A metabolic study of the regulation of proteolysis by sugars in maize root tips: effects of glycerol and dihydroxyacetone

Brouquisse, Renaud; Cortès, Sandra; Gaudillère, Monique; Evrard, Adeline; Roby, Claude

doi:10.1007/s00425-006-0378-x

Cited by 12 publications

(15 citation statements)

References 57 publications

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“…As described above, mannose is one of the major hexose components of plant cell constituents such as cell wall polysaccharides and many types of glycoproteins (33,(53)(54)(55). Under sugar-starved conditions, the degradation of cell walls and proteins was increased in plant cells (57)(58)(59). Mannose can be readily phosphorylated by hexokinase and further metabolized by PMI to Fru-6P, which can enter into glycolysis.…”

Section: Discussionmentioning

confidence: 99%

Arabidopsis Phosphomannose Isomerase 1, but Not Phosphomannose Isomerase 2, Is Essential for Ascorbic Acid Biosynthesis

Maruta

Yonemitsu

Yabuta

et al. 2008

Journal of Biological Chemistry

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We studied molecular and functional properties of Arabidopsis phosphomannose isomerase isoenzymes (PMI1 and PMI2) that catalyze reversible isomerization between D-fructose 6-phosphate and D-mannose 6-phosphate (Man-6P). The apparent K m and V max values for Man-6P of purified recombinant PMI1 were 41.3 ؎ 4.2 M and 1.89 mol/min/mg protein, respectively, whereas those of purified recombinant PMI2 were 372 ؎ 13 M and 22.5 mol/min/mg protein, respectively. Both PMI1 and PMI2 were inhibited by incubation with EDTA, Zn 2؉ , Cd 2؉ , and L-ascorbic acid (AsA). Arabidopsis PMI1 protein was constitutively expressed in both vegetative and reproductive organs under normal growth conditions, whereas the PMI2 protein was not expressed in any organs under light. The induction of PMI1 expression and an increase in the AsA level were observed in leaves under continuous light, whereas the induction of PMI2 expression and a decrease in the AsA level were observed under long term darkness. PMI1 showed a diurnal expression pattern in parallel with the total PMI activity and the total AsA content in leaves. Moreover, a reduction of PMI1 expression through RNA interference resulted in a substantial decrease in the total AsA content of leaves of knockdown PMI1 plants, whereas the complete inhibition of PMI2 expression did not affect the total AsA levels in leaves of knock-out PMI2 plants. Consequently, this study improves our understanding of the molecular and functional properties of Arabidopsis PMI isoenzymes and provides genetic evidence of the involvement of PMI1, but not PMI2, in the biosynthesis of AsA in Arabidopsis plants.

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Section: Discussionmentioning

confidence: 99%

Arabidopsis Phosphomannose Isomerase 1, but Not Phosphomannose Isomerase 2, Is Essential for Ascorbic Acid Biosynthesis

Maruta

Yonemitsu

Yabuta

et al. 2008

Journal of Biological Chemistry

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“…by using HPLC (Morkunas et al 2010), nuclear 1HNMR spectroscopy (Brouquisse et al 2007, Kim et al 2007, and 13 C and 31 P-NMR spectroscopy (Vauclare et al 2010, Gout et al 2011. Electron paramagnetic resonance (EPR) spectroscopy is applied to measure free radicals (Morkunas et al 2004.…”

Section: Materials and Methods Of Research On Sugar Starvationmentioning

confidence: 99%

Plant Responses to Sugar Starvation

Morkunas¹,

Borek²,

Formela³

et al. 2012

Carbohydrates - Comprehensive Studies on Glycobiology and Glycotechnology

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“…6). In sycamore (Acer pseudoplatanus) cells and in maize (Zea mays) root tips, glycerol has thus been successfully used to discriminate between the respective roles of the lower and upper parts of glycolysis in autophagy in response to C starvation and in the regulation of proteolysis by sugars (Aubert et al, 1994(Aubert et al, , 1996Brouquisse et al, 2007). Interestingly, the hypothesis that the signal regulating NRT1.1 and NRT2.1 may originate from upper glycolysis and not from lower glycolysis downstream the G3P dehydrogenase step is in agreement with our previous finding that carboxylic acids, such as malate and 2-oxoglutarate, are unable to mimic the inductive effect of sugars on the expression of both genes .…”

