bims-toxgon Biomed News
on Toxoplasma gondii metabolism
Issue of 2023–08–27
twelve papers selected by
Lakesh Kumar, BITS Pilani
  1. Monocyte-Derived Chicken Macrophages Exposed to Eimeria tenella Sporozoites Display Reduced Susceptibility to Invasion by Toxoplasma gondii Tachyzoite.
  2. CDPK2A and CDPK1 form a signaling module upstream of Toxoplasma motility.
  3. Assessment of Toxoplasma gondii lytic cycle and the impact of a gene deletion using 3D label-free optical diffraction holotomography.
  4. Metabolic changes to host cells with Toxoplasma gondii infection.
  5. Manipulative neuroparasites: uncovering the intricacies of neurological host control.
  6. The Toxoplasma subpellicular network is highly interconnected and defines parasite shape for efficient motility and replication.
  7. A global view of the human post-translational modification landscape.
  8. Progress in discovery and development of natural inhibitors of histone deacetylases (HDACs) as anti-cancer agents.
  9. Crystal Structure of Histone Deacetylase 6 Complexed with ( R )-Lipoic Acid, an Essential Cofactor in Central Carbon Metabolism.
  10. The molecular basis of nutrient sensing and signalling by mTORC1 in metabolism regulation and disease.
  11. Review of knockout technology approaches in bacterial drug resistance research.
  12. Outer membrane vesicles from a mosquito commensal mediate targeted killing of Plasmodium parasites via the phosphatidylcholine scavenging pathway.
  1. Microorganisms. 2023 Aug 03. pii: 1999. [Epub ahead of print]11(8):
    Monocyte-Derived Chicken Macrophages Exposed to Eimeria tenella Sporozoites Display Reduced Susceptibility to Invasion by Toxoplasma gondii Tachyzoite.
    Runhui Zhang, Wanpeng Zheng, Arwid Daugschies, Berit Bangoura.
      Both Eimeria tenella and Toxoplasma gondii are common apicomplexan parasites in chickens. Host cell invasion by both protozoans includes gliding motility, host cell attachment and active penetration. Chicken macrophages as phagocytic cells participate in the innate host immune response against these two parasites. In this study, primary chicken monocyte-derived macrophages (MM) were infected with both pathogens to investigate mutual and host-parasite interactions. MM cultures were assigned to groups that were infected with E. tenella, T. gondii or both. In co-infected cultures, MM were first exposed to E. tenella sporozoites for 2 h. Afterwards, T. gondii tachyzoite infection was performed. Live-cell imaging was carried out to observe cell invasion and survival of T. gondii by single parasite tracking over a period of 20 h post infection (hpi). Quantitative analysis for parasite replication was performed by real-time quantitative PCR (qPCR) at 2, 6, 12 and 24 hpi. Overall, the ability of T. gondii to penetrate the cell membrane of the potential host cell was reduced, although high motility was displayed. We found that T. gondii tachyzoites adhered for more than 4 h to macrophages during early co-infection. qPCR results confirmed that significantly less T. gondii entered in E. tenella-activated MM at 2 hpi, and a reduced proportion of intracellular T. gondii survived and replicated in these cells at 24 hpi. We conclude that E. tenella modulates host cell responses to another apicomplexan agent, T. gondii, reducing active invasion and multiplication in chicken primary macrophages.
    Keywords:  Eimeria tenella; Toxoplasma gondii; chicken; co-infection; live cell imaging; macrophages
    DOI:  https://doi.org/10.3390/microorganisms11081999
  2. mBio. 2023 Aug 23. e0135823
    CDPK2A and CDPK1 form a signaling module upstream of Toxoplasma motility.
    Emily Shortt, Caroline G Hackett, Rachel V Stadler, Robyn S Kent, Alice L Herneisen, Gary E Ward, Sebastian Lourido.
