigenic properties, highlighting its potential as a target for vaccine development against toxoplasmosis. By leveraging the predicted characteristics of ROP13, researchers can explore various vaccine strategies to enhance host immunity and combat T. gondii infection effectively. Continued investigation into the molecular mechanisms underlying ROP13's interactions with host cells will further elucidate its role in T. gondii pathogenesis and guide the development of innovative approaches to mitigate this prevalent parasitic disease.
    Keywords:   In silico; Rhoptry protein 13; Toxoplasma gondii
    DOI:  https://doi.org/10.32598/ARI.80.5.3301
  4. PLoS Pathog. 2026 Jun;22(6): e1014280
    Is heme metabolism a promising drug target in Toxoplasma gondii?
    Zhicheng Dou.
      
    DOI:  https://doi.org/10.1371/journal.ppat.1014280
  5. Parasit Vectors. 2026 Jun 05.
    Multi-epitope mRNA vaccine and protein vaccine protect mice against Toxoplasma gondii.
    Yulin Cui, Hongnan Qu, Chunxue Zhou, Ziyue Liang, Bing Han, Huaiyu Zhou, Hua Cong.
       BACKGROUND: Toxoplasma gondii, an obligate intracellular protozoan parasite, infects almost one-third of the world's population and all warm-blooded animals, posing a substantial threat to public health. Accordingly, the development of effective vaccines against T. gondii has become an urgent priority. In this study, we constructed a multi-epitope chimeric antigen T-SGR targeting three key protective antigens of T. gondii (SAG1, GRA7, and ROP16), and developed both a messenger RNA (mRNA) lipid nanoparticle (LNP) vaccine and a recombinant protein vaccine based on T-SGR. The immunogenicity and protective effects were further evaluated in C57BL/6 mice.
    METHODS: The T-SGR mRNA-LNP vaccine was prepared via in vitro transcription followed by LNP encapsulation, while the T-SGR protein vaccine was obtained via prokaryotic expression and purification. Mice were administered a two-dose immunization regimen. Serum levels of specific IgG, IgG1, and IgG2a antibodies and cytokine levels were measured by enzyme-linked immunosorbent assay (ELISA). T lymphocyte subsets and lymphocyte proliferation were assessed by flow cytometry and Cell Counting Kit-8 (CCK-8) assay. Protective efficacy was evaluated by monitoring survival rates after challenge with highly virulent T. gondii RH strain tachyzoites and moderately virulent ME49 strain tachyzoites.
    RESULTS: Both T-SGR mRNA and protein vaccines induced robust humoral and cellular immune responses in mice. Notably, the IgG antibody titer induced by the mRNA-LNP vaccine was significantly higher than that of the protein vaccine (P < 0.05). Both vaccines drove a Th1-biased immune response, as evidenced by markedly higher IgG2a levels relative to IgG1. Compared with the phosphate-buffered saline (PBS) control group, both vaccine groups significantly promoted splenocyte proliferation (P < 0.05). The mRNA vaccine induced significantly higher secretion of IFN-γ, IL-10, IL-12, and IL-2 than the protein vaccine. Both vaccines conferred significant protection against T. gondii infection and prolonged mouse survival. Strikingly, the T-SGR mRNA-LNP vaccine provided 100% protection against the T. gondii ME49 strain, outperforming the recombinant protein vaccine.
    CONCLUSIONS: We successfully developed a multi-epitope T-SGR mRNA-LNP vaccine and a recombinant protein vaccine against T. gondii. The T-SGR mRNA-LNP vaccine elicited stronger humoral and cellular immune responses and conferred superior protective efficacy, representing a promising candidate vaccine against toxoplasmosis.
    Keywords:   Toxoplasma gondii ; Lipid nanoparticle (LNP); Multi-epitope vaccine; Protective immunity; Recombinant protein vaccine; mRNA vaccine
    DOI:  https://doi.org/10.1186/s13071-026-07447-5
  6. Parasit Vectors. 2026 Jun 02.
    Protein arginine methyltransferase 5 is essential for virulence in Toxoplasma gondii.
    Limei Xu, Huiru Liang, Shengchen Bai, Ruochen Xu, Bin Liu, Xiaohong Xu, Xinrong Xu, Min Liu.
