Fe-superoxide Dismutase Research Articles

Synergistic inhibition effect and mechanism of an inhibitor for entire process inhibition of coal spontaneous combustion

Traditional coal spontaneous combustion (CSC) inhibitors, while effective, have limitations such as frequent application or short-term efficacy. To this end, we developed a slow-release and water-soluble synergistic inhibitor (SWSI) to achieve long-term CSC inhibition. The SWSI was formulated by integrating synergistic antioxidants (SA) composed of ascorbic acid (AsA) and Fe-superoxide dismutase (Fe-SOD) dissolved in a super absorbent polymer (SAP) encapsulated within hydrogel microcapsules. The effectiveness of SWSI was evaluated through simultaneous thermal analysis and in-situ free radical tests. The formulation optimization demonstrated that AsA and Fe-SOD had the maximum synergistic inhibition effect at a 1:1 molar ratio. The optimal SA: SAP ratio of 3:1 achieved the lowest oxygen consumption rate and highest inhibition rate. The encapsulation formulation, consisting of 3% SA, 6% PAM, 1% CaCl2, and 0.5% citric acid, generated the highest swelling ratio. Simultaneous thermal analysis and in-situ free radical tests indicated that SWSI greatly increased feature temperatures and the apparent activation energy, lowered reaction heat, and substantially reduced free radical concentration in the full oxidation process. The newly developed SWSI offers a significant advancement in long-term CSC prevention by integrating physical and chemical inhibition, which provides sustained and effective inhibition throughout the entire oxidation process.

Allelic variants confer Arabidopsis adaptation to small regional environmental differences.

Natural populations of Arabidopsis thaliana provide powerful systems to study the adaptation of wild plant species. Previous research has predominantly focused on global populations or accessions collected from regions with diverse climates. However, little is known about the genetics underlying adaptation in regions with mild environmental clines. We have examined a diversity panel consisting of 192 A. thaliana accessions collected from the Netherlands, a region with limited climatic variation. Despite the relatively uniform climate, we identified evidence of local adaptation within this population. Notably, semidwarf accessions, due to mutation of the GIBBERELLIC ACID REQUIRING 5 (GA5) gene, occur at a relatively high frequency near the coast and these displayed enhanced tolerance to high wind velocities. Additionally, we evaluated the performance of the population under iron deficiency conditions and found that allelic variation in the FE SUPEROXIDE DISMUTASE 3 (FSD3) gene affects tolerance to low iron levels. Moreover, we explored patterns of local adaptation to environmental clines in temperature and precipitation, observing that allelic variation at LA RELATED PROTEIN 1C (LARP1c) likely affects drought tolerance. Not only is the genetic variation observed in a diversity panel of A. thaliana collected in a region with mild environmental clines comparable to that in collections sampled over larger geographic ranges but it is also sufficiently rich to elucidate the genetic and environmental factors underlying natural plant adaptation.

Reduction in the cadmium (Cd) accumulation and toxicity in pearl millet (Pennisetum glaucum L.) by regulating physio-biochemical and antioxidant defense system via soil and foliar application of melatonin

Cadmium (Cd) is among the toxic pollutants that harms the both animals and plants. The natural antioxidant, melatonin can improve Cd-stress tolerance but its potential role in reducing Cd stress and resilience mechanisms in pearl millet (Pennisetum glaucum L.) is remain unclear. The present study suggests that Cd causes severe oxidative damage by decreasing photosynthesis, and increasing reactive oxygen species (ROS), malondialdehyde content (MDA), and Cd content in different parts of pearl millet. However, exogenous melatonin (soil application and foliar treatment) mitigated the Cd toxicity and enhanced the growth, antioxidant defense system, and differentially regulated the expression of antioxidant-responsive genes i. e superoxide dismutase SOD-[Fe] 2, Fe-superoxide dismutase, Peroxiredoxin 2C, and L-ascorbate peroxidase-6. The results showed that foliar melatonin at F-200/50 significantly increased the plant height, chlorophyll a, b, a+b and carotenoids by 128%, 121%, 150%, 122%, and 69% over the Cd treatment, respectively. The soil and foliar melatonin at S-100/50 and F-100/50 reduced the ROS by 36%, and 44%, and MDA by 42% and 51% over the Cd treatment, respectively. Moreover, F200/50 significantly boosted the activities of antioxidant enzymes i. e SOD by 141%, CAT 298%, POD 117%, and APX 155% over the Cd treatment. Similarly, a significant reduction in Cd content in root, stem, and leaf was found on exposure to higher concentrations of exogenous melatonin. These findings suggest that exogenous melatonin may significantly and differentially improve the tolerance to Cd stress in crop plants. However, field applications, type of plant species, concentration of dose, and type of stress may vary with the degree of tolerance in crop plants.

