Biological and Catalytic Properties of Selenoproteins

deep-Sep: a deep learning-based method for fast and accurate prediction of selenoprotein genes in bacteria

Selenoproteins are a special group of proteins with major roles in cellular antioxidant defense. They contain the 21st amino acid selenocysteine (Sec) in the active sites, which is encoded by an in-frame UGA codon. Compared to eukaryotes, identification of selenoprotein genes in bacteria remains challenging due to the absence of an effective strategy for distinguishing the Sec-encoding UGA codon from a normal stop signal. In this study, we have developed a deep learning-based algorithm, deep-Sep, for quickly and precisely identifying selenoprotein genes in bacterial genomic sequences. This algorithm uses a Transformer-based neural network architecture to construct an optimal model for detecting Sec-encoding UGA codons and a homology search-based strategy to remove additional false positives. During the training and testing stages, deep-Sep has demonstrated commendable performance, including an F1 score of 0.939 and an area under the receiver operating characteristic curve of 0.987. Furthermore, when applied to 20 bacterial genomes as independent test data sets, deep-Sep exhibited remarkable capability in identifying both known and new selenoprotein genes, which significantly outperforms the existing state-of-the-art method. Our algorithm has proved to be a powerful tool for comprehensively characterizing selenoprotein genes in bacterial genomes, which should not only assist in accurate annotation of selenoprotein genes in genome sequencing projects but also provide new insights for a deeper understanding of the roles of selenium in bacteria.IMPORTANCESelenium is an essential micronutrient present in selenoproteins in the form of Sec, which is a rare amino acid encoded by the opal stop codon UGA. Identification of all selenoproteins is of vital importance for investigating the functions of selenium in nature. Previous strategies for predicting selenoprotein genes mainly relied on the identification of a special cis-acting Sec insertion sequence (SECIS) element within mRNAs. However, due to the complexity and variability of SECIS elements, recognition of all selenoprotein genes in bacteria is still a major challenge in the annotation of bacterial genomes. We have developed a deep learning-based algorithm to predict selenoprotein genes in bacterial genomic sequences, which demonstrates superior performance compared to currently available methods. This algorithm can be utilized in either web-based or local (standalone) modes, serving as a promising tool for identifying the complete set of selenoprotein genes in bacteria.

Novel selenoprotein neighborhoods suggest specialized biochemical processes

Prokaryotic genomes encode selenoproteins sparsely, roughly one protein per 5,000. Finding novel selenoprotein families can expose unknown biological processes that are enabled, or at least enhanced, by having a selenium atom replace a sulfur atom in some cysteine residues. Here, we report the discovery of 18 novel selenoprotein families or second selenocysteine sites in previously unrecognized extensions of protein translations. Most of these families had some confounding factors-too small a family, too few selenoproteins in the family, selenocysteine (U) too close to one end, a skew toward understudied or uncultured lineages, and consequently were missed previously. Discoveries were triggered by observations during the ongoing construction of protein family models for the National Center for Biotechnology Information's RefSeq and Prokaryotic Gene Annotation Pipeline or made by targeted searches for novel selenoproteins in the vicinity of known ones, rather than by any broadly applied genome mining method. Unrelated families TsoA, TsoB, TsoC, and TsoX are adjacent in tso (three selenoprotein operon) loci in the bacterial phylum Thermodesulfobacteriota. TrsS (third radical SAM selenoprotein) occurs strictly in the context of a molybdopterin-dependent aldehyde oxidoreductase. A short carboxy-terminal motif, U-X-X-stop (UXX-star), occurs in selenoproteins with various architectures, usually providing the second U in the protein. The multiple new selenocysteine insertion sites, selenoprotein families, and selenium-dependent operons we curated manually suggest that many more proteins and pathways remain to be discovered; once improved computational methods are applied comprehensively to the latest collections of microbial genomes and metagenomes, they may reveal surprising new biochemical processes.

