Methionine Sulfoxide Reductase Research Articles

Formylation facilitates the reduction of oxidized initiator methionines

Within a cell, protein-bound methionines can be chemically or enzymatically oxidized, and subsequently reduced by methionine sulfoxide reductases (Msrs). Methionine oxidation can result in structural damage or be the basis of functional regulation of enzymes. In addition to participating in redox reactions, methionines play an important role as the initiator residue of translated proteins where they are commonly modified at their α-amine group by formylation or acetylation. Here, we investigated how formylation and acetylation of initiator methionines impact their propensity for oxidation and reduction. We show that in vitro, N-terminal methionine residues are particularly prone to chemical oxidation and that their modification by formylation or acetylation greatly enhances their subsequent enzymatic reduction by MsrA and MsrB. Concordantly, in vivo ablation of methionyl-tRNA formyltransferase (MTF) in Escherichia coli increases the prevalence of oxidized methionines within synthesized proteins. We show that oxidation of formylated initiator methionines is detrimental in part because it obstructs their ensuing deformylation by peptide deformylase (PDF) and hydrolysis by methionyl aminopeptidase (MAP). Thus, by facilitating their reduction, formylation mitigates the misprocessing of oxidized initiator methionines.

COVID-19 and hyperinflammation: Could the methionine sulfoxide reductase enzymes play a role?

COVID-19 and hyperinflammation: Could the methionine sulfoxide reductase enzymes play a role?

Aquificae overcomes competition by archaeal thermophiles, and crowding by bacterial mesophiles, to dominate the boiling vent-water of a Trans-Himalayan sulfur-borax spring.

Trans-Himalayan hot spring waters rich in boron, chlorine, sodium and sulfur (but poor in calcium and silicon) are known based on PCR-amplified 16S rRNA gene sequence data to harbor high diversities of infiltrating bacterial mesophiles. Yet, little is known about the community structure and functions, primary productivity, mutual interactions, and thermal adaptations of the microorganisms present in the steaming waters discharged by these geochemically peculiar spring systems. We revealed these aspects of a bacteria-dominated microbiome (microbial cell density ~8.5 × 104 mL-1; live:dead cell ratio 1.7) thriving in the boiling (85°C) fluid vented by a sulfur-borax spring called Lotus Pond, situated at 4436 m above the mean sea-level, in the Puga valley of eastern Ladakh, on the Changthang plateau. Assembly, annotation, and population-binning of >15-GB metagenomic sequence illuminated the numeral predominance of Aquificae. While members of this phylum accounted for 80% of all 16S rRNA-encoding reads within the metagenomic dataset, 14% of such reads were attributed to Proteobacteria. Post assembly, only 25% of all protein-coding genes identified were attributable to Aquificae, whereas 41% was ascribed to Proteobacteria. Annotation of metagenomic reads encoding 16S rRNAs, and/or PCR-amplified 16S rRNA genes, identified 163 bacterial genera, out of which 66 had been detected in past investigations of Lotus Pond's vent-water via 16S amplicon sequencing. Among these 66, Fervidobacterium, Halomonas, Hydrogenobacter, Paracoccus, Sulfurihydrogenibium, Tepidimonas, Thermus and Thiofaba (or their close phylogenomic relatives) were presently detected as metagenome-assembled genomes (MAGs). Remarkably, the Hydrogenobacter related MAG alone accounted for ~56% of the entire metagenome, even though only 15 out of the 66 genera consistently present in Lotus Pond's vent-water have strains growing in the laboratory at >45°C, reflecting the continued existence of the mesophiles in the ecosystem. Furthermore, the metagenome was replete with genes crucial for thermal adaptation in the context of Lotus Pond's geochemistry and topography. In terms of sequence similarity, a majority of those genes were attributable to phylogenetic relatives of mesophilic bacteria, while functionally they rendered functions such as encoding heat shock proteins, molecular chaperones, and chaperonin complexes; proteins controlling/modulating/inhibiting DNA gyrase; universal stress proteins; methionine sulfoxide reductases; fatty acid desaturases; different toxin-antitoxin systems; enzymes protecting against oxidative damage; proteins conferring flagellar structure/function, chemotaxis, cell adhesion/aggregation, biofilm formation, and quorum sensing. The Lotus Pond Aquificae not only dominated the microbiome numerically but also acted potentially as the main primary producers of the ecosystem, with chemolithotrophic sulfur oxidation (Sox) being the fundamental bioenergetic mechanism, and reductive tricarboxylic acid (rTCA) cycle the predominant carbon fixation pathway. The Lotus Pond metagenome contained several genes directly or indirectly related to virulence functions, biosynthesis of secondary metabolites including antibiotics, antibiotic resistance, and multi-drug efflux pumping. A large proportion of these genes being attributable to Aquificae, and Proteobacteria (very few were ascribed to Archaea), it could be worth exploring in the future whether antibiosis helped the Aquificae overcome niche overlap with other thermophiles (especially those belonging to Archaea), besides exacerbating the bioenergetic costs of thermal endurance for the mesophilic intruders of the ecosystem.