       BACKGROUND: Protein arginine methyltransferase 5 (PRMT5) is a key enzyme responsible for catalyzing symmetric dimethylarginine (SDMA) modifications and plays crucial roles in epigenetic regulation, transcription, and cell cycle progression in eukaryotes. Although our previous study determined the expression and cellular localization of PRMT5 in tachyzoites and bradyzoites, and confirmed its type II PRMT activity, its functional significance in Toxoplasma gondii remains entirely uncharacterized.
    METHODS: This study aimed to explore the biological functions of PRMT5 in T. gondii. The prmt5 gene was disrupted in the type I RH strain using the clustered regularly interspaced short palindromic repeats (CRISPR) Cas9 system. The biological roles of PRMT5 were evaluated via multiple functional assays, including plaque formation, intracellular proliferation, host cell invasion, virulence, and tachyzoite to bradyzoite conversion assays. RNA sequencing was further performed to profile transcriptomic alterations induced by prmt5 disruption.
    RESULTS: Phenotypic characterization revealed that the ∆prmt5 strain exhibited reduced symmetric dimethylarginine (SDMA) levels as well as severe defects in plaque formation, invasion, intracellular replication, and bradyzoite differentiation. Accordingly, the virulence of the ∆prmt5 strain was dramatically attenuated, as all infected BALB/c mice survived over a 10-day period, in stark contrast to the 100% mortality observed in the wild-type control group within 10 days. RNA-sequencing analysis uncovered the molecular basis for these phenotypes, demonstrating that prmt5 disruption leads to global transcriptional dysregulation. Specifically, we identified a significant downregulation of genes associated with motor protein function and fatty acid metabolism pathways.
    CONCLUSIONS: Our research has demonstrated that PRMT5 plays a critical role in the proliferation, survival, pathogenicity, and regulation of gene expression in Toxoplasma gondii.
    Keywords:   Toxoplasma gondii ; Bradyzoite differentiation; Gene expression; Protein arginine methyltransferase 5; Virulence
    DOI:  https://doi.org/10.1186/s13071-026-07473-3
  7. bioRxiv. 2026 May 19. pii: 2026.05.18.725985. [Epub ahead of print]
    Identification of a Putative Metal Transporter in the Apicoplast of Malaria Parasites.
    Shai-Anne Nalder, Adarsh K Mayank, Willisa Liou, James A Wohlschlegel, Paul A Sigala.
      Plasmodium falciparum malaria parasites harbor an essential plastid organelle, called the apicoplast, which produces key metabolites required for organelle function and parasite viability. Apicoplast functions depend on iron and other metals, but the membrane transporters that mediate metal import into this organelle have been challenging to identify. Tetracycline antibiotics, including doxycycline, specifically target the apicoplast and can exhibit metal-dependent activity. Using tetracycline-affinity proteomics, we identified a doxycycline-interacting, uncharacterized transmembrane protein (UCT) targeted to the apicoplast periphery but not proteolytically processed. Although lacking sequence similarity to proteins of known function, UCT has a predicted structure with high similarity to pentameric CorA-family metal transporters that mediate metal uptake in other organisms. Functional tests revealed that UCT is dispensable for blood-stage asexual parasites, suggesting that the apicoplast has evolved redundant mechanisms for metal uptake. UCT knockdown in gametocytes, however, impairs the development of sexual parasites, which are critical for mosquito transmission. Our study identifies an apicoplast membrane protein with localization and structural properties that predict a role in metal transport into this key organelle. This discovery can provide a biochemical springboard to unravel broader apicoplast mechanisms of metal uptake across multiple stages of parasite development, including mosquito-stage parasites that display heightened UCT expression.
    DOI:  https://doi.org/10.64898/2026.05.18.725985
  8. PLoS Pathog. 2026 Jun 03. 22(6): e1014317
    ATAD3 megadalton complex in Plasmodium falciparum is essential for mitochondrial and cellular viability.
    Ijeoma C Okoye, Ian M Lamb, Yee-Wai Cheung, Joanne M Morrisey, Manish Sharma, Rajat Kumar, Swati Dass, Anurag Shukla, River S Rell, Michael W Mather, Manuel Llinás, Yi-Wei Chang, Akhil B Vaidya.
