Methionine Sulfoxide Reductase Research Articles

Genome-Wide Identification and Characterization of the Msr Gene Family in Alfalfa under Abiotic Stress.

Alfalfa (Medicago sativa) is an important leguminous forage, known as the "The Queen of Forages". Abiotic stress seriously limits the growth and development of alfalfa, and improving the yield and quality has become an important research area. However, little is known about the Msr (methionine sulfoxide reductase) gene family in alfalfa. In this study, 15 Msr genes were identified through examining the genome of the alfalfa "Xinjiang DaYe". The MsMsr genes differ in gene structure and conserved protein motifs. Many cis-acting regulatory elements related to the stress response were found in the promoter regions of these genes. In addition, a transcriptional analysis and qRT-PCR (quantitative reverse transcription PCR) showed that MsMsr genes show expression changes in response to abiotic stress in various tissues. Overall, our results suggest that MsMsr genes play an important role in the response to abiotic stress for alfalfa.

Metabolism of hydrogen peroxide by Lactobacillus plantarum NJAU-01: A proteomics study.

This study aimed to investigate the time-course effect of Lactobacillus plantarum NJAU-01 in scavenging exogenous hydrogen peroxide (H2O2). The results showed that L. plantarum NJAU-01 at 107CFU/mL was able to eliminate a maximum of 4mM H2O2 within a prolonged lag phase and resume to proliferate during the following culture. Redox state in the start-lag phase (0h, without the addition of H2O2), indicated by glutathione and protein sulfhydryl, was impaired in the lag phase (3h and 12h) and then gradually recovered during subsequent growing stages (20h and 30h). By using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and proteomics analysis, a total of 163 proteins such as PhoP family transcriptional regulator, glutamine synthetase, peptide methionine sulfoxide reductase, thioredoxin reductase, ribosomal proteins, acetolactate synthase, ATP binding subunit ClpX, phosphoglycerate kinase, UvrABC system protein A and UvrABC system protein B were identified as differential proteins across the entire growth phase. Those proteins were mainly involved in H2O2 sensing, protein synthesis, repairing proteins and DNA lesions, amino sugar and nucleotide sugar metabolism. Our data suggest that biomolecules of L. plantarum NJAU-01 are oxidized to passively consume H2O2 and are restored by the enhanced protein and/or gene repair systems.

A single exercise exertion initiates antioxidant and vascular-protective mechanisms in patients with heart failure

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): DZHK (German Centre for Cardiovascular Research). Background Increased systemic inflammation and metabolic dysfunction at rest are observed in heart failure with reduced ejection fraction (HFrEF). Regular (endurance) exercise training can alleviate both. On the other hand, cardiorespiratory exercise testing (CPET) exerts a physical challenge thereby initiating the acute activation of the immune system and several metabolic pathways. Aim To characterize the differences and similarities acute inflammatory and metabolic activation in response to an acute exercise challenge, and their resolution after 2 hours of rest in patients with HFrEF as compared to controls. Methods Participants with HFrEF (n = 16) as well as age and sex matched controls (CON, n = 13) were investigated at baseline (T1), immediately after CPET (T2), and after 2 hours of resting post-CPET (T3). Clinical and physiological parameters, leukocyte profile, plasma cytokines and metabolites were assessed along with inflammatory and metabolic parameters at all three time points. Results and Discussion Cardiovascular risk profile as well as leukocyte, cytokine and metabolic parameters at T1 was similar in CON and HFrEF. Immediately after CPET, lactate, natural killer (NK) and NK-T cell blood counts, among others, were significantly increased in both groups. In HFrEF specifically, platelet aggregates with NK cells, CD8+ cytotoxic T cells and "classical" CD14++CD16-monocytes as well as phosphatidylcholines and triglycerides were increased. After 2h of rest post-CPET, almost all altered parameters returned to baseline in CON. In HFrEF, blood counts and morphological markers of inflammatory effector cell types, including CD8+ T cells and neutrophils remained elevated. Blood levels of inflammatory cytokines were associated to elevated levels of various phosphatidycholines in HFrEF, but not in CON, potentially pointing towards a link to cell death. Blood levels of methionine sulfoxide-to-methionine, declined at T3 versus T1 in both groups, potentially indicating activation of anti-oxidant methionine sulfoxide reductases. In addition, trigonelline, an inhibitor of trimethylamine N-oxide (TMAO) synthesis from choline was elevated by CPET in both groups and this increase correlated inversely with TMAO-to-choline ratio. This might indicate a so far unexplored exercise-induced vascular-protective mechanism by limiting the pro-atherogenic effects of TMAO. Conclusion CPET induced a complex acute immuno-metabolic response, whose restitution to baseline levels differed between HFrEF and healthy controls. Despite longer persistence of pro-inflammatory and metabolic mediators present in the circulation after the end of an acute exercise session, novel anti-oxidant and vascular protective mechanisms of exercise have been identified and appear to be still active in patients with HFrEF.