Chronological transcriptome changes induced by exposure to cyanoacrylate resin nanoparticles in Chlamydomonas reinhardtii with a focus on ROS development and cell wall lysis-related genes

Resin nanoparticles composed of isobutyl cyanoacrylate polymers (iBCA-NPs) are reported to induce acute cell death in many microalgal species. Chronological transcriptome changes induced by exposure to iBCA-NPs in Chlamydomonas reinhardtii (Chlorophyceae) were investigated using next-generation sequencing. Genes encoding antioxidant enzymes, such as glutathione peroxidase (GPX5), Fe-superoxide dismutase (Fe-SOD), and glutathione S-transferase (GSTS1), were prominently upregulated when the cell death ratio reached approximately 3 %. Subsequently, strong expression of these genes was maintained even when the cell death ratio reached ~30 %. Apart from these genes, nine out of 20 heat shock protein (HSP)-coding genes were also upregulated. There was a positive correlation between cell death and ROS accumulation. Upregulation of these genes must be a response to cope with the stresses induced by the ROS accumulation.Cre13.g605200, which is one of 31 genes annotated to encode cell wall hydrolytic enzymes, was highly upregulated by exposure to iBCA-NPs. Three tag-insertion mutants of the Cre13.g605200 gene showed considerably more resistance to cell wall hydrolysis and nanoparticle-induced cell death than the parent strain, suggesting that the Cre13.g605200 gene encodes a cell wall hydrolytic enzyme, and that its upregulation contributes to acute cell death induced by the iBCA-NPs. Positive contribution of the Cre13.g605200 to cell death suggests that the target of nanoparticles (NPs) to induce cell death is located inside the cell walls.The laddering DNA of nucleosome units, a hallmark of programmed cell death (PCD), was barely detectable in the smeared DNA of C. reinhardtii cells exposed to iBCA-NPs. This shows that necrosis-like cell death is the most common type of induced cell death caused by iBCA-NPs exposure. Induced cell death can be the result of intracellular damage to proteins, lipids and DNA caused by ROS.

A Study of the Interface of Gold Nanoparticles Conjugated to Cowpea Fe-Superoxide Dismutase.

The iron superoxide dismutase (FeSOD) is a first barrier to defend photosynthetic organisms from superoxide radicals. Although it is broadly present in plants and bacteria, FeSODs are absent in animals. They belong to the same phylogenic family as Mn-containing SODs, which are also highly efficient at detoxifying superoxide radicals. In addition, SODs can react with peroxynitrite, and FeSOD enzyme has already been used to evaluate the anti-nitrative capacity of plant antioxidants. Gold nanoparticles (AuNPs) have been shown to significantly improve the functionality and the efficiency of ligands, providing they are properly assembled. In this work, the characteristics of the recombinant cowpea (Vigna unguiculata) FeSOD (rVuFeSOD) immobilized onto AuNPs were investigated as a function of (1) NP surface chemistry and (2) biofunctionalization methods, either physical adsorption or covalent bonding. The NP surface chemistry was studied by varying the concentration of the ligand molecule 11-mercaptoundecanoic acid (MUA) on the NP surface. The coverage and activity of the protein on AuNPs was determined and correlated to the surface chemistry and the two biofunctionalization methods. rVuFeSOD-AuNPs conjugate stability was monitored through absorption measurements, agarose gel electrophoresis and DLS, enzymatic activity by a colorimetric assay and by in-gel activity assay, and coverage was measured by colorimetric assay. When using physical adsorption, the NP is the most perturbing agent for the activity of the enzyme. In contrast, only the NP coverage was affected by MUA ligand concentration. However, during covalent attachment, both the NP and the concentration of MUA on the surface influenced the enzyme activity, while the coverage of the NP remained constant. The results evidence the importance of the biomolecule and AuNP interaction for the functionality of the hybrid. These strategies can be used to develop electrochemical biosensors for O2•- and for peroxynitrite in biomedical applications.