Methionine oxidation of actin cytoskeleton attenuates traumatic memory retention via reactivating dendritic spine morphogenesis

Post-traumatic stress disorder (PTSD) is characterized by hypermnesia of the trauma and a persistent fear response. The molecular mechanisms underlying the retention of traumatic memories remain largely unknown, which hinders the development of more effective treatments. Utilizing auditory fear conditioning, we demonstrate that a redox-dependent dynamic pathway for dendritic spine morphogenesis in the basolateral amygdala (BLA) is crucial for traumatic memory retention. Exposure to a fear-induced event markedly increased the reduction of oxidized filamentous actin (F-actin) and decreased the expression of the molecule interacting with CasL 1 (MICAL1), a methionine-oxidizing enzyme that directly oxidizes and depolymerizes F-actin, leading to cytoskeletal dynamic abnormalities in the BLA, which impairs dendritic spine morphogenesis and contributes to the persistence of fearful memories. Following fear conditioning, overexpression of MICAL1 in the BLA inhibited freezing behavior during fear memory retrieval via reactivating cytokinesis, whereas overexpression of methionine sulfoxide reductase B 1, a key enzyme that reduces oxidized F-actin monomer, increased freezing behavior during retrieval. Notably, intra-BLA injection of semaphorin 3A, an endogenous activator of MICAL1, rapidly disrupted fear memory within a short time window after conditioning. Collectively, our results indicate that redox modulation of actin cytoskeleton in the BLA is functionally linked to fear memory retention and PTSD-like memory.

S-Methyl-L-cysteine targeting MsrA attenuates Ang II-induced oxidative stress and atrial remodeling via the p38 MAPK signaling pathway.

