bims-toxgon 2024-09-15 papers

bims-toxgon

Biomed News

on Toxoplasma gondii metabolism

Issue of 2024‒09‒15
twenty papers selected by
Lakesh Kumar, BITS Pilani

Identification of subtelomeric cluster-genes associated to sexual stage in Toxoplasma gondii.
Functional Characterization of 11 Tentative Microneme Proteins in Type I RH Strain of Toxoplasma gondii Using the CRISPR-Cas9 System.
PP1 phosphatase controls both daughter cell formation and amylopectin levels in Toxoplasma gondii.
Alveolin proteins in the Toxoplasma inner membrane complex form a highly interconnected structure that maintains parasite shape and replication.
Trem2/Syk/PI3K axis contributes to the host protection against Toxoplasma gondii-induced adverse pregnancy outcomes via modulating decidual macrophages.
Advances in understanding the roles of plant HAT and HDAC in non-histone protein acetylation and deacetylation.
Acetate to the rescue: Acetyl-CoA facilitates placental development.
Toxoplasma gondii Infection of Alzheimer's Disease Mice Reduces Brain Amyloid Density Globally and Regionally.
Subversion from Within and Without: Effector Molecule Transfer from Obligate Intracellular Apicomplexan Parasites to Human Host Cells.
Inflammatory response and parasite regulation in acute toxoplasmosis: the role of P2X7 receptor in controlling virulent atypical genotype strain of Toxoplasma gondii.
The dual-edged role of SIRT1 in energy metabolism and cardiovascular disease.
Plasmodium falciparum Mitochondrial Complex III, the Target of Atovaquone, Is Essential for Progression to the Transmissible Sexual Stages.
Synthesis of ferrocenyl benzimidazole derivatives as novel anti-Toxoplasma gondii agents.
Inhibition of Sirtuin Deacylase Activity by Peroxynitrite.
Advances in metabolic engineering for enhanced acetyl-CoA availability in yeast.
Lock out SIRT4.
The study on the role of O-GlcNAcylation of SIRT3 in regulating mitochondrial oxidative stress during simulate myocardial ischemia-reperfusion.
Biochemical and biophysical characterization of Leishmania donovani citrate synthase.
Rewired glutamate metabolism diminishes cytostatic action of L-asparaginase.
HDAC5 deacetylates c-Myc and facilitates cell cycle progression in hepatocellular carcinoma cells.

Gene. 2024 Sep 06. pii: S0378-1119(24)00805-9. [Epub ahead of print]933 148924

Identification of subtelomeric cluster-genes associated to sexual stage in Toxoplasma gondii.

Laura Vanagas, Andres M Alonso, Sergio O Angel.

  Toxoplasma gondii is an obligate intracellular parasite with sexual reproduction in the intestinal epithelium of felines. The depletion of two gene repressors, AP2XI-2 and AP2XII-1, induces merozoite formation and gene expression towards sexual commitment. Based on RNA-seq datasets of AP2XI-2 and AP2XII-1 knock downs we identified subtelomeric (ST) TgB12 and hypothetical (HP) genes upregulated. Some of the differentially expressed genes (DEGs) are arranged in ST clusters. These DEG products are characterized by high isoelectric points (pI) and may encode small proteins. The potential roles of these clusters of DEG ST genes in environmental resistance or parasite sexual development of T. gondii is discussed.

Keywords:  Alkaline protein; Gene expression; Sexual development; Subtelomere; Toxoplasma

DOI:  https://doi.org/10.1016/j.gene.2024.148924
Animals (Basel). 2024 Sep 01. pii: 2543. [Epub ahead of print]14(17):

Functional Characterization of 11 Tentative Microneme Proteins in Type I RH Strain of Toxoplasma gondii Using the CRISPR-Cas9 System.

Zhi-Ya Ma, Xiao-Jing Wu, Chuan Li, Jin Gao, Yong-Jie Kou, Meng Wang, Xing-Quan Zhu, Xiao-Nan Zheng.

