bims-toxgon 2025-01-19 papers

bims-toxgon

Biomed News

on Toxoplasma gondii metabolism

Issue of 2025–01–19
24 papers selected by
Lakesh Kumar, BITS Pilani

The luminal domain of Toxoplasma gondii sortilin adopts a ring-shaped structure exhibiting motifs specific to apicomplexan parasites.
Exploring the Inhibition of Toxoplasma gondii α-Carbonic Anhydrase by Sulfonamides: Insights into Potential Drug Targeting.
Proteomic identification of a Toxoplasma gondii sporozoite-specific antigen using HDAC3 inhibitor-treated tachyzoites as surrogate.
Establishment and application of a sandwich ELISA method for measuring Toxoplasma gondii circulating fructose-1,6-bisphosphate aldolase (ALD) protein in cats.
Regulation of Histone Acetylation Modification on Biosynthesis of Secondary Metabolites in Fungi.
Microtubule acetylation is not required for HIV-1 infection or TRIM69-mediated restriction of HIV-1 infection.
Structural characterization of the ACDC domain from ApiAP2 proteins, a potential molecular target against apicomplexan parasites.
Seronegativity of Iberian ibex (Capra pyrenaica) against Toxoplasma gondii and Neospora caninum is consistent with eco-epidemiological and environmental features in Mediterranean mountainous areas.
Molecular Targets and Small Molecules Modulating Acetyl Coenzyme A in Physiology and Diseases.
Class III Phosphatidylinositol-3 Kinase/Vacuolar Protein Sorting 34 in Cardiovascular Health and Disease.
Mechanism-Based Inhibition of Histone Deacetylase 6 by a Selenocyanate is Subject to Redox Modulation.
Discovery and mechanism of a highly selective, antifungal acetyl CoA synthetase inhibitor.
H3K9 post-translational modifications regulate epiblast/primitive endoderm specification in rabbit blastocysts.
Norditerpene natural products from subterranean fungi with anti-parasitic activity.
Loss of Sirtuin 7 impairs cell motility and proliferation and enhances S-phase cell arrest after 5-fluorouracil treatment in head and neck cancer.
The malaria parasite PP1 phosphatase controls the initiation of the egress pathway of asexual blood-stages by regulating the rounding-up of the vacuole.
Tubulin detyrosination shapes Leishmania cytoskeletal architecture and virulence.
Metabolic changes that allow Plasmodium falciparum artemisinin-resistant parasites to tolerate oxidative stress.
Mechanisms and rationales of SAM homeostasis.
SIRT2 and ALDH1A1 as critical enzymes for astrocytic GABA production in Alzheimer's disease.
Proteins with alternative folds reveal blind spots in AlphaFold-based protein structure prediction.
Structural Modifications and Prospects of Histone Deacetylase (HDAC) Inhibitors in Cancer.
GlSIRT1 deacetylates and activates pyruvate kinase to improve pyruvate content and enhance heat stress resistance in Ganoderma lucidum.
Illuminating the impact of N-terminal acetylation: from protein to physiology.

Front Parasitol. 2023 ;2 1103772

The luminal domain of Toxoplasma gondii sortilin adopts a ring-shaped structure exhibiting motifs specific to apicomplexan parasites.

Ariane Honfozo, Rania Ghouil, Tchilabalo Dilezitoko Alayi, Malika Ouldali, Ana-Andreea Arteni, Cynthia Menonve Atindehou, Lucie Ayi Fanou, Yetrib Hathout, Sophie Zinn-Justin, Stanislas Tomavo.

  Rhoptries and micronemes are essential for host cell invasion and survival of all apicomplexan parasites, which are composed of numerous obligate intracellular protozoan pathogens including Plasmodium falciparum (malaria) and Toxoplasma gondii (toxoplasmosis) that infect humans and animals causing severe diseases. We identified Toxoplasma gondii TgSORT as an essential cargo receptor, which drives the transport of rhoptry (ROP) and microneme (MIC) proteins to ensure the biogenesis of these secretory organelles. The luminal domain of 752 amino acid long situated at the N-terminus end of TgSORT has been described to bind to MIC and ROP proteins. Here, we present an optimized protocol for expression of the entire luminal N-terminus of TgSORT (Tg-NSORT) in the yeast Pichia pastoris. Optimization of its coding sequence, cloning and transformation of the yeast P. pastoris allowed the secretion of Tg-NSORT. The protein was purified and further analyzed by negative staining electron microscopy. In addition, molecular modeling using AlphaFold identified key differences between the human and the T gondii sortilin. The structural features that are only present in T. gondii and other apicomplexan parasites were highlighted. Elucidating the roles of these specific structural features may be useful for designing new therapeutic agents against apicomplexan parasites.

Keywords:  3D-models; AlphaFold; Pichia pastoris; Toxoplasma gondii; sortilin

DOI:  https://doi.org/10.3389/fpara.2023.1103772
Int J Mol Sci. 2024 Dec 26. pii: 116. [Epub ahead of print]26(1):

Exploring the Inhibition of Toxoplasma gondii α-Carbonic Anhydrase by Sulfonamides: Insights into Potential Drug Targeting.

Simone Giovannuzzi, Viviana De Luca, Clemente Capasso, Claudiu T Supuran.