IDENTIFICATION OF GENES REGULATED IN RESPONSE TO Cu EXPOSURE IN Brassica nigra L.

Copper (Cu) is one of the essential trace metals required for plant growth. High amount of Cu in the media inhibits plant growth and is toxic to the plants. Brassica nigra L., a Cu accumulator, can tolerate a high amount of Cu and have specific mechanisms to relocate Cu within the cell compartments and keep the toxic amount of Cu away from the cytoplasm. This study aimed to evaluate the Cu-induced gene expression pattern of B. nigra Diyarbakir ecotype subjected to low Cu treatment. The Arabidopsis ATH1 genome array was used to determine the Cu-induced gene expression in the leaves of B. nigra grown at 25 µM Cu. Ninety-five genes were upregulated, and seventy-two genes were downregulated in the leaves of plants grown under 25 µM Cu. Cu responsive genes, such as glutathione S-transferase, glutathione reductase, heavy metal transporters, natural resistance-associated macrophage proteins, cytochrome p450, MYB-like transcription factor, copper/zinc, and Fe superoxide dismutases, and some protein kinases were highly expressed in the leaves of Cu-treated plants. The present work provides the global gene expression pattern in facultative metallophyte B. nigra, which could serve as a molecular tool for future phytoremediation studies.

Tolerance of Pseudomonas strain to the 2,4-D herbicide through a peroxidase system.

Herbicides are widely used in agricultural practices for preventing the proliferation of weeds. Upon reaching soil and water, herbicides can harm nontarget organisms, such as bacteria, which need an efficient defense mechanism to tolerate stress induced by herbicides. 2,4-Dichlorophenoxyacetic acid (2,4-D) is a herbicide that exerts increased oxidative stress among bacterial communities. Bacterial isolates were obtained from the biofilm of tanks containing washing water from the packaging of different pesticides, including 2,4-D. The Pseudomonas sp. CMA-7.3 was selected because of its tolerance against 2,4-D toxicity, among several sensitive isolates from the biofilm collection. This study aimed to evaluate the antioxidative response system of the selected strain to 2,4-D. It was analyzed the activity of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidase GPX enzymes, that are poorly known in the literature for bacterial systems. The Pseudomonas sp. CMA-7.3 presented an efficient response system in balancing the production of hydrogen peroxide, even at 25x the dose of 2,4-D used in agriculture. The antioxidative system was composed of Fe-SOD enzymes, less common than Mn-SOD in bacteria, and through the activities of KatA and KatB isoforms, working together with APX and GPX, having their activities coordinated possibly by quorum sensing molecules. The peroxide control is poorly documented for bacteria, and this work is unprecedented for Pseudomonas and 2,4-D. Not all bacteria harbor efficient response system to herbicides, therefore they could affect the diversity and functionality of microbiome in contaminated soils, thereby impacting agricultural production, environment sustainability and human health.

Evolution of Superoxide Dismutases and Catalases in Cyanobacteria: Occurrence of the Antioxidant Enzyme Genes before the Rise of Atmospheric Oxygen.