  Toxoplasma gondii, a pathogenic apicomplexan parasite, infects approximately one third of the world's population and poses a serious threat to global public health. Microneme proteins (MICs) secreted by the microneme, an apical secretory organelle of T. gondii, play important roles in the invasion, motility, and intracellular survival of T. gondii. In this study, we selected 11 genes of interest (GOIs) of T. gondii, tentative MICs predicted to be localized in micronemes, and we used the CRISPR-Cas9 system to construct epitope tagging strains and gene knockout strains to explore the localization and function of these 11 tentative MICs. Immunofluorescence assay showed that nine tentative MICs (TGME49_243930, TGME49_200270, TGME49_273320, TGME49_287040, TGME49_261710, TGME49_205680, TGME49_304490, TGME49_245485, and TGME49_224620) were localized or partially localized in the microneme, consistent with the prediction. However, TGME49_272380 and TGME49_243790 showed different localizations from the prediction, being localized in the endoplasmic reticulum and the dense granule, respectively. Further functional characterization of the 11 RHΔGOI strains revealed that deletion of these 11 GOIs had no significant effect on plaque formation, intracellular replication, egress, invasion ability, and virulence of T. gondii. Although these 11 GOIs are not essential genes for the growth and virulence of tachyzoites of type I RH strain, they may have potential roles in other developmental stages or other genotypes of T. gondii. Thus, further research should be performed to explore the possible role of the nine mics and the other two GOIs in other life cycle stages and other genotypes of T. gondii.

Keywords:  CRISPR-Cas9; Toxoplasma gondii; genes of interest (GOIs); microneme protein; toxoplasmosis

DOI:  https://doi.org/10.3390/ani14172543
PLoS Biol. 2024 Sep 10. 22(9): e3002791

PP1 phosphatase controls both daughter cell formation and amylopectin levels in Toxoplasma gondii.

Asma Sarah Khelifa, Maanasa Bhaskaran, Tom Boissavy, Thomas Mouveaux, Tatiana Araujo Silva, Cerina Chhuon, Marcia Attias, Ida Chiara Guerrera, Wanderley De Souza, David Dauvillee, Emmanuel Roger, Mathieu Gissot.

Virulence of apicomplexan parasites is based on their ability to divide rapidly to produce significant biomass. The regulation of their cell cycle is therefore key to their pathogenesis. Phosphorylation is a crucial posttranslational modification that regulates many aspects of the eukaryotic cell cycle. The phosphatase PP1 is known to play a major role in the phosphorylation balance in eukaryotes. We explored the role of TgPP1 during the cell cycle of the tachyzoite form of the apicomplexan parasite Toxoplasma gondii. Using a conditional mutant strain, we show that TgPP1 regulates many aspects of the cell cycle including the proper assembly of the daughter cells' inner membrane complex (IMC), the segregation of organelles, and nuclear division. Unexpectedly, depletion of TgPP1 also results in the accumulation of amylopectin, a storage polysaccharide that is usually found in the latent bradyzoite form of the parasite. Using transcriptomics and phospho-proteomics, we show that TgPP1 mainly acts through posttranslational mechanisms by dephosphorylating target proteins including IMC proteins. TgPP1 also dephosphorylates a protein bearing a starch-binding domain. Mutagenesis analysis reveals that the targeted phospho-sites are linked to the ability of the parasite to regulate amylopectin steady-state levels. Therefore, we show that TgPP1 has pleiotropic roles during the tachyzoite cell cycle regulation, but also regulates amylopectin accumulation.

DOI: https://doi.org/10.1371/journal.pbio.3002791
PLoS Biol. 2024 Sep 12. 22(9): e3002809

Alveolin proteins in the Toxoplasma inner membrane complex form a highly interconnected structure that maintains parasite shape and replication.

Peter S Back, Vignesh Senthilkumar, Charles P Choi, Justin J Quan, Qing Lou, Anne K Snyder, Andrew M Ly, Justin G Lau, Z Hong Zhou, 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 in Toxoplasma, IMC6. Disruption of IMC6 resulted in striking morphological defects that led to aberrant invasion and replication but surprisingly minor effects on motility. 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 2 other cytoskeletal IMC proteins-IMC3 and ILP1. This provides 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/10.1371/journal.pbio.3002809
PLoS Pathog. 2024 Sep 09. 20(9): e1012543

Trem2/Syk/PI3K axis contributes to the host protection against Toxoplasma gondii-induced adverse pregnancy outcomes via modulating decidual macrophages.

Qing Wang, Yining Cao, Songyi Ye, Maoyuan Ding, Wenliang Ge, Yuejin Liang, Jinling Chen.

