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Ludger Beerhues - One of the best experts on this subject based on the ideXlab platform.
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Molecular cloning and functional analysis of a Biphenyl phytoalexin-specific O-methyltransferase from apple cell suspension cultures
Planta, 2019Co-Authors: Amol Sarkate, Ludger Beerhues, Shashank Sagar Saini, Mariam Gaid, Deepa Teotia, Javid Iqbal Mir, Pawan Kumar Agrawal, Debabrata SircarAbstract:Main conclusion This manuscript describes the cloning and functional characterization of a Biphenyl phytoalexin biosynthetic gene, 3,5 - dihydroxyBiphenyl O - methyltransferase from elicitor-treated cell cultures of scab resistant apple cultivar ‘Florina’. Apples belong to the subtribe Malinae of the Rosaceae family. Biphenyls and dibenzofurans are the specialized phytoalexins of Malinae, of which aucuparin is the most widely distributed Biphenyl. The precursor of aucuparin, 3,5-dihydroxyBiphenyl, is a benzoate-derived polyketide, which is formed by the sequential condensation of three molecules of malonyl-CoA and one molecule of benzoyl-CoA in a reaction catalyzed by Biphenyl synthase (BIS). This 3,5-dihydroxyBiphenyl then undergoes sequential 5- O -methylation, 4-hydroxylation, and finally 3- O -methylation to form aucuparin. A cDNA encoding O -methyltransferase (OMT) was isolated and functionally characterized from the cell cultures of scab-resistant apple cultivar ‘Florina’ ( Malus domestica cultivar ‘Florina’; MdOMT) after treatment with elicitor prepared from the apple scab causing fungus Venturia inaequalis. MdOMT catalyzed the regiospecific O -methylation of 3,5-dihydroxyBiphenyl at the 5-position to form 3-hydroxy-5-methoxyBiphenyl. The enzyme showed absolute substrate preference for 3,5-dihydroxyBiphenyl. The elicitor-treated apple cell cultures showed transient increases in the MdOMT (GenBank ID MF740747) and MdBIS3 (GenBank ID JQ390523) transcript levels followed by the accumulation of Biphenyls (aucuparin and noraucuparin) and dibenzofuran (eriobofuran) phytoalexins. MdOMT fused with N- and C -terminal yellow fluorescent protein showed cytoplasmic localization in the epidermis of Nicotiana benthamiana leaves. In scab inoculated greenhouse-grown ‘Florina’ plants, the expression of MdOMT was transiently induced in the stem followed by the accumulation of Biphenyl phytoalexins.
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Phytoalexins of the Pyrinae: Biphenyls and dibenzofurans.
Beilstein journal of organic chemistry, 2012Co-Authors: Cornelia Chizzali, Ludger BeerhuesAbstract:Biphenyls and dibenzofurans are the phytoalexins of the Pyrinae, a subtribe of the plant family Rosaceae. The Pyrinae correspond to the long-recognized Maloideae. Economically valuable species of the Pyrinae are apples and pears. Biphenyls and dibenzofurans are formed de novo in response to infection by bacterial and fungal pathogens. The inducible defense compounds were also produced in cell suspension cultures after treatment with biotic and abiotic elicitors. The antimicrobial activity of the phytoalexins was demonstrated. To date, 10 Biphenyls and 17 dibenzofurans were isolated from 14 of the 30 Pyrinae genera. The most widely distributed compounds are the Biphenyl aucuparin and the dibenzofuran γ-cotonefuran. The biosynthesis of the two classes of defense compounds is not well understood, despite the importance of the fruit crops. More recent studies have revealed simultaneous accumulation of Biphenyls and dibenzofurans, suggesting sequential, rather than the previously proposed parallel, biosynthetic pathways. Elicitor-treated cell cultures of Sorbus aucuparia served as a model system for studying phytoalexin metabolism. The key enzyme that forms the carbon skeleton is Biphenyl synthase. The starter substrate for this type-III polyketide synthase is benzoyl-CoA. In apples, Biphenyl synthase is encoded by a gene family, members of which are differentially regulated. Metabolism of the phytoalexins may provide new tools for designing disease control strategies for fruit trees of the Pyrinae subtribe.