Knowledge on the evolution of antioxidant systems in cyanobacteria is crucial for elucidating the cause and consequence of the rise of atmospheric oxygen in the Earth's history. In this study, to elucidate the origin and evolution of cyanobacterial antioxidant enzymes, we analyzed the occurrence of genes encoding four types of superoxide dismutases and three types of catalases in 85 complete cyanobacterial genomes, followed by phylogenetic analyses. We found that Fe superoxide dismutase (FeSOD), Mn superoxide dismutase (MnSOD), and Mn catalase (MnCat) are widely distributed among modern cyanobacteria, whereas CuZn superoxide dismutase (CuZnSOD), bifunctional catalase (KatG), and monofunctional catalase (KatE) are less common. Ni superoxide dismutase (NiSOD) is distributed among marine Prochlorococcus and Synechococcus species. Phylogenetic analyses suggested that bacterial MnSOD evolved from cambialistic Fe/MnSOD before the diversification of major bacterial lineages. The analyses suggested that FeSOD evolved from MnSOD before the origin of cyanobacteria. MnCat also evolved in the early stages of bacterial evolution, predating the emergence of cyanobacteria. KatG, KatE, and NiSOD appeared 2.3-2.5 billion years ago. Thus, almost all cyanobacterial antioxidant enzymes emerged before or during the rise of atmospheric oxygen. The loss and appearance of these enzymes in marine cyanobacteria may be also related to the change in the metal concentration induced by the increased oxygen concentration in the ocean.

Evaluation of high salinity tolerance in Pongamia pinnata (L.) Pierre by a systematic analysis of hormone‐metabolic network

Salinity stress results in significant losses in plant productivity and loss of cultivable lands. Although Pongamia pinnata is reported to be a salt-tolerant semiarid biofuel tree, the adaptive mechanisms to saline environments are elusive. Despite a reduction in carbon exchange rate (CER), the unchanged relative water content provides no visible salinity induced symptoms in leaves of hydroponic cultivated Pongamia seedlings for 8 days. Our Na+ -specific fluorescence results demonstrated that there was an effective apoplastic sodium sequestration in the roots. Salinity stress significantly increased zeatin (~5.5-fold), and jasmonic acid (~3.8-fold) levels in leaves while zeatin (~2.5-fold) content increased in leaves as well as in roots of salt-treated plants. Metabolite analysis suggested that osmolytes such as myo-inositol and mannitol were enhanced by ~12-fold in leaves and roots of salt-treated plants. Additionally, leaves of Pongamia showed a significant enhancement in carbohydrate content, while fatty acids were accumulated in roots under salt stress condition. At the molecular level, salt stress enhanced the expression of genes related to transporters, including the Salt Overly Sensitive 2 gene (SOS2), SOS3, vacuolar-cation/proton exchanger, and vacuolar-proton/ATPase exclusively in leaves, whereas the Sodium Proton Exchanger1 (NHX1), Cation Calcium Exchanger (CCX), and Cyclic Nucleotide Gated Channel 5 (CNGC5) were up-regulated in roots. Antioxidant gene expression analysis clearly demonstrated that peroxidase levels were significantly enhanced by ~10-fold in leaves, while Catalase and Fe-superoxide Dismutase (Fe-SOD) genes were increased in roots under salt stress. The correlation interaction studies between phytohormones and metabolites revealed new insights into the molecular and metabolic adaptations that confer salinity tolerance to Pongamia.

Distribution and functional analysis of the two types of 8-vinyl reductase involved in chlorophyll biosynthesis in marine cyanobacteria.

In the chlorophyll biosynthesis pathway, the 8-vinyl group of the chlorophyll precursor is reduced to an ethyl group by 8-vinyl reductase. Two isozymes of 8-vinyl reductase have been described in oxygenic photosynthetic organisms: one encoded by BciA and another by BciB. Only BciB contains an [Fe-S] cluster and most cyanobacteria harbor this form; whereas a few contain BciA. Given this disparity in distribution, cyanobacterial BciA has remained largely overlooked, which has limited understanding of chlorophyll biosynthesis in these microorganisms. Here, we reveal that cyanobacterial BciA encodes a functional 8-vinyl reductase, as evidenced by measuring the in vitro activity of recombinant Synechococcus and Acaryochloris BciA. Genomic comparison revealed that BciB had been replaced by BciA during evolution of the marine cyanobacterium Synechococcus, and coincided with replacement of Fe-superoxide dismutase (SOD) with Ni-SOD. These findings imply that the acquisition of BciA confers an adaptive advantage to cyanobacteria living in low-iron oceanic environments.