Atrial fibrillation (AF) is the most prevalent sustained tachyarrhythmia in patients with cardiovascular diseases. Recently, it has been discovered that oxidative stress is an important contributor to AF. Therefore, antioxidant therapies for AF have great potential for clinical applications. Methionine, a sulfur-containing amino acid residue other than cysteine, is recognized as a functional redox switch, which could be rescued from the reversible oxidation of methionine sulfoxide by methionine sulfoxide reductase A (MsrA). S-Methyl-L-cysteine (SMLC), a natural analogue of Met, which is abundantly found in garlic and cabbage, could substitute for Met oxidations and mediate MsrA to scavenge free radicals. However, whether SMLC alleviates AF is unclear. This study aims to clarify the effects of SMLC on AF and elucidate the underlying pharmacological and molecular mechanisms. In vivo, SMLC (70, 140 and 280 mg kg-1 day-1) was orally administered to mice for 4 weeks with angiotensin II (Ang II) by subcutaneous infusion using osmotic pumps to induce AF. Ang II significantly prompted high AF susceptibility and atrial remodeling characterized by oxidative stress, conductive dysfunction and fibrosis. SMLC played a remarkable protective role in Ang II-induced atrial remodeling dose-dependently. Moreover, RNA sequencing was performed on atrial tissues to identify the differentially expressed mRNA, which was to screen out MSRA, CAMK2 and MAPK signaling pathways. Western blots confirmed that Ang II-induced downregulation of MsrA and upregulation of oxidized CaMKII (ox-CaMKII) and p38 MAPK could be reversed in a concentration-dependent manner by SMLC. To investigate the underlying mechanisms, HL-1 cells (mouse atria-derived cardiomyocytes) treated with Ang II were used for an in vitro model. SMLC alleviated Ang II-induced cytotoxicity, mitochondrial damage and oxidative stress. Additionally, knockdown MsrA could attenuate the protective effects of SMLC, which were eliminated by the p38 MAPK inhibitor SB203580. In summary, the present study demonstrates that SMLC protects against atrial remodeling in AF by inhibiting oxidative stress through the mediation of the MsrA/p38 MAPK signaling pathway.

Characterization and mechanism investigation of salt-activated methionine sulfoxide reductase A from halophiles

Halophiles, thriving in harsh saline environments, capture scientific interest due to their remarkable ability to prosper under extreme salinity. This study unveils the distinct salt-induced activation of methionine sulfoxide reductases (MsrA) from Halobacterium hubeiense, showcasing a significant enhancement in enzymatic activity across various salt concentrations ranging from 0.5 to 3.5 M. This contrasts sharply with the activity profiles of non-halophilic counterparts. Through comprehensive molecular dynamics simulations, we demonstrate that salt ions stabilize and compact the enzyme's structure, notably enhancing its substrate affinity. Mutagenesis analysis further confirms the essential role of salt bridges formed bythe basic Arg168 residue in salt-induced activation. Mutating Arg168 to an acidic or neutral residue disruptssalt-induced activation, substantially reducing the enzyme activity under salt conditions. Our research provides evidence of salt-activated MsrA activity in halophiles, elucidating the molecular basis of halophilic enzyme activity in response to salts.

Engineering of Methionine Sulfoxide Reductase A with Expanded Substrate Scope for Deracemization of Sulfinyl Esters

Engineering of Methionine Sulfoxide Reductase A with Expanded Substrate Scope for Deracemization of Sulfinyl Esters

Methionine sulfoxide reductase B2 protects against cardiac complications in diabetes mellitus

Diabetes mellitus (DM) is a progressive, chronic metabolic disorder characterized by high oxidative stress, which can lead to cardiac damage. Methionine sulfoxylation (MetO) of proteins by excessive reactive oxygen species (ROS) can impair the basic functionality of essential cellular proteins, contributing to heart failure. Methionine sulfoxide reductase B2 (MsrB2) can reverse oxidation induced MetO in mitochondrial proteins, so we investigated its role in diabetic cardiomyopathy. We observed that DM-induced heart damage in diabetic mice model is characterized by increased ROS, increased protein MetO with mitochondria structural pathology, and cardiac fibrosis. In addition, MsrB2 was significantly increased in mouse DM cardiomyocytes, supporting the induction of a protective process. Further, MsrB2 directly induces Parkin and LC3 activation (mitophagy markers) in cardiomyocytes. In MsrB2, knockout mice displayed abnormal electrophysiological function, as determined by ECG analysis. Histological analysis confirmed increased cardiac fibrosis and disrupted cardiac tissue in MsrB2 knockout DM mice. We then corroborated our findings in human DM heart samples. Our study demonstrates that increased MsrB2 expression in the heart protects against diabetic cardiomyopathy.Graphic

Integrated genetic analysis identifies a protective effect of MSRA against renal cell carcinoma