IMPORTANCE

Next-generation DNA sequencing and assembly of metagenome-assembled genomes (MAGs) for uncultured species of various microbiomes adds a vast "dark matter" of hard-to-decipher protein sequences. Selenoproteins, optimized by natural selection to encode selenocysteine where cysteine might have been encoded much more easily, carry a strong clue to their function-some specialized aspect of binding or catalysis. Operons with multiple adjacent, but otherwise unrelated, selenoproteins should provide even more vivid information. In this study, efforts in protein family construction and curation, aimed at improving the PGAP genome annotation pipeline, generated multiple novel selenoprotein-containing genomic contexts that may lead to the future characterization of several systems of proteins. Past observations suggest roles in the metabolic handling of trace elements (mercury, tungsten, arsenic, etc.) or of organic compounds refractory to simpler enzymatic pathways. In addition, the work significantly expands the truth set of validated selenoproteins, which should aid future, more automated genome mining efforts.

Selenium-containing compounds, selenium nanoparticles and selenoproteins in the prevention and treatment of lung cancer

THE OBJECTIVE

Is to review the latest data on the role of key organic and inorganic compounds of the essential trace element selenium, selenium-containing nanocomposites and nanoparticles, and selenoproteins in lung cancer therapy.

OBJECT OF RESEARCH

Sodium selenite, methylselenic acid, selenomethionine, selenium nanoparticles, mammalian selenoproteins KEY OBJECTIVES:: To describe the molecular mechanisms of the cytotoxic effect of sodium selenite, methylselenic acid and selenomethionine on lung cancer cells, to discuss the latest advances in lung cancer nanomedicine using selenium-based nanoparticles and nanocomposites and to assess the prospects for creating antitumor drugs based on them, to assess the role of selenoproteins in the progression or inhibition of lung cancer and to study the molecular mechanisms of such regulation CONCLUSIONS:: This review provides a complete picture of the role of selenium and selenium-containing agents of various natures in the regulation of carcinogenesis and therapy of lung cancer, which significantly complements the fundamental data on the functions of these compounds, on the molecular mechanisms of regulation of processes associated with lung cancer. This knowledge provides insight into the latest developments and future prospects in the treatment and prevention of lung cancer with the active participation of the trace element selenium.

The Promising Role of Selenium and Yeast in the Fight Against Protein Amyloidosis

In recent years, increasing attention has been paid to research on diseases related to the deposition of misfolded proteins (amyloids) in various organs. Moreover, modern scientists emphasise the importance of selenium as a bioelement necessary for the proper functioning of living organisms. The inorganic form of selenium-sodium selenite (redox-active)-can prevent the formation of an insoluble polymer in proteins. It is very important to undertake tasks aimed at understanding the mechanisms of action of this element in inhibiting the formation of various types of amyloid. Furthermore, yeast cells play an important role in this matter as a eukaryotic model organism, which is intensively used in molecular research on protein amyloidosis. Due to the lack of appropriate treatment in the general population, the problem of amyloidosis remains unsolved. This extracellular accumulation of amyloid is one of the main factors responsible for the occurrence of Alzheimer's disease. The review presented here contains scientific information discussing a brief description of the possibility of amyloid formation in cells and the use of selenium as a factor preventing the formation of these protein aggregates. Recent studies have shown that the yeast model can be successfully used as a eukaryotic organism in biotechnological research aimed at understanding the essence of the entire amyloidosis process. Understanding the mechanisms that regulate the reaction of yeast to selenium and the phenomenon of amyloidosis is important in the aetiology and pathogenesis of various disease states. Therefore, it is imperative to conduct further research and analysis aimed at explaining and confirming the role of selenium in the processes of protein misfolding disorders. The rest of the article discusses the characteristics of food protein amyloidosis and their use in the food industry. During such tests, their toxicity is checked because not all food proteins can produce amyloid that is toxic to cells. It should also be noted that a moderate diet is beneficial for the corresponding disease relief caused by amyloidosis.

