Localization and synthesis of prenylquinones in isolated outer and inner envelope membranes from spinach chloroplasts

Soll, Jürgen; Schultz, Gernot; Joyard, Jacques; Douce, Roland; Block, Maryse A.

doi:10.1016/0003-9861(85)90167-5

Cited by 155 publications

(133 citation statements)

References 18 publications

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“…1B). This chloroplastic localization of StSXD1 is consistent with the results obtained by chloroplast import assays for ZmSXD1 (Provencher et al, 2001), as well as with the reported TC activity and tocopherol biosynthesis in plastids (Soll et al, 1985;Arango and Heise, 1998). Third, silencing of StSXD1 resulted in a loss of TC activity and caused the accumulation of the TC substrate DMPQ as well as tocopherol deficiency in leaves of transgenic potato plants, indicating that StSXD1 is required for tocopherol biosynthesis (Fig.…”

Section: Stsxd1 Encodes a Functional Chloroplast-targeted Tc Enzymesupporting

confidence: 90%

RNAi-Mediated Tocopherol Deficiency Impairs Photoassimilate Export in Transgenic Potato Plants

et al. 2004

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Tocopherols (vitamin E) are lipophilic antioxidants presumed to play a key role in protecting chloroplast membranes and the photosynthetic apparatus from photooxidative damage. Additional nonantioxidant functions of tocopherols have been proposed after the recent finding that the Suc export defective1 maize (Zea mays) mutant (sxd1) carries a defect in tocopherol cyclase (TC) and thus is devoid of tocopherols. However, the corresponding vitamin E deficient1 Arabidopsis mutant (vte1) lacks a phenotype analogous to sxd1, suggesting differences in tocopherol function between C4 and C3 plants. Therefore, in this study, the potato (Solanum tuberosum) ortholog of SXD1 was isolated and functionally characterized. StSXD1 encoded a protein with high TC activity in vitro, and chloroplastic localization was demonstrated by transient expression of green fluorescent protein-tagged fusion constructs. RNAi-mediated silencing of StSXD1 in transgenic potato plants resulted in the disruption of TC activity and severe tocopherol deficiency similar to the orthologous sxd1 and vte1 mutants. The nearly complete absence of tocopherols caused a characteristic photoassimilate export-defective phenotype comparable to sxd1, which appeared to be a consequence of vascular-specific callose deposition observed in source leaves. CO 2 assimilation rates and photosynthetic gene expression were decreased in source leaves in close correlation with excess sugar accumulation, suggesting a carbohydrate-mediated feedback inhibition rather than a direct impact of tocopherol deficiency on photosynthetic capacity. This conclusion is further supported by an increased photosynthetic capacity of young leaves regardless of decreased tocopherol levels. Our data provide evidence that tocopherol deficiency leads to impaired photoassimilate export from source leaves in both monocot and dicot plant species and suggest significant differences among C3 plants in response to tocopherol reduction.

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Section: Stsxd1 Encodes a Functional Chloroplast-targeted Tc Enzymesupporting

confidence: 90%

RNAi-Mediated Tocopherol Deficiency Impairs Photoassimilate Export in Transgenic Potato Plants

et al. 2004

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“…VTE1 mediates the conversion of 2,3-dimethyl-5-phytyl-1,4-benzoquinol (DMPBQ) into c-tocopherol. While most of the VTE1 appears to be present in PG, the three enzymes (VTE2, 3, 4) catalyzing the other biosynthetic reactions have been localized to the chloroplast inner envelope membrane (Soll et al 1985;Cheng et al 2003;Vidi et al 2006;Kobayashi and DellaPenna 2008;Zbierzak et al 2010). VTE1 has also been implicated in the recycling of the tocopherol oxidation product, a-tocopherol quinone, that accumulates in response to oxidative stress (Kobayashi and DellaPenna 2008).…”

Section: Implication Of Plastoglobules In Isoprenoid Synthesismentioning

confidence: 99%

A mechanism implicating plastoglobules in thylakoid disassembly during senescence and nitrogen starvation

Besagni

Kessler

2012

Planta

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Plastoglobules are lipid droplets present in all plastid types. In chloroplasts, they are connected to the thylakoid membrane by the outer lipid half-bilayer. The plastoglobule core is composed of neutral lipids most prominently the prenylquinones, triacylglycerols, fatty acid phytyl esters but likely also unknown compounds. During stress and various developmental stages such as senescence, plastoglobule size and number increase due to the accumulation of lipids. However, their role is not limited to lipid storage. Indeed, the characterization of the plastoglobule proteome revealed the presence of enzymes. Importantly it has been demonstrated that these participate in isoprenoid lipid metabolic pathways at the plastoglobule, notably in the metabolism of prenylquinones. Recently, the characterization of two phytyl ester synthases has established a firm metabolic link between PG enzymatic activity and thylakoid disassembly during chloroplast senescence and nitrogen starvation.

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“…4) Envelope membranes are the site of prenylquinone biosynthesis in chloroplasts [122,125,1261: a-tocopherol and plastoquinone-9 synthesis involves a series of enzymes located in the inner envelope membrane [122]. The precursor for both a-tocopherol and plastoquinone-9, homogentisic acid, is synthesized from 4-hydroxyphenylpyruvate (a product of the plastid shikimate pathway) by a 4-hydroxyphenylpyruvate dioxygenase probably located in envelope membranes [ 1261.…”

Section: Envelope Membranes Contain Prenylquinonesmentioning

confidence: 99%

Molecular aspects of plastid envelope biochemistry

Joyard

Block

Douce

1991

European Journal of Biochemistry

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118

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Localization and synthesis of prenylquinones in isolated outer and inner envelope membranes from spinach chloroplasts

Cited by 155 publications

References 18 publications

RNAi-Mediated Tocopherol Deficiency Impairs Photoassimilate Export in Transgenic Potato Plants

RNAi-Mediated Tocopherol Deficiency Impairs Photoassimilate Export in Transgenic Potato Plants

A mechanism implicating plastoglobules in thylakoid disassembly during senescence and nitrogen starvation

Molecular aspects of plastid envelope biochemistry

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