Purpose: Deficiencies in methionine sulfoxide reductase (MSR) enzymes, which function as a defense system against oxidative stress, have been linked to age-related diseases, including cancer and neurodegenerative diseases. This study aimed to assess the association between genetic variants in MSR genes and susceptibility to renal cell carcinoma (RCC). Materials and methods: We systematically evaluated the effects of 89 common MSR gene polymorphisms on the risk of developing RCC in a cohort of 630 patients and controls. Furthermore, publicly available gene expression datasets were used to analyze gene expression and patient prognosis. Results: After adjusting for covariates and multiple testing corrections, MSRA rs56198596 and rs11782000 showed significant associations with the risk of RCC. Analysis of expression quantitative trait loci indicated that the risk alleles of these 2 variants tended to correlate with reduced MSRA expression. Pooled analyses of 19 kidney cancer gene expression datasets revealed that RCC exhibited lower MSRA expression than did normal tissues (P < 0.001) and that higher MSRA expression was associated with improved patient prognosis (P < 0.001). Conclusion: These findings suggest that MSRA gene variants may affect the risk of RCC, highlighting the potential protective role of MSRA and its contribution to a favorable RCC prognosis.

A comprehensive comparative genomic analysis revealed that plant growth promoting traits are ubiquitous in strains of Stenotrophomonas.

Stenotrophomonas strains, which are often described as plant growth promoting (PGP) bacteria, are ubiquitous in many environments. A total of 213 genomes of strains of Stenotrophomonas were analyzed using comparative genomics to better understand the ecological roles of these bacteria in the environment. The pan-genome of the 213 strains of Stenotrophomonas consists of 27,186 gene families, including 710 core gene families, 11,039 unique genes and 15,437 accessory genes. Nearly all strains of Stenotrophomonas harbor the genes for GH3-family cellulose degradation and GH2- and GH31-family hemicellulose hydrolase, as well as intact glycolysis and tricarboxylic acid cycle pathways. These abilities suggest that the strains of this genus can easily obtain carbon and energy from the environment. The Stenotrophomonas strains can respond to oxidative stress by synthesizing catalase, superoxide dismutase, methionine sulfoxide reductase, and disulfide isomerase, as well as managing their osmotic balance by accumulating potassium and synthesizing compatible solutes, such as betaine, trehalose, glutamate, and proline. Each Stenotrophomonas strain also contains many genes for resistance to antibiotics and heavy metals. These genes that mediate stress tolerance increase the ability of Stenotrophomonas strains to survive in extreme environments. In addition, many functional genes related to attachment and plant colonization, growth promotion and biocontrol were identified. In detail, the genes associated with flagellar assembly, motility, chemotaxis and biofilm formation enable the strains of Stenotrophomonas to effectively colonize host plants. The presence of genes for phosphate-solubilization and siderophore production and the polyamine, indole-3-acetic acid, and cytokinin biosynthetic pathways confer the ability to promote plant growth. These strains can produce antimicrobial compounds, chitinases, lipases and proteases. Each Stenotrophomonas genome contained 1-9 prophages and 17-60 genomic islands, and the genes related to antibiotic and heavy metal resistance and the biosynthesis of polyamines, indole-3-acetic acid, and cytokinin may be acquired by horizontal gene transfer. This study demonstrates that strains of Stenotrophomonas are highly adaptable for different environments and have strong potential for use as plant growth-promoting bacteria.