  Toxoplasma gondii, the causative agent of toxoplasmosis, is a protozoan parasite capable of infecting a wide range of hosts, posing significant health risks, particularly to immunocompromised individuals and congenital transmission. Current therapeutic options primarily target the active tachyzoite stage but are limited by issues such as toxicity and incomplete efficacy. As a result, there is an urgent need for alternative therapies that can selectively target parasite-specific mechanisms critical for metabolic processes and host-parasite interactions. In this context, α-carbonic anhydrase (Tg_CA), an enzyme essential for T. gondii survival has emerged as a promising drug target. Tg_CA was successfully expressed and purified to evaluate its susceptibility to sulfonamide-based inhibitors, represented by compounds 1-24 and the AAZ-HCT series. These inhibitors demonstrated a broad spectrum of activity, with KI values ranging from 17.8 to 8450 nM. Several compounds exhibited moderate to high potency against Tg_CA; however, concerns regarding selectivity arose because of the inhibition of human isoforms, particularly CA I and CA II. Thus, although some inhibitors showed strong activity against Tg_CA, optimizing selectivity remains crucial for minimizing off-target effects and improving therapeutic efficacy. Further structural modifications may enhance selectivity and advance the development of effective treatments for toxoplasmosis.

Keywords:  Toxoplasma gondii; carbonic anhydrase; inhibition constants; protozoan parasite; sulfonamide-based inhibitors; toxoplasmosis

DOI:  https://doi.org/10.3390/ijms26010116
FEMS Microbes. 2025 ;6 xtae034

Proteomic identification of a Toxoplasma gondii sporozoite-specific antigen using HDAC3 inhibitor-treated tachyzoites as surrogate.

David Warschkau, Sandra Klein, Ella Schadt, Joerg Doellinger, Gereon Schares, Frank Seeber.

  The apicomplexan parasite Toxoplasma gondii has a complex life cycle. Access to sexual stages and sporozoite-containing oocysts, essential for studying the parasite's environmental transmission, is limited and requires animal experiments with cats. Thus, alternatives and resource-efficient methods are needed. Several molecular factors and transcriptional switches responsible for differentiation have been identified in recent years. In tachyzoites, drug-induced inhibition of the histone deacetylase HDAC3, or genetic depletion of transcription factors regulating HDAC3, leads to the expression of genes that are specific to sexual stages and oocysts. Here, we applied this concept and showed that the commercially available HDAC3 inhibitor apicidin could be used to identify the hitherto unknown antigen of the sporozoite-specific monoclonal antibody G1/19 in tachyzoites. Using mass spectrometry of immunoprecipitated G1/19 target protein from apicidin-treated cultures, we identified it as SporoSAG. In addition, for the much less abundant sporozoite-specific protein LEA860, apicidin treatment was still sufficient to induce a detectable protein level in immunofluorescence microscopy. We also discuss further applications and the limitations of this approach. This allows to overcome issues with the paucity of material of sexual stages and oocysts from T. gondii to some extent without the need for cat-derived material.

Keywords:  Apicomplexa; late embryogenesis abundant proteins; proteomics; sexual stages; sporozoites

DOI:  https://doi.org/10.1093/femsmc/xtae034
Vet Parasitol. 2025 Jan 13. pii: S0304-4017(25)00006-8. [Epub ahead of print]334 110395

Establishment and application of a sandwich ELISA method for measuring Toxoplasma gondii circulating fructose-1,6-bisphosphate aldolase (ALD) protein in cats.

Jing-Zhi Gong, Yi-Min Fan, Yun-Ping Wu, Ming Pan, Zhao-Feng Hou, Si-Yang Huang.

  Toxoplasmosis is an important public health concern. Cats play a crucial role in increasing the risk of toxoplasmosis transmission to humans. Early diagnosis in cats is essential for the prevention and control of toxoplasmosis. In this study, we found that T. gondii aldolase (ALD) could be an effective diagnostic antigen, and then the recombinant ALD protein was expressed using the pET SUMO protein expression system, the mouse monoclonal antibody (MoAb) and rabbit polyclonal antibody (PoAb) of ALD were successfully produced, respectively. Furthermore, a reliable sandwich enzyme-linked immunosorbent assay (sELISA) was developed to detect circulating ALD in the sera of experimentally and naturally infected cats. rALD sELISA could detect T. gondii infection from 7DPI (post-infection day) to 14DPI with 100 % sensitivity and speciﬁcity, but could not detect T. gondii infection after 21DPI, indicating that it is a good early diagnosis tool. The detection limit was 7.8 ng/ml, the coefficients of variation (CV) of repeated tests within batches and between batches were confirmed to be less than 10 %. The results of 70 cat clinical serum samples detected by rALD sELISA were in almost perfect agreement beyond chance with those of a commercial ELISA kit (Cohen's kappa coefficient = 0.883). This sandwich ELISA method has high accuracy and can be used for early diagnosis of toxoplasmosis in cats.

Keywords:  6-bisphosphate aldolase (ALD); Cats; Fructose-1; Sandwich ELISA; Serodiagnosis; Toxoplasma gondii

DOI:  https://doi.org/10.1016/j.vetpar.2025.110395
Int J Mol Sci. 2024 Dec 24. pii: 25. [Epub ahead of print]26(1):

Regulation of Histone Acetylation Modification on Biosynthesis of Secondary Metabolites in Fungi.

Xuwen Hou, Liyao Liu, Yu Li, Pengfei Wang, Xiaoqian Pan, Dan Xu, Daowan Lai, Ligang Zhou.

