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Sixue Chen - One of the best experts on this subject based on the ideXlab platform.
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Chemodiversity of the Glucosinolate-Myrosinase System at the Single Cell Type Resolution
Frontiers Media S.A., 2019Co-Authors: Sixue Chen, Shweta Chhajed, Biswapriya B. Misra, Nathalia TelloAbstract:Glucosinolates (GLSs) are a well-defined group of specialized metabolites, and like any other plant specialized metabolites, their presence does not directly affect the plant survival in terms of growth and development. However, specialized metabolites are essential to combat environmental stresses, such as pathogens and herbivores. GLSs naturally occur in many pungent plants in the order of Brassicales. To date, more than 200 different GLS structures have been characterized and their distribution differs from species to species. GLSs co-exist with classical and atypical Myrosinases, which can hydrolyze GLS into an unstable aglycone thiohydroximate-O-sulfonate, which rearranges to produce different degradation products. GLSs, Myrosinases, Myrosinase interacting proteins, and GLS degradation products constitute the GLS-Myrosinase (GM) system (“mustard oil bomb”). This review discusses the cellular and subcellular organization of the GM system, its chemodiversity, and functions in different cell types. Although there are many studies on the functions of GLSs and/or Myrosinases at the tissue and whole plant levels, very few studies have focused on different single cell types. Single cell type studies will help to reveal specific functions that are missed at the tissue and organismal level. This review aims to highlight (1) recent progress in cellular and subcellular compartmentation of GLSs, Myrosinases, and Myrosinase interacting proteins; (2) molecular and biochemical diversity of GLSs and Myrosinases; and (3) Myrosinase interaction with its interacting proteins, and how it regulates the degradation of GLSs and thus the biological functions (e.g., plant defense against pathogens). Future prospects may include targeted approaches for engineering/breeding of plants and crops in the cell type-specific manner toward enhanced plant defense and nutrition
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Table_1_Chemodiversity of the Glucosinolate-Myrosinase System at the Single Cell Type Resolution.pdf
2019Co-Authors: Shweta Chhajed, Biswapriya B. Misra, Nathalia Tello, Sixue ChenAbstract:Glucosinolates (GLSs) are a well-defined group of specialized metabolites, and like any other plant specialized metabolites, their presence does not directly affect the plant survival in terms of growth and development. However, specialized metabolites are essential to combat environmental stresses, such as pathogens and herbivores. GLSs naturally occur in many pungent plants in the order of Brassicales. To date, more than 200 different GLS structures have been characterized and their distribution differs from species to species. GLSs co-exist with classical and atypical Myrosinases, which can hydrolyze GLS into an unstable aglycone thiohydroximate-O-sulfonate, which rearranges to produce different degradation products. GLSs, Myrosinases, Myrosinase interacting proteins, and GLS degradation products constitute the GLS-Myrosinase (GM) system (“mustard oil bomb”). This review discusses the cellular and subcellular organization of the GM system, its chemodiversity, and functions in different cell types. Although there are many studies on the functions of GLSs and/or Myrosinases at the tissue and whole plant levels, very few studies have focused on different single cell types. Single cell type studies will help to reveal specific functions that are missed at the tissue and organismal level. This review aims to highlight (1) recent progress in cellular and subcellular compartmentation of GLSs, Myrosinases, and Myrosinase interacting proteins; (2) molecular and biochemical diversity of GLSs and Myrosinases; and (3) Myrosinase interaction with its interacting proteins, and how it regulates the degradation of GLSs and thus the biological functions (e.g., plant defense against pathogens). Future prospects may include targeted approaches for engineering/breeding of plants and crops in the cell type-specific manner toward enhanced plant defense and nutrition.