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endogenous hydrogen peroxide is a key factor in the yeast extract induced activation of Biphenyl biosynthesis in cell cultures of sorbus aucuparia
Planta, 2012Co-Authors: Lili Huang, Xing Li, Zhigao Du, Hechun Ye, Hong Wang, Ludger BeerhuesAbstract:Biphenyls are unique phytoalexins produced by plants belonging to Pyrinae, a subtribe of the economically important Rosaceae family. The formation of aucuparin, a well-known Biphenyl, is induced by yeast extract (YE) in cell cultures of Sorbus aucuparia. However, the molecular mechanism underlying YE-induced activation of Biphenyl biosynthesis remains unknown. Here we demonstrate that the addition of YE to the cell cultures results in a burst of reactive oxygen species (ROS; H2O2 and O2 −), followed by transcriptional activation of the Biphenyl synthase 1 gene (BIS1) encoding the key enzyme of the Biphenyl biosynthetic pathway and aucuparin accumulation. Pretreatment of the cell cultures with ROS scavenger dihydrolipoic acid and NADPH oxidase-specific inhibitor diphenylene iodonium abolished all of the above YE-induced biological events. However, when the cell cultures was pretreated with superoxide dismutase specific inhibitor N,N-diethyldithiocarbamic acid, although O2 − continued to be generated, the H2O2 accumulation, BIS1 expression and aucuparin production were blocked. Interestingly, exogenous supply of H2O2 in the range of 0.05–10 mM failed to induce aucuparin accumulation. These results indicate that endogenous generation of H2O2 rather than that of O2 − is a key factor in YE-induced accumulation of Biphenyl phytoalexins in cell cultures of S. aucuparia.
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Biphenyl synthase from yeast extract treated cell cultures of sorbus aucuparia
Planta, 2004Co-Authors: Till Beuerle, Tim Klundt, Ludger BeerhuesAbstract:Biphenyls and dibenzofurans are the phytoalexins of the Maloideae, a subfamily of the economically important Rosaceae. The Biphenyl aucuparin accumulated in Sorbus aucuparia L. cell cultures in response to yeast extract treatment. Incubation of cell-free extracts from challenged cell cultures with benzoyl-CoA and malonyl-CoA led to the formation of 3,5-dihydroxyBiphenyl. This reaction was catalysed by a novel polyketide synthase, which will be named Biphenyl synthase. The most efficient starter substrate for the enzyme was benzoyl-CoA. Relatively high activity was also observed with 2-hydroxybenzoyl-CoA but, instead of the corresponding Biphenyl, the derailment product 2-hydroxybenzoyltriacetic acid lactone was formed.
David T. Gibson - One of the best experts on this subject based on the ideXlab platform.
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DIHYDROXYLATION AND DECHLORINATION OF CHLORINATED BiphenylS BY PURIFIED Biphenyl 2,3-DIOXYGENASE FROM PSEUDOMONAS SP. STRAIN LB400
Journal of bacteriology, 1995Co-Authors: J D Haddock, J R Horton, David T. GibsonAbstract:Oxidation of Biphenyl and nine chlorinated Biphenyls (CBs) by the Biphenyl 2,3-dioxygenase from Pseudomonas sp. strain LB400 was examined. The purified terminal oxygenase required the addition of partially purified electron transport components, NAD(P)H, and ferrous iron to oxidize Biphenyl and CBs. cis-Biphenyl 2,3-dihydrodiol was produced with Biphenyl as the substrate. Dihydrodiols were produced from all CBs, and more than one compound was produced with most substrates. Catechols were produced when the dioxygenase-catalyzed reaction occurred at the 2,3 position of a 2-chlorophenyl ring, resulting in dechlorination of the substrate. Oxidation at the 3,4 position of a 2,5-dichlorophenyl ring produced a 3,4-dihydrodiol. Compounds resulting from both types of reaction were produced during oxidation of 2,5,2'-trichloroBiphenyl. The broad substrate specificity and the ability to oxidize at different ring positions suggest that the Biphenyl 2,3-dioxygenase is responsible for the wide range of CBs oxidized by Pseudomonas sp. strain LB400.