Genetically Elevated Selenoprotein S Levels and Risk of Stroke: A Two-Sample Mendelian Randomization Analysis

Selenoprotein S (SELENOS), one of the carrier proteins of dietary selenium (Se), is a key regulator of inflammation, oxidative stress, and endoplasmic reticulum (ER) stress, all of which are implicated in the pathogenesis of stroke. However, the causality between SELENOS and stroke risk remains poorly understood. This study aimed to explore the association between genetically determined plasma SELENOS levels and the risk of all-cause stroke, ischemic stroke, and intracerebral hemorrhage (ICH) using a two-sample Mendelian randomization (MR) approach. We analyzed data from three large-scale Genome-Wide Association Study (GWAS) meta-analyses of individuals of European descent. The fixed-effect inverse-variance weighted (IVW) model analysis revealed that genetically elevated SELENOS levels were associated with an increased risk of all-cause stroke, ischemic stroke, and ICH. Sensitivity analyses showed no evidence of pleiotropy or heterogeneity, and leave-one-out analyses confirmed the robustness of our results. Here, we show that elevated plasma SELENOS levels are causally linked to increased stroke risk. Although the effect sizes were modest, these findings suggest SELENOS may play a role in stroke pathogenesis, emphasizing the need for further mechanistic and functional studies. Finally, our findings shed light on the importance of tailored Se intake management in the context of stroke prevention.

New magnetic iron nanoparticle doped with selenium nanoparticles and the mechanisms of their cytoprotective effect on cortical cells under ischemia-like conditions

Ischemic stroke is the cause of high mortality and disability Worldwide. The material costs of stroke treatment and recovery are constantly increasing, making the search for effective and more cost-effective treatment approaches an urgent task for modern biomedicine. In this study, iron nanoparticles doped with selenium nanoparticles, FeNP@SeNPs, which are three-layered structures, were created and characterized using physical methods. Fluorescence microscopy, inhibitor and PCR analyzes were used to determine the signaling pathways involved in the activation of the Ca2+ signaling system of cortical astrocytes and the protection of cells from ischemia-like conditions (oxygen-glucose deprivation and reoxygenation). In particular, when using magnetic selenium nanoparticles together with electromagnetic stimulation, an additional pathway for nanoparticle penetration into the cell is activated through the activation of TRPV4 channels and the mechanism of their endocytosis is facilitated. It has been shown that the use of magnetic selenium nanoparticles together with magnetic stimulation represents an advantage over the use of classical selenium nanoparticles, as the effective concentration of nanoparticles can be reduced many times over.

Selenium and Selenoproteins: Mechanisms, Health Functions, and Emerging Applications

Selenium (Se) is an essential trace element crucial for human health that primarily functions as an immunonutrient. It is incorporated into polypeptides such as selenocysteine (SeC) and selenomethionine (SeMet), two key amino acids involved in various biochemical processes. All living organisms can convert inorganic Se into biologically active organic forms, with SeMet being the predominant form and a precursor for SeC production in humans and animals. The human genome encodes 25 selenoprotein genes, which incorporate low-molecular-weight Se compounds in the form of SeC. Organic Se, especially in the form of selenoproteins, is more efficiently absorbed than inorganic Se, driving the demand for selenoprotein-based health products, such as functional foods. Se-enriched functional foods offer a practical means of delivering bioavailable Se and are associated with enhanced antioxidant properties and various health benefits. Recent advancements in selenoprotein synthesis have improved our understanding of their roles in antioxidant defense, cancer prevention, immune regulation, anti-inflammation, hypoglycemia, cardiovascular health, Alzheimer's disease, fertility, and COVID-19. This review highlights key selenoproteins and their biological functions, biosynthetic pathways, and emerging applications while highlighting the need for further research.

Synthesis of 5-Seleno-Substituted Spirocyclopenta[b]pyridine-2,5-dien-4-ones and Benzo[h]quinolines via Radical Cyclization of Arylethynylpyridines

A practical strategy for obtaining novel 5-seleno-substituted spirocyclopenta[b]pyridines-2,5-dien-4-ones and benzo[h]quinolines via radical cyclization is reported. The synthetic protocol explores the reaction between arylethynylpyridines and diorganyl diselenides in acetonitrile as solvent and Oxone® as oxidant at 82 °C. This easy-to-handle, eco-friendly metal-free approach was carried out under an open atmosphere, affording functionalized organoselenium compounds in good to excellent yields. Control experiments and scale-up test were performed to demonstrate the efficiency of this methodology.