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characterization of glucosinolate Myrosinase system in developing salt cress thellungiella halophila
Physiologia Plantarum, 2009Co-Authors: Sixue Chen, Qiuying Pang, Xiufeng YanAbstract:Glucosinolates are specialized plant metabolites derived from amino acids. They can be hydrolyzed by Myrosinases into different degradation products, which have a variety of biological activities. In this study, the compositions and contents of glucosinolates in salt cress (Thellungiella halophila) at different developmental stages were analyzed by high performance liquid chromatography and mass spectrometry (HPLC-MS). Myrosinase activities were also measured. Seven glucosinolates were identified in T. halophila throughout its life cycle. The glucosinolate profiles varied significantly among different tissues. The roots at stage 4 contained the highest concentrations of total, aromatic and indole glucosinolates among all tissues. Whereas roots, flowers and siliques contained all seven glucosinolates, seeds contained only four aliphatic glucosinolates. During development, the concentrations also displayed significant changes. From seeds to cotyledons and from stage 4 roots to stage 5 roots, there were dramatic declines of glucosinolates, which correlated well with changes in Myrosinase activities. In other tissues, Myrosinase activity alone could not explain the glucosinolate concentration changes. Certain tissues of T. halophila contained Arabidopsis Myrosinase TGG1 and TGG2 orthologs. The molecular basis and functional significance of our findings are discussed here.
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comparative investigations of the glucosinolate Myrosinase system in arabidopsis suspension cells and hypocotyls
Plant and Cell Physiology, 2008Co-Authors: Sophie Alvarez, Sixue Chen, Yan HeAbstract:: Glucosinolates are secondary metabolites derived from amino acids. Upon hydrolysis by Myrosinases, they produce a variety of biologically active compounds. In this study, the glucosinolate-Myrosinase system was characterized in Arabidopsis suspension cells. A total of seven glucosinolates were identified and the Myrosinase activity was determined. Plant suspension cells have been used as model systems in many areas of study. To investigate whether the glucosinolate-Myrosinase system in suspension cells works similarly to that in planta, 10-day-old seedling hypocotyls were used for comparative studies. A total of 16 glucosinolates were identified in hypocotyls. The two types of samples were also treated with methyljasmonate (MeJA)--a signaling compound induced by herbivore attack and wounding to initiate plant defense processes. The glucosinolate levels and their responses to MeJA varied greatly with the age of the cells. Two-day-old cells were most responsive, with the levels of all seven glucosinolates induced by MeJA, while in 4-day-old cells only the levels of indole glucosinolates were increased. In hypocotyls, the levels of indole glucosinolates and aliphatic glucosinolates (especially 4-methylsulfinylbutyl- and 8-methylsulfinyloctylglucosinolates) were significantly increased by MeJA treatment. The transcript levels of several genes involved in glucosinolate biosynthesis were induced in both suspension cells and hypocotyls after MeJA treatment. Myrosinase levels and activities were also monitored. The molecular bases underlying the differences of glucosinolate metabolism in the suspension cells and hypocotyls were discussed.
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functional expression and characterization of the Myrosinase myr1 from brassica napus in saccharomyces cerevisiae
Protein Expression and Purification, 1999Co-Authors: Sixue Chen, Barbara Ann HalkierAbstract:Myrosinases are thioglucosidases that hydrolyze the natural plant products glucosinolates. We have expressed the Myrosinase MYR1 from Brassica napus in Saccharomyces cerevisiae. The recombinant Myrosinase was enzymatically active which shows that the MYR1, which in the plant is complex bound with Myrosinase-binding proteins and Myrosinase-associated proteins, is functional in its free form. Characterization of the recombinant MYR1 with respect to pH optimum, substrate specificity, activation by ascorbic acid, and inhibitors showed similar characteristics as previously observed for other plant Myrosinases. The indolizidine alkaloid castanospermine, an inhibitor of O-glycosidases, inhibited the hydrolysis of p-hydroxybenzylglucosinolate with a K(i) value of 0.3 microM and 2-deoxy-2-fluoroglucotropaeolin, a specific inhibitor of thioglucosidases, inhibited the enzyme with a K(i) value of 1 mM. The expression of the Myrosinase in yeast was transient and the growth of the yeast cells was significantly reduced during the period of expression of the Myrosinase. Immunoblot analysis showed that the highest level of expression of MYR1 was obtained 24 h after induction with galactose. The amount of Myrosinase protein correlated with the level of enzyme activity. The transient expression of Myrosinase indicates that Myrosinase is toxic to the cells. This is the first report on successful heterologous expression of a Myrosinase and provides an important tool for, e.g., further characterization of Myrosinase by site-directed mutagenesis and for studying the interaction between Myrosinase and Myrosinase-binding proteins, Myrosinase-associated proteins, and epithiospecifier proteins.
Ann Van Loey - One of the best experts on this subject based on the ideXlab platform.