  The histone acetylation modification is a conservative post-translational epigenetic regulation in fungi. It includes acetylation and deacetylation at the lysine residues of histone, which are catalyzed by histone acetyltransferase (HAT) and deacetylase (HDAC), respectively. The histone acetylation modification plays crucial roles in fungal growth and development, environmental stress response, secondary metabolite (SM) biosynthesis, and pathogenicity. One of the most important roles is to regulate the gene expression that is responsible for SM biosynthesis in fungi. This mini-review summarized the regulation of histone acetylation modification by HATs and HDACs on the biosynthesis of SMs in fungi. In most cases, histone acetylation by HATs positively regulated the biosynthesis of fungal SMs, while HDACs had their negative regulations. Some HATs and HDACs were revealed to regulate fungal SM biosynthesis. Hda1 was found to be the most efficient regulator to affect the biosynthesis of SMs in fungi. The regulated fungal species were mainly from the genera of Aspergillus, Calcarisporium, Cladosporium, Fusarium, Monascus, Penicillium, and Pestalotiopsis. With the strategy of histone acetylation modification, the biosynthesis of some harmful SMs will be inhibited, while the production of useful bioactive SMs will be promoted in fungi. The subsequent research should focus on the study of regulatory mechanisms.

Keywords:  biological activities; biosynthetic gene cluster; epigenetic regulation; histone acetylation modification; histone acetytransferase; histone deacetylase; regulation mechanisms; secondary metabolite biosynthesis; secondary metabolites

DOI:  https://doi.org/10.3390/ijms26010025
J Virol. 2025 Jan 13. e0102624

Microtubule acetylation is not required for HIV-1 infection or TRIM69-mediated restriction of HIV-1 infection.

Drew M Lichon, Natalie J LoMascolo, Bryan C Mounce, Edward M Campbell.

  Microtubule acetylation, a post-translational modification catalyzing the addition of acetyl groups to lysine residues on alpha tubulin, confers mechanical resilience to microtubules and influences intracellular cargo transport. Despite its known cellular functions, its role in viral infections remains poorly understood. The goal of this study was to determine the role of microtubule acetylation in both HIV-1 infection and TRIM69-mediated restriction. To this end, we generated CRIPSR/Cas9 vectors to disrupt alpha-tubulin acetyltransferase (αTAT1), the main enzyme responsible for microtubule acetylation. We assessed the role of acetylation in HIV-1 infectivity and the degree to which TRIM69 relies on microtubule acetylation for its ability to restrict HIV-1. We determined that microtubule acetylation is not required for HIV-1 infection and that preventing microtubule acetylation actually leads to a modest increase in HIV-1 infection. We also determined that TRIM69 can restrict a diverse range of viruses and that its restriction of HIV-1 does not rely on microtubule acetylation.
IMPORTANCE: Although microtubule acetylation is a well-studied post-translational modification in the context of cellular processes, its role during viral infections remains underexplored. Existing studies often rely on various protein and drug perturbations to indirectly examine microtubule acetylation. In this study, we directly target the enzyme responsible for microtubule acetylation to delineate its role in both HIV-1 infection and TRIM69-mediated restriction.

Keywords:  HIV-1; TRIM69; acetylated microtubules; microtubules

DOI:  https://doi.org/10.1128/jvi.01026-24
Acta Crystallogr D Struct Biol. 2025 Jan 01. 81(Pt 1): 38-48

Structural characterization of the ACDC domain from ApiAP2 proteins, a potential molecular target against apicomplexan parasites.

Marine Le Berre, Thibault Tubiana, Philippa Reuterswärd Waldner, Noureddine Lazar, Ines Li de la Sierra-Gallay, Joana M Santos, Manuel Llinás, Sylvie Nessler.

  The apicomplexan AP2 (ApiAP2) proteins are the best characterized family of DNA-binding proteins in Plasmodium spp. malaria parasites. Apart from the AP2 DNA-binding domain, there is little sequence similarity between ApiAP2 proteins. However, a conserved AP2-coincident domain mostly at the C-terminus (ACDC domain) is observed in a subset of the ApiAP2 proteins. The structure and function of this domain remain unknown. We report two crystal structures of ACDC domains derived from distinct Plasmodium ApiAP2 proteins, revealing a conserved, unique, noncanonical, four-helix bundle architecture. We used these structures to perform in silico docking calculations against a library of known antimalarial compounds and identified potential small-molecule ligands that bind in a highly conserved hydrophobic pocket that is present in all apicomplexan ACDC domains. These ligands provide a new molecular basis for the future design of ACDC inhibitors.

Keywords:  ApiAP2 and ACDC domain; Plasmodium; docking simulation; transcription factors; unique fold

DOI:  https://doi.org/10.1107/S2059798324012518
Res Vet Sci. 2025 Jan 07. pii: S0034-5288(25)00004-9. [Epub ahead of print]184 105530

Seronegativity of Iberian ibex (Capra pyrenaica) against Toxoplasma gondii and Neospora caninum is consistent with eco-epidemiological and environmental features in Mediterranean mountainous areas.

Alejandro Cano-Manuel, José Enrique Granados, Gema Álvarez-García, Ana Huertas-López, Carlos Diezma-Díaz, Francisco Javier Cano-Manuel, Luis Miguel Ortega-Mora, Paulino Fandos, Gregorio Mentaberre, Jorge Ramón López-Olvera, Carlos Martínez-Carrasco.