      In apicomplexan parasites, the transition between replication and dissemination is regulated by fluctuations in cytosolic calcium concentrations, transduced in part by calcium-dependent protein kinases (CDPKs). We examined the role of CDPK2A in the lytic cycle of Toxoplasma, analyzing its role in the regulation of cellular processes associated with parasite motility. We used chemical-genetic approaches and conditional depletion to determine that CDPK2A contributes to the initiation of parasite motility through microneme discharge. We demonstrate that the N-terminal extension of CDPK2A is necessary for the protein's function. Conditional depletion revealed an epistatic interaction between CDPK2A and CDPK1, suggesting that the two kinases work together to mediate motility in response to certain stimuli. This signaling module appears distinct from that of CDPK3 and protein kinase G, which also control egress. CDPK2A is revealed as an important regulator of the Toxoplasma kinetic phase, linked to other kinases that govern this critical transition. Our work uncovers extensive interconnectedness between the signaling pathways that regulate parasite motility. IMPORTANCE This work uncovers interactions between various signaling pathways that govern Toxoplasma gondii egress. Specifically, we compare the function of three canonical calcium-dependent protein kinases (CDPKs) using chemical-genetic and conditional-depletion approaches. We describe the function of a previously uncharacterized CDPK, CDPK2A, in the Toxoplasma lytic cycle, demonstrating that it contributes to parasite fitness through regulation of microneme discharge, gliding motility, and egress from infected host cells. Comparison of analog-sensitive kinase alleles and conditionally depleted alleles uncovered epistasis between CDPK2A and CDPK1, implying a partial functional redundancy. Understanding the topology of signaling pathways underlying key events in the parasite life cycle can aid in efforts targeting kinases for anti-parasitic therapies.
    Keywords:  CDPK; Toxoplasma gondii; calcium signaling; protein kinases
    DOI:  https://doi.org/10.1128/mbio.01358-23
  3. Front Cell Infect Microbiol. 2023 ;13 1237594
    Assessment of Toxoplasma gondii lytic cycle and the impact of a gene deletion using 3D label-free optical diffraction holotomography.
    Zisis Koutsogiannis, John G M Mina, Rakesh Suman, Paul William Denny.
      Toxoplasma gondii is a widespread single-celled intracellular eukaryotic apicomplexan protozoan parasite primarily associated with mammalian foetal impairment and miscarriage, including in humans. Is estimated that approximately one third of the human population worldwide is infected by this parasite. Here we used cutting-edge, label-free 3D quantitative optical diffraction holotomography to capture and evaluate the Toxoplasma lytic cycle (invasion, proliferation and egress) in real-time based on the refractive index distribution. In addition, we used this technology to analyse an engineered CRISPR-Cas9 Toxoplasma mutant to reveal differences in cellular physical properties when compared to the parental line. Collectively, these data support the use of holotomography as a powerful tool for the study of protozoan parasites and their interactions with their host cells.
    Keywords:  3D imaging; Toxoplasma gondii; apicomplexa; label-free imaging; optical diffraction holotomography
    DOI:  https://doi.org/10.3389/fcimb.2023.1237594
  4. bioRxiv. 2023 Aug 10. pii: 2023.08.10.552811. [Epub ahead of print]
    Metabolic changes to host cells with Toxoplasma gondii infection.
    Gina M Gallego-López, Emmanuel Contreras Guzman, Laura J Knoll, Melissa Skala.
      Toxoplasma gondii , the causative agent of toxoplasmosis, is an obligate intracellular parasite that infects warm-blooded vertebrates across the world. In humans, seropositivity rates of T. gondii range from 10% to 90%. Despite its prevalence, few studies address how T. gondii infection changes the metabolism of host cells. Here, we investigate how T. gondii manipulates the host cell metabolic environment by monitoring metabolic response over time using non-invasive autofluorescence lifetime imaging of single cells, seahorse metabolic flux analysis, reactive oxygen species (ROS) production, and metabolomics. Autofluorescence lifetime imaging indicates that infected host cells become more oxidized and have an increased proportion of bound NAD(P)H with infection. These findings are consistent with changes in mitochondrial and glycolytic function, decrease of intracellular glucose, fluctuations in lactate and ROS production in infected cells over time. We also examined changes associated with the pre-invasion "kiss and spit" process using autofluorescence lifetime imaging, which similarly showed a more oxidized host cell with an increased proportion of bound NAD(P)H over 48 hours. Glucose metabolic flux analysis indicated that these changes are driven by NADH and NADP+ in T. gondii infection. In sum, metabolic changes in host cells with T. gondii infection were similar during full infection, and kiss and spit. Autofluorescence lifetime imaging can non-invasively monitor metabolic changes in host cells over a microbial infection time-course.