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behavior of mustard seed sinapis alba l Myrosinase during temperature pressure treatments a case study on enzyme activity and stability
European Food Research and Technology, 2008Co-Authors: D Van Eylen, Marc Hendrickx, Ann Van LoeyAbstract:The activity of Myrosinase, an enzyme found mainly in Brassicaceae, is influenced by some intrinsic (e.g. pH, ascorbic acid) and extrinsic (e.g. temperature, pressure) factors. In this study, the effect of intrinsic and extrinsic factors on the activity of mustard seed Myrosinase (Sinapis alba L.) was determined in a buffer system and in broccoli juice. Ascorbic acid and to a much lesser extent MgCl2 were found to enhance the Myrosinase activity. In buffer solution, the optimal temperature for Myrosinase activity at atmospheric pressure was 60 °C. At elevated pressure, the reaction rate increased until 200 MPa and the optimal temperature shifted to 40 °C in a buffer system. In broccoli juice, mustard seed Myrosinase behaved somewhat different compared to the buffer system. The highest enzyme activity was found at 60 °C, both at atmospheric and elevated pressures. In broccoli juice, the enzymatic reaction rate also increased up to pressures of 200 MPa. Enzyme inactivation could be described by first order kinetics.
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behavior of mustard seed sinapis alba l Myrosinase during temperature pressure treatments a case study on enzyme activity and stability
European Food Research and Technology, 2008Co-Authors: D Van Eylen, Marc Hendrickx, Ann Van LoeyAbstract:The activity of Myrosinase, an enzyme found mainly in Brassicaceae, is influenced by some intrinsic (e.g. pH, ascorbic acid) and extrinsic (e.g. temperature, pressure) factors. In this study, the effect of intrinsic and extrinsic factors on the activity of mustard seed Myrosinase (Sinapis alba L.) was determined in a buffer system and in broccoli juice. Ascorbic acid and to a much lesser extent MgCl2 were found to enhance the Myrosinase activity. In buffer solution, the optimal temperature for Myrosinase activity at atmospheric pressure was 60 °C. At elevated pressure, the reaction rate increased until 200 MPa and the optimal temperature shifted to 40 °C in a buffer system. In broccoli juice, mustard seed Myrosinase behaved somewhat different compared to the buffer system. The highest enzyme activity was found at 60 °C, both at atmospheric and elevated pressures. In broccoli juice, the enzymatic reaction rate also increased up to pressures of 200 MPa. Enzyme inactivation could be described by first order kinetics.
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kinetics of the stability of broccoli brassica oleracea cv italica Myrosinase and isothiocyanates in broccoli juice during pressure temperature treatments
Journal of Agricultural and Food Chemistry, 2007Co-Authors: D Van Eylen, Marc Hendrickx, Ann Van LoeyAbstract:The Brassicaceae plant family contains high concentrations of glucosinolates, which can be hydrolyzed by Myrosinase yielding products having an anticarcinogenic activity. The pressure and temperature stabilities of endogenous broccoli Myrosinase, as well as of the synthetic isothiocyanates sulforaphane and phenylethyl isothiocyanate, were studied in broccoli juice on a kinetic basis. At atmospheric pressure, kinetics of thermal (45−60 °C) Myrosinase inactivation could be described by a consecutive step model. In contrast, only one phase of Myrosinase inactivation was observed at elevated pressure (100−600 MPa) combined with temperatures from 10 up to 60 °C, indicating inactivation according to first-order kinetics. An antagonistic effect of pressure (up to 200 MPa) on thermal inactivation (50 °C and above) of Myrosinase was observed indicating that pressure retarded the thermal inactivation. The kinetic parameters of Myrosinase inactivation were described as inactivation rate constants (k values), activat...
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temperature and pressure stability of mustard seed sinapis alba l Myrosinase
Food Chemistry, 2006Co-Authors: D Van Eylen, Marc Hendrickx, Ann Van LoeyAbstract:Myrosinase, an enzyme found in all glucosinolate containing plants, is responsible for the conversion of glucosinolates into products that can be beneficial to our health. In this study, the temperature and pressure stability of partially purified Myrosinase from mustard seeds was studied in a model system. Temperature inactivation started at 60 °C and the inactivation kinetics were studied in detail between 65 and 75 °C. Inactivation could be described by the consecutive step or the biphasic model. Mustard seed Myrosinase was quite pressure stable, as its activity was retained after pressure treatments up to 600 MPa combined with temperatures up to 60 °C. At low pressures there was an antagonistic effect between pressure and thermal treatment, since Myrosinase activity was retained after treatments at 70 °C up to 300 MPa. This pressure stability indicates that pressure treatment may be a valuable alternative for thermal treatment if one wants to retain Myrosinase activity.