Decidual macrophages residing at the maternal-fetal interface have been recognized as pivotal factors for maintaining normal pregnancy; however, they are also key target cells of Toxoplasma gondii (T. gondii) in the pathology of T. gondii-induced adverse pregnancy. Trem2, as a functional receptor on macrophage surface, recognizes and binds various kinds of pathogens. The role and underlying mechanism of Trem2 in T. gondii infection remain elusive. In the present study, we found that T. gondii infection downregulated Trem2 expression and that Trem2-/- mice exhibited more severe adverse pregnancy outcomes than wildtype mice. We also demonstrated that T. gondii infection resulted in increased decidual macrophages, which were significantly reduced in the Trem2-/- pregnant mouse model as compared to wildtype control animals. We further described the inhibited proliferation, migration, and invasion functions of trophoblast cell by T. gondii antigens through macrophages as an "intermediate bridge", while this inhibition can be rescued by Trem2 agonist HSP60. Concurrently, Trem2 deficiency in bone marrow-derived macrophages (BMDMs) heightened the inhibitory effect of TgAg on the migration and invasion of trophoblast cells, accompanied by higher pro-inflammatory factors (IL-1β, IL-6 and TNF-α) but a lower chemokine (CXCL1) in T. gondii antigens-treated BMDMs. Furthermore, compelling evidence from animal models and in vitro cell experiments suggests that T. gondii inhibits the Trem2-Syk-PI3K signaling pathway, leading to impaired function of decidual macrophages. Therefore, our findings highlight Trem2 signaling as an essential pathway by which decidual macrophages respond to T. gondii infection, suggesting Trem2 as a crucial sensor of decidual macrophages and potential therapeutic target in the pathology of T. gondii-induced adverse pregnancy.

DOI: https://doi.org/10.1371/journal.ppat.1012543
Planta. 2024 Sep 12. 260(4): 93

Advances in understanding the roles of plant HAT and HDAC in non-histone protein acetylation and deacetylation.

Zihan Zhang, Yan Zeng, Jiaqi Hou, Lijia Li.

  MAIN CONCLUSION: This review focuses on HATs and HDACs that modify non-histone proteins, summarizes functional mechanisms of non-histone acetylation as well as the roles of HATs and HDACs in rice and Arabidopsis. The growth and development of plants, as well as their responses to biotic and abiotic stresses, are governed by intricate gene and protein regulatory networks, in which epigenetic modifying enzymes play a crucial role. Histone lysine acetylation levels, modulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs), are well-studied in the realm of transcriptional regulation. However, the advent of advanced proteomics has unveiled that non-histone proteins also undergo acetylation, with its underlying mechanisms now being clarified. Indeed, non-histone acetylation influences protein functionality through diverse pathways, such as modulating protein stability, adjusting enzymatic activity, steering subcellular localization, influencing interactions with other post-translational modifications, and managing protein-protein and protein-DNA interactions. This review delves into the recent insights into the functional mechanisms of non-histone acetylation in plants. We also provide a summary of the roles of HATs and HDACs in rice and Arabidopsis, and explore their potential involvement in the regulation of non-histone proteins.

Keywords:  Acetylation; HAT; HDAC; Non-histone protein; Plant development; Post-translational modification

DOI:  https://doi.org/10.1007/s00425-024-04518-8
Cell Stem Cell. 2024 Sep 05. pii: S1934-5909(24)00289-3. [Epub ahead of print]31(9): 1241-1243

Acetate to the rescue: Acetyl-CoA facilitates placental development.

Joseph Festa, Sophie Trefely.

While the placenta regulates nutritional exchange between mother and fetus, Yu et al. reveal that human placental development is itself nutrient-sensitive. They elucidate entwined metabolic and epigenetic transitions driving syncytialization and pinpoint a requirement for the metabolite acetyl-CoA, which is sensitive to glucose metabolism.

DOI: https://doi.org/10.1016/j.stem.2024.08.003
J Infect Dis. 2024 Sep 10. 230(Supplement_2): S165-S172

Toxoplasma gondii Infection of Alzheimer's Disease Mice Reduces Brain Amyloid Density Globally and Regionally.

Katherine J O Yanes, Nathanial A Guanzon, Ricardo Azevedo, Damian G Wheeler, Sunil P Gandhi, Melissa B Lodoen.