The association of protein-bound methionine sulfoxide with proteomic basis for aging in beech seeds

BackgroundEuropean beech (Fagus sylvatica L.) trees produce seeds irregularly; therefore, it is necessary to store beech seeds for forestation. Despite the acquisition of desiccation tolerance during development, beech seeds are classified as intermediate because they lose viability during long-term storage faster than typical orthodox seeds. In this study, beech seeds stored for short (3 years) or long (20 years) periods under optimal conditions and displaying 92 and 30% germination capacity, respectively, were compared.ResultsAged seeds displayed increased membrane damage, manifested as electrolyte leakage and lipid peroxidation levels. Analyses have been based on embryonic axes, which contained higher levels of reactive oxygen species (ROS) and higher levels of protein-bound methionine sulfoxide (MetO) in aged seeds. Using label-free quantitative proteomics, 3,949 proteins were identified, of which 2,442 were reliably quantified pointing to 24 more abundant proteins and 35 less abundant proteins in beech seeds under long-term storage conditions. Functional analyses based on gene ontology annotations revealed that nucleic acid binding activity (molecular function), ribosome organization or biogenesis and transmembrane transport (cellular processes), translational proteins (protein class) and membranous anatomical entities (cellular compartment) were affected in aged seeds. To verify whether MetO, the oxidative posttranslational modification of proteins that can be reversed via the action of methionine sulfoxide reductase (Msr) enzymes, is involved in the aging of beech seeds, we identified and quantified 226 MetO-containing proteins, among which 9 and 19 exhibited significantly up- and downregulated MetO levels, respectively, in beech seeds under long-term storage conditions. Several Msr isoforms were identified and recognized as MsrA1-like, MsrA4, MsrB5 and MsrB5-like in beech seeds. Only MsrA1-like displayed decreased abundance in aged seeds.ConclusionsWe demonstrated that the loss of membrane integrity reflected in the elevated abundance of membrane proteins had a higher impact on seed aging progress than the MetO/Msr system. Proteome analyses enabled us to propose protein Sec61 and glyceraldehyde-3-phosphate dehydrogenase as potential longevity modulators in beech seeds.

Follistatin-like protein 1 attenuates doxorubicin-induced cardiomyopathy by inhibiting MsrB2-mediated mitophagy.

Doxorubicin (DOX) is a potent chemotherapeutic drug; however, its clinical use is limited due to its cardiotoxicity. Mitochondrial dysfunction plays a vital role in the pathogenesis of DOX-induced cardiomyopathy. Follistatin-like protein 1 (FSTL1) is a potent cardiokine that protects the heart from diverse cardiac diseases, such as myocardial infarction, cardiac ischemia/reperfusion injury, and heart failure. However, its role in DOX-induced cardiomyopathy is unclear. Therefore, the present study investigated whether administering recombinant FSTL1 could mitigate DOX-induced cardiomyopathy and clarified the underlying molecular mechanisms. FSTL1 treatment attenuated DOX-induced cardiac dysfunction, cardiac fibrosis, and cellular apoptosis by inhibiting excess mitochondrial matrix protein methionine sulfoxide reductase B2 (MsrB2)-mediated mitophagy. Furthermore, FSTL1 administration reduced the expression of apoptotic proteins, including MsrB2, Bax, caspase 3, mitochondrial Parkin, and LC3-II, increased myocardial ATP content, and decreased cardiac malondialdehyde levels, thus protecting mitochondrial function against DOX-induced cardiac injury. Furthermore, FSTL1 treatment protected the contractile properties of adult cardiomyocytes against DOX-induced injury in vitro. Furthermore, carbonyl cyanide m-chlorophenylhydrazone, a mitophagy inducer, impaired the protective effects of FSTL1 in DOX-treated H9c2 cardiomyocytes. In conclusion, these results show that FSTL1 is a novel therapeutic agent against DOX-induced cardiotoxicity that improves mitochondrial function and decreases mitophagy.