Nitric oxide modulates folate-mediated one-carbon metabolism and mitochondrial energy levels of peaches during cold storage.

Folate-mediated one-carbon metabolism (FOCM) is closely associated with postharvest preservation. This study investigated the effects of exogenous nitric oxide (NO) on FOCM, storage quality, energy metabolism, and mitochondrial membrane integrity in cold-storage peach fruit. In this experiment, peaches were soaked with 1.5 mmol L-1S-nitrosoglutathione (GSNO) as NO donor, and the negative treatment (NT) solution containing 5 μmol L-1 carboxy-PTIO (c-PTIO, NO scavenger), 200 μmol L-1 NG-Nitro-L-arginine methyl ester (L-NAME, NO synthase-like enzyme inhibitor), and 200 μmol L-1 sodium tungstate dihydrate (nitrate reductase inhibitor) and stored at 0°C. The results showed that NO decreased the activity of S-adenosylmethionine synthase and S-adenosylhomocysteine hydrolase and increased the activity of methionine sulfoxide reductase A, as well as the content of N5-methyl-THF, the ratio of tetrahydrofolate (THF), homocysteine, methionine, S-adenosylmethionine (SAM), and SAM to S-adenosylhomocysteine compared with the control, indicating that NO effectively increased FOCM flux by affecting the activity of FOCM enzymes. Meanwhile, NO increased the activities of H+-ATPase, Ca2+-ATPase, cytochrome c oxidase, succinate dehydrogenase, and the contents of adenosine triphosphate and adenosine diphosphate, and maintained high energy charge in peaches during storage. NO retarded the increase in mitochondrial permeability transition, reactive oxygen species content, and the decrease in mitochondrial membrane fluidity, membrane potential, and swelling. NT treatment exhibited the opposite results. In conclusion, these results suggested that NO could induce the accumulation of folate and FOCM flux and maintain mitochondrial energy levels, which might be responsible for maintaining the quality of peaches during cold storage.

The Key Role of Chalcogenurane Intermediates in the Reduction Mechanism of Sulfoxides and Selenoxides by Thiols Explored In Silico.

Sulfoxides and selenoxides oxidize thiols to disulfides while being reduced back to sulfides and selenides. While the reduction mechanism of sulfoxides to sulfides has been thoroughly explored experimentally as well as computationally, less attention has been devoted to the heavier selenoxides. In this work, we explore the reductive mechanism of dimethyl selenoxide, as an archetypal selenoxide and, for the sake of comparison, the reductive mechanism of dimethyl sulfoxide to gain insight into the role of the chalcogen on the reaction substrate. Particular attention is devoted to the key role of sulfurane and selenurane intermediates. Moreover, the capacity of these system to oxidize selenols rather than thiols, leading to the formation of selenyl sulfide bridges, is explored in silico. Notably, this analysis provides molecular insight into the role of selenocysteine in methionine sulfoxide reductase selenoenzyme. The activation strain model of chemical reactivity is employed in the studied reactions as an intuitive tool to bridge the computationally predicted effect of the chalcogen on the chalcogenoxide as well as on the chalcogenol.

A comprehensive genomic analysis provides insights on the high environmental adaptability of Acinetobacter strains.