  BACKGROUND: Toxoplasma gondii infection of Alzheimer's disease model mice decreases amyloid β plaques. We aimed to determine if there is a brain regional difference in amyloid β reduction in the brains of T. gondii-infected compared to control mice.METHOD: Three-month-old 5xFAD (AD model) mice were injected with T. gondii or with phosphate-buffered saline as a control. Intact brains were harvested at 6 weeks postinfection, optically cleared using iDISCO+, and brain-wide amyloid burden was visualized using volumetric light-sheet imaging. Amyloid signal was quantified across each brain and computationally mapped to the Allen Institute Brain Reference Atlas to determine amyloid density in each region.
RESULTS: A brain-wide analysis of amyloid in control and T. gondii-infected 5xFAD mice revealed that T. gondii infection decreased amyloid burden in the brain globally as well as in the cortex and hippocampus, and many daughter regions. Daughter regions that showed reduced amyloid burden included the prelimbic cortex, visual cortex, and retrosplenial cortex. The olfactory tubercle, a region known to have increased monocytes following T. gondii infection, also showed reduced amyloid after infection.
CONCLUSIONS: T. gondii infection of AD mice reduces amyloid burden in a brain region-specific manner that overlaps with known regions of T. gondii infection and peripheral immune cell infiltration.

Keywords:   Toxoplasma gondii ; 5xFAD; Alzheimer's disease; amyloid β; brain; iDISCO+; light-sheet imaging; neuroinfection

DOI:  https://doi.org/10.1093/infdis/jiae227
Results Probl Cell Differ. 2024 ;73 521-535

Subversion from Within and Without: Effector Molecule Transfer from Obligate Intracellular Apicomplexan Parasites to Human Host Cells.

Ramakrishnan Sitaraman.

  Intracellular protozoan pathogens have to negotiate the internal environment of the host cell they find themselves in, as well as manipulate the host cell to ensure their own survival, replication, and dissemination. The transfer of key effector molecules from the pathogen to the host cell is crucial to this interaction and is technically more demanding to study as compared to an extracellular pathogen. While several effector molecules have been identified, the mechanisms and conditions underlying their transfer to the host cell remain partly or entirely unknown. Improvements in experimental systems have revealed tantalizing details of such intercellular transfer, which form the subject of this chapter.

Keywords:  Extracellular vesicles; Host-pathogen interaction; Maurer’s clefts; Microneme; Neglected tropical diseases; Parasitophorous vacuole; Rhoptry; Translocon

DOI:  https://doi.org/10.1007/978-3-031-62036-2_20
Front Immunol. 2024 ;15 1452828

Inflammatory response and parasite regulation in acute toxoplasmosis: the role of P2X7 receptor in controlling virulent atypical genotype strain of Toxoplasma gondii.

Thuany Prado-Rangel, Aline Cristina Abreu Moreira-Souza, Sthefani Rodrigues Batista da Silva, Thais Barboza-Araujo, Archimedes Barbosa Castro-Junior, Isalira Peroba Rezende Ramos, Christina Maeda Takiya, Rossiane Claudia Vommaro, Robson Coutinho-Silva.

  Toxoplasmosis is a globally significant disease that poses a severe threat to immunocompromised individuals, especially in Brazil, where a high prevalence of virulent and atypical strains of Toxoplasma gondii is observed. In 1998, the EGS strain, exhibiting a unique infection phenotype, was isolated in Brazil, adding to the complexity of strain diversity. The P2X7 receptor is critical in inflammation and controlling intracellular microorganisms such as T. gondii. However, its genetic variability can result in receptor dysfunction, potentially worsening susceptibility. This study investigates the role of the P2X7 receptor during acute infection induced by the EGS atypical strain, offering insight into the mechanisms of T. gondii infection in this context. We infected the female C57BL/6 (WT) or P2X7 knockout (P2X7-/-) by gavage. The EGS infection causes intestinal inflammation. The P2X7-/- mice presented higher parasite load in the intestine, spleen, and liver. The absence of the P2X7 receptor disrupts inflammatory cell balance by reducing NLRP3, IL-1β, and Foxp3 expression while increasing IFN-γ expression and production in the intestine. In the liver, P2X7-/- animals demonstrate diminished inflammatory infiltrate within the portal and lobular regions concurrent with an enlargement of the spleen. In conclusion, the infection of mice with the EGS strain elicited immune alterations, leading to acute inflammation and cytokine dysregulation, while the P2X7 receptor conferred protection against parasitic proliferation across multiple organs.

