title: Benzoxazolinone detoxification by N-Glucosylation: The multi-compartment-network of Zea mays L.
abstract: The major detoxification product in maize roots after 24 h benzoxazolin-2(3H)-one (BOA) exposure was identified as glucoside carbamate resulting from rearrangement of BOA-N-glucoside, but the pathway of N-glucosylation, enzymes involved and the site of synthesis were previously unknown. Assaying whole cell proteins revealed the necessity of H2O2 and Fe(2+) ions for glucoside carbamate production. Peroxidase produced BOA radicals are apparently formed within the extraplastic space of the young maize root. Radicals seem to be the preferred substrate for N-glucosylation, either by direct reaction with glucose or, more likely, the N-glucoside is released by glucanase/glucosidase catalyzed hydrolysis from cell wall components harboring fixed BOA. The processes are accompanied by alterations of cell wall polymers. Glucoside carbamate accumulation could be suppressed by the oxireductase inhibitor 2-bromo-4´-nitroacetophenone and by peroxidase inhibitor 2,3-butanedione. Alternatively, activated BOA molecules with an open heterocycle may be produced by microorganisms (e.g., endophyte Fusarium verticillioides) and channeled for enzymatic N-glucosylation. Experiments with transgenic Arabidopsis lines indicate a role of maize glucosyltransferase BX9 in BOA-N-glycosylation. Western blots with BX9 antibody demonstrate the presence of BX9 in the extraplastic space. Proteomic analyses verified a high BOA responsiveness of multiple peroxidases in the apoplast/cell wall. BOA incubations led to shifting, altered abundances and identities of the apoplast and cell wall located peroxidases, glucanases, glucosidases and glutathione transferases (GSTs). GSTs could function as glucoside carbamate transporters. The highly complex, compartment spanning and redox-regulated glucoside carbamate pathway seems to be mainly realized in Poaceae. In maize, carbamate production is independent from benzoxazinone synthesis.
authors.affiliation: a IMBIO Institut für Biotechnologie der Pflanzen, Universität Bonn , Karlrobert Kreiten Str. 13, 53115 Bonn , Germany.
authors.forename: Margot
authors.initials: M
authors.lastname: Schulz
authors.affiliation: a IMBIO Institut für Biotechnologie der Pflanzen, Universität Bonn , Karlrobert Kreiten Str. 13, 53115 Bonn , Germany.
authors.forename: Barbara
authors.initials: B
authors.lastname: Filary
authors.affiliation: a IMBIO Institut für Biotechnologie der Pflanzen, Universität Bonn , Karlrobert Kreiten Str. 13, 53115 Bonn , Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Kühn
authors.affiliation: b Max-Planck-Institut für Pflanzenzüchtungsforschung, Carl von Linné Weg 10 , 50829 Köln , Germany.|c Max Planck Institute for Biology of Aging , Joseph-Stelzmann Str. 9b, 50931 Köln , Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Colby
authors.affiliation: d Institut für Organische Chemie, Universität Leipzig, Johannisallee 29 , 04103 Leipzig , Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Harzen
authors.affiliation: a IMBIO Institut für Biotechnologie der Pflanzen, Universität Bonn , Karlrobert Kreiten Str. 13, 53115 Bonn , Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Schmidt
authors.affiliation: d Institut für Organische Chemie, Universität Leipzig, Johannisallee 29 , 04103 Leipzig , Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Sicker
authors.affiliation: d Institut für Organische Chemie, Universität Leipzig, Johannisallee 29 , 04103 Leipzig , Germany.
authors.forename: Lothar
authors.initials: L
authors.lastname: Hennig
authors.affiliation: e IBG-3: Agrossphäre, Forschungszentrum Jülich GmbH , 52428 Jülich , Germany.
authors.forename: Diana
authors.initials: D
authors.lastname: Hofmann
authors.affiliation: e IBG-3: Agrossphäre, Forschungszentrum Jülich GmbH , 52428 Jülich , Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Disko
authors.affiliation: f AVT-Enzyme Process Technology, RWTH Aachen University, Worringer Weg 1 , 52074 Aachen , Germany.
authors.forename: Nico
authors.initials: N
authors.lastname: Anders
mesh_terms: D000098:Acetophenones / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics; D001583:Benzoxazoles / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D001681:Biological Assay; D015153:Blotting, Western; D002219:Carbamates / Q000378:metabolism; D002473:Cell Wall / Q000187:drug effects / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D003931:Diacetyl / Q000494:pharmacology; D004976:Ethacrynic Acid / Q000494:pharmacology; D005670:Fusarium / Q000187:drug effects / Q000502:physiology; D005960:Glucosides / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D006031:Glycosylation / Q000187:drug effects; D008658:Inactivation, Metabolic / Q000187:drug effects; D010544:Peroxidases / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D030821:Plants, Genetically Modified; D036226:Seedlings / Q000187:drug effects / Q000378:metabolism; D003313:Zea mays / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000098:Acetophenones; D001583:Benzoxazoles; D002219:Carbamates; D005960:Glucosides; D010940:Plant Proteins; C017057:benzoxazolone; C018473:2-bromo-4'-nitroacetophenone; D010544:Peroxidases; D005982:Glutathione Transferase; D003931:Diacetyl; D004976:Ethacrynic Acid
keywords: Benzoxazolinone detoxification; Zea mays L; cell wall polymer; extraplastic space; glucanase; glucoside carbamate pathway; peroxidase; protein shifting