Exogenous Application of 24-Epibrassinolide Improves Manganese Tolerance in Arabidopsis thaliana L. via the Modulation of Antioxidant System

The goal of the present study was to investigate the role of 24-Epibrassinolide (EBL) hormone in supporting adaptation of plant to manganese (Mn) stress. For this purpose, changes in antioxidant system and stress-related gene expression were determined in rosette leaves of Arabidopsis thaliana following 24-h exposure to Mn (0.5 and 1.0 mM) and/or EBL (1 µM). Decreased chlorophyll level in the rosette leaves of seedlings due to Mn stress increased consequent to exogeneous EBL application. Superoxide dismutase (SOD) and catalase (CAT) enzyme activities alongside transcript level of copper/zinc superoxide dismutase 1 (CSD1), copper/zinc superoxide dismutase 2 (CSD2), copper/zinc superoxide dismutase 3 (CSD3), Fe superoxide dismutase 2 (FSD2), Fe superoxide dismutase 3 (FSD3), and catalase 2 (CAT2) genes were found to increase depending on Mn concentration; however, co-exposure of EBL and Mn led to a further improvement in enzyme activities and gene expressions (except CSD1 and CSD2 genes). The mRNA level of Fe superoxide dismutase 1 (FSD1) gene was downregulated following Mn and/or EBL treatments. Exogenous treatment of EBL improved the total antioxidant and proline level, while it decreased the lipid peroxidation under Mn stress. EBL treatment upregulated transcript level of delta 1-pyrroline-5-carboxylate synthase 1 (P5CS1) and delta 1-pyrroline-5-carboxylate synthase 2 (P5CS2) genes in seedlings treated with Mn. Co-treatment of Mn and EBL enhanced expression level of A. thaliana detoxification 1 (AtDTX1) and A. thaliana detoxification 3 (AtDTX3) genes when compared to the seedlings treated with Mn. Biochemical and molecular results from the current study revealed that EBL regulates antioxidant system in a coordinated manner under A. thaliana Mn stress.

ALM1, encoding a Fe-superoxide dismutase, is critical for rice chloroplast biogenesis and drought stress response

Chloroplasts are the center of plant life activities including photosynthesis, growth and development, and abiotic stress response. Chloroplast development and biogenesis in rice have been studied in detail, but how does abiotic stress affect chloroplasts is less studied. We obtained an albino mutant, alm1, whose chlorophyll content was greatly decreased. Transmission electron microscopy showed that chloroplast development in alm1 was blocked, especially in thylakoid-like structures, which could not form normally. The ALM1 gene encodes a chloroplast-localized superoxide dismutase. Full-length ALM1 successfully restored the non-albino phenotype, and in knockout lines, the albino phenotype reappeared. The ALM1 gene is expressed mainly in young leaves. alm1 plants died as a consequence of excessive reactive oxygen accumulation after the third-leaf stage. A series of biochemical assays verified that ALM1 interacted with the OsTrxz protein, which is one of the components of plastid-encoded RNA polymerase (PEP) complexes. A western blot experiment indicated that ALM1 played an important role in stabilizing OsTrxz in rice. An overexpression test of ALM1 revealed that ALM1 can increase drought resistance by removing excess reactive oxygen in rice seedlings. This study suggests that ALM1 not only participates in rice chloroplast biogenesis, but also increases rice stress resistance by scavenging excess reactive oxygen.

The copper economy response is partially conserved in rice (Oryza sativa L.)

Copper (Cu) is an essential element for plants, especially in photosynthesis, as it is required for plastocyanin function in electron transfer reactions at thylakoid membranes. In Arabidopsis thaliana, Cu deficiency leads to the Cu economy response, in which plants prioritize Cu usage by plastocyanin in detriment of non-essential cupric proteins. In rice (Oryza sativa), however, this response has not been characterized. Rice OsHMA5 is a Cu xylem-loading transporter involved in Cu translocation from roots to shoots, as suggested by the analysis of oshma5 mutant plants. Aiming to understand how rice plants respond to Cu deficiency and how decreased Cu translocation to shoots can affect this response, we characterized the physiological and molecular responses of WT and oshma5 plants under control and Cu deficiency treatments. We found evidence that shoots of oshma5 plants are more prone to Cu deficiency compared to shoots of WT plants, as demonstrated by decreased chlorophyll and Cu concentrations, and electron transport rate. Gene expression analysis revealed that Cu high-affinity transporters OsCOPT1 and OsCOPT5, along with a set of miRNAs and three Cu/Zn superoxide dismutases are responsive to Cu deficiency in both WT and oshma5 plants, suggesting their involvement in the Cu economy response. However, Fe superoxide dismutase was not up-regulated in rice, indicating a difference compared to the A. thaliana Cu economy model. Therefore, we provide evidence for a partially conserved Cu economy response in rice, in comparison to A. thaliana.