Keywords:  Brazilian strain; EGS strain; inflammation; parasite control; purinergic signaling; toxoplasmosis

DOI:  https://doi.org/10.3389/fimmu.2024.1452828
Am J Physiol Heart Circ Physiol. 2024 Sep 13.

The dual-edged role of SIRT1 in energy metabolism and cardiovascular disease.

Redemptor Zhou, Kaleb Barnes, Savannah Gibson, Natasha Fillmore.

  Regulation of energy metabolism is pivotal in the development of cardiovascular diseases. Dysregulation in mitochondrial fatty acid oxidation (FAO) has been linked to cardiac lipid accumulation and diabetic cardiomyopathy. Sirtuin 1 (SIRT1) is a deacetylase that regulates the acetylation of various proteins involved in mitochondrial energy metabolism. SIRT1 mediates energy metabolism by directly and indirectly affecting multiple aspects of mitochondrial processes, such as mitochondrial biogenesis. SIRT1 interacts with essential mitochondrial energy regulators such as Peroxisome Proliferator-Activated Receptor α (PPARα), PPARgcoactivator-1 (PGC1α), Estrogen-Related Receptor α (ERRα), and their downstream targets. Apart from that, SIRT1 regulates additional proteins, including Forkhead Box Protein O1 (FOXO1) and AMP-Activated Protein Kinase (AMPK) in cardiac disease. Interestingly, studies have also shown that the expression of SIRT1 plays a dual-edged role in energy metabolism. Depending on the physiological state, SIRT1 expression can be detrimental or protective. This review focuses on the molecular pathways through which SIRT1 regulates energy metabolism in cardiovascular diseases. We will review SIRT1 and discuss its role in cardiac energy metabolism and its benefits and detrimental effects in heart disease.

Keywords:  PPARα; SIRT1; cardiovascular disease; energy metabolism

DOI:  https://doi.org/10.1152/ajpheart.00001.2024
Int J Mol Sci. 2024 Aug 26. pii: 9239. [Epub ahead of print]25(17):

Plasmodium falciparum Mitochondrial Complex III, the Target of Atovaquone, Is Essential for Progression to the Transmissible Sexual Stages.

Pradeep Kumar Sheokand, Sabyasachi Pradhan, Andrew E Maclean, Alexander Mühleip, Lilach Sheiner.

  The Plasmodium falciparum mitochondrial electron transport chain (mETC) is responsible for essential metabolic pathways such as de novo pyrimidine synthesis and ATP synthesis. The mETC complex III (cytochrome bc1 complex) is responsible for transferring electrons from ubiquinol to cytochrome c and generating a proton gradient across the inner mitochondrial membrane, which is necessary for the function of ATP synthase. Recent studies have revealed that the composition of Plasmodium falciparum complex III (PfCIII) is divergent from humans, highlighting its suitability as a target for specific inhibition. Indeed, PfCIII is the target of the clinically used anti-malarial atovaquone and of several inhibitors undergoing pre-clinical trials, yet its role in parasite biology has not been thoroughly studied. We provide evidence that the universally conserved subunit, PfRieske, and the new parasite subunit, PfC3AP2, are part of PfCIII, with the latter providing support for the prediction of its divergent composition. Using inducible depletion, we show that PfRieske, and therefore, PfCIII as a whole, is essential for asexual blood stage parasite survival, in line with previous observations. We further found that depletion of PfRieske results in gametocyte maturation defects. These phenotypes are linked to defects in mitochondrial functions upon PfRieske depletion, including increased sensitivity to mETC inhibitors in asexual stages and decreased cristae abundance alongside abnormal mitochondrial morphology in gametocytes. This is the first study that explores the direct role of the PfCIII in gametogenesis via genetic disruption, paving the way for a better understanding of the role of mETC in the complex life cycle of these important parasites and providing further support for the focus of antimalarial drug development on this pathway.

Keywords:  Plasmodium; Rieske; complex III; gametocytes; mETC; mitochondrion

DOI:  https://doi.org/10.3390/ijms25179239
New J Chem. 2024 Sep 10.

Synthesis of ferrocenyl benzimidazole derivatives as novel anti-Toxoplasma gondii agents.