Lars Rask - One of the best experts on this subject based on the ideXlab platform.
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differential wound induction of the Myrosinase system in oilseed rape brassica napus contrasting insect damage with mechanical damage
Plant Science, 2005Co-Authors: Bo Pontoppidan, Lars Rask, Richard J Hopkins, Johan MeijerAbstract:Abstract Diamond-back moth ( Plutella xylostella ) is a serious insect pest specialised for herbivory on Crucifers although such plants contains the glucosinolate–Myrosinase system implied as an important resource to withstand insect pests. We have compared the effects of mechanical wounding using forceps or scissors with herbivory by diamond-back moth larvae on oilseed rape ( Brassica napus ). The transcript levels of Myrosinase binding protein (MBP), Myrosinase associated protein (MyAP) and Myrosinase were studied of leaf samples at different time points together with Myrosinase enzyme activity measurements. In all cases, wounding gave a transient local increase in transcript levels of MBP and MyAP that were similar to control levels again within 24–48 h. Systemic induction of MBP and MyAP transcripts was observed after diamond-back moth herbivory and mechanical wounding by scissors while wounding by forceps caused down-regulation. In contrast, the Myrosinase transcript levels were induced less and in wounded leaves after diamond-back moth feeding only. The Myrosinase activity decreased especially in the soluble fraction prepared from wounded leaves after herbivory. The changes in MBP and Myrosinase transcript levels were reflected in protein levels according to Western blot analysis. Mechanical wounding with forceps is often used for convenience as a substitute for insect attack but does not mimic well the effects of diamond-back moth herbivory to the plants.
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infestation by cabbage aphid brevicoryne brassicae on oilseed rape brassica napus causes a long lasting induction of the Myrosinase system
Entomologia Experimentalis Et Applicata, 2003Co-Authors: Bo Pontoppidan, Lars Rask, Richard J Hopkins, Johan MeijerAbstract:Cabbage aphid, Brevicoryne brassicae (L.) (Hemiptera: Aphididae), is specialised on cruciferous plants and constitutes a world-wide problem with a substantial negative impact on agriculture and horticulture. The Myrosinase-glucosinolate system present in crucifers is believed to serve as an important barrier to general herbivores, whereas specialist insects rely on this system for host recognition. Two proteins with unknown function, Myrosinase binding protein (MBP) and Myrosinase associated protein (MyAP), are also present in such plants and bind to specific Myrosinases. In order to study regulation and overall effects on the Myrosinase system, one leaf of oilseed rape ( Brassica napus L.) (Brassicaceae) plants at the two-leaf stage was exposed to cabbage aphids for 1 h. After removal of the insects, infested and non-infested leaves were analysed by Northern blot analysis for the presence of MBP, MyAP, and Myrosinase transcripts at different time points up to 48 h. MBP transcript levels continued to rise during the whole experiment, and were seven- to eight-fold higher compared with control plants 48 h after removal of the aphids. At 24 h the MyAP transcripts reached maximal levels and were four-fold higher than the control levels. Myrosinase transcripts were down regulated by aphid infestation and the level was less than half that of the control plants at 48 h. Apparently cabbage aphid infestation causes both transient and more long lasting (up to 48 h) effects on the Myrosinase system of the host.