  Knowledge of pathogen epidemiological dynamics and habitat ecological features is essential for wildlife population and health monitoring and management. Toxoplasma gondii and Neospora caninum are two broadly distributed multi-host parasites that affect both wild and domestic animals and, in the case of T. gondii, cause zoonosis. This study reports the seroprevalence of both parasites in Iberian ibex (Capra pyrenaica), a mountain wild ruminant native to the Iberian Peninsula, from the Natural Space of Sierra Nevada (NSSN) in southeastern Spain. Serum from 146 Iberian ibexes were analysed using two in-house ELISA techniques. The positive and doubtful sera were further checked by Western Blot (WB). Seventeen ibexes (11.6 %; 95 % confidence interval 6.4-16.7) were positive for T. gondii and seven (4.8 %; 95 % confidence interval 1.3-8.2) for N. caninum. However, no sera were positive to T. gondii nor to N. caninum by WB. Using at least two different serological techniques is recommended when they are not validated for the target host species. The NSSN is a hypoendemic area for T. gondii and N. caninum, probably determined by the reduced abundance and restricted distribution of their definitive hosts. This would explain the hypoendemic situation in the NSSN and the lack of specific antibodies against these two parasites in the Iberian ibex population. This eco-epidemiological scenario can be challenged by climate and anthropogenic changes, recommending long-term monitoring Iberian ibex population and health, both as a conservation measure for the species and as an indicator of the potential impact of global change on high mountain ecosystems.

Keywords:  ELISA; Eco-epidemiology; Iberian ibex; Neospora caninum; Toxoplasma gondii; Western blot

DOI:  https://doi.org/10.1016/j.rvsc.2025.105530
ACS Pharmacol Transl Sci. 2025 Jan 10. 8(1): 36-46

Molecular Targets and Small Molecules Modulating Acetyl Coenzyme A in Physiology and Diseases.

Heba Ewida, Harrison Benson, Syed Tareq, Mahmoud Salama Ahmed.

Acetyl coenzyme A (acetyl-CoA), a pivotal regulatory metabolite, is a product of numerous catabolic reactions and a substrate for various anabolic responses. Its role extends to crucial physiological processes, such as glucose homeostasis and free fatty acid utilization. Moreover, acetyl-CoA plays a significant part in reshaping the metabolic microenvironment and influencing the progression of several diseases and conditions, including cancer, insulin resistance, diabetes, heart failure, fear, and neuropathic pain. This Review delves into the role of acetyl-CoA in both physiological and pathological conditions, shedding light on the key players in its formation within the cytosol. We specifically focus on the physiological impact of malonyl-CoA decarboxylase (MCD), acetyl-CoA synthetase2 (ACSS2), and ATP-citrate lyase (ACLY) on metabolism, glucose homeostasis, free fatty acid utilization, and post-translational modification cellular processes. Additionally, we present the pathological implications of MCD, ACSS2, and ACLY in various clinical manifestations. This Review also explores the potential and limitations of targeting MCD, ACSS2, and ACLY using small molecules in different clinical settings.

DOI: https://doi.org/10.1021/acsptsci.4c00476
J Cardiovasc Transl Res. 2025 Jan 16.

Class III Phosphatidylinositol-3 Kinase/Vacuolar Protein Sorting 34 in Cardiovascular Health and Disease.

Yuanjun Shen, Jason P Gleghorn.

  Phosphatidylinositol-3 kinases (PI3Ks) play a critical role in maintaining cardiovascular health and the development of cardiovascular diseases (CVDs). Specifically, vacuolar Protein Sorting 34 (VPS34) or PIK3C3, the only member of Class III PI3K, plays an important role in CVD progression. The main function of VPS34 is inducing the production of phosphatidylinositol 3-phosphate, which, together with other essential structural and regulatory proteins in forming VPS34 complexes, further regulates the mammalian target of rapamycin activation, autophagy, and endocytosis. VPS34 is found to have crucial functions in the cardiovascular system, including dictating the proliferation and survival of vascular smooth muscle cells and cardiomyocytes and the formation of thrombosis. This review aims to summarize our current knowledge and recent advances in understanding the function and regulation of VPS34 in cardiovascular health and disease. We also discuss the current development of VPS34 inhibitors and their potential to treat CVDs.

Keywords:  Cardiovascular disease; Cardiovascular health; Vacuolar protein sorting 34

DOI:  https://doi.org/10.1007/s12265-024-10581-z
bioRxiv. 2025 Jan 04. pii: 2025.01.04.631333. [Epub ahead of print]

Mechanism-Based Inhibition of Histone Deacetylase 6 by a Selenocyanate is Subject to Redox Modulation.

Juana Goulart Stollmaier, B Abigail R Czarnecki, David W Christianson.

Organoselenocyanates have attracted considerable attention in recent years due to their therapeutic potential and versatility in medicinal chemistry. Here, we report on the mechanism of inhibition by 5-phenylcarbamoylpentyl selenocyanide (SelSA-2), an analogue of the well-characterized histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA, a.k.a. Vorinostat). We show that histone deacetylases 6 and 10 can promote selenocyanate hydrolysis to generate a selenolate anion, and we explore the redox chemistry of selenium as it modulates inhibitory activity through reversible formation of the diselenide. The 2.15 Å-resolution crystal structure of histone deacetylase 6 cocrystallized with SelSA-2 conclusively demonstrates that it is not the selenocyanate, but instead the selenolate anion, that is the active pharmacophore responsible for enzyme inhibition.