Malcolm T Ndlovu, Clare R Harding, Catherine H Kaschula, Prinessa Chellan.

Toxoplasmosis, a disease caused by the apicomplexan parasite Toxoplasma gondii, affects up to one third of the global population. Although immunocompetent individuals rarely experience severe symptoms, those with immunodeficiencies may potentially face fatal disease. The frontline treatments are currently sulphadiazine and pyrimethamine, which suffer from adverse side effects, and lack efficiency in clearing parasite cysts from the muscles and brain of patients. To address the need for novel, more effective, and less toxic treatments, four new ferrocenyl benzimidazole complexes 15-18 were synthesised and evaluated against the ΔKu80:mNeonGreen strain of T. gondii. Complexes 15 and 17 were found to be active with EC50 values of 17.9 and 17.5 μM respectively, with comparable activity to pyrimethamine, which had an EC50 value of 13.8 μM, and less effective than sulphadiazine, which had an EC50 value of 2.56 μM. Additionally, the compounds were found to be relatively non-toxic against HEK 293T and PNT1A human cell lines. Further investigations found that the complexes act by generating reactive oxygen species (ROS) through the ferrocenyl moiety. These complexes show potential for the development of new treatments against Toxoplasmosis.

DOI: https://doi.org/10.1039/d3nj05116a
Biochemistry. 2024 Sep 10.

Inhibition of Sirtuin Deacylase Activity by Peroxynitrite.

Kelsey Bohl, Sarah L Wynia-Smith, Rachel A Jones Lipinski, Brian C Smith.

Sirtuins are a class of enzymes that deacylate protein lysine residues using NAD+ as a cosubstrate. Sirtuin deacylase activity has been historically regarded as protective; loss of sirtuin deacylase activity potentially increases susceptibility to aging-related disease development. However, which factors may inhibit sirtuins during aging or disease is largely unknown. Increased oxidant and inflammatory byproduct production damages cellular proteins. Previously, we and others found that sirtuin deacylase activity is inhibited by the nitric oxide (NO)-derived cysteine post-translational modification S-nitrosation. However, the comparative ability of the NO-derived oxidant peroxynitrite (ONOO-) to affect human sirtuin activity had not yet been assessed under uniform conditions. Here, we compare the ability of ONOO- (donated from SIN-1) to post-translationally modify and inhibit SIRT1, SIRT2, SIRT3, SIRT5, and SIRT6 deacylase activity. In response to SIN-1 treatment, inhibition of SIRT1, SIRT2, SIRT3, SIRT5, and SIRT6 deacylase activity correlated with increased tyrosine nitration. Mass spectrometry identified multiple novel tyrosine nitration sites in SIRT1, SIRT3, SIRT5, and SIRT6. As each sirtuin isoform has at least one tyrosine nitration site within the catalytic core, nitration may result in sirtuin inhibition. ONOO- can also react with cysteine residues, resulting in sulfenylation; however, only SIRT1 showed detectable peroxynitrite-mediated cysteine sulfenylation. While SIRT2, SIRT3, SIRT5, and SIRT6 showed no detectable sulfenylation, SIRT6 likely undergoes transient sulfenylation, quickly resolving into an intermolecular disulfide bond. These results suggest that the aging-related oxidant peroxynitrite can post-translationally modify and inhibit sirtuins, contributing to susceptibility to aging-related disease.

DOI: https://doi.org/10.1021/acs.biochem.4c00257
Crit Rev Biotechnol. 2024 Sep 12. 1-19

Advances in metabolic engineering for enhanced acetyl-CoA availability in yeast.

Yuanyuan Sha, Mianshen Ge, Minrui Lu, Zhaoxian Xu, Rui Zhai, Mingjie Jin.