    DOI:  https://doi.org/10.1101/2023.08.10.552811
  5. Arch Microbiol. 2023 Aug 21. 205(9): 314
    Manipulative neuroparasites: uncovering the intricacies of neurological host control.
    Vishvas Gowda, Susha Dinesh, Sameer Sharma.
      Manipulative neuroparasites are a fascinating group of organisms that possess the ability to hijack the nervous systems of their hosts, manipulating their behavior in order to enhance their own survival and reproductive success. This review provides an overview of the different strategies employed by manipulative neuroparasites, ranging from viruses to parasitic worms and fungi. By examining specific examples, such as Toxoplasma gondii, Leucochloridium paradoxum, and Ophiocordyceps unilateralis, we highlight the complex mechanisms employed by these parasites to manipulate their hosts' behavior. We explore the mechanisms through which these parasites alter the neural processes and behavior of their hosts, including the modulation of neurotransmitters, hormonal pathways, and neural circuits. This review focuses less on the diseases that neuroparasites induce and more on the process of their neurological manipulation. We also investigate the fundamental mechanisms of host manipulation in the developing field of neuroparasitology, which blends neuroscience and parasitology. Finally, understanding the complex interaction between manipulative neuroparasites and their hosts may help us to better understand the fundamentals of behavior, neurology, and host-parasite relationships.
    Keywords:  Leucochloridium paradoxum; Neurological manipulation; Neuroscience; Ophiocordyceps unilateralis; Parasitology; Toxoplasma gondii
    DOI:  https://doi.org/10.1007/s00203-023-03637-2
  6. bioRxiv. 2023 Aug 10. pii: 2023.08.10.552545. [Epub ahead of print]
    The Toxoplasma subpellicular network is highly interconnected and defines parasite shape for efficient motility and replication.
    Peter S Back, Vignesh Senthilkumar, Charles P Choi, Andrew M Ly, Anne K Snyder, Justin G Lau, Gary E Ward, Peter J Bradley.
      Apicomplexan parasites possess several specialized structures to invade their host cells and replicate successfully. One of these is the inner membrane complex (IMC), a peripheral membrane-cytoskeletal system underneath the plasma membrane. It is composed of a series of flattened, membrane-bound vesicles and a cytoskeletal subpellicular network (SPN) comprised of intermediate filament-like proteins called alveolins. While the alveolin proteins are conserved throughout the Apicomplexa and the broader Alveolata, their precise functions and interactions remain poorly understood. Here, we describe the function of one of these alveolin proteins, TgIMC6. Disruption of IMC6 resulted in striking morphological defects that led to aberrant motility, invasion, and replication. Deletion analyses revealed that the alveolin domain alone is largely sufficient to restore localization and partially sufficient for function. As this highlights the importance of the IMC6 alveolin domain, we implemented unnatural amino acid photoreactive crosslinking to the alveolin domain and identified multiple binding interfaces between IMC6 and two other cytoskeletal proteins - IMC3 and ILP1. To our knowledge, this provides the first direct evidence of protein-protein interactions in the alveolin domain and supports the long-held hypothesis that the alveolin domain is responsible for filament formation. Collectively, our study features the conserved alveolin proteins as critical components that maintain the parasite's structural integrity and highlights the alveolin domain as a key mediator of SPN architecture.
    DOI:  https://doi.org/10.1101/2023.08.10.552545
  7. Biochem J. 2023 Aug 30. 480(16): 1241-1265
    A global view of the human post-translational modification landscape.
    Naoya Kitamura, James J Galligan.
      Post-translational modifications (PTMs) provide a rapid response to stimuli, finely tuning metabolism and gene expression and maintain homeostasis. Advances in mass spectrometry over the past two decades have significantly expanded the list of known PTMs in biology and as instrumentation continues to improve, this list will surely grow. While many PTMs have been studied in detail (e.g. phosphorylation, acetylation), the vast majority lack defined mechanisms for their regulation and impact on cell fate. In this review, we will highlight the field of PTM research as it currently stands, discussing the mechanisms that dictate site specificity, analytical methods for their detection and study, and the chemical tools that can be leveraged to define PTM regulation. In addition, we will highlight the approaches needed to discover and validate novel PTMs. Lastly, this review will provide a starting point for those interested in PTM biology, providing a comprehensive list of PTMs and what is known regarding their regulation and metabolic origins.