Design, synthesis and biological evaluation of artesunate-Se derivatives as anticancer agents by inducing GPX4-mediated ferroptosis

A series of organoselenium compounds based on the hybridization of artesunate (ART) scaffolds and Se functionalities (-SeCN and -SeCF3) were synthesized. The redox properties of artesunate-SeCN and artesunate-SeCF3 derivatives were conducted by 2, 2-didiphenyl-1-picrylhydrazyl (DPPH), and the results showed that compounds 2c, 2f and 3e have a good free radical scavenging activity. Their cytotoxicity was evaluated against four types of cancer cell lines, SW480 (human colon adenocarcinoma cells), HCT116 (human colorectal adenocarcinoma cells), HepG2 (human hepatocellular carcinoma cells), MCF-7 (human breast cancer cells). The MTT results showed that compared with ART and 5-FU, compound 2c exhibited potent in vitro antiproliferative activity in SW480, HCT116, and MCF-7 cancer cell lines, and was thus chose for further antitumor mechanism investigation. The antitumor mechanism study revealed that compound 2c induced ferroptosis in HCT116 cells by inhibiting the expression of GPX4 protein, accompanying by the up-regulation of intracellular ROS levels. Mitochondria in HCT116 cells exhibit depolarization of mitochondrial membrane potential (MMP) and ultrastructural changes in morphology, which indicated that 2c resulted in mitochondrial dysfunction and ferroptosis. Moreover, 2c could increase the levels of lipid peroxidation and ferrous ion, which further confirm that compound 2c may exert its antitumor effect through ferroptosis. Overall, these results suggest that the artesunate-Se candidates could provide promising new lead derivatives for further potential anticancer drug development.

Extracellular vesicles and citrullination signatures are novel biomarkers in sturgeon (Acipenser gueldenstaedtii) during chronic stress due to seasonal temperature challenge

Acipenser gueldenstaedtii is one of the most cultured sturgeon species worldwide and of considerable economic value for caviar production. There are though considerable challenges around chronic stress responses due to increased summer temperatures, impacting sturgeons' immune responses and their susceptibility to opportunistic infections. The identification of molecular and cellular pathways involved in stress responses may contribute to identifying novel biomarkers reflective of fish health status, crucial for successful sturgeon aquaculture. Protein citrullination is a calcium-catalysed post-translational modification caused by peptidylarginine deiminases (PADs), altering target protein function and affecting protein interactions in physiological and pathobiological processes. PADs can also modulate extracellular vesicle (EVs) profiles, which play critical roles in cellular communication, via transport of their cargoes (proteins, including post-translationally modified proteins, genetic material and micro-RNAs). This study identified differences in EV signatures, and citrullinated proteins in sera from winter and summer farmed sturegeons. EVs were significantly elevated in sera of the summer chronically stressed group. The citrullinated proteins and associated gene ontology (GO) pathways in sera and serum-EVs of chronically heat stressed A. gueldenstaedtii, showed some changes, with specific citrullinated serum protein targets including alpa-2-macroglobulin, alpha globin, calcium-dependent secretion activator, ceruloplasmin, chemokine XC receptor, complement C3 isoforms, complement C9, plectin, selenoprotein and vitellogenin. In serum-EVs, citrullinated protein cargoes identified only in the chronically stressed summer group included alpha-1-antiproteinase, apolipoprotein B-100, microtubule actin crosslinking factor and histone H3. Biological gene ontology (GO) pathways related to citrullinated serum proteins in the chronically stressed group were associated with innate and adaptive immune responses, stress responses and metabolic processes. In serum-EVs of the heat-stressed group the citrullinome associated with various metabolic GO pathways. In addition to modified citrullinated protein content, Serum-EVs from the stressed summer group showed significantly increased levels of the inflammatory associated miR-155 and the hypoxia-associated miR-210, but significantly reduced levels of the growth-associated miR-206. Our findings highlight roles for protein citrullination and EV signatures in response to chronic heat stress in A. gueldenstaedtii, indicating a trade-off in immunity versus growth and may be of value for sturgeon aquaculture.