MSRB2 Ameliorates H2O2-induced Chondrocyte Oxidative Stress and Suppresses Apoptosis in Osteoarthritis

ABSTRACT Background Chondrocyte oxidative stress and apoptosis are critical factors contributing to the pathogenesis of osteoarthritis (OA). Methionine sulfoxide reductase B2 (MSRB2) is a mitochondrial protein that protects cells from oxidative stress and is involved in apoptosis. This study aimed to investigated the expression of MSRB2 in articular cartilage tissues and elucidated its effect on H2O2-stimulated chondrocytes. Methods Human chondrocytes were cultured in Dulbecco’s modified Eagle’s medium (DMEM)/F12. MSRB2 overexpression in chondrocytes was achieved by transfecting with an MSRB2 overexpression plasmid. Western blot, quantitative RT-PCR, Immunofluorescence staining, and TUNEL assay were employed in this study. Results MSRB2 expression was found to be reduced in OA patients. Furthermore, overexpression of MSRB2 in H2O2-induced chondrocytes mitigated apoptosis and enhanced cell viability. Elevated MSRB2 expression diminished chondrocyte ROS contents, decreased cytochrome C (Cyc) in the cytoplasm, and regulated mitochondrial membrane potential to maintain mitochondrial homeostasis. Interestingly, knockdown of charged multivesicular body protein 5 (CHMP5) led to a decreased inMSRB2 expression in chondrocytes. Additionally, protein levels of CHMP5 and MSRB2 were reduced in H2O2-stimulated chondrocytes, and silencing CHMP5 reduced MSRB2 expression. Knockdown of CHMP5 increased cleaved caspase-3 expression in H2O2-induced chondrocytes and elevated TUNEL-positive chondrocytes. Conclusion MSRB2 decreased in OA, and overexpression of MSRB2 alleviated oxidative stress and apoptosis of chondrocyte.

The DmsABC S-oxide reductase is an essential component of a novel, hypochlorite-inducible system of extracellular stress defense in Haemophilus influenzae.

Defenses against oxidative damage to cell components are essential for survival of bacterial pathogens during infection, and here we have uncovered that the DmsABC S-/N-oxide reductase is essential for virulence and in-host survival of the human-adapted pathogen, Haemophilus influenzae. In several different infection models, H. influenzae ΔdmsA strains showed reduced immunogenicity as well as lower levels of survival in contact with host cells. Expression of DmsABC was induced in the presence of hypochlorite and paraquat, closely linking this enzyme to defense against host-produced antimicrobials. In addition to methionine sulfoxide, DmsABC converted nicotinamide- and pyrimidine-N-oxide, precursors of NAD and pyrimidine for which H. influenzae is an auxotroph, at physiologically relevant concentrations, suggesting that these compounds could be natural substrates for DmsABC. Our data show that DmsABC forms part of a novel, periplasmic system for defense against host-induced S- and N-oxide stress that also comprises the functionally related MtsZ S-oxide reductase and the MsrAB peptide methionine sulfoxide reductase. All three enzymes are induced following exposure of the bacteria to hypochlorite. MsrAB is required for physical resistance to HOCl and protein repair. In contrast, DmsABC was required for intracellular colonization of host cells and, together with MtsZ, contributed to resistance to N-Chlorotaurine. Our work expands and redefines the physiological role of DmsABC and highlights the importance of different types of S-oxide reductases for bacterial virulence.

Methionine biosynthetic genes and methionine sulfoxide reductase A are required for Rhizoctonia solani AG1-IA to cause sheath blight disease in rice.

Rhizoctonia solani is a polyphagous necrotrophic fungal pathogen that causes sheath blight disease in rice. It deploys effector molecules as well as carbohydrate-active enzymes and enhances the production of reactive oxygen species for killing host tissues. Understanding R. solani ability to sustain growth under an oxidative-stress-enriched environment is important for developing disease control strategies. Here, we demonstrate that R. solani upregulates methionine biosynthetic genes, including Rs_MET13 during infection in rice, and double-stranded RNA-mediated silencing of these genes impairs the pathogen's ability to cause disease. Exogenous treatment with methionine restores the disease-causing ability of Rs_MET13-silenced R. solani and facilitates its growth on 10 mM H2O2-containing minimal-media. Notably, the Rs_MsrA gene that encodes methionine sulfoxide reductase A, an antioxidant enzyme involved in the repair of oxidative damage of methionine, is upregulated upon H2O2 treatment and also during infection in rice. Rs_MsrA-silenced R. solani is unable to cause disease, suggesting that it is important for the repair of oxidative damage in methionine during host colonization. We propose that spray-induced gene silencing of Rs_MsrA and designing of antagonistic molecules that block MsrA activity can be exploited as a drug target for effective control of sheath blight disease in rice.