Acinetobacter is ubiquitous, and it has a high species diversity and a complex evolutionary pattern. To elucidate the mechanism of its high ability to adapt to various environment, 312 genomes of Acinetobacter strains were analyzed using the phylogenomic and comparative genomics methods. It was revealed that the Acinetobacter genus has an open pan-genome and strong genome plasticity. The pan-genome consists of 47,500 genes, with 818 shared by all the genomes of Acinetobacter, while 22,291 are unique genes. Although Acinetobacter strains do not have a complete glycolytic pathway to directly utilize glucose as carbon source, most of them harbored the n-alkane-degrading genes alkB/alkM (97.1% of tested strains) and almA (96.7% of tested strains), which were responsible for medium-and long-chain n-alkane terminal oxidation reaction, respectively. Most Acinetobacter strains also have catA (93.3% of tested strains) and benAB (92.0% of tested strains) genes that can degrade the aromatic compounds catechol and benzoic acid, respectively. These abilities enable the Acinetobacter strains to easily obtain carbon and energy sources from their environment for survival. The Acinetobacter strains can manage osmotic pressure by accumulating potassium and compatible solutes, including betaine, mannitol, trehalose, glutamic acid, and proline. They respond to oxidative stress by synthesizing superoxide dismutase, catalase, disulfide isomerase, and methionine sulfoxide reductase that repair the damage caused by reactive oxygen species. In addition, most Acinetobacter strains contain many efflux pump genes and resistance genes to manage antibiotic stress and can synthesize a variety of secondary metabolites, including arylpolyene, β-lactone and siderophores among others, to adapt to their environment. These genes enable Acinetobacter strains to survive extreme stresses. The genome of each Acinetobacter strain contained different numbers of prophages (0-12) and genomic islands (GIs) (6-70), and genes related to antibiotic resistance were found in the GIs. The phylogenetic analysis revealed that the alkM and almA genes have a similar evolutionary position with the core genome, indicating that they may have been acquired by vertical gene transfer from their ancestor, while catA, benA, benB and the antibiotic resistance genes could have been acquired by horizontal gene transfer from the other organisms.

Salmonella Typhimurium uses the Cpx stress response to detect N-chlorotaurine and promote the repair of oxidized proteins

The cell envelope of gram-negative bacteria constitutes the first protective barrier between a cell and its environment. During host infection, the bacterial envelope is subjected to several stresses, including those induced by reactive oxygen species (ROS) and reactive chlorine species (RCS) produced by immune cells. Among RCS, N-chlorotaurine (N-ChT), which results from the reaction between hypochlorous acid and taurine, is a powerful and less diffusible oxidant. Here, using a genetic approach, we demonstrate that Salmonella Typhimurium uses the CpxRA two-component system to detect N-ChT oxidative stress. Moreover, we show that periplasmic methionine sulfoxide reductase (MsrP) is part of the Cpx regulon. Our findings demonstrate that MsrP is required to cope with N-ChT stress by repairing N-ChT-oxidized proteins in the bacterial envelope. By characterizing the molecular signal that induces Cpx when S. Typhimurium is exposed to N-ChT, we show that N-ChT triggers Cpx in an NlpE-dependent manner. Thus, our work establishes a direct link between N-ChT oxidative stress and the envelope stress response.

Discovery and Rational Mutagenesis of Methionine Sulfoxide Reductase Biocatalysts To Expand the Substrate Scope of the Kinetic Resolution of Chiral Sulfoxides.

Methionine sulfoxide reductase A (MsrA) enzymes have recently found applications as nonoxidative biocatalysts in the enantioselective kinetic resolution of racemic sulfoxides. This work describes the identification of selective and robust MsrA biocatalysts able to catalyze the enantioselective reduction of a variety of aromatic and aliphatic chiral sulfoxides at 8-64 mM concentration with high yields and excellent ees (up to 99%). Moreover, with the aim to expand the substrate scope of MsrA biocatalysts, a library of mutant enzymes has been designed via rational mutagenesis utilizing in silico docking, molecular dynamics, and structural nuclear magnetic resonance (NMR) studies. The mutant enzyme MsrA33 was found to catalyze the kinetic resolution of bulky sulfoxide substrates bearing non-methyl substituents on the sulfur atom with ees up to 99%, overcoming a significant limitation of the currently available MsrA biocatalysts.

Arabidopsis AtMSRB5 functions as a salt-stress protector for both Arabidopsis and rice.

Salinity, drought and low temperature are major environmental factors that adversely affect crop productivity worldwide. In this study we adopted an activation tagging approach to identify salt tolerant mutants of Arabidopsis. Thousands of tagged Arabidopsis lines were screened to obtain several potential mutant lines resistant to 150 mM NaCl. Transcript analysis of a salt-stress tolerance 1 (sst1) mutant line indicated activation of AtMSRB5 and AtMSRB6 which encode methionine sulfoxide reductases. Overexpression of AtMSRB5 in Arabidopsis (B5OX) showed a similar salt tolerant phenotype. Furthermore, biochemical analysis indicated stability of the membrane protein, H+-ATPase 2 (AHA2) through regulation of Na+/K+ homeostasis which may be involved in a stress tolerance mechanism. Similarly, overexpression of AtMSRB5 in transgenic rice demonstrated a salt tolerant phenotype via the modulation of Na+/K+ homeostasis without a yield drag under salt and oxidative stress conditions.