Increased Expression of PHGDH Under High-Selenium Stress In Vivo

The purpose of this study is to explore the glycolytic remodeling under high-selenium (Se) stress. Three groups of male C57BL/6J mice were fed on diets with different Se contents (0.03, 0.15, and 0.30 mg Se/kg). Glucose tolerance test (GTT) and insulin tolerance test (ITT) were measured at the third month. Mice were killed at the fourth month. Plasma, liver, and muscle tissues were fetched for biochemistry and Se analysis. The expressions of insulin signaling pathway (PI3K-AKT-mTOR), glutathione peroxidase 1 (GPX1), selenoprotein N (SELENON), 3-phosphoglycerate dehydrogenase (PHGDH), serine hydroxymethyltransferases 1 (SHMT1), 5,10-methylenetetrahydrofolate reductase (MTHFR), and methionine synthase (MS) were analyzed by western blotting (WB) in liver and muscle tissues. The results of GTT and ITT showed that glucose tolerance and insulin tolerance were both abnormal in the 0.03 mg Se/kg and 0.3 mg Se/kg groups. Se concentrations in plasma, liver, and muscle of 0.03 mg Se/kg group were significantly lower than that of 0.15 mg Se/kg and 0.30 mg Se/kg groups (p < 0.05 or p < 0.01). The expressions of P-Akt (Thr-308) in muscle (p < 0.05) and PI3K and mTOR in liver (p < 0.001) of 0.30 mg Se/kg group were downregulated. The expressions of GPX1 in liver and muscle (p < 0.05 and p < 0.001), SELENON in muscle (p < 0.05), PHGDH in liver and muscle (p < 0.05), and SHMT1 (p < 0.05), MTHFR (p < 0.001), and MS (p < 0.001) in muscle of 0.3 mg Se/kg group were upregulated. The de novo serine synthesis pathway (SSP) was found to be activated in liver and muscle tissues of mice with a high-Se diet for the first time.

Acclimation during Embryogenesis Remodulates Telomerase Activity and Gene Expression in Baikal Whitefish Larvae, Mitigating the Effects of Acute Temperature Stress

Acclimation through the hormesis effect increases the plasticity of organisms, which has been shown for many ectothermic animals, including fish. We investigated the effect of temperature acclimation in Baikal whitefish Coregonus baicalensis (Dybowski, 1874). Telomere length, telomerase activity, and the expression of genes, whose products are involved in the regulation of telomere length and defense against reactive oxygen species, were selected to assess the state of the larvae. Acclimation and acute temperature stress (+12 °C) had no effect on telomere length, but altered telomerase activity (acclimation decreased it; stress increased it) and the levels of genes expression. Under stress, the expression of superoxide dismutase genes was increased in acclimated larvae and that of glutathione peroxidases in non-acclimated larvae, which may indicate lower reactive oxygen species formation and slower antioxidant responses in acclimated fish. The expression of some telomere-related genes was reduced under temperature stress, but the expression of the tzap and smg genes, whose products improve the control of telomere length by preventing them from lengthening or shortening, was increased in acclimated individuals. The data obtained indicate a positive effect of acclimation on the state of the Baikal whitefish larvae by remodulation of their telomerase activity and the transcriptional profile.

Dietary selenium intake and sarcopenia in American adults

Background

The relationship between dietary selenium intake and sarcopenia remains poorly understood. Therefore, this study investigates the associations between dietary selenium intake and sarcopenia among American adults.

Methods

This cross-sectional study analyzed data from 19,696 participants in the National Health and Nutrition Examination Survey (NHANES) for the periods 1999-2006 and 2011-2018. Appendicular muscle mass, assessed using dual-energy x-ray absorptiometry and adjusted for body mass index, was used as a marker for sarcopenia. Dietary selenium intake was evaluated using the 24-h dietary recall system, and the study accounted for the complex sampling methodology and incorporated dietary sample weights in the analysis.

Results

Among the 19,696 participants, the prevalence of sarcopenia was found to be 8.46%. When compared to the lowest quintile of dietary selenium intake (Q1, < 80.10 μg/day), the odds ratios for sarcopenia in the second quintile (Q2, 80.10-124.61 μg/day) and the third quintile (Q3, >124.61 μg/day) were 0.80 [95% confidence interval (CI): 0.70-0.92, p = 0.002] and 0.61 (95% CI: 0.51-0.73, p < 0.001), respectively. A negative relationship was observed between dietary selenium intake and sarcopenia (non-linear: p = 0.285). Furthermore, sensitivity analyses revealed a robust association between selenium intake and the prevalence of sarcopenia after further adjusting for blood selenium levels.