DOI: https://doi.org/10.1101/2025.01.04.631333
Res Sq. 2025 Jan 01. pii: rs.3.rs-5619443. [Epub ahead of print]

Discovery and mechanism of a highly selective, antifungal acetyl CoA synthetase inhibitor.

Damian Krysan.

Acetyl CoA synthetases (ACS) have emerged as drug targets for the treatment of cancer, metabolic diseases as well as fungal and parasitic infections. Although a variety of small molecule ACS inhibitors have been discovered, the systematic optimization of these molecules has been slowed by a lack of structural information regarding their mechanism of inhibition. Through a chemical genetic-based, synthetic lethal screen of the human fungal pathogen Cryptococcus neoformans, we identified an isoxazole-based ACS inhibitor with antifungal activity and exquisite selectivity for the C. neoformans Acs1 relative to human ACSS2 as well as other fungal ACSs. Xray crystallographic characterization of the isoxazole-CnAcs1 complex revealed that the isoxazole functions as an acetyl CoA mimic and occupies both the acetyl- and CoA-binding sites of CnAcs1. Consistent with this novel mode of inhibition, the isoxazoles display uncompetitive inhibition kinetics that are similar to antimalarial ACS inhibitors also proposed to target the CoA binding site. Consequently, these data provide structural and mechanistic insights into the remarkable selectivity of Acetyl CoA pocket-targeting ACS inhibitors. In addition, these data provide strong proof-of-principle that targeting fungal and parasitic ACSs for the development of novel anti-infectives can be achieved with high selectivity and, thereby, low host toxicity.

DOI: https://doi.org/10.21203/rs.3.rs-5619443/v1
Epigenetics Chromatin. 2025 Jan 13. 18(1): 2

H3K9 post-translational modifications regulate epiblast/primitive endoderm specification in rabbit blastocysts.

Wilhelm Bouchereau, Hong-Thu Pham, Worawalan Samruan, Van-Hong Vu, Thierry Joly, Marielle Afanassieff, Pierre Savatier, Rangsun Parnpai, Nathalie Beaujean.

  Post-translational modifications of histone H3 on lysine 9, specifically acetylation (H3K9ac) and tri-methylation (H3K9me3), play a critical role in regulating chromatin accessibility. However, the role of these modifications in lineage segregation in the mammalian blastocyst remains poorly understood. We demonstrate that di- and tri-methylation marks, H3K9me2 and H3K9me3, decrease during cavitation and expansion of the rabbit blastocyst. Notably, H3K9me3 levels are particularly low in inner cell mass cells at the onset of blastocyst formation but increase again just before gastrulation. Conversely, H3K9ac is abundant in early blastocyst stages but decreases during the transition from the inner cell mass to the epiblast. These distinct distribution patterns correlate with high expression levels of methyltransferases (EHMT1, EHMT2, SETDB1) and deacetylases (HDAC1, HDAC2, HDAC5) in expanding blastocysts. Functionally, inhibiting H3K9me2/3 through an EHMT1/2 inhibitor disrupts primitive endoderm segregation, whereas enhancing histone acetylation (including H3K9ac) using a class I HDAC inhibitor promotes epiblast expansion at the expense of the primitive endoderm. These modifications impact the expression of genes associated with pluripotency and lineage determination, underscoring the importance of H3K9 modifications in embryonic cell fate decisions.

Keywords:  Embryo; Endoderm; Epiblast; H3K9 post-translational modifications; Histone deacetylase; Histone methyltransferase; Rabbit

DOI:  https://doi.org/10.1186/s13072-025-00568-8
bioRxiv. 2025 Jan 03. pii: 2025.01.02.631097. [Epub ahead of print]

Norditerpene natural products from subterranean fungi with anti-parasitic activity.

Alexandra Kolas, Yudi Rusman, Ana C G Maia, Jessica Williams, Fernanda G Fumuso, Alexis Cotto-Rosario, Chidiebere Onoh, Hanen Baggar, Mary L Piaskowski, Christian Baigorria, Raphaella Paes, Debopam Chakrabarti, Lyssa Weible, Kayode K Ojo, Roberta M O'Connor, Christine E Salomon.

Cryptosporidium is a common, waterborne gastrointestinal parasite that causes diarrheal disease worldwide. Currently there are no effective therapeutics to treat cryptosporidiosis in at-risk populations. Since natural products are a known source of anti-parasitic compounds, we screened a library of extracts and pure natural product compounds isolated from bacteria and fungi collected from subterranean environments for activity against Cryptosporidium parvum . Eight structurally related norditerpene lactones isolated from the fungus Oidiodendron truncatum collected from the Soudan Iron mine in Minnesota showed potent activity and were further tested to identify the most active compounds. The availability of a diverse suite of natural structural analogs with varying activities allowed us to determine some structure activity relationships for both anti-parasitic activity as well as cytotoxicity. The two most potent compounds, oidiolactones A and B, had EC 50 s against intracellular Cryptosporidium parvum of 530 and 240 nM respectively without cytotoxicity to confluent HCT-8 host cells. Both compounds also inhibited the related parasite Toxoplasma gondii . Oidiolactone A was active against asexual, but not sexual, stages of C. parvum , and killed 80% of the parasites within 8 hours of treatment. This compound reduced C. parvum infection by 70% in IFNγ-/- mice, with no signs of toxicity. The high potency, low cytotoxicity, and in vivo activity combined with high production, easy isolation from fungi, and synthetic accessibility make oidiolactones A and B attractive scaffolds for the development of new anti- Cryptosporidium therapeutics.