Larry L Needham - One of the best experts on this subject based on the ideXlab platform.
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retrospective time trend study of polybrominated diphenyl ether and polybrominated and polychlorinated Biphenyl levels in human serum from the united states
Environmental Health Perspectives, 2004Co-Authors: Andreas Sjodin, Richard S Jones, Chester R Lapeza, Bill Slazyk, Ernest Mcgahee, Wayman E Turner, Yalin Zhang, Richard Y. Wang, Jean-françois Focant, Larry L NeedhamAbstract:Six polybrominated diphenyl ethers (PBDEs), one hexabromoBiphenyl [polybrominated Biphenyl (PBB)], and one hexachloroBiphenyl [polychlorinated Biphenyl (PCB)] were measured in 40 human serum pools collected in the southeastern United States during 1985 through 2002 and in Seattle, Washington, for 1999 through 2002. The concentrations of most of the PBDEs, which are commercially used as flame retardants in common household and commercial applications, had significant positive correlations with time of sample collection, showing that the concentrations of these compounds are increasing in serum collected in the United States. In contrast, PCB and PBB levels were negatively correlated with sample collection year, indicating that the levels of these compounds have been decreasing since their phaseout in the 1970s.
Michael Seeger - One of the best experts on this subject based on the ideXlab platform.
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response to chloro Biphenyls of the polychloroBiphenyl degrader burkholderia xenovorans lb400 involves stress proteins also induced by heat shock and oxidative stress
Fems Microbiology Letters, 2007Co-Authors: Loreine Agullo, Beatriz Camara, Paula Martinez, Valeria Latorre, Michael SeegerAbstract:We report the effects of 4-chloroBiphenyl and Biphenyl on the physiology, morphology and proteome of the polychloroBiphenyl-degrader Burkholderia xenovorans LB400. The exposure to 4-chloroBiphenyl decreases the growth of LB400 on glucose, and cells exhibit irregular outer membranes, a larger periplasmic space and electron-dense granules in the cytoplasm. Additionally, lysis of cells was observed during incubation with 4-chloroBiphenyl or Biphenyl. Proteome of B. xenovorans LB400 exposed to Biphenyl and 4-chloroBiphenyl were analysed by two-dimensional gel electrophoresis. Besides induction of the Bph enzymes of Biphenyl catabolic pathways, incubation with 4-chloroBiphenyl or Biphenyl results in the induction of the molecular chaperones DnaK and GroEL. Induction of these chaperones, which were also induced during heat shock, strongly suggests that exposure to (chloro)Biphenyls constitutes stress conditions for LB400. During growth of LB400 on Biphenyl, oxidative stress was evidenced by the induction of alkyl hydroperoxide reductase AhpC, which was also induced during exposure to H2O2. 4-chloroBiphenyl and Biphenyl induced catechol 1,2-dioxygenase, as well as polypeptides involved in energy production, amino acid metabolism and transport.