Different Effects and Mechanisms of Selenium Compounds in Improving Pathology in Alzheimer’s Disease

Owing to the strong antioxidant capacity of selenium (Se) in vivo, a variety of Se compounds have been shown to have great potential for improving the main pathologies and cognitive impairment in Alzheimer's disease (AD) models. However, the differences in the anti-AD effects and mechanisms of different Se compounds are still unclear. Theoretically, the absorption and metabolism of different forms of Se in the body vary, which directly determines the diversification of downstream regulatory pathways. In this study, low doses of Se-methylselenocysteine (SMC), selenomethionine (SeM), or sodium selenate (SeNa) were administered to triple transgenic AD (3× Tg-AD) mice for short time periods. AD pathology, activities of selenoenzymes, and metabolic profiles in the brain were studied to explore the similarities and differences in the anti-AD effects and mechanisms of the three Se compounds. We found that all of these Se compounds significantly increased Se levels and antioxidant capacity, regulated amino acid metabolism, and ameliorated synaptic deficits, thus improving the cognitive capacity of AD mice. Importantly, SMC preferentially increased the expression and activity of thioredoxin reductase and reduced tau phosphorylation by inhibiting glycogen synthase kinase-3 beta (GSK-3β) activity. Glutathione peroxidase 1 (GPx1), the selenoenzyme most affected by SeM, decreased amyloid beta production and improved mitochondrial function. SeNa improved methionine sulfoxide reductase B1 (MsrB1) expression, reflected in AD pathology as promoting the expression of synaptic proteins and restoring synaptic deficits. Herein, we reveal the differences and mechanisms by which different Se compounds improve multiple pathologies of AD and provide novel insights into the targeted administration of Se-containing drugs in the treatment of AD.

Mycobacterium smegmatis secreting methionine sulfoxide reductase A (MsrA) modulates cellular processes in mouse macrophages

Methionine sulfoxide reductase A (MsrA) is an antioxidant repair enzyme that reduces the oxidized methionine (Met-O) in proteins to methionine (Met). Its pivotal role in the cellular processes has been well established by overexpressing, silencing, and knocking down MsrA or deleting the gene encoding MsrA in several species. We are specifically interested in understanding the role of secreted MsrA in bacterial pathogens. To elucidate this, we infected mouse bone marrow-derived macrophages (BMDMs) with recombinant Mycobacterium smegmatis strain (MSM), secreting a bacterial MsrA or M. smegmatis strain (MSC) carrying only the control vector. BMDMs infected with MSM induced higher levels of ROS and TNF-α than BMDMs infected with MSC. The increased ROS and TNF-α levels in MSM-infected BMDMs correlated with elevated necrotic cell death in this group. Further, RNA-seq transcriptome analysis of BMDMs infected with MSC and MSM revealed differential expression of protein and RNA coding genes, suggesting that bacterial-delivered MsrA could modulate the host cellular processes. Finally, KEGG pathway enrichment analysis identified the down-regulation of cancer-related signaling genes in MSM-infected cells, indicating that MsrA can potentially regulate the development and progression of cancer.

Chlorate Contamination in Commercial Growth Media as a Source of Phenotypic Heterogeneity within Bacterial Populations.

Under anaerobic conditions, chlorate is reduced to chlorite, a cytotoxic compound that triggers oxidative stress within bacterial cultures. We previously found that BD Bacto Casamino Acids were contaminated with chlorate. In this study, we investigated whether chlorate contamination is detectable in other commercial culture media. We provide evidence that in addition to different batches of BD Bacto Casamino Acids, several commercial agar powders are contaminated with chlorate. A direct consequence of this contamination is that, during anaerobic growth, Escherichia coli cells activate the expression of msrP, a gene encoding periplasmic methionine sulfoxide reductase, which repairs oxidized protein-bound methionine. We further demonstrate that during aerobic growth, progressive oxygen depletion triggers msrP expression in a subpopulation of cells due to the presence of chlorate. Hence, we propose that chlorate contamination in commercial growth media is a source of phenotypic heterogeneity within bacterial populations. IMPORTANCE Agar is arguably the most utilized solidifying agent for microbiological media. In this study, we show that agar powders from different suppliers, as well as certain batches of BD Bacto Casamino Acids, contain significant levels of chlorate. We demonstrate that this contamination induces the expression of a methionine sulfoxide reductase, suggesting the presence of intracellular oxidative damage. Our results should alert the microbiology community to a pitfall in the cultivation of microorganisms under laboratory conditions.