DOI: https://doi.org/10.1101/2025.01.02.631097
Sci Rep. 2025 Jan 16. 15(1): 2123

Loss of Sirtuin 7 impairs cell motility and proliferation and enhances S-phase cell arrest after 5-fluorouracil treatment in head and neck cancer.

Marta Halasa, Syeda Afshan, Anna Wawruszak, Agata Borkowska, Klaudia Brodaczewska, Alicja Przybyszewska-Podstawka, Joanna Kalafut, Marzena Baran, Adolfo Rivero-Müller, Andrzej Stepulak, Matthias Nees.

  Sirtuin 7 (SIRT7), a member of the sirtuin family of NAD+-dependent deacetylases, plays a vital role in cancer, exhibiting context-dependent functions across various malignancies. Our study investigates the role of SIRT7 depletion in head and neck squamous cell carcinoma (HNSCC) progression. In vitro and 3D organotypic models demonstrated that SIRT7 knock-out attenuates cancer cell viability, proliferation, and motility as well as induces downregulation of migration- and epithelial-mesenchymal transition (EMT)-related gene expression. Moreover, the SIRT7 loss results in slower organoid formation and less invasive organoid morphology, validated by vimentin downregulation. The SIRT7 loss potentiates S-phase arrest in cell cycle progression after 5-FU treatment and elevates the ratio of dead cells. Additionally, SIRT7 deletion reduces the expression of G1 phase-associated proteins, Cyclin D and CDK4. Altogether, our study highlights SIRT7 as a promising therapeutic target in HNSCC, enhancing the effectiveness of treatment modalities such as combinational treatment.

Keywords:  5-FU; HDAC; HNSCC; SIRT7; cell cycle

DOI:  https://doi.org/10.1038/s41598-024-83349-9
PLoS Pathog. 2025 Jan;21(1): e1012455

The malaria parasite PP1 phosphatase controls the initiation of the egress pathway of asexual blood-stages by regulating the rounding-up of the vacuole.

Marie Seveno, Manon N Loubens, Laurence Berry, Arnault Graindorge, Maryse Lebrun, Catherine Lavazec, Mauld H Lamarque.

A sustained blood-stage infection of the human malaria parasite P. falciparum relies on the active exit of merozoites from their host erythrocytes. During this process, named egress, the infected red blood cell undergoes sequential morphological events: the rounding-up of the surrounding parasitophorous vacuole, the disruption of the vacuole membrane and finally the rupture of the red blood cell membrane. These events are coordinated by two intracellular second messengers, cGMP and calcium ions (Ca2+), that control the activation of their dedicated kinases, PKG and CDPKs respectively, and thus the secretion of parasitic factors that assist membranes rupture. We had previously identified the serine-threonine phosphatase PP1 as an essential enzyme required for the rupture of the surrounding vacuole. Here, we address its precise positioning and function within the egress signaling pathway by combining chemical genetics and live-microscopy. Fluorescent reporters of the parasitophorous vacuole morphology were expressed in the conditional PfPP1-iKO line which allowed to monitor the kinetics of natural and induced egress, as well as the rescue capacity of known egress inducers. Our results underscore a dual function for PP1 in the egress cascade. First, we provide further evidence that PP1 controls the homeostasis of the second messenger cGMP by modulating the basal activity of guanylyl cyclase alpha and consequently the PKG-dependent downstream Ca2+ signaling. Second, we demonstrate that PP1 also regulates the rounding-up of the parasitophorous vacuole, as this step is almost completely abolished in PfPP1-null schizonts. Strikingly, our data show that rounding-up is the step triggered by egress inducers, and support its reliance on Ca2+, as the calcium ionophore A23187 bypasses the egress defect of PfPP1-null schizonts, restores proper egress kinetics and promotes the initiation of the rounding-up step. Therefore, this study places the phosphatase PP1 upstream of the cGMP-PKG signaling pathway, and sheds new light on the regulation of rounding-up, the first step in P. falciparum blood stage egress cascade.

DOI: https://doi.org/10.1371/journal.ppat.1012455
Proc Natl Acad Sci U S A. 2025 Jan 21. 122(3): e2415296122

Tubulin detyrosination shapes Leishmania cytoskeletal architecture and virulence.

Rosa Milagros Corrales, Jeremy Vincent, Lucien Crobu, Rachel Neish, Binita Nepal, Julien Espeut, Grégoire Pasquier, Ghislain Gillard, Chantal Cazevieille, Jeremy C Mottram, Dawn M Wetzel, Yvon Sterkers, Krzysztof Rogowski, Maude F Lévêque.

  Tubulin detyrosination has been implicated in various human disorders and is important for regulating microtubule dynamics. While in most organisms this modification is restricted to α-tubulin, in trypanosomatid parasites, it occurs on both α- and β-tubulin. Here, we show that in Leishmania, a single vasohibin (LmVASH) enzyme is responsible for differential kinetics of α- and β-tubulin detyrosination. LmVASH knockout parasites, which are completely devoid of detyrosination, show decreased levels of glutamylation and exhibit a strongly diminished pathogenicity in mice, correlating with decreased proliferation in macrophages. Reduced virulence is associated with altered morphogenesis and flagellum remodeling in detyrosination-deficient amastigotes. Flagellum shortening in the absence of detyrosination is caused by hyperactivity of a microtubule-depolymerizing Kinesin-13 homolog, demonstrating its function as a key reader of the trypanosomatid-tubulin code. Taken together, our work establishes the importance of tubulin detyrosination in remodeling the microtubule-based cytoskeleton required for efficient proliferation in the mammalian host. This highlights tubulin detyrosination as a potential target for therapeutic action against leishmaniasis.