Assessment of cytotoxicity biomarkers on the microalga Chlamydomonas reinhardtii exposed to emerging and priority pollutants

Contamination of aquatic ecosystems linked to anthropogenic activity is currently a major concern; therefore, ecotoxicological studies are needed to assess its effect on organisms. The main objective of this study was to investigate the effects of different pollutants on microalgae in search of sensitive biomarkers that can promote a common cytotoxic response regardless of the contaminant. Cultures of the freshwater microalga Chlamydomonas reinhardtii were exposed for 24 h to four chemicals, three emerging pollutants (benzophenone-3, bisphenol A and oxytetracycline) and one priority substance (atrazine). A cytometric panel was carried out to assess toxicity biomarkers including cellular growth, inherent cell properties, viability, vitality, cytoplasmic membrane potential and ROS levels. Lipid peroxidation, photosynthetic efficiency and transcriptional responses of photosynthesis- and oxidative stress-related genes using RT-qPCR were also studied. Some toxicity responses showed a similar pattern; a decrease in growth rate, vitality and photosynthetic efficiency and an increase in autofluorescence and in the number of cells with depolarised cytoplasmic membrane and were found for all chemicals tested. However, ATZ and OTC provoked a decrease in cell size, whereas BP-3 and BPA caused an increase in cell size, intracellular complexity and ROS levels and a decrease in cell viability. Assayed pollutants generally promoted an overexpression of genes related to cellular antioxidant defence system and a subexpression of photosynthesis-related genes. In addition to the traditional growth endpoint, cell vitality, autofluorescence and gene expression of catalase, glutathione peroxidase and Fe-superoxide dismutase were significantly affected for all chemicals tested, showing a common cytotoxic response. Among the tested substances, BP-3 provoked the strongest cytotoxic alterations on this microalga, pointing out that some emerging contaminants could be more harmful to organisms than priority pollutants.

Genome-wide in silico analysis of SOD genes in common bean (Phaseolus vulgaris L.)

Superoxide dismutases (SODs) are a group of enzymes that play essential roles in catalyzing the dismutation of superoxide radicals to protect cells from oxidative damage caused by various adverse conditions. SODs are classified into three types based on their metal cofactors: Cu/ZnSOD, FeSOD, and MnSOD. This study presents the first genome-wide identification of SOD genes in Phaseolus vulgaris L. Eight SOD genes were identified in the genome of P. vulgaris L., including four Cu/ZnSODs (CSD), three FeSODs (FSD) and one MnSOD (MSD). The protein sequence ranged between 166 and 312 amino acids with 5–8 introns each. Most PvSOD genes are in chromosome 7. The syntenic analysis revealed that PvFSD1 and PvFSD2 genes were derived from segmental duplication. As expected, phylogenetic analyses grouped the PvSOD proteins into three classes based on their metal cofactors: copper/zinc (Cu/Zn)SOD, manganese (Mn)SOD, and iron (Fe)SOD. Expression pattern analysis using RNAseq data indicated that three of the PvSOD genes (PvMSD1, PvCSD3, and PvFSD1) were detected in majority of tissues and developmental stages. This study provides a comprehensive analysis about SOD genes in P. vulgaris L. and new resources for future studies on the functional analysis of PvSOD genes in this species of great agronomic importance.

Injectable Enzyme-Based Hydrogel Matrix with Precisely Oxidative Stress Defense for Promoting Dermal Repair of Burn Wound.