Methionine Sulfoxide Reductases Suppress the Formation of the [PSI+] Prion and Protein Aggregation in Yeast

Prions are self-propagating, misfolded forms of proteins associated with various neurodegenerative diseases in mammals and heritable traits in yeast. How prions form spontaneously into infectious amyloid-like structures without underlying genetic changes is poorly understood. Previous studies have suggested that methionine oxidation may underlie the switch from a soluble protein to the prion form. In this current study, we have examined the role of methionine sulfoxide reductases (MXRs) in protecting against de novo formation of the yeast [PSI+] prion, which is the amyloid form of the Sup35 translation termination factor. We show that [PSI+] formation is increased during normal and oxidative stress conditions in mutants lacking either one of the yeast MXRs (Mxr1, Mxr2), which protect against methionine oxidation by reducing the two epimers of methionine-S-sulfoxide. We have identified a methionine residue (Met124) in Sup35 that is important for prion formation, confirming that direct Sup35 oxidation causes [PSI+] prion formation. [PSI+] formation was less pronounced in mutants simultaneously lacking both MXR isoenzymes, and we show that the morphology and biophysical properties of protein aggregates are altered in this mutant. Taken together, our data indicate that methionine oxidation triggers spontaneous [PSI+] prion formation, which can be alleviated by methionine sulfoxide reductases.

Ndufaf2, a protein in mitochondrial complex I, interacts in vivo with methionine sulfoxide reductases

ABSTRACTBackgroundMethionine sulfoxide reductases are found in all aerobic organisms. They function in antioxidant defense, cellular regulation by reversible oxidation of methionine in proteins, and in protein structure. However, very few in vivo binding partners or substrates of the reductases have been identified.MethodsWe implemented a proximity labeling method, TurboID, to covalently link mitochondrial methionine sulfoxide reductase A (MSRA) to its binding partners in HEK293 cells. Proteomic analyses were performed to identify putative binding partners.ResultsWe show that human Ndufaf2, also called mimitin, is a binding partner of MSRA as well as all 3 MSRBs. We found that both methionine residues in Ndufaf2 were susceptible to oxidation by hydrogen peroxide and that the methionine sulfoxide reductases can reduce these methionine sulfoxide residues back to methionine.ConclusionMethionine sulfoxide reductases can reduce methionine sulfoxide back to methionine in Ndufaf2. In addition to a repair function, it also creates a mechanism that could regulate cellular processes by modulation of methionine oxidation in Ndufaf2.

Interaction of methionine sulfoxide reductase B5 with SlMYC2 stimulates the transcription of MeJA-mediated autophagy-related genes in tomato fruit.

Methyl jasmonate (MeJA) has been shown to induce autophagy in various plant stress responses and metabolic pathways. MYC2 is involved in MeJA-mediated postharvest fruit biological metabolism, but it is unclear how it affects MeJA-induced fruit autophagy. In this study, we noticed that silencing SlMYC2 significantly reduced the increase in autophagy-related genes (SlATGs) expression induced by MeJA. SlMYC2 could also bind to the promoters of several SlATGs, including SlATG13a, SlATG13b, SlATG18a, and SlATG18h, and activate their transcript levels. Moreover, SlMsrB5, a methionine sulfoxide reductase, could interact with SlMYC2. Methionine oxidation in SlMYC2 and mimicking sulfoxidation in SlMYC2 by mutation of methionine-542 to glutamine reduced the DNA-binding ability and transcriptional activity of SlMYC2, respectively. SlMsrB5 partially repaired oxidized SlMYC2 and restored its DNA-binding ability. On the other hand, silencing SlMsrB5 inhibited the transcript levels of SlMYC2-targeted genes (SlATG13a, SlATG13b, SlATG18a, and SlATG18h). Similarly, dual-luciferase reporter (DLR) analysis revealed that SlMsrB5-SlMYC2 interaction significantly increased the ability of SlMYC2-mediated transcriptional activation of SlATG13a, SlATG13b, SlATG18a, and SlATG18h. These findings demonstrate that SlMsrB5-mediated cyclic oxidation/reduction of methionine in SlMYC2 influences SlATGs expression. Collectively, these findings reveal the mechanism of SlMYC2 in SlATGs transcriptional regulation, providing insight into the mechanism of MeJA-mediated postharvest fruit quality regulation.