  Acetyl-CoA is an intermediate metabolite in cellular central metabolism. It's a precursor for various valuable commercial products, including: terpenoids, fatty acids, and polyketides. With the advancement of metabolic and synthetic biology tools, microbial cell factories have been constructed for the efficient synthesis of acetyl-CoA and derivatives, with the Saccharomyces cerevisiae and Yarrowia lipolytica as two prominent chassis. This review summarized the recent developments in the biosynthetic pathways and metabolic engineering approaches for acetyl-CoA and its derivatives synthesis in these two yeasts. First, the metabolic routes involved in the biosynthesis of acetyl-CoA and derived products were outlined. Then, the advancements in metabolic engineering strategies for channeling acetyl-CoA toward the desired products were summarized, with particular emphasis on: enhancing metabolic flux in different organelles, refining precursor CoA synthesis, optimizing substrate utilization, and modifying protein acetylation level. Finally, future developments in advancing the metabolic engineering strategies for acetyl-CoA and related derivatives synthesis, including: reducing CO2 emissions, dynamically regulating metabolic pathways, and exploring the regulatory functions between acetyl-CoA levels and protein acetylation, are highlighted. This review provided new insights into regulating acetyl-CoA synthesis to create more effective microbial cell factories for bio-manufacturing.

Keywords:  Acetyl-CoA; acetyl-CoA derivatives; metabolic engineering; protein acetylation; synthetic pathway; yeast

DOI:  https://doi.org/10.1080/07388551.2024.2399542
Elife. 2024 Sep 13. pii: e102355. [Epub ahead of print]13

Lock out SIRT4.

Kaiqiang Zhao, Zhongjun Zhou.

  The accumulation of SIRT4 in the nuclei of kidney cells drives kidney fibrosis, so blocking the movement of this protein could be a potential therapeutic strategy against fibrosis.

Keywords:  CCN2; TGF-β1; cell biology; kidney fibrosis; mouse; nuclear translocation; sirtuin 4; splicing

DOI:  https://doi.org/10.7554/eLife.102355
Sci Rep. 2024 09 11. 14(1): 21201

The study on the role of O-GlcNAcylation of SIRT3 in regulating mitochondrial oxidative stress during simulate myocardial ischemia-reperfusion.

Han Zhou, Yingjie Ji, Jingjie Li, Lin Sun.

  Myocardial ischemia-reperfusion injury (MIRI) is a significant complication following reperfusion therapy after myocardial infarction. Mitochondrial oxidative stress is a critical factor in MIRI, and Sirtuin 3 (SIRT3), as a major mitochondrial deacetylase, plays a key protective role, with its activity potentially regulated by O-GlcNAcylation. This study used the H9C2 cell line to establish a simulated ischemia/reperfusion (SI/R) model, we utilized co-immunoprecipitated to validate the relationship between O-GlcNAc transferase (OGT) and SIRT3, demonstrated SIRT3 O-GlcNAcylation sites through LC-MS/MS, and performed site mutations using CRISPR/Cas9 technology. The results were validated using immunoblotting. SIRT3 and superoxide dismutase 2 (SOD2) activities were detected using a fluorometric assay, while mitochondrial reactive oxygen species (MROS) levels and cellular apoptosis were assessed using immunofluorescence. We have identified an interaction between SIRT3 and OGT, where SIRT3 undergoes dynamic O-GlcNAcylation at the S190 site, facilitating SIRT3 deacetylase activity. During SI/R, elevated levels of O-GlcNAcylation activate SOD2 by promoting SIRT3 enzyme activity, thereby inhibiting excessive MROS production. This significantly mitigates the occurrence of malignant autophagy in myocardial cells during reperfusion, promoting their survival. Conversely, blocking SIRT3 O-GlcNAcylation at the S190 site exacerbates SI/R injury. We demonstrate that O-GlcNAcylation is a crucial post-translational modification (PTM) of SIRT3 during SI/R, shedding light on a promising mechanism for future therapeutic approaches.

Keywords:  O-GlcNAcylation; SI/R; SIRT3

DOI:  https://doi.org/10.1038/s41598-024-72324-z
Int J Biol Macromol. 2024 Sep 06. pii: S0141-8130(24)06208-1. [Epub ahead of print]279(Pt 3): 135400

Biochemical and biophysical characterization of Leishmania donovani citrate synthase.

Preeti Ranjan, Manash Sarma, Vikash Kumar Dubey.