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Complex Formation of Myrosinase Isoenzymes in Oilseed Rape Seeds Are Dependent on the Presence of Myrosinase-Binding Proteins
Plant Physiology, 2002Co-Authors: Susanna Eriksson, Lars Rask, Erik Andreasson, Barbara Ekbom, Bo Pontoppidan, Georg Granér, Jan Taipalensuu, Jiaming Zhang, Johan MeijerAbstract:The enzyme Myrosinase (EC 3.2.3.1) degrades the secondary compounds glucosinolates upon wounding and serves as a defense to generalist pests in Capparales. Certain Myrosinases are present in complexes together with other proteins such as Myrosinase-binding proteins (MBP) in extracts of oilseed rape (Brassica napus) seeds. Immunhistochemical analysis of wild-type seeds showed that MBPs were present in most cells but not in the myrosin cells, indicating that the complex formation observed in extracts is initiated upon tissue disruption. To study the role of MBP in complex formation and defense, oilseed rape antisense plants lacking the seed MBPs were produced. Western blotting and immunohistochemical staining confirmed depletion of MBP in the transgenic seeds. The exclusive expression of Myrosinase in idioblasts (myrosin cells) of the seed was not affected by the down-regulation of MBP. Using size-exclusion chromatography, we have shown that Myrosinases with subunit molecular masses of 62 to 70 kD were present as free dimers from the antisense seed extract, whereas in the wild type, they formed complexes. In accordance with this, MBPs are necessary for Myrosinase complex formation of the 62- to 70-kD Myrosinases. The product formed from sinalbin hydrolysis by Myrosinase was the same whether MBP was present or not. The performance of a common beetle generalist (Tenebrio molitor) fed with seeds, herbivory by flea beetles (Phyllotreta undulata) on cotyledons, or growth rate of the Brassica fungal pathogens Alternaria brassicae or Lepthosphaeria maculans in the presence of seed extracts were not affected by the down-regulation of MBP, leaving the physiological function of this protein family open.
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different Myrosinase and idioblast distribution in arabidopsis and brassica napus
Plant Physiology, 2001Co-Authors: Erik Andreasson, Lars Rask, Annastina Hoglund, Lise Bolt Jorgensen, Johan MeijerAbstract:Myrosinase (EC 3.2.3.1) is a glucosinolate-degrading enzyme mainly found in special idioblasts, myrosin cells, in Brassicaceae. This two-component system of secondary products and degradative enzymes is important in plant-insect interactions. Immunocytochemical analysis of Arabidopsis localized Myrosinase exclusively to myrosin cells in the phloem parenchyma, whereas no myrosin cells were detected in the ground tissue. In Brassica napus, Myrosinase could be detected in myrosin cells both in the phloem parenchyma and in the ground tissue. The myrosin cells were similar in Arabidopsis and B. napus and were found to be different from the companion cells and the glucosinolate-containing S-cells present in Arabidopsis. Confocal laser scanning immunomicroscopy analysis of myrosin cells in B. napus embryos showed that the myrosin grains constitute a continuous reticular system in the cell. These findings indicate that in the two species studied, initial cells creating the ground tissue have different potential for making idioblasts and suggest that the Myrosinase-glucosinolate system has at least partly different functions. Several Myrosinases in B. napus extracts are recovered in complex together with Myrosinase-binding protein (MBP), and the localization of MBP was therefore studied in situ. The expression of MBP was highest in germinating seedlings of B. napus and was found in every cell except the myrosin cells of the ground tissue. Rapid disappearance of the MBP from the non-myrosin cells and emergence of MBP in the myrosin cells resulted in an apparent colocalization of MBP and Myrosinase in 7-d-old seedlings.
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identification and characterization of soluble and insoluble Myrosinase isoenzymes in different organs of sinapis alba
Physiologia Plantarum, 2001Co-Authors: Susanna Eriksson, Lars Rask, Jiaping Xue, Johan MeijerAbstract:Extraction of Sinapis alba seeds under native conditions solubilized 3 Myrosinase isoforms, pool I, II and III, which could be separated by ion exchange chromatography. Sequencing of numerous peptides of the I and III isoforms showed that they belonged to the Myrosinase A (MA) family of Myrosinases and that they were encoded by different genes. Western blot analysis of S. alba seed proteins, extracted with a sodium dodecyl sulphate-containing buffer, using an anti-Myrosinase monoclonal antibody, showed the presence of two additional Myrosinase isoforms with approximate molecular sizes of 62 and 59 kDa. These Myrosinases, which only could be solubilized from seeds by inclusion of denaturing agents in the extraction buffer, were by sequence analysis identified as MB Myrosinases. These isoenzymes or very similar forms were also present in seedling cotyledons. However, from this tissue, they could be extracted with non-denaturing buffers. In addition, cotyledons contained a 65-kDa MB Myrosinase not found in seeds. In contrast, seedling cotyledons contained only minute amounts of pool I and no pool III MA Myrosinases, emphasizing the tissue-specific expression of the corresponding gene families. Sequence analysis of Myrosinase cDNAs generated cDNA by reversed transcription-polymerase chain reaction using degenerate primers with mRNA isolated from seeds, cotyledons and leaves confirmed the result that the MA isoforms were expressed only in seed tissue, while MB Myrosinases were found in all tissues investigated. Furthermore, seed and leaf contained unique MB Myrosinase transcripts, suggesting organ-specific expression of individual MB genes.