Burn wound healing remains a challenging health problem worldwide due to the lack of efficient and precise therapy. Inherent oxidative stress following burn injury is importantly responsible for prolonged inflammation, fibrotic scar, and multiple organ failure. Herein, a bioinspired antioxidative defense system coupling with in situ forming hydrogel, namely, multiresponsive injectable catechol-Fe3+ coordination hydrogel (MICH) matrix, is engineered to promote burn-wound dermal repair by inhibiting tissue oxidative stress. This MICH matrix serves as the special traits of "Fe-superoxide dismutases," small molecular antioxidant (vitamin E), and extracellular matrix (ECM) in alleviating cellular oxidative damage, which demonstrates precise scavenging on reactive oxygen species (ROS) of different cellular locations, blocking lipid peroxidation and cell apoptosis. In in vivo burn-wound treatment, this MICH promptly integrates with injured surrounding tissue to provide hydration microenvironment and physicochemical ECM for burn wounds. Importantly, the MICH matrix suppresses tissue ROS production, reducing the inflammatory response, prompting re-epithelization and neoangiogenesis during wound healing. Meanwhile, the remodeling skin treated with MICH matrix demonstrates low collagen deposition and normal dermal collagen architecture. Overall, the MICH prevents burn wound progression and enhances skin regeneration, which might be a promising biomaterial for burn-wound care and other disease therapy induced by oxidative stress.

Cyclophilin OsCYP20-2 with a novel variant integrates defense and cell elongation for chilling response in rice.

Summary Coordinating stress defense and plant growth is a survival strategy for adaptation to different environments that contains a series of processes, such as, cell growth, division and differentiation. However, little is known about the coordination mechanism for protein conformation change.A cyclophilin OsCYP20‐2 with a variant interacts with SLENDER RICE1 (SLR1) and OsFSD2 in the nucleus and chloroplasts, respectively, to integrate chilling tolerance and cell elongation in rice (Oryza sativa) (FSD2, Fe-superoxide dismutase 2).Mass spectrum assay showed that OsNuCYP20‐2 localized at the nucleus (nuclear located OsCYP20‐2) was a new variant of OsCYP20‐2 that truncated 71 amino‐acid residues in N‐terminal. The loss‐of function OsCYP20‐2 mutant showed sensitivity to chilling stress with accumulation of extra reactive oxygen species (ROS). In chloroplasts, the full‐length OsCYP20‐2 promotes OsFSD2 forming homodimers which enhance its activity, eliminating the accumulation of ROS under chilling stress. However, the mutant had shorter epidermal cells in comparison with wild‐type Hwayoung (HY). In the nucleus, OsCYP20‐2 caused conformation change of SLR1 to promote its degradation for cell elongation.Our data reveal a cyclophilin with a variant with dual‐localization in chloroplasts and the nucleus, which mediate chilling tolerance and cell elongation.

Semiholoenzyme optimizes activity and stability of a hyperthermostable iron-superoxide dismutase

Metal ion coordination is an essential step for the maturation of metalloenzymes. Generally, the metal coordination sites are thought to be fully occupied to achieve the maximum activity and stability. In this research, we compared the structural features, activity and stability of the apo-, semiholo- and holo-forms of a hyperthermostable tetrameric Fe-superoxide dismutase (SOD). Strikingly, the three forms of enzymes had similar compact tetrameric structures. Removal of iron ions destabilized subunit-subunit interactions during guanidine hydrochloride-induced unfolding. The partially metalized semiholoenzyme possessed most of the activity and identical hyperthermostability of the holoenzyme, but weaker propensity to aggregate. Furthermore, both of the iron content and activity of the semiholoenzyme were unaffected by a 200-fold excess iron ions in solutions, suggesting that conformation of the apo-subunits were forced to the close state by the iron-containing subunits. These observations suggest that fully metalized enzyme is probably nonessential for multimeric metalloenzymes and the semiholoenzyme may be a better choice. The unique properties of semiholoenzyme also provide the organisms a compromised solution to survival under metal deficiency conditions.