Keywords:  dynamics; kinesin-13; microtubules; trypanosomatids; vasohibin

DOI:  https://doi.org/10.1073/pnas.2415296122
Front Parasitol. 2024 ;3 1461641

Metabolic changes that allow Plasmodium falciparum artemisinin-resistant parasites to tolerate oxidative stress.

Alejandro David Bonive-Boscan, Héctor Acosta, Ascanio Rojas.

  Artemisinin-based treatments (ACTs) are the first therapy currently used to treat malaria produced by Plasmodium falciparum. However, in recent years, increasing evidence shows that some strains of P. falciparum are less susceptible to ACT in the Southeast Asian region. A data reanalysis of several omics approaches currently available about parasites of P. falciparum that have some degree of resistance to ACT was carried out. The data used were from transcriptomics and metabolomics studies. One mitochondrial carrier of the parasite possibly involved in the mechanisms of tolerance to oxidative stress was modeled and subjected to molecular dockings with citrate and oxoglutarate. An increase in glutathione production was detected, changing the direction of the flux of metabolites in the tricarboxylic acid cycle and boosting the glucose consumed. The models of the mitochondrial carrier, called PfCOCP, show that it may be important in transporting citrate and oxoglutarate from the mitochondrial matrix to the cytosol. If so, it may allow the parasite to tolerate the oxidative stress produced by artemisinin. This in-silico analysis shows that P. falciparum may tolerate artemisinin's oxidative stress through metabolic changes not reported before, showing the need for further experimental research on the many metabolic aspects linked to this phenotype.

Keywords:  P. falciparum; artemisinin resistance; metabolism; mitochondrial carrier; oxidative stress

DOI:  https://doi.org/10.3389/fpara.2024.1461641
Trends Biochem Sci. 2025 Jan 15. pii: S0968-0004(24)00281-0. [Epub ahead of print]

Mechanisms and rationales of SAM homeostasis.

Zheng Xing, Benjamin P Tu.

  S-Adenosylmethionine (SAM) is the primary methyl donor for numerous cellular methylation reactions. Its central role in methylation and involvement with many pathways link its availability to the regulation of cellular processes, the dysregulation of which can contribute to disease states, such as cancer or neurodegeneration. Emerging evidence indicates that intracellular SAM levels are maintained within an optimal range by a variety of homeostatic mechanisms. This suggests that the need to maintain SAM homeostasis represents a significant evolutionary pressure across all kingdoms of life. Here, we review how SAM controls cellular functions at the molecular level and discuss strategies to maintain SAM homeostasis. We propose that SAM exerts a broad and underappreciated influence in cellular regulation that remains to be fully elucidated.

Keywords:  S-adenosylmethionine (SAM); epigenetics; methionine; methyl-sink; methylation; one-carbon metabolism

DOI:  https://doi.org/10.1016/j.tibs.2024.12.009
Mol Neurodegener. 2025 Jan 15. 20(1): 6

SIRT2 and ALDH1A1 as critical enzymes for astrocytic GABA production in Alzheimer's disease.

Mridula Bhalla, Jinhyeong Joo, Daeun Kim, Jeong Im Shin, Yongmin Mason Park, Yeon Ha Ju, Uiyeol Park, Seonguk Yoo, Seung Jae Hyeon, Hyunbeom Lee, Junghee Lee, Hoon Ryu, C Justin Lee.

   BACKGROUND: Alzheimer's Disease (AD) is a neurodegenerative disease with drastically altered astrocytic metabolism. Astrocytic GABA and H2O2 are associated with memory impairment in AD and synthesized through the Monoamine Oxidase B (MAOB)-mediated multi-step degradation of putrescine. However, the enzymes downstream to MAOB in this pathway remain unidentified.
METHODS: Using transcriptomics analysis, we identified two candidate enzymes, Aldehyde Dehydrogenase 1 family member A1 (ALDH1A1) and Sirtuin 2 (SIRT2) for the steps following MAOB in the astrocytic GABA production pathway. We used immunostaining, metabolite analysis and electrophysiology, both in vitro and in vivo, to confirm the participation of these enzymes in astrocytic GABA production. We checked for the presence of SIRT2 in human AD patients as well as the mouse model APP/PS1 and finally, we selectively ablated SIRT2 in the astrocytes of APP/PS1 mice to observe its effects on pathology.
RESULTS: Immunostaining, metabolite analysis, and electrophysiology recapitulated the participation of ALDH1A1 and SIRT2 in GABA production. Inhibition of SIRT2 reduced the production of astrocytic GABA but not H2O2, a key molecule in neurodegeneration. Elevated expression of these enzymes was found in hippocampal astrocytes of AD patients and APP/PS1 mice. Astrocyte-specific gene-silencing of SIRT2 in APP/PS1 mice restored GABA production and partially improved memory function.
CONCLUSIONS: Our study is the first to identify the specific role of SIRT2 in reactive astrogliosis and determine the specific pathway and metabolic step catalyzed by the enzyme. We determine the partial, yet significant role of ALDH1A1 in this process, thereby highlighting 2 new players the astrocytic GABA production pathway. Our findings therefore, offer SIRT2 as a new tool to segregate GABA from H2O2 production, aiding future research in neurodegenerative diseases.