Atle M. Bones - One of the best experts on this subject based on the ideXlab platform.
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arabidopsis Myrosinases link the glucosinolate Myrosinase system and the cuticle
Scientific Reports, 2016Co-Authors: Ishita Ahuja, Ric C H De Vos, Jens Rohloff, Geert Stoopen, Kari Krizak Halle, Samina Jam Nazeer Ahmad, Linh Hoang, Robert Hall, Atle M. BonesAbstract:Both physical barriers and reactive phytochemicals represent two important components of a plant's defence system against environmental stress. However, these two defence systems have generally been studied independently. Here, we have taken an exclusive opportunity to investigate the connection between a chemical-based plant defence system, represented by the glucosinolate-Myrosinase system, and a physical barrier, represented by the cuticle, using Arabidopsis Myrosinase (thioglucosidase; TGG) mutants. The tgg1, single and tgg1 tgg2 double mutants showed morphological changes compared to wild-type plants visible as changes in pavement cells, stomatal cells and the ultrastructure of the cuticle. Extensive metabolite analyses of leaves from tgg mutants and wild-type Arabidopsis plants showed altered levels of cuticular fatty acids, fatty acid phytyl esters, glucosinolates, and indole compounds in tgg single and double mutants as compared to wild-type plants. These results point to a close and novel association between chemical defence systems and physical defence barriers.
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oilseed rape seeds with ablated defence cells of the glucosinolate Myrosinase system production and characteristics of double haploid mineless plants of brassica napus l
Journal of Experimental Botany, 2011Co-Authors: Ishita Ahuja, John T. Rossiter, Caroline Muller, Jens Rohloff, Birgit Hafeld Borgen, Magnor Hansen, Bjorn Ivar Honne, Atle M. BonesAbstract:Oilseed rape and other crop plants of the family Brassicaceae contain a unique defence system known as the glucosinolate-Myrosinase system or the 'mustard oil bomb'. The 'mustard oil bomb' which includes Myrosinase and glucosinolates is triggered by abiotic and biotic stress, resulting in the formation of toxic products such as nitriles and isothiocyanates. Myrosinase is present in specialist cells known as 'myrosin cells' and can also be known as toxic mines. The myrosin cell idioblasts of Brassica napus were genetically reprogrammed to undergo controlled cell death (ablation) during seed development. These myrosin cell-free plants have been named MINELESS as they lack toxic mines. This has led to the production of oilseed rape with a significant reduction both in Myrosinase levels and in the hydrolysis of glucosinolates. Even though the Myrosinase activity in MINELESS was very low compared with the wild type, variation was observed. This variability was overcome by producing homozygous seeds. A microspore culture technique involving non-fertile haploid MINELESS plants was developed and these plants were treated with colchicine to produce double haploid MINELESS plants with full fertility. Double haploid MINELESS plants had significantly reduced Myrosinase levels and glucosinolate hydrolysis products. Wild-type and MINELESS plants exhibited significant differences in growth parameters such as plant height, leaf traits, matter accumulation, and yield parameters. The growth and developmental pattern of MINELESS plants was relatively slow compared with the wild type. The characteristics of the pure double haploid MINELESS plant are described and its importance for future biochemical, agricultural, dietary, functional genomics, and plant defence studies is discussed.
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the mustard oil bomb not so easy to assemble localization expression and distribution of the components of the Myrosinase enzyme system
Phytochemistry Reviews, 2009Co-Authors: Ralph Kissen, John T. Rossiter, Atle M. BonesAbstract:Glucosinolates are plant secondary metabolites that are hydrolysed by the action of Myrosinases into various products (isothiocyanates, thiocyanates, epithionitriles, nitriles, oxazolidines). Massive hydrolysis of glucosinolates occurs only upon tissue damage but there is also evidence indicating metabolism of glucosinolates in intact plant tissues. It was originally believed that the glucosinolate–Myrosinase system in intact plants was stable due to a spatial separation of the components. This has been coined as the ‘mustard oil bomb’ theory. Proteins that form complexes with Myrosinases have been described: Myrosinase-binding proteins (MBPs) and Myrosinase-associated proteins (MyAPs/ESM). The roles of these proteins and their biological relevance are not yet completely known. Other proteins of the Myrosinase enzyme system are the epithiospecifier protein (ESP) and the thiocyanate-forming protein (TFP) that divert the glucosinolate hydrolysis from isothiocyanate production to nitrile/epithionitrile or thiocyanate production. Some glucosinolate hydrolysis products act as plant defence compounds against insects and pathogens or have beneficial health effects on humans. In this review, we survey and critically assess the available information concerning the localization, both at the tissular/cellular and subcellular level, of the different components of the Myrosinase enzyme system. Data from the model plant Arabidopsis thaliana is compared to that from other glucosinolate-producing Brassicaceae in order to show common as well as divergent features of the ‘mustard oil bomb’ among these species.
