The Role of Ascorbate Free Radical as an Electron Acceptor to Cytochrome b-Mediated Trans-Plasma Membrane Electron Transport in Higher Plants

Horemans, Nele; Asard, Han; Caubergs, R.

doi:10.1104/pp.104.4.1455

Cited by 99 publications

(54 citation statements)

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“…In whole cells or intact tissues, reduction of electron acceptors was found associated with apoplast acidification, membrane depolarization, or oxidation of internal electron donors, suggesting a transmembrane electron transfer chain fed by cytosolic reductants (Vuletić et al, 2005). PM vesicles loaded with physiological electron donors [ascorbate, NAD (P)H] were found to reduce impermeable electron acceptors (MDA, ferrichelates, ferricyanide) on the apoplastic side of the membrane (Askerlund and Larsson, 1991;Asard et al, 1992;Horemans et al, 1994;Menckhoff and Lü thje, 2004). In this way, PM redox systems may influence the redox state of the apoplast and provide a redox connection between apoplast and symplast.…”

Section: Discussionmentioning

confidence: 99%

“…Ascorbate-reducible cytochromes with a symmetric a-band at 561 nm were shown to be involved in trans-PM electron transport from cytosolic ascorbate to apoplastic MDA (Horemans et al, 1994). The reaction was thought to be catalyzed by a cytochrome b561 of the PM (Asard et al, 2001) in analogy with the system for ascorbate regeneration in chromaffin vesicles of mammals (Kelley and Njus, 1986).…”

Section: Discussionmentioning

confidence: 99%

“…In fact, in ascorbate-loaded PM vesicles, the totality of ascorbate-reducible cytochromes could be oxidized by an external electron acceptor such as ferricyanide or MDA (Asard et al, 1992;Horemans et al, 1994), and AIR12 certainly represents a major ascorbate-reducible cytochrome of plant PM. Trans-PM electron transport involving cytosolic NAD(P)H was also demonstrated, although it is not known whether a cytochrome was involved (Askerlund and Larsson, 1991;Menckhoff and Lü thje, 2004).…”

Section: Discussionmentioning

confidence: 99%

“…Oxidation of ascorbate gives rise to the monodehydroascorbate (MDA) radical, which can disproportionate into ascorbate and fully oxidized dehydroascorbate. In addition, the apoplastic MDA radical can be reduced back to ascorbate by a trans-PM redox system that uses cytosolic ascorbate as a reductant and involves a highpotential cytochrome b (Horemans et al, 1994). The latter has escaped molecular identification thus far Bérczi et al, 2003;Griesen et al, 2004;Preger et al, 2005).…”

mentioning

confidence: 99%

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Auxin-Responsive Genes AIR12 Code for a New Family of Plasma Membrane b-Type Cytochromes Specific to Flowering Plants

et al. 2009

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We report here on the identification of the major plasma membrane (PM) ascorbate-reducible b-type cytochrome of bean (Phaseolus vulgaris) and soybean (Glycine max) hypocotyls as orthologs of Arabidopsis (Arabidopsis thaliana) AIR12 (for auxin induced in root cultures). Soybean AIR12, which is glycosylated and glycosylphosphatidylinositol-anchored to the external side of the PM in vivo, was expressed in Pichia pastoris in a recombinant form, lacking the glycosylphosphatidylinositol modification signal and purified from the culture medium. Recombinant AIR12 is a soluble protein predicted to fold into a b-sandwich domain and belonging to the DOMON (for dopamine b-monooxygenase N terminus) domain superfamily. It is shown to be a b-type cytochrome with a symmetrical a-band at 561 nm, fully reduced by ascorbate, and fully oxidized by monodehydroascorbate radical. AIR12 is a high-potential cytochrome b showing a wide bimodal dependence from the redox potential between +80 mV and +300 mV. Optical absorption and electron paramagnetic resonance analysis indicate that AIR12 binds a single, highly axial low-spin heme, likely coordinated by methionine-91 and histidine-76, which are strongly conserved in AIR12 sequences. Phylogenetic analyses reveal that the auxin-responsive genes AIR12 represent a new family of PM b-type cytochromes specific to flowering plants. Circumstantial evidence suggests that AIR12 may interact with other redox partners within the PM to constitute a redox link between cytoplasm and apoplast.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Auxin-Responsive Genes AIR12 Code for a New Family of Plasma Membrane b-Type Cytochromes Specific to Flowering Plants

et al. 2009

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“…b 561 in the PM (Horemans, Asard & Caubergs 1994;Asard et al 1995a). This may be an important mechanism for keeping the apoplastic ascorbate reduced.…”

Section: Hemesmentioning

confidence: 99%

Redox enzymes in the plant plasma membrane and their possible roles

Bérczi

Møller

2000

Plant Cell & Environment

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PlantL-ascorbic acid: chemistry, function, metabolism, bioavailability and effects of processing

Davey

Montagu

Inzé

et al. 2000

J. Sci. Food Agric.

1,072

173

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Humans are unable to synthesise L‐ascorbic acid (L‐AA, ascorbate, vitamin C), and are thus entirely dependent upon dietary sources to meet needs. In both plant and animal metabolism, the biological functions of L‐ascorbic acid are centred around the antioxidant properties of this molecule. Considerable evidence has been accruing in the last two decades of the importance of L‐AA in protecting not only the plant from oxidative stress, but also mammals from various chronic diseases that have their origins in oxidative stress. Evidence suggests that the plasma levels of L‐AA in large sections of the population are sub‐optimal for the health protective effects of this vitamin. Until quite recently, little focus has been given to improving the L‐AA content of plant foods, either in terms of the amounts present in commercial crop varieties, or in minimising losses prior to ingestion. Further, while L‐AA biosynthesis in animals was elucidated in the 1960s,1 it is only very recently that a distinct biosynthetic route for plants has been proposed.2 The characterisation of this new pathway will undoubtedly provide the necessary focus and impetus to enable fundamental questions on plant L‐AA metabolism to be resolved. This review focuses on the role of L‐AA in metabolism and the latest studies regarding its biosynthesis, tissue compartmentalisation, turnover and catabolism. These inter‐relationships are considered in relation to the potential to improve the L‐AA content of crops. Methodology for the reliable analysis of L‐AA in plant foods is briefly reviewed. The concentrations found in common food sources and the effects of processing, or storage prior to consumption are discussed. Finally the factors that determine the bioavailability of L‐AA and how it may be improved are considered, as well as the most important future research needs. © 2000 Society of Chemical Industry

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The Role of Ascorbate Free Radical as an Electron Acceptor to Cytochrome b-Mediated Trans-Plasma Membrane Electron Transport in Higher Plants

Cited by 99 publications

References 13 publications

Auxin-Responsive Genes AIR12 Code for a New Family of Plasma Membrane b-Type Cytochromes Specific to Flowering Plants

Auxin-Responsive Genes AIR12 Code for a New Family of Plasma Membrane b-Type Cytochromes Specific to Flowering Plants

Redox enzymes in the plant plasma membrane and their possible roles

PlantL-ascorbic acid: chemistry, function, metabolism, bioavailability and effects of processing

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