    Keywords:  acetylation/deacetylation; acylation; glycation; mass spectrometry; methylglyoxal; post-translational modification
    DOI:  https://doi.org/10.1042/BCJ20220251
  8. Naunyn Schmiedebergs Arch Pharmacol. 2023 Aug 24.
    Progress in discovery and development of natural inhibitors of histone deacetylases (HDACs) as anti-cancer agents.
    Abhishek Wahi, Priti Jain, Apurba Sinhari, Hemant R Jadhav.
      The study of epigenetic translational modifications had drawn great interest for the last few decades. These processes play a vital role in many diseases and cancer is one of them. Histone acetyltransferase (HAT) and histone deacetylases (HDACs) are key enzymes involved in the acetylation and deacetylation of histones and ultimately in post-translational modifications. Cancer frequently exhibits epigenetic changes, particularly disruption in the expression and activity of HDACs. It includes the capacity to regulate proliferative signalling, circumvent growth inhibitors, escape cell death, enable replicative immortality, promote angiogenesis, stimulate invasion and metastasis, prevent immunological destruction, and genomic instability. The majority of tumours develop and spread as a result of HDAC dysregulation. As a result, HDAC inhibitors (HDACis) were developed, and they today stand as a very promising therapeutic approach. One of the most well-known and efficient therapies for practically all cancer types is chemotherapy. However, the efficiency and safety of treatment are constrained by higher toxicity. The same has been observed with the synthetic HDACi. Natural products, owing to many advantages over synthetic compounds for cancer treatment have always been a choice for therapy. Hence, naturally available molecules are of particular interest for HDAC inhibition and HDAC has drawn the attention of the research fraternity due to their potential to offer a diverse array of chemical structures and bioactive compounds. This diversity opens up new avenues for exploring less toxic HDAC inhibitors to reduce side effects associated with conventional synthetic inhibitors. The review presents comprehensive details on natural product HDACi, their mechanism of action and their biological effects. Moreover, this review provides a brief discussion on the structure activity relationship of selected natural HDAC inhibitors and their analogues which can guide future research to discover selective, more potent HDACi with minimal toxicity.
    Keywords:  Cancer; Epigenetic; HDAC inhibitors; Histone acetyltransferase (HAT); Histone deacetylase (HDAC); Natural products; Small molecules
    DOI:  https://doi.org/10.1007/s00210-023-02674-4
  9. bioRxiv. 2023 Aug 09. pii: 2023.08.08.552419. [Epub ahead of print]
    Crystal Structure of Histone Deacetylase 6 Complexed with ( R )-Lipoic Acid, an Essential Cofactor in Central Carbon Metabolism.
    Paris R Watson, Juana Goulart Stollmaier, David W Christianson.
      The enzyme cofactor ( R )-lipoic acid plays a critical role in central carbon metabolism due to its catalytic function in the generation of acetyl-CoA, which links glycolysis with the tricarboxylic acid cycle. This cofactor is also essential for the generation of succinyl CoA within the tricarboxylic acid cycle. However, the biological functions of ( R )-lipoic acid extend beyond metabolism owing to its facile redox chemistry. Most recently, the reduced form of ( R )-lipoic acid, ( R )-dihydrolipoic acid, has been shown to inhibit histone deacetylases (HDACs) with selectivity for the inhibition of HDAC6. Here, we report the 2.4 Å-resolution X-ray crystal structure of the HDAC6-( R )-dihydrolipoic acid complex, and we report a dissociation constant (K D ) of 350 nM for this complex as determined by isothermal titration calorimetry. The crystal structure illuminates key affinity determinants in the enzyme active site, including thiolate-Zn 2+ coordination and S-π interactions in the F583-F643 aromatic crevice. This study provides the first visualization of the connection between HDAC function and the biological response to oxidative stress: the dithiol moiety of ( R )-dihydrolipoic acid can serve as a redox-regulated pharmacophore capable of simultaneously targeting the catalytic Zn 2+ ion and the aromatic crevice in the active site of HDAC6.