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crystal structure at 1 1 a resolution of an insect Myrosinase from brevicoryne brassicae shows its close relationship to β glucosidases
Insect Biochemistry and Molecular Biology, 2005Co-Authors: Harald Husebye, Wim P. Burmeister, John T. Rossiter, Steffi Arzt, Frauke V Hartel, Anders Brandt, Atle M. BonesAbstract:Abstract The aphid Brevicoryne brassicae is a specialist feeding on Brassicaceae plants. The insect has an intricate defence system involving a β- d -thioglucosidase (Myrosinase) that hydrolyses glucosinolates sequestered from the host plant into volatile isothiocyanates. These isothiocyanates act synergistically with the pheromone E-β-farnesene to form an alarm system when the aphid is predated. In order to investigate the enzymatic characteristics of the aphid Myrosinase and its three-dimensional structure, milligram amounts of pure recombinant aphid Myrosinase were obtained from Echerichia coli. The recombinant enzyme had similar physiochemical properties to the native enzyme. The global structure is very similar to Sinapis alba Myrosinase and plant β-O-glucosidases. Aphid Myrosinase has two catalytic glutamic acid residues positioned as in plant β-O-glucosidases, and it is not obvious why this unusual enzyme hydrolyses glucosinolates, the common substrates of plant Myrosinases which are normally not hydrolyzed by plant β-O-glucosidases. The only residue specific for aphid Myrosinase in proximity of the glycosidic linkage is Tyr180 which may have a catalytic role. The aglycon binding site differs strongly from plant Myrosinase, whereas due to the presence of Trp424 in the glucose binding site, this part of the active site is more similar to plant β-O-glucosidases, as plant Myrosinases carry a phenylalanine residue at this position.
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guard cell and phloem idioblast specific expression of thioglucoside glucohydrolase 1 Myrosinase in arabidopsis
Plant Physiology, 2002Co-Authors: Harald Husebye, Per Winge, Supachitra Chadchawan, O P Thangstad, Atle M. BonesAbstract:Thioglucoside glucohydrolase 1 (TGG1) is one of two known functional Myrosinase enzymes in Arabidopsis. The enzyme catalyzes the hydrolysis of glucosinolates into compounds that are toxic to various microbes and herbivores. Transgenic Arabidopsis plants carrying β-glucuronidase and green fluorescent protein reporter genes fused to 0.5 or 2.5 kb of the TGG1 promoter region were used to study spatial promoter activity. Promoter activity was found to be highly specific and restricted to guard cells and distinct cells of the phloem. No promoter activity was detected in the root or seed. All guard cells show promoter activity. Positive phloem cells are distributed in a discontinuous pattern and occur more frequent in young tissues. Immunocytochemical localization of Myrosinase in transverse and longitudinal sections of embedded material show that the TGG1 promoter activity reflects the position of the Myrosinase enzyme. In the flower stalk, the Myrosinase-containing phloem cells are located between phloem sieve elements and glucosinolate-rich S cells. Our results suggest a cellular separation of Myrosinase enzyme and glucosinolate substrate, and that Myrosinase is contained in distinct cells. We discuss the potential advantages of locating defense and communication systems to only a few specific cell types.
D Van Eylen - One of the best experts on this subject based on the ideXlab platform.