Mechanisms of scavenging superoxide, hydroxyl, nitrogen dioxide and methoxy radicals by allicin: catalytic role of superoxide dismutase in scavenging superoxide radical

The occurrence of free radicals such as superoxide radical anion ( $${\hbox {O}_{2}}^{\cdot -}$$ ), hydroxyl radical ( $$\hbox {O}\hbox {H}^{\cdot }$$ ), methoxy radical ( $${\hbox {OC}\hbox {H}_{3}}^{\cdot }$$ ) and nitrogen dioxide radical ( $${\hbox {N}\hbox {O}_{2}}^{\cdot }$$ ) inside living cells can be very hazardous as these radicals can modify structures and functions of different biomolecules. Both exogenous antioxidants taken as components of diet and endogenous enzyme antioxidants can scavenge $${\hbox {O}_{2}}^{\cdot -}$$ separately. Mechanisms of scavenging $${\hbox {O}_{2}}^{\cdot -}$$ by combinations of exogenous and endogenous enzyme antioxidants are not understood properly. In order to understand mechanisms of scavenging $${\hbox {O}_{2}}^{\cdot -}$$ , $${\hbox {O}\hbox {H}}^{\cdot }$$ , $${\hbox {OC}\hbox {H}_{3}}^{\cdot }$$ , and $${\hbox {N}\hbox {O}_{2}}^{\cdot }$$ by allicin, and possible roles of superoxide dismutase (SOD) in scavenging $${\hbox {O}_{2}}^{\cdot -}$$ , density functional theory was employed. Marcus theory was also employed to study scavenging of $${\hbox {O}\hbox {H}}^{\cdot }$$ , $${\hbox {OC}\hbox {H}_{3}}^{\cdot }$$ and $${\hbox {N}\hbox {O}_{2}}^{\cdot }$$ by electron transfer. In order to find the most probable mechanisms of scavenging these radicals, different types of reactions such as one and two hydrogen atom transfer (HAT), single electron transfer (SET) and sequential proton loss electron transfer (SPLET) processes were investigated. It is found that allicin can scavenge $${\hbox {O}_{2}}^{\cdot -}$$ via double hydrogen atom transfer catalyzed by Fe-SOD efficiently. Further, allicin can scavenge $${\hbox {O}\hbox {H}}^{\cdot }$$ by SET, and $${\hbox {OC}\hbox {H}_{3}}^{\cdot }$$ and $${\hbox {N}\hbox {O}_{2}}^{\cdot }$$ by SPLET mechanisms most efficiently. Our results are in qualitative agreement with the available experimental data wherever these are available. SYNOPSIS It is shown for the first time, theoretically, that while allicin in the absence of a catalyst would not scavenge $$\hbox {O2}\cdot ^{-}$$ , it would do so efficiently in the presence of the Fe-superoxide dismutase enzyme. It is also shown that allicin is not a scavenger of hydroxyl, nitrogen dioxide and methoxy radicals but its anion would scavenge efficiently all the three radicals by single electron transfer (SET). Further, it is shown that scavenging of nitrogen dioxide and methoxy radicals would occur very efficiently by sequential proton loss electron transfer (SPLET) from allicin.

P-162 - Cytosolic Fe-superoxide dismutase protects Trypanosoma cruzi from macrophage-derived superoxide radical increasing pathogen virulence in vivo

Trypanosoma cruzi, the causative agent of Chagas’ Disease, contains Fe-dependent superoxide dismutases (FeSODs). After invasion, parasites deal with large amounts of macrophage-derived superoxide radical (O2•-), nitric oxide (•NO) and peroxynitrite. In this work, we show that T. cruzi cytosolic Fe-SODB limits intra-parasite peroxynitrite formation during macrophage invasion and protects T. cruzi from macrophage killing. Moreover, Fe-SODB overexpressing parasites caused higher parasitemias and parasite burden in the heart tissue of C57BL/6-infected mice. To understand these observations, we estimated the phagosomal steady-state concentration of O2•- and also, the permeation of its protonated form perhydroxyl radical (HO2•) towards the internalized parasite. The phagosome pH was measured as 5.4 ± 0.1; HO2• fluxes were particularly high (100–150 µM/s) under the acidic pH conditions of the phagosomal compartment (pKa O2•-/ HO2•=4.8). Indeed, inhibition of the macrophage v-ATPase proton pump significantly decreased O2•-detection inside phagocytized T. cruzi. These results indicate that macrophage-derived O2•-/HO2• reach T. cruzi cytosol and that Fe-SODB can detoxify O2•- preventing damage and promoting parasite survival during the infection process.