Exploring the anticancer and antibacterial potential of naphthoquinone derivatives: a comprehensive computational investigation.

This study investigates the potential of 2-(4-butylbenzyl)-3-hydroxynaphthalene-1,4-dione (11) and its 12 derivatives as anticancer and biofilm formation inhibitors for methicillin-resistant staphylococcus aureus using in silico methods. The study employed various computational methods, including molecular dynamics simulation molecular docking, density functional theory, and global chemical descriptors, to evaluate the interactions between the compounds and the target proteins. The docking results revealed that compounds 9, 11, 13, and ofloxacin exhibited binding affinities of -7.6, -7.9, -7.5, and -7.8kcalmol-1, respectively, against peptide methionine sulfoxide reductase msrA/msrB (PDB: 3E0M). Ligand (11) showed better inhibition for methicillin-resistant staphylococcus aureus msrA/msrB enzyme. The complex of the 3E0M-ligand 11 remained highly stable across all tested temperatures (300, 305, 310, and 320K). Principal Component Analysis (PCA) was employed to evaluate the behavior of the complex at various temperatures (300, 305, 310, and 320K), demonstrating a total variance of 85%. Convergence was confirmed by the eigenvector's cosine content value of 0.43, consistently displaying low RMSD values, with the minimum observed at 310K. Furthermore, ligand 11 emerges as the most promising candidate among the compounds examined, showcasing notable potential when considering a combination of in vitro, in vivo, and now in silico data. While the naphthoquinone derivative (11) remains the primary candidate based on comprehensive in silico studies, further analysis using Frontier molecular orbital (FMO) suggests while the Egap value of compound 11 (2.980eV) and compound 13 (2.975eV) is lower than ofloxacin (4.369eV), indicating their potential, so it can be a statement that compound 13 can also be investigated in further research.

Ultrasonic seed treatment improved seed germination, growth, and yield of rice by modulating associated physio-biochemical mechanisms

Ultrasonic seed (US) treatment could alter seed germination mechanism, however, US induced alterations in morph-physiological attributes and yield of fragrant rice were rarely reported. In the present study, the seeds of three fragrant rice cultivars viz., Xiangyaxiangzhan, Meixiangzhan 2, Ruanhuayou 6100 and one non-fragrant rice viz., Wufengyou 615 were exposed to ultrasonic waves at 20–40 kHz for 1.5 min (T) whereas the seeds without exposure were taken as control (CK). Results showed that US treatment caused minor cracks on seed surface while improved seed germination rate (1.79 %-11.09 %) and 3-indoleacetic acid (IAA) (3.36 %-46.91 %). Furthermore, peroxidase (POD) activity and methionine sulfoxide reductase activity was increased by 29.15 %-74.13 % and 11.26 %-20.87 %, respectively; however, methionine sulfoxide reductase related protein repairing gene MSRA4 was down-regulated by 17.93 % −41.04 % under T, compared to CK. Besides, US treatment also improved soluble protein in flag leaf (0.92 %-40.79 %), photosynthesis (3.37 %-16.46 %), biomass (5.17 %-31.87 %), as well as 2-acetyl-1-pyrroline content (4.77 %-15.48 %) in rice grains. In addition, multivariate analysis showed that the dry weight at the maturity stage were significantly related to the POD, glutathione reductase (GR) activity, IAA, and abscisic acid (ABA) content while germination rate was positively related to the GR activity, ABA content, and yield, but which were negatively related to the IAA and gibberellic acid content.