  Citrate synthase is a crucial enzyme in the TCA cycle and represents a potential therapeutic target. However, knowledge about this enzyme in Leishmania parasites remains limited. In this study, we have successfully cloned, expressed, and purified citrate synthase from Leishmania donovani (LdCS) using a bacterial system, and characterized it through various biophysical and biochemical methods. Circular dichroism analysis at physiological pH indicates that LdCS is properly folded. Further investigation into its tertiary structure using a quencher reveals that most tryptophan residues are located within the protein's hydrophobic core. Biochemical assays show that the recombinant enzyme is catalytically active, with optimal activity at pH 7.0. Kinetic studies provided parameters such as Km and Vmax. Enzyme inhibition assays revealed that LdCS activity is competitively inhibited by FDA-approved compounds-Abemaciclib, Bazedoxifene, Vorapaxar, and Imatinib-with Ki values ranging from 2 to 3 μM, demonstrating significant binding affinity. This research paves the way for exploring LdCS as a potential drug target for treating leishmaniasis.

Keywords:  Biochemistry; Citrate synthase; Drug discovery; Leishmaniasis

DOI:  https://doi.org/10.1016/j.ijbiomac.2024.135400
Cancer Lett. 2024 Sep 11. pii: S0304-3835(24)00637-2. [Epub ahead of print] 217242

Rewired glutamate metabolism diminishes cytostatic action of L-asparaginase.

Katerina Hlozkova, Maryna Vasylkivska, Adam Boufersaoui, Bryan Marzullo, Matus Kolarik, Natividad Alquezar-Artieda, Mehak Shaikh, Fatemeh Alaei Faradonbeh, Marketa Zaliova, Martina Zwyrtkova, Violeta Bakardijeva-Mihaylova, Meritxell Alberich-Jorda, Jan Trka, Daniel A Tennant, Julia Starkova.

Tumor cells often adapt to amino acid deprivation through metabolic rewiring, compensating for the loss with alternative amino acids/substrates. We have described such a scenario in leukemic cells treated with L-asparaginase (ASNase). Clinical effect of ASNase is based on nutrient stress achieved by its dual enzymatic action which leads to depletion of asparagine and glutamine and is accompanied with elevated aspartate and glutamate concentrations in serum of acute lymphoblastic leukemia patients. We showed that in these limited conditions glutamate uptake compensates for the loss of glutamine availability. Extracellular glutamate flux detection confirms its integration into the TCA cycle and its participation in nucleotide and glutathione synthesis. Importantly, it is glutamate-driven de novo synthesis of glutathione which is the essential metabolic pathway necessary for glutamate's pro-survival effect. In vivo findings support this effect by showing that inhibition of glutamate transporters enhances the therapeutic effect of ASNase. In summary, ASNase induces elevated extracellular glutamate levels under nutrient stress, which leads to a rewiring of intracellular glutamate metabolism and has a negative impact on ASNase treatment.

DOI: https://doi.org/10.1016/j.canlet.2024.217242
Cell Signal. 2024 Sep 06. pii: S0898-6568(24)00354-1. [Epub ahead of print]124 111386

HDAC5 deacetylates c-Myc and facilitates cell cycle progression in hepatocellular carcinoma cells.

Min Lin, Weihua Zhou, Yizhang Wang, Jiangwei Ye, TingJia Jiang, Shanshan Han, Fengjiao Zhu, Ming Ye, Zejun Fang.

  Histone deacetylase 5 (HDAC5) is an enzyme that deacetylates lysine residues on the N-terminal of histones and other proteins. It has been reported that HDAC5 deacetylates p53, the critical factor regulating cell cycle, in response to cellular stress, but the transcriptional products haven't been identified. Herein, we used p53 signaling pathway qPCR-chip to determine how HDAC5-mediated deacetylation of p53 affects cell cycle. However, validation using immunoblotting analysis revealed that acetylation of p53 at K120 impacted little to the expression of the genes identified using the qPCR-chip, indicating HDAC5 might deacetylate some other proteins to facilitate cell cycle via transactivating the differentially expressed genes determined by the qPCR-chip. The subsequent assays demonstrated that HDAC5 deacetylated c-Myc at K143 and K157 to facilitate the transactivation of CDK1, CDK4, and CDC25C, promoting cell cycle progression of hepatocellular carcinoma (HCC). This study shows that HDAC5 plays important roles in modulating deacetylation of c-Myc and regulating cell cycle progression, and it proves that LMK-235, the inhibitor targeting HDAC5 potentially serves as a drug for combating HCC via promoting acetylation of c-Myc at K143 and K157.

Keywords:  C-Myc; Cell cycle; HDAC5; Hepatocellular carcinoma

DOI:  https://doi.org/10.1016/j.cellsig.2024.111386