Conclusion

The results suggest an inverse association between dietary selenium intake and the prevalence of sarcopenia among American adults.

Unveiling the vital role of soil microorganisms in selenium cycling: a review

Selenium (Se) is a vital trace element integral to numerous biological processes in both plants and animals, with significant impacts on soil health and ecosystem stability. This review explores how soil microorganisms facilitate Se transformations through reduction, oxidation, methylation, and demethylation processes, thereby influencing the bioavailability and ecological functions of Se. The microbial reduction of Se compounds, particularly the conversion of selenate and selenite to elemental Se nanoparticles (SeNPs), enhances Se assimilation by plants and impacts soil productivity. Key microbial taxa, including bacteria such as Pseudomonas and Bacillus, exhibit diverse mechanisms for Se reduction and play a substantial role in the global Se cycle. Understanding these microbial processes is essential for advancing soil management practices and improving ecosystem health. This review underscores the intricate interactions between Se and soil microorganisms, emphasizing their significance in maintaining ecological balance and promoting sustainable agricultural practices.

Brazil nuts potential: effects on lipid peroxidation and heart health in nephrectomized rats

OBJECTIVES

To investigate the effects of a Brazil nut-enriched diet on the wall thickness and the left ventricular chamber diameter of the heart, and lipid peroxidation in a CKD-induced model.

METHODS

Male Wistar rats at 12 weeks of age were divided into two groups (n=16/group): the Nx group, which underwent 5/6 nephrectomy, and the Sham group, as a control. After 5 weeks, the groups were subdivided according to diet (n=8/group): the Nx and Sham groups received a control diet; the Nx5% and Sham5% groups received a diet enriched with 5 % Brazil nuts for 8 weeks. The left ventricular thickening and chamber diameter were determined. Plasma biochemical parameters were evaluated. Analysis of thiobarbituric acid reactive substances (TBARS) and antioxidant enzyme activity was performed in the plasma and the left ventricle (LV). LV mRNA expression of nuclear factor-kappa B (NF-κB) and nuclear factor erythroid 2-related factor 2 (Nrf2) was evaluated by reverse transcription-polymerase chain reaction.

RESULTS

The Nx5% group showed a remodeled LV wall with decreased thickness compared to the Nx group (p=0.016). Furthermore, LV TBARS concentration was reduced in the Nx5% group (p=0.0064). In addition, the Nx5% group showed an increase in plasma GPx activity (p=0.0431). No significant results were found concerning the LV mRNA expression of NF-κB and Nrf2 genes.

CONCLUSIONS

A Brazil nut-enriched diet decreased LV thickness and LV TBARS concentration and increased GPx activity in a 5/6 nephrectomy experimental model, making it a promising adjuvant therapy to improve antioxidant status and cardiovascular outcomes in chronic kidney disease.

Reprogramming Tumor-Associated Macrophages with a Se-Based Core-Satellite Nanoassembly to Enhance Cancer Immunotherapy

Tumor-associated macrophages (TAMs), as the most prevalent immune cells in the tumor microenvironment, play a pivotal role in promoting tumor development through various signaling pathways. Herein, we have engineered a Se@ZIF-8 core-satellite nanoassembly to reprogram TAMs, thereby enhancing immunotherapy outcomes. When the nanoassembly reaches the tumor tissue, selenium nanoparticles and Zn2+ are released in response to the acidic tumor microenvironment, resulting in a collaborative effort to promote the production of reactive oxygen species (ROS). The generated ROS, in turn, activate the nuclear factor κB (NF-κB) signaling pathway, driving the repolarization of TAMs from M2-type to M1-type, effectively eliminating cancer cells. Moreover, the nanoassembly can induce the immunogenic death of cancer cells through excess ROS to expose calreticulin and boost macrophage phagocytosis. The Se@ZIF-8 core-satellite nanoassembly provides a potential paradigm for cancer immunotherapy by reversing the immunosuppressive microenvironment.