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Dehalogenation, Denitration, Dehydroxylation, and Angular Attack on Substituted Biphenyls and Related Compounds by a Biphenyl Dioxygenase
Journal of bacteriology, 2001Co-Authors: Michael Seeger, Beatriz Camara, Bernd HoferAbstract:ABSTRACT The attack by the bph-encoded Biphenyl dioxygenase ofBurkholderia sp. strain LB400 on a number of symmetricalortho-substituted Biphenyls or quasiortho-substituted Biphenyl analogues has been investigated. 2,2′-Difluoro-, 2,2′-dibromo-, 2,2′-dinitro-, and 2,2′-dihydroxyBiphenyl were accepted as substrates. Dioxygenation of all of these compounds showed a strong preference for the semisubstituted pair of vicinal ortho and metacarbons, leading to the formation of 2′-substituted 2,3-dihydroxyBiphenyls by subsequent elimination of HX (X = F, Br, NO2, or OH). All of these products were further metabolized by 2,3-dihydroxyBiphenyl 1,2-dioxygenases of Burkholderiasp. strain LB400 or of Rhodococcus globerulus P6. Dibenzofuran and dibenzodioxin, which may be regarded as analogues of doubly ortho-substituted Biphenyls or diphenylethers, respectively, were attacked at the “quasi ortho” carbon (the angular position 4a) and its neighbor. This shows that an aromatic ring-hydroxylating dioxygenase of class IIB is able to attack angular carbons. The catechols formed, 2,3,2′-trihydroxyBiphenyl and 2,3,2′-trihydroxydiphenylether, were further metabolized by 2,3-dihydroxyBiphenyl 1,2-dioxygenase. While angular attack by the Biphenyl dioxygenase was the main route of dibenzodioxin oxidation, lateral dioxygenation leading to dihydrodiols was the major reaction with dibenzofuran. These results indicate that this enzyme is capable of hydroxylating ortho or angular carbons carrying a variety of substituents which exert electron-withdrawing inductive effects. They also support the view that the conversions of phenols into catechols by ring-hydroxylating dioxygenases, such as the transformation of 2,2′-dihydroxyBiphenyl into 2,3,2′-trihydroxyBiphenyl, are the results of di- rather than of monooxygenations. Lateral dioxygenation of dibenzofuran and subsequent dehydrogenation and extradiol dioxygenation by a number of Biphenyl-degrading strains yielded intensely colored dead-end products. Thus, dibenzofuran can be a useful chromogenic indicator for the activity of the first three enzymes of Biphenyl catabolic pathways.
John Haddock - One of the best experts on this subject based on the ideXlab platform.
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Influence of chlorine substituents on rates of oxidation of chlorinated Biphenyls by the Biphenyl dioxygenase of Burkholderia sp. strain LB400.
Applied and environmental microbiology, 2000Co-Authors: Clint M. Arnett, Juanito V. Parales, John HaddockAbstract:Biphenyl dioxygenase from Burkholderia (Pseudomonas) sp. strain LB400 catalyzes the first reaction of a pathway for the degradation of Biphenyl and a broad range of chlorinated Biphenyls (CBs). The effect of chlorine substituents on catalysis was determined by measuring the specific activity of the enzyme with Biphenyl and 18 congeners. The catalytic oxygenase component was purified and incubated with individual CBs in the presence of electron transport proteins and cofactors that were required for enzyme activity. The rate of depletion of Biphenyl from the assay mixture and the rate of formation of cis-Biphenyl 2,3-dihydrodiol, the oxidation product, were almost equal, indicating that the assay accurately measured enzyme-specific activity. Four classes of CBs were defined based on their oxidation rates. Class I contained 3-CB and 2,5-CB, which gave rates that were approximately twice that of Biphenyl. Class II contained 2,5,3′,4′-CB, 2,3,2′,5′-CB, 2,3,4,5-CB, 2,3,2′,3′-CB, 2,4,5,2′,5′-CB, 2,5,3′-CB, 2,5,4′-CB, 2-CB, and 3,4,5-CB, which gave rates that ranged from 97 to 35% of the Biphenyl rate. Class III contained only 2,3,4,2′,5′-CB, which gave a rate that was 4% of the Biphenyl rate. Class IV contained 2,4,4′-CB, 2,4,2′,4′-CB, 3,4,5,2′-CB, 3,4,5,3′-CB, 3,5,3′,5′-CB, and 3,4,5,2′,5′-CB, which showed no detectable depletion. Rates were not significantly correlated with the aqueous solubilities of the CBs or the number of chlorine substituents on the rings. Oxidation products were detected for all class I, II, and III congeners and were identified as chlorinated cis-dihydrodiols for classes I and II. The specificity of Biphenyl dioxygenase for the CBs examined in this study was determined by the relative positions of the chlorine substituents on the aromatic rings rather than the number of chlorine substituents on the rings.