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behavior of mustard seed sinapis alba l Myrosinase during temperature pressure treatments a case study on enzyme activity and stability
European Food Research and Technology, 2008Co-Authors: D Van Eylen, Marc Hendrickx, Ann Van LoeyAbstract:The activity of Myrosinase, an enzyme found mainly in Brassicaceae, is influenced by some intrinsic (e.g. pH, ascorbic acid) and extrinsic (e.g. temperature, pressure) factors. In this study, the effect of intrinsic and extrinsic factors on the activity of mustard seed Myrosinase (Sinapis alba L.) was determined in a buffer system and in broccoli juice. Ascorbic acid and to a much lesser extent MgCl2 were found to enhance the Myrosinase activity. In buffer solution, the optimal temperature for Myrosinase activity at atmospheric pressure was 60 °C. At elevated pressure, the reaction rate increased until 200 MPa and the optimal temperature shifted to 40 °C in a buffer system. In broccoli juice, mustard seed Myrosinase behaved somewhat different compared to the buffer system. The highest enzyme activity was found at 60 °C, both at atmospheric and elevated pressures. In broccoli juice, the enzymatic reaction rate also increased up to pressures of 200 MPa. Enzyme inactivation could be described by first order kinetics.
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behavior of mustard seed sinapis alba l Myrosinase during temperature pressure treatments a case study on enzyme activity and stability
European Food Research and Technology, 2008Co-Authors: D Van Eylen, Marc Hendrickx, Ann Van LoeyAbstract:The activity of Myrosinase, an enzyme found mainly in Brassicaceae, is influenced by some intrinsic (e.g. pH, ascorbic acid) and extrinsic (e.g. temperature, pressure) factors. In this study, the effect of intrinsic and extrinsic factors on the activity of mustard seed Myrosinase (Sinapis alba L.) was determined in a buffer system and in broccoli juice. Ascorbic acid and to a much lesser extent MgCl2 were found to enhance the Myrosinase activity. In buffer solution, the optimal temperature for Myrosinase activity at atmospheric pressure was 60 °C. At elevated pressure, the reaction rate increased until 200 MPa and the optimal temperature shifted to 40 °C in a buffer system. In broccoli juice, mustard seed Myrosinase behaved somewhat different compared to the buffer system. The highest enzyme activity was found at 60 °C, both at atmospheric and elevated pressures. In broccoli juice, the enzymatic reaction rate also increased up to pressures of 200 MPa. Enzyme inactivation could be described by first order kinetics.
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kinetics of the stability of broccoli brassica oleracea cv italica Myrosinase and isothiocyanates in broccoli juice during pressure temperature treatments
Journal of Agricultural and Food Chemistry, 2007Co-Authors: D Van Eylen, Marc Hendrickx, Ann Van LoeyAbstract:The Brassicaceae plant family contains high concentrations of glucosinolates, which can be hydrolyzed by Myrosinase yielding products having an anticarcinogenic activity. The pressure and temperature stabilities of endogenous broccoli Myrosinase, as well as of the synthetic isothiocyanates sulforaphane and phenylethyl isothiocyanate, were studied in broccoli juice on a kinetic basis. At atmospheric pressure, kinetics of thermal (45−60 °C) Myrosinase inactivation could be described by a consecutive step model. In contrast, only one phase of Myrosinase inactivation was observed at elevated pressure (100−600 MPa) combined with temperatures from 10 up to 60 °C, indicating inactivation according to first-order kinetics. An antagonistic effect of pressure (up to 200 MPa) on thermal inactivation (50 °C and above) of Myrosinase was observed indicating that pressure retarded the thermal inactivation. The kinetic parameters of Myrosinase inactivation were described as inactivation rate constants (k values), activat...
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temperature and pressure stability of mustard seed sinapis alba l Myrosinase
Food Chemistry, 2006Co-Authors: D Van Eylen, Marc Hendrickx, Ann Van LoeyAbstract:Myrosinase, an enzyme found in all glucosinolate containing plants, is responsible for the conversion of glucosinolates into products that can be beneficial to our health. In this study, the temperature and pressure stability of partially purified Myrosinase from mustard seeds was studied in a model system. Temperature inactivation started at 60 °C and the inactivation kinetics were studied in detail between 65 and 75 °C. Inactivation could be described by the consecutive step or the biphasic model. Mustard seed Myrosinase was quite pressure stable, as its activity was retained after pressure treatments up to 600 MPa combined with temperatures up to 60 °C. At low pressures there was an antagonistic effect between pressure and thermal treatment, since Myrosinase activity was retained after treatments at 70 °C up to 300 MPa. This pressure stability indicates that pressure treatment may be a valuable alternative for thermal treatment if one wants to retain Myrosinase activity.