      Malaria remains an urgent threat to global health as the mortality and infection rates keep rising annually and our frontline antimalarials are becoming less effective due to the emergence and spread of resistance-conferring mutations. Although the mitochondrion of P. falciparum parasites is a validated drug target, there remain many uncharacterized mitochondrial proteins. The goal of this study was to investigate the essentiality and functions of a recently identified mitochondrial protein - PF3D7_0707400. Our results show that PF3D7_0707400 is an ATAD3A homolog that is essential to parasite survival and is present in a megadalton complex that is critical for multiple mitochondrial processes such as mitochondrial RNA stability, membrane potential, ultrastructure, and protein import. ATAD3A has been previously studied in multicellular eukaryotes and has been implicated in several childhood mitochondrial diseases, with suggested functions in mitochondrial nucleoid stabilization, mitochondrial RNA translation, and mitochondrial inner membrane integrity. This study is the first characterization, to our knowledge, of ATAD3A in unicellular organisms. Our findings here expand our knowledge on apicomplexan mitochondrial biology and our arsenal of potential antimalarial drug targets.
    DOI:  https://doi.org/10.1371/journal.ppat.1014317
  9. J Med Chem. 2026 Jun 03.
    Lead Optimization of TgCDPK1 Inhibitors for the Treatment of Toxoplasmosis.
    Michael P Mannino, Anusha Gokanapalle, Shrushti Patil, Anoopjit Singh Kooner, Chhuttan Lal Meena, Matthew Medcalf, Igi Vilza, Jennifer Barks, Yong Fu, Jing Xia, Jay C Nix, Chris Nelson, Daved Fremont, Arun Dhillon, L David Sibley, James W Janetka.
      Toxoplasma gondii is an important opportunistic pathogen that infects many individuals and threatens the health of those with compromised immunity. Current therapies are unable to eradicate chronic infections and pose risks of adverse reactions. Using X-ray structure-based drug design, we have developed a new series of biaryl-substituted pyrazolopyrimidine inhibitors of the essential parasite enzyme calcium-dependent protein kinase 1 (TgCDPK1). These inhibitors have excellent potency against the enzyme and in vitro antiparasitic activity. We further optimized the compounds for increased metabolic stability, lowered plasma protein binding, decreased efflux, and improved pharmacokinetics (PK). Several of the inhibitors had desirable PK with high oral bioavailability, low clearance, and extended half-life, leading to excellent compound exposure in the plasma and brain over a 24-h period. Three compounds were tested during acute infection in both immunocompetent and immunocompromised mice. We identified 16c as a promising preclinical candidate to treat toxoplasmosis.
    DOI:  https://doi.org/10.1021/acs.jmedchem.6c00065
  10. bioRxiv. 2026 May 22. pii: 2026.05.20.726656. [Epub ahead of print]
    Mitochondrial copper stabilizes lipoylated TCA cycle proteins to sustain metabolism and proliferation.
    Santanu Ghosh, Andrew F Jarvis, Jordi C J Hintzen, Nate R McKnight, Pedro Costa-Pinheiro, Noelle H Noughton, Yumi Kim, Alison Jaccard, Scot C Leary, Paul A Cobine, Caroline R Bartman, Gina M DeNicola, Nathaniel W Snyder, Kathryn E Wellen, George M Burslem, Donita C Brady.
      Copper (Cu) is an essential cofactor for mitochondrial cytochrome c oxidase, yet whether it directly regulates mitochondrial metabolism beyond respiration remains unclear. Here we show that mitochondrial Cu, delivered by SLC25A3, is required to maintain the stability of lipoylated TCA cycle proteins. Loss of Slc25a3 or pharmacological Cu depletion selectively destabilized the lipoylated E2 subunits of mitochondrial dehydrogenases and the lipoylation enzymes LIPT1 and LIPT2, an effect not reproduced by acute electron transport chain inhibition. Mechanistically, we find that Cu directly engages the reduced lipoyl moiety using chemical probes and synthetic peptide approaches. Cu depletion impaired PDH and OGDH activity, rewired TCA cycle metabolism, and imposed a dependence on pyruvate carboxylase for anaplerosis. This metabolic defect depleted aspartate, suppressed mTORC1 signaling, and limited proliferation. Conversely, selective delivery of Cu to the mitochondria restored lipoylation, TCA cycle function, and cell growth. Together, these findings identify mitochondrial Cu as a structural regulator of the lipoylation machinery and reveal a direct link between Cu homeostasis and central carbon metabolism.
    DOI:  https://doi.org/10.64898/2026.05.20.726656
  11. mSphere. 2026 Jun 01. e0002126
    The bromodomain protein Bdf3 is sufficient to activate expression of a procyclin gene in bloodstream stage African trypanosomes.