Synthesis of Chiral Sulfoxides by A Cyclic Oxidation-Reduction Multi-Enzymatic Cascade Biocatalysis.

Optically pure sulfoxides are valuable organosulfur compounds extensively employed in medicinal and organic synthesis. In this study, we present a biocatalytic oxidation-reduction cascade system designed for the preparation of enantiopure sulfoxides. The system involves the cooperation of a low-enantioselective chimeric oxidase SMO (styrene monooxygenase) with a high-enantioselective reductase MsrA (methionine sulfoxide reductase A), facilitating "non-selective oxidation and selective reduction" cycles for prochiral sulfide oxidation. The regeneration of requisite cofactors for MsrA and SMO was achieved via a cascade catalysis process involving three auxiliary enzymes, sustained by cost-effective D-glucose. Under the optimal reaction conditions, a series of heteroaryl alkyl, aryl alkyl and dialkyl sulfoxides in R configuration were synthesized through this "one-pot, one step" cascade reaction. The obtained compounds exhibited high yields of >90 % and demonstrated enantiomeric excess (ee) values exceeding 90 %. This study represents an unconventional and efficient biocatalytic way in utilizing the low-enantioselective oxidase for the synthesis of enantiopure sulfoxides.

Anaerobic respiration of host-derived methionine sulfoxide protects intracellular Salmonella from the phagocyte NADPH oxidase

Intracellular Salmonella experiencing oxidative stress downregulates aerobic respiration. To maintain cellular energetics during periods of oxidative stress, intracellular Salmonella must utilize terminal electron acceptors of lower energetic value than molecular oxygen. We show here that intracellular Salmonella undergoes anaerobic respiration during adaptation to the respiratory burst of the phagocyte NADPH oxidase in macrophages and in mice. Reactive oxygen species generated by phagocytes oxidize methionine, generating methionine sulfoxide. Anaerobic Salmonella uses the molybdenum cofactor-containing DmsABC enzymatic complex to reduce methionine sulfoxide. The enzymatic activity of the methionine sulfoxide reductase DmsABC helps Salmonella maintain an alkaline cytoplasm that supports the synthesis of the antioxidant hydrogen sulfide via cysteine desulfuration while providing a source of methionine and fostering redox balancing by associated dehydrogenases. Our investigations demonstrate that nontyphoidal Salmonella responding to oxidative stress exploits the anaerobic metabolism associated with dmsABC gene products, a pathway that has accrued inactivating mutations in human-adapted typhoidal serovars.

An integrative pan-cancer bioinformatics analysis of MSRB1 and its association with tumor immune microenvironment, prognosis, and immunotherapy

Methionine sulfoxide reductase B1 (MSRB1) is involved in the development and immune regulation of multiple tumors. However, the role of MSRB1 in the tumor microenvironment and its potential as a therapeutic target remain largely unknown. In this study, MSRB1 expression patterns were evaluated using pan-cancer RNA sequencing data from multiple cell lines, tissues, and single cells. The pan-cancer prognostic role of MSRB1 was assessed and the association between MSRB1 expression and certain cancer characteristics was analyzed. We showed that MSRB1 expression levels were increased in several types of cancer (P < 0.05) and in certain cell types (macrophages, dendritic cells, and malignant tumor cells). The upregulation of MSRB1 expression was due to DNA copy number amplification. Furthermore, MSRB1 was significantly associated with the activation of immune pathways (P < 0.05, NES > 0), immune cell infiltration, and expression of immune checkpoint molecules. In addition, high expression of MSRB1 was found in a series of in vivo and in vitro immunotherapy response models (P < 0.05), and showed resistance to most targeted drugs. Our results indicated that MSRB1 may regulate the tumor immune microenvironment through an immunoresponse and potentially influence cancer development. This could make it a promising predictive biomarker and therapeutic target for precise tumor immunotherapy.