Abstract
The aim of this study was to clone and characterize the SUGAR-DEPENDENT6 (SDP6) gene, which is essential for postgerminative growth in Arabidopsis (Arabidopsis thaliana). Mutant alleles of sdp6 were able to break down triacylglycerol following seed germination but failed to accumulate soluble sugars, suggesting that they had a defect in gluconeogenesis. Map-based cloning of SDP6 revealed that it encodes a mitochondrial flavin adenine dinucleotide (FAD)-dependent glycerol-3-P (G3P) dehydrogenase:ubiquinone oxidoreductase called FAD-GPDH. This gene has previously been proposed to play a role both in the break down of glycerol (derived from triacylglycerol) and in NAD(+)/NADH homeostasis. Germinated seeds of sdp6 were severely impaired in the metabolism of [U-(14)C]glycerol to CO(2) and accumulated high levels of G3P. These data suggest that SDP6 is essential for glycerol catabolism. The activity of the glycolytic enzyme phosphoglucose isomerase is competitively inhibited by G3P in vitro. We show that phosphoglucose isomerase is likely to be inhibited in vivo because there is a 6-fold reduction in the transfer of (14)C-label into the opposing hexosyl moiety of sucrose when [U-(14)C]glucose or [U-(14)C]fructose is fed to sdp6 seedlings. A block in gluconeogenesis, at the level of hexose phosphate isomerization, would account for the arrested seedling growth phenotype of sdp6 and explain its rescue by sucrose and glucose but not by fructose. Measurements of NAD(+) and NADH levels in sdp6 seedlings also suggest that NAD(+)/NADH homeostasis is altered, and this observation is consistent with the hypothesis that SDP6 participates in a mitochondrial G3P shuttle by cooperating with the cytosolic NAD-dependent GPDH protein GPDHC1.
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Claims 17
Claim · model-written summary
sdp6 mutants could break down triacylglycerol after germination.
- Taxon
- Arabidopsis
Arabidopsist0 - Material
- Mutant alleles of sdp6e0
- Outcome
- break down triacylglycerole0
- Qualifier
- following seed germinatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mutant alleles of sdp6 were able to break down triacylglycerol following seed germination”
t0“Arabidopsis”
Claim · model-written summary
sdp6 mutants failed to accumulate soluble sugars after germination.
- Taxon
- ArabidopsisArabidopsist0
- Material
- Mutant alleles of sdp6e0
- Outcome
- accumulate soluble sugarse0
- Direction
- failede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mutant alleles of sdp6 were able to break down triacylglycerol following seed germination but failed to accumulate soluble sugars”
t0“Arabidopsis”
Claim · model-written summary
sdp6 mutant results suggest a gluconeogenesis defect.
- Taxon
- ArabidopsisArabidopsist0
- Material
- Mutant alleles of sdp6e0
- Outcome
- failed to accumulate soluble sugarse0
- Qualifier
- a defect in gluconeogenesise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mutant alleles of sdp6 were able to break down triacylglycerol following seed germination but failed to accumulate soluble sugars, suggesting that they had a defect in gluconeogenesis”
t0“Arabidopsis”
Claim · model-written summary
SDP6 encodes mitochondrial FAD-GPDH.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- SDP6e0
- Outcome
- encodes a mitochondrial flavin adenine dinucleotide (FAD)-dependent glycerol-3-P (G3P) dehydrogenase:ubiquinone oxidoreductase called FAD-GPDHe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Map-based cloning of SDP6 revealed that it encodes a mitochondrial flavin adenine dinucleotide (FAD)-dependent glycerol-3-P (G3P) dehydrogenase:ubiquinone oxidoreductase called FAD-GPDH”
t0“Arabidopsis”
Claim · model-written summary
Germinated sdp6 seeds were severely impaired in glycerol metabolism to carbon dioxide.
- Taxon
- ArabidopsisArabidopsist0
- Material
- sdp6e0
- Organ / stage
- Germinated seedse0
- Outcome
- metabolism of [U-(14)C]glycerol to CO(2)e0
- Direction
- severely impairede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Germinated seeds of sdp6 were severely impaired in the metabolism of [U-(14)C]glycerol to CO(2)”
t0“Arabidopsis”
Claim · model-written summary
Germinated sdp6 seeds accumulated high G3P levels.
- Taxon
- ArabidopsisArabidopsist0
- Material
- sdp6e0
- Organ / stage
- Germinated seedse0
- Outcome
- levels of G3Pe0
- Direction
- highe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Germinated seeds of sdp6 were severely impaired in the metabolism of [U-(14)C]glycerol to CO(2) and accumulated high levels of G3P”
t0“Arabidopsis”
Claim · model-written summary
The data suggest SDP6 is essential for glycerol catabolism.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- SDP6e0
- Outcome
- glycerol catabolisme0
- Qualifier
- essentiale0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These data suggest that SDP6 is essential for glycerol catabolism”
t0“Arabidopsis”
Claim · model-written summary
G3P competitively inhibited phosphoglucose isomerase activity in vitro.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- G3Pe0
- Gene
- phosphoglucose isomerasee0
- Outcome
- activitye0
- Direction
- competitively inhibitede0
- Setting
- in vitroe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The activity of the glycolytic enzyme phosphoglucose isomerase is competitively inhibited by G3P in vitro”
t0“Arabidopsis”
Claim · model-written summary
Feeding labeled glucose to sdp6 seedlings showed a sixfold reduction in label transfer to the opposing sucrose hexosyl moiety.