Exploring the Link between Oxidative Stress, Selenium Levels, and Obesity in Youth

Obesity is a worldwide increasing concern. Although in adults this is easily estimated with the body mass index, in children, who are constantly growing and whose bodies are changing, the reference points to assess weight status are age and gender, and need corroboration with complementary data, making their quantification highly difficult. The present review explores the interaction spectrum of oxidative stress, selenium status, and obesity in children and adolescents. Any factor related to oxidative stress that triggers obesity and, conversely, obesity that induces oxidative stress are part of a vicious circle, a complex chain of mechanisms that derive from each other and reinforce each other with serious health consequences. Selenium and its compounds exhibit key antioxidant activity and also have a significant role in the nutritional evaluation of obese children. The balance of selenium intake, retention, and metabolism emerges as a vital aspect of health, reflecting the complex interactions between diet, oxidative stress, and obesity. Understanding whether selenium status is a contributor to or a consequence of obesity could inform nutritional interventions and public health strategies aimed at preventing and managing obesity from an early age.

Unveiling potent inhibitors for schistosomiasis through ligand-based drug design, molecular docking, molecular dynamics simulations and pharmacokinetics predictions

Schistosomiasis is a neglected tropical disease which imposes a considerable and enduring impact on affected regions, leading to persistent morbidity, hindering child development, diminishing productivity, and imposing economic burdens. Due to the emergence of drug resistance and limited management options, there is need to develop additional effective inhibitors for schistosomiasis. In view of this, quantitative structure-activity relationship studies, molecular docking, molecular dynamics simulations, drug-likeness and pharmacokinetics predictions were applied to 39 Schistosoma mansoni Thioredoxin Glutathione Reductase (SmTGR) inhibitors. The chosen QSAR model demonstrated robust statistical parameters, including an R2 of 0.798, R2adj of 0.767, Q2cv of 0.681, LOF of 0.930, R2test of 0.776, and cR2p of 0.746, confirming its reliability. The most active derivative (compound 40) was identified as a lead candidate for the development of new potential non-covalent inhibitors through ligand-based design. Subsequently, 12 novel compounds (40a-40l) were designed with enhanced anti-schistosomiasis activity and binding affinity. Molecular docking studies revealed strong and stable interactions, including hydrogen bonding, between the designed compounds and the target receptor. Molecular dynamics simulations over 100 nanoseconds and MM-PBSA free binding energy (ΔGbind) calculations validated the stability of the two best-designed molecules. Furthermore, drug-likeness and pharmacokinetics prediction analyses affirmed the potential of these designed compounds, suggesting their promise as innovative agents for the treatment of schistosomiasis.

Repurposing Glutathione Transferases: Directed Evolution Combined with Chemical Modification for the Creation of a Semisynthetic Enzyme with High Hydroperoxidase Activity

Glutathione peroxidases (GPXs) are antioxidant selenoenzymes, which catalyze the reduction of hydroperoxides via glutathione (GSH), providing protection to cells against oxidative stress metabolites. The present study aims to create an efficient semisynthetic GPX based on the scaffold of tau class glutathione transferase (GSTU). A library of GSTs was constructed via DNA shuffling, using three homologue GSTUs from Glycine max as parent sequences. The DNA library of the shuffled genes was expressed in E. coli and the catalytic activity of the shuffled enzymes was screened using cumene hydroperoxide (CuOOH) as substrate. A chimeric enzyme variant (named Sh14) with 4-fold enhanced GPX activity, compared to the wild-type enzyme, was identified and selected for further study. Selenocysteine (Sec) was substituted for the active-site Ser13 residue of the Sh14 variant via chemical modification. The GPX activity (kcat) and the specificity constant (kcat/Κm) of the evolved seleno-Sh14 enzyme (SeSh14) was increased 177- and 2746-fold, respectively, compared to that of the wild-type enzyme for CuOOH. Furthermore, SeSh14 effectively catalyzed the reduction of hydrogen peroxide, an activity that is completely undetectable in all GSTs. Such an engineered GPX-like biocatalyst based on the GSTU scaffold might serve as a catalytic bioscavenger for the detoxification of hazardous hydroperoxides. Furthermore, our results shed light on the evolution of GPXs and their structural and functional link with GSTs.