Section: Regulation Of Root Ion Transporters Bymentioning

confidence: 99%

“…1988; Sheen, 1990) and thus results in roots in a lowered availability of Glc originating from Suc imported from the phloem. As a consequence of both this shunt in glycolysis and diminished Glc provision, glycerol supply leads to a strong decrease of G6P concentration that impairs further metabolism of this compound, including OPPP, T6P synthesis, and the upper part of glycolysis down to F1,6P (Aubert et al, 1994;Brouquisse et al, 2007).…”

Section: Regulation Of Root Ion Transporters Bymentioning

confidence: 99%

“…In the absence of added sugar in the medium, the supply of glycerol to plant cells or roots leads to an accumulation of glycerol-3-P in the cytoplasm, which can be used to fuel glycolysis downstream of G3P but not as a source of C skeletons for sugar biosynthesis (Aubert et al, 1994;Brouquisse et al, 2007). Indeed, while glycerol-3-P sustains respiration, it prevents the flow back of C from triose phosphates to G6P by inhibiting G6P isomerase (Aubert et al, 1994).…”

Section: Regulation Of Root Ion Transporters Bymentioning

confidence: 99%

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Oxidative Pentose Phosphate Pathway-Dependent Sugar Sensing as a Mechanism for Regulation of Root Ion Transporters by Photosynthesis

et al. 2008

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Root ion transport systems are regulated by light and/or sugars, but the signaling mechanisms are unknown. We showed previously that induction of the NRT2.1 NO 3 2 transporter gene by sugars was dependent on carbon metabolism downstream hexokinase (HXK) in glycolysis. To gain further insights on this signaling pathway and to explore more systematically the mechanisms coordinating root nutrient uptake with photosynthesis, we studied the regulation of 19 light-/sugar-induced ion transporter genes. A combination of sugar, sugar analogs, light, and CO 2 treatments provided evidence that these genes are not regulated by a common mechanism and unraveled at least four different signaling pathways involved: regulation by light per se, by HXK-dependent sugar sensing, and by sugar sensing upstream or downstream HXK, respectively. More specific investigation of sugar-sensing downstream HXK, using NRT2.1 and NRT1.1 NO 3 2 transporter genes as models, highlighted a correlation between expression of these genes and the concentration of glucose-6-P in the roots. Furthermore, the phosphogluconate dehydrogenase inhibitor 6-aminonicotinamide almost completely prevented induction of NRT2.1 and NRT1.1 by sucrose, indicating that glucose-6-P metabolization within the oxidative pentose phosphate pathway is required for generating the sugar signal. Out of the 19 genes investigated, most of those belonging to the NO 3 2 , NH 4 1 , and SO 4 22 transporter families were regulated like NRT2.1 and NRT1.1. These data suggest that a yet-unidentified oxidative pentose phosphate pathwaydependent sugar-sensing pathway governs the regulation of root nitrogen and sulfur acquisition by the carbon status of the plant to coordinate the availability of these three elements for amino acid synthesis.

show abstract

A metabolic study of the regulation of proteolysis by sugars in maize root tips: effects of glycerol and dihydroxyacetone

Cited by 12 publications

References 57 publications

Arabidopsis Phosphomannose Isomerase 1, but Not Phosphomannose Isomerase 2, Is Essential for Ascorbic Acid Biosynthesis

Arabidopsis Phosphomannose Isomerase 1, but Not Phosphomannose Isomerase 2, Is Essential for Ascorbic Acid Biosynthesis

Plant Responses to Sugar Starvation

Oxidative Pentose Phosphate Pathway-Dependent Sugar Sensing as a Mechanism for Regulation of Root Ion Transporters by Photosynthesis

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