    DOI:  https://doi.org/10.1101/2023.08.08.552419
  10. Nat Rev Mol Cell Biol. 2023 Aug 23.
    The molecular basis of nutrient sensing and signalling by mTORC1 in metabolism regulation and disease.
    Claire Goul, Roberta Peruzzo, Roberto Zoncu.
      The Ser/Thr kinase mechanistic target of rapamycin (mTOR) is a central regulator of cellular metabolism. As part of mTOR complex 1 (mTORC1), mTOR integrates signals such as the levels of nutrients, growth factors, energy sources and oxygen, and triggers responses that either boost anabolism or suppress catabolism. mTORC1 signalling has wide-ranging consequences for the growth and homeostasis of key tissues and organs, and its dysregulated activity promotes cancer, type 2 diabetes, neurodegeneration and other age-related disorders. How mTORC1 integrates numerous upstream cues and translates them into specific downstream responses is an outstanding question with major implications for our understanding of physiology and disease mechanisms. In this Review, we discuss recent structural and functional insights into the molecular architecture of mTORC1 and its lysosomal partners, which have greatly increased our mechanistic understanding of nutrient-dependent mTORC1 regulation. We also discuss the emerging involvement of aberrant nutrient-mTORC1 signalling in multiple diseases.
    DOI:  https://doi.org/10.1038/s41580-023-00641-8
  11. PeerJ. 2023 ;11 e15790
    Review of knockout technology approaches in bacterial drug resistance research.
    Chunyu Tong, Yimin Liang, Zhelin Zhang, Sen Wang, Xiaohui Zheng, Qi Liu, Bocui Song.
      Gene knockout is a widely used method in biology for investigating gene function. Several technologies are available for gene knockout, including zinc-finger nuclease technology (ZFN), suicide plasmid vector systems, transcription activator-like effector protein nuclease technology (TALEN), Red homologous recombination technology, CRISPR/Cas, and others. Of these, Red homologous recombination technology, CRISPR/Cas9 technology, and suicide plasmid vector systems have been the most extensively used for knocking out bacterial drug resistance genes. These three technologies have been shown to yield significant results in researching bacterial gene functions in numerous studies. This study provides an overview of current gene knockout methods that are effective for genetic drug resistance testing in bacteria. The study aims to serve as a reference for selecting appropriate techniques.
    Keywords:  Bacterial drug resistance; CRISPR/Cas9; Gene knockout; Red homologous recombination; Suicide plasmid
    DOI:  https://doi.org/10.7717/peerj.15790
  12. Nat Commun. 2023 Aug 24. 14(1): 5157
    Outer membrane vesicles from a mosquito commensal mediate targeted killing of Plasmodium parasites via the phosphatidylcholine scavenging pathway.
    Han Gao, Yongmao Jiang, Lihua Wang, Guandong Wang, Wenqian Hu, Ling Dong, Sibao Wang.
      The gut microbiota is a crucial modulator of Plasmodium infection in mosquitoes, including the production of anti-Plasmodium effector proteins. But how the commensal-derived effectors are translocated into Plasmodium parasites remains obscure. Here we show that a natural Plasmodium blocking symbiotic bacterium Serratia ureilytica Su_YN1 delivers the effector lipase AmLip to Plasmodium parasites via outer membrane vesicles (OMVs). After a blood meal, host serum strongly induces Su_YN1 to release OMVs and the antimalarial effector protein AmLip into the mosquito gut. AmLip is first secreted into the extracellular space via the T1SS and then preferentially loaded on the OMVs that selectively target the malaria parasite, leading to targeted killing of the parasites. Notably, these serum-induced OMVs incorporate certain serum-derived lipids, such as phosphatidylcholine, which is critical for OMV uptake by Plasmodium via the phosphatidylcholine scavenging pathway. These findings reveal that this gut symbiotic bacterium evolved to deliver secreted effector molecules in the form of extracellular vesicles to selectively attack parasites and render mosquitoes refractory to Plasmodium infection. The discovery of the role of gut commensal-derived OMVs as carriers in cross-kingdom communication between mosquito microbiota and Plasmodium parasites offers a potential innovative strategy for blocking malaria transmission.
    DOI:  https://doi.org/10.1038/s41467-023-40887-6
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