Oxidative stress regulates talin mechanosensing.

Cellular mechanostransduction relies on the conversion of mechanical cues into chemical signals, which propagate from the focal adhesion hub through the cytoskeleton to ultimately reach the nucleus and switch on specific force-dependent transcriptional programmes. Whether the chemical properties of the environment -and namely oxidative stress- affect the first steps in mechanosensing remains unknown. Here we use a newly developed single molecule magnetic tweezers combined with UV-light to probe how oxidation of specific amino acids affects the mechanical folding of the R3 domain of the talin mechanosensor. Combined with mass spectrometry, we demonstrate that the successive oxidation of a previously cryptic methionine, first to sulfoxide and then to sulfone, decreases in each case talin's mechanical stability by ∼2 pN. While the first oxidation step can be reversed by methionine sulfoxide reductase (Msr) enzymes, evolution to sulfone is irreversible, leading to a mechanically labile protein form. Crucially, vinculin binding to the oxidised protein is significantly impaired, which we demonstrate both, at the single-molecule and single-cell levels. Our results showcase how cryptic oxidation on a single talin domain might lead to severe knock-on effects on the mechanosensing properties at the cellular level.

A Novel Organic Selenium Compound Exerts Unique Regulation of Selenium Speciation, Selenogenome, and Selenoproteins in Broiler Chicks

BackgroundA new organic selenium compound, 2-hydroxy-4-methylselenobutanoic acid (SeO), displayed a greater bioavailability than sodium selenite (SeNa) or seleno-yeast (SeY) in several species. ObjectiveThis study sought to determine the regulation of the speciation of selenium, expression of selenogenome and selenocysteine biosynthesis and degradation-related genes, and production of selenoproteins by the 3 forms of selenium in the tissues of broiler chicks. MethodsDay-old male chicks (n = 6 cages/diet, 6 chicks/cage) were fed a selenium-deficient, corn and soy–based diet [base diet (BD), 0.05 mg Se/kg] or the BD + SeNa, SeY, or SeO at 0.2 mg Se/kg for 6 wk. Plasma, livers, and pectoral and thigh muscles were collected at weeks 3 and 6 to assay for total selenium, selenomethionine, selenocysteine, redox status, and selected genes, proteins, and enzymes. ResultsAlthough both SeY and SeO produced greater concentrations (P < 0.05) of total selenium (20–172%) and of selenomethionine (≤15-fold) in the liver, pectoral muscle, and thigh than those of SeNa, SeO further raised (P < 0.05) these concentrations by 13–37% and 43–87%, respectively, compared with SeY. Compared with the BD, only SeO enhanced (P < 0.05) the mRNA of selenoprotein (Seleno) s and methionine sulfoxide reductase B1 (Msrb1) in the liver and thigh (62–98%) and thioredoxin reductase (TXRND) activity in the pectoral and thigh muscles (20–37%) at week 3. Furthermore, SeO increased (P < 0.05) the expression of glutathione peroxidase (Gpx) 3, GPX4, SELENOP, and SELENOU relative to the SeNa group by 26–207%, and the expression of Selenop, O-phosphoseryl-transfer RNA (tRNA):selenocysteinyl-tRNA synthase, GPX4, and SELENOP relative to the SeY group by 23–55% in various tissues. ConclusionsCompared with SeNa or SeY, SeO demonstrated a unique ability to enrich selenomethionine and total selenium depositions, to induce the early expression of Selenos and Mrsb1 mRNA and TXRND activity, and to enhance the protein production of GPX4, SELENOP, and SELENOU in the tissues of chicks.

Periplasmic methionine sulfoxide reductase (MsrP)-a secondary factor in stress survival and virulence of Salmonella Typhimurium.