- Taxon
- ArabidopsisArabidopsist0
- Material
- sdp6e0
- Organ / stage
- seedlingse0
- Treatment
- [U-(14)C]glucosee0
- Outcome
- transfer of (14)C-label into the opposing hexosyl moiety of sucrosee0
- Direction
- reductione0
- Value
- 6-folde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there is a 6-fold reduction in the transfer of (14)C-label into the opposing hexosyl moiety of sucrose when [U-(14)C]glucose or [U-(14)C]fructose is fed to sdp6 seedlings”
t0“Arabidopsis”
Claim · model-written summary
Feeding labeled fructose to sdp6 seedlings showed a sixfold reduction in label transfer to the opposing sucrose hexosyl moiety.
- Taxon
- ArabidopsisArabidopsist0
- Material
- sdp6e0
- Organ / stage
- seedlingse0
- Treatment
- [U-(14)C]fructosee0
- Outcome
- transfer of (14)C-label into the opposing hexosyl moiety of sucrosee0
- Direction
- reductione0
- Value
- 6-folde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there is a 6-fold reduction in the transfer of (14)C-label into the opposing hexosyl moiety of sucrose when [U-(14)C]glucose or [U-(14)C]fructose is fed to sdp6 seedlings”
t0“Arabidopsis”
Claim · model-written summary
Phosphoglucose isomerase is likely inhibited in vivo in sdp6 seedlings.
- Taxon
- ArabidopsisArabidopsist0
- Material
- sdp6e1
- Gene
- phosphoglucose isomerasee0
- Outcome
- inhibitede0
- Qualifier
- likelye0
- Setting
- in vivoe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We show that phosphoglucose isomerase is likely to be inhibited in vivo”
e1“is fed to sdp6 seedlings”
t0“Arabidopsis”
Claim · model-written summary
A gluconeogenesis block at hexose phosphate isomerization could explain arrested sdp6 seedling growth.
- Taxon
- ArabidopsisArabidopsist0
- Material
- sdp6e0
- Outcome
- arrested seedling growth phenotypee0
- Qualifier
- A block in gluconeogenesis, at the level of hexose phosphate isomerizatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A block in gluconeogenesis, at the level of hexose phosphate isomerization, would account for the arrested seedling growth phenotype of sdp6”
t0“Arabidopsis”
Claim · model-written summary
Sucrose rescues the arrested sdp6 seedling growth phenotype.
- Taxon
- ArabidopsisArabidopsist0
- Material
- sdp6e0
- Treatment
- sucrosee0
- Outcome
- arrested seedling growth phenotypee0
- Direction
- rescuee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the arrested seedling growth phenotype of sdp6 and explain its rescue by sucrose and glucose but not by fructose”
t0“Arabidopsis”
Claim · model-written summary
Glucose rescues the arrested sdp6 seedling growth phenotype.
- Taxon
- ArabidopsisArabidopsist0
- Material
- sdp6e0
- Treatment
- glucosee0
- Outcome
- arrested seedling growth phenotypee0
- Direction
- rescuee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the arrested seedling growth phenotype of sdp6 and explain its rescue by sucrose and glucose but not by fructose”
t0“Arabidopsis”
Claim · model-written summary
Fructose does not rescue the arrested sdp6 seedling growth phenotype.
- Taxon
- ArabidopsisArabidopsist0
- Material
- sdp6e0
- Treatment
- fructosee0
- Outcome
- arrested seedling growth phenotypee0
- Direction
- note0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the arrested seedling growth phenotype of sdp6 and explain its rescue by sucrose and glucose but not by fructose”
t0“Arabidopsis”
Claim · model-written summary
NAD(+) and NADH measurements suggest altered NAD(+)/NADH homeostasis in sdp6 seedlings.
- Taxon
- ArabidopsisArabidopsist0
- Material
- sdp6e0
- Organ / stage
- seedlingse0
- Outcome
- NAD(+)/NADH homeostasise0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Measurements of NAD(+) and NADH levels in sdp6 seedlings also suggest that NAD(+)/NADH homeostasis is altered”
t0“Arabidopsis”
Claim · model-written summary
The homeostasis result supports the hypothesis that SDP6 cooperates with GPDHC1 in a mitochondrial G3P shuttle.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- SDP6e0
- Outcome
- participates in a mitochondrial G3P shuttlee0
- Qualifier
- by cooperating with the cytosolic NAD-dependent GPDH protein GPDHC1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this observation is consistent with the hypothesis that SDP6 participates in a mitochondrial G3P shuttle by cooperating with the cytosolic NAD-dependent GPDH protein GPDHC1”
t0“Arabidopsis”
The same questions in other papers
glucose · growth · ArabidopsisPositive and negative results
2 in the opposite direction
- negative
- negative
sucrose · growth · ArabidopsisPositive and negative results
8 papers in the same direction as this paper · 8 in the opposite direction
- negative
- negative
- negative
13 papers more in this group
See all 17 papers →fructose · growth · ArabidopsisResults agree
1 paper in the same direction as this paper
- negative
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.