    Evan J Kim, Ethan L Goroza, Ashley Y Tan, Jolyne J Lin, Kieran C Saucedo, Fuminori Tanizawa, Jaclyn E Smith, Danae Schulz.
      The early-branching eukaryotic parasite, Trypanosoma brucei, lives extracellularly in the mammalian host, where it expresses variant surface glycoprotein (VSG). Antigenic variation of VSGs allows the parasite to evade the host immune response while in the bloodstream. Upon transition to the tsetse fly vector, the parasite remodels its surface to express procyclin protein from a limited set of EP and GPEET genes. While the environmental signals that trigger the switch from expressing VSG genes to expressing EP and GPEET genes are known, the molecular mechanism that initiates transcription of the EP and GPEET genes during parasite differentiation to the procyclic stage within the tsetse is not well understood. Previous work has shown that the chromatin-interacting bromodomain protein Bdf3 is absent from the RNA polymerase I promoter of the EP locus in bloodstream parasites, but appears there shortly after initiation of differentiation from the bloodstream to the procyclic stage. Here, we show that tethering of Bdf3 to the EP promoter using a dCas9-Bdf3 fusion protein and a guide RNA is sufficient to increase transcript levels of EP1 in bloodstream parasites, where the gene is normally silenced. This result supports the model that Bdf3 appears at the EP locus during differentiation to facilitate initiation of transcription, which is consistent with the role of Bdf3 as a transcriptional activator in other systems. Understanding gene regulatory mechanisms in this early-branching eukaryote may help build a more complete picture of the conserved and unique features of gene regulatory proteins across diverse biological systems.
    IMPORTANCE: The Trypanosoma brucei parasite is transmitted via the tsetse fly vector to a mammalian host , where it causes African trypanosomiasis, a fatal disease that imposes a severe human and economic burden for people living in areas of sub-Saharan Africa. While drug treatments have improved for some strains, some infections still require treatment with drugs that have serious side effects. One avenue for drug development is to try to manipulate the life cycle of the parasite to make it poorly adapted to the mammalian host. However, this requires detailed knowledge of the mechanisms by which parasites regulate their genes as they progress through the life cycle. Here, we show that the DNA-interacting bromodomain protein Bdf3 may be a key driver for turning on insect-specific genes that code for insect-stage surface proteins. This finding could aid in the development of life cycle-manipulating drugs and shed light on how gene regulatory mechanisms evolved.
    Keywords:  Trypanosoma brucei; bromodomain protein; chromatin; epigenetics; molecular parasitology
    DOI:  https://doi.org/10.1128/msphere.00021-26
  12. Sci Rep. 2026 Jun 05.
    Characterization of ovine abortion in Uruguay reveals extensive non-clonal diversity and multiple evolutionary origins of Toxoplasma gondii.
    Leandro Tana-Hernandez, Pablo Fresia, Andrés M Cabrera, Alejandra Valentin, Matías Dorsch, Sergio Fierro, Federico Giannitti, Luisa Berná, María E Francia.
      Toxoplasma gondii is a major cause of reproductive losses in farm animals worldwide, with sheep being a particularly sensitive species. Yet, the diversity and biological characteristics of strains associated with ovine abortion remain incompletely understood in many regions, including South America whereby genetic diversity is known to be high. In this study, we investigated the genetic diversity of T. gondii associated with ovine abortion in Uruguay through genotyping and phylogenetic analyses of samples obtained from abortion cases. To place the observed diversity in a broader epidemiological context, ovine data were compared with previously reported genotypes circulating in humans locally. In addition, two novel strains were isolated from independent ovine abortion cases and subjected to determination of their infectivity both in vitro and in vivo, as well as to whole-genome sequencing. Integrated analyses revealed that the isolates represent previously undescribed genotypes and display marked differences in virulence-associated traits. Genomic analysis identified variation in loci previously linked to parasite virulence, including differences in ROP5 copy number. Together, our results provide new insight into the diversity of T. gondii associated with ovine abortion in Uruguay and expand current knowledge of the biological and genomic features of strains circulating in this species.
    Keywords:   In-silico RFLP; Toxoplasma gondii ; Gene copy number variation; Genome sequencing; Genotyping; Sheep abortion; Virulence
    DOI:  https://doi.org/10.1038/s41598-026-55698-0
This page is being maintained by Thomas Krichel. It was last updated on 2026‒06‒14 at 1:20.