Among others, methionine residues are highly susceptible to host-generated oxidants. Repair of oxidized methionine (Met-SO) residues to methionine (Met) by methionine sulfoxide reductases (Msrs) play a chief role in stress survival of bacterial pathogens, including Salmonella Typhimurium. Periplasmic proteins, involved in many important cellular functions, are highly susceptible to host-generated oxidants. According to location in cell, two types of Msrs, cytoplasmic and periplasmic are present in S. Typhimurium. Owing to its localization, periplasmic Msr (MsrP) might play a crucial role in defending the host-generated oxidants. Here, we have assessed the role of MsrP in combating oxidative stress and colonization of S. Typhimurium. ΔmsrP (mutant strain) grew normally in in-vitro media. In comparison to S. Typhimurium (wild type), mutant strain showed mild hypersensitivity to HOCl and chloramine-T (ChT). Following exposure to HOCl, mutant strain showed almost similar protein carbonyl levels (a marker of protein oxidation) as compared to S. Typhimurium strain. Additionally, ΔmsrP strain showed higher susceptibility to neutrophils than the parent strain. Further, the mutant strain showed very mild defects in survival in mice spleen and liver as compared to wild-type strain. In a nutshell, our results indicate that MsrP plays only a secondary role in combating oxidative stress and colonization of S. Typhimurium.

Comparing proteome changes involved in biofilm formation by Streptococcus mutans after exposure to sucrose and starch.

Streptococcus mutans is a main organism of tooth infections including tooth decay and periodontitis. The aim of this study was to assess the influence of sucrose and starch on biofilm formation and proteome profile of S. mutans ATCC 35668 strain. The biofilm formation was assessed by microtiter plating method. Changes in bacterial proteins after exposure to sucrose and starch carbohydrates were analyzed using matrix-assisted laser desorption/ionization mass spectrometry. The biofilm formation of S. mutans was increased to 391.76% in 1% sucrose concentration, 165.76% in 1% starch, and 264.27% in the 0.5% sucrose plus 0.5% starch in comparison to biofilm formation in the media without sugars. The abundance of glutamines, adenylate kinase, and 50S ribosomal protein L29 was increased under exposure to sucrose. Upregulation of lactate utilization protein C, 5-hydroxybenzimidazole synthase BzaA, and 50S ribosomal protein L16 was formed under starch exposure. Ribosome-recycling factor, peptide chain release factor 1, and peptide methionine sulfoxide reductase MsrB were upregulated under exposure to sucrose in combination with starch. The results demonstrated that the carbohydrates increase microbial pathogenicity. In addition, sucrose and starch carbohydrates can induce biofilm formation of S. mutans via various mechanisms such as changes in the expression of special proteins.

Effects of maternal methionine supplementation on the response of Japanese quail (Coturnix coturnix japonica) chicks to heat stress.

This study investigated the hypothesis that methionine supplementation of Japanese quail (Coturnix coturnix japonica) hens can reduce the effects of oxidative stress and improve the performance of the offspring exposed to heat stress during growth. For that, the quail hens were fed with three diets related to the methionine supplementation: methionine-deficient diet (Md); diet supplemented with the recommended methionine level (Met1); and diet supplemented with methionine above the recommended level (Met2). Their chicks were identified, weighed, and housed according to the maternal diet group from 1 to 14 d of age. On 15 d of age, chicks were weighed and divided into two groups: thermoneutral ambient (constant temperature of 23 °C) and intermittent heat stress ambient (daily exposure to 34 °C for 6 h). Methionine-supplemented (Met1 and Met2) hens had higher egg production, better feed conversion ratio, higher hatchability of total and fertile eggs, and offspring with higher body weight. Supplemented (Met1 and Met2) hens showed greater expression of glutathione synthase (GSS) and methionine sulfoxide reductase A (MSRA) genes, greater total antioxidant capacity, and lower lipid peroxidation in the liver. The offspring of hens fed the Met2 diet had lower death rate (1 to 14 d), higher weight on 15 d of age, weight gain, and better feed conversion ratio from 1 to 14 d of age. Among chicks reared under heat stress, the progeny of methionine-supplemented hens had higher weight on 35 d, weight gain, expression of GSS, MSRA, and thermal shock protein 70 (HSP70) genes, and total antioxidant capacity in the liver, as well as lower heterophil/lymphocyte ratio. Positive correlations between expression of glutathione peroxidase 7 (GPX7) and MSRA genes in hens and offspring were observed. Our results show that maternal methionine supplementation contributes to offspring development and performance in early stages and that, under conditions of heat stress during growth, chicks from methionine-supplemented hens respond better to hot environmental conditions than chicks from nonsupplemented hens. Supplementation of quail hens diets with methionine promoted activation of different metabolic pathways in offspring subjected to stress conditions.