Keywords:  ALDH1A1; Alzheimer’s disease; Amyloid-beta; GABA; Reactive astrocytes; SIRT2

DOI:  https://doi.org/10.1186/s13024-024-00788-8
ArXiv. 2024 Oct 18. pii: arXiv:2410.14898v1. [Epub ahead of print]

Proteins with alternative folds reveal blind spots in AlphaFold-based protein structure prediction.

Devlina Chakravarty, Myeongsang Lee, Lauren L Porter.

In recent years, advances in artificial intelligence (AI) have transformed structural biology, particularly protein structure prediction. Though AI-based methods, such as AlphaFold (AF), often predict single conformations of proteins with high accuracy and confidence, predictions of alternative folds are often inaccurate, low-confidence, or simply not predicted at all. Here, we review three blind spots that alternative conformations reveal about AF-based protein structure prediction. First, proteins that assume conformations distinct from their training-set homologs can be mispredicted. Second, AF overrelies on its training set to predict alternative conformations. Third, degeneracies in pairwise representations can lead to high-confidence predictions inconsistent with experiment. These weaknesses suggest approaches to predict alternative folds more reliably.
Curr Med Chem. 2025 Jan 09.

Structural Modifications and Prospects of Histone Deacetylase (HDAC) Inhibitors in Cancer.

Yu Chen, Jiahong Su, Sha Li, Feier Chen, Yan Zhang, Xingyue Wang, Yinping Zhang, Xiang Wang, Zijun Yuan, Siqi Ren, Xinyu He, Yueshui Zhao, Xu Wu, Mingxing Li, Fukuan Du, Shuai Deng, Jing Shen, Zhangang Xiao.

  Histone deacetylases (HDACs) play a crucial role in the regulation of cancer progression and have emerged as key targets for antitumor therapy. Histone Deacetylase Inhibitors (HDACis) effectively suppress tumor cell proliferation, induce apoptosis, and cause cell cycle arrest, demonstrating broad-spectrum antitumor activity. This article primarily focuses on enhancing the selectivity of HDACis through structural modification using natural compounds. It provides detailed insights into the structure modification of histone deacetylase 8 (HDAC8) and histone deacetylase 10 (HDAC10), as well as dual-- target inhibitors and their pharmacological effects. Furthermore, conventional HDAC inhibitors are susceptible to off-target effects and the development of drug resistance. Our research focuses on augmenting the targeting specificity of HDAC inhibitors through their combination with proteolysis targeting chimera (PROTAC). Lastly, the latest advancements in clinical research on HDAC inhibitors were summarized, revealing that these inhibitors possess limitations in their clinical applications due to intrinsic or acquired resistance. Consequently, this article primarily focuses on summarizing the current status and prospects of structural modifications for HDAC inhibitors, with the aim of inspiring researchers to develop novel HDAC inhibitors exhibiting enhanced activity for improved application in clinical research.

Keywords:  HDAC10; HDAC8; HDACis; PROTAC; cancer; clinical research.; dual target inhibitors

DOI:  https://doi.org/10.2174/0109298673332285241104091609
Microbiol Res. 2025 Jan 09. pii: S0944-5013(25)00010-2. [Epub ahead of print]293 128055

GlSIRT1 deacetylates and activates pyruvate kinase to improve pyruvate content and enhance heat stress resistance in Ganoderma lucidum.

Jing Han, Xin Tang, Lingshuai Wang, Huhui Chen, Rui Liu, Mingwen Zhao.

  Heat stress is a prevalent environmental stressor. Previous studies have shown that heat stress drives many cellular changes in Ganoderma lucidum. Interestingly, glycolysis is activated during heat stress, which could contribute to increased heat resistance. However, the molecular mechanisms underlying the enhanced heat resistance of G. lucidum following heat exposure are not yet fully understood. In this study, we explored the possibility that acetylation modification plays a significant role in responses to abiotic stress. After heat treatment, an enhanced interaction between the deacetylase GlSIRT1 and pyruvate kinase (PK) was observed, and the acetylation level of PK was decreased. Further studies revealed that GlSIRT1 increases PK activity through deacetylation, thereby increasing pyruvate content. Consistent with these findings, both PK activity and pyruvate content were reduced in GlSIRT1 knockdown strains, which exhibited greater sensitivity to heat stress compared to the wild-type (WT) strain. Collectively, our results reveal a novel molecular mechanism by which heat treatment increases pyruvate content.

Keywords:  Ganoderma lucidum; GlPK; GlSIRT1; Heat resistance; Pyruvate

DOI:  https://doi.org/10.1016/j.micres.2025.128055
Nat Commun. 2025 Jan 15. 16(1): 703

Illuminating the impact of N-terminal acetylation: from protein to physiology.

Nina McTiernan, Ine Kjosås, Thomas Arnesen.

N-terminal acetylation is a highly abundant protein modification in eukaryotic cells. This modification is catalysed by N-terminal acetyltransferases acting co- or post-translationally. Here, we review the eukaryotic N-terminal acetylation machinery: the enzymes involved and their substrate specificities. We also provide an overview of the impact of N-terminal acetylation, including its effects on protein folding, subcellular targeting, protein complex formation, and protein turnover. In particular, there may be competition between N-terminal acetyltransferases and other enzymes in defining protein fate. At the organismal level, N-terminal acetylation is highly influential, and its impairment was recently linked to cardiac dysfunction and neurodegenerative diseases.

DOI: https://doi.org/10.1038/s41467-025-55960-5