Abstract
Sucrose phosphate synthase (SPS), a key enzyme in sucrose biosynthesis, is regulated by protein phosphorylation and shows a circadian pattern of activity in tomato. SPS is most active in its dephosphorylated state, which normally coincides with daytime. Applying okadaic acid, a potent protein phosphatase inhibitor, prevents SPS activation. More interesting is that a brief treatment with cycloheximide, a cytoplasmic translation inhibitor, also prevents the light activation of SPS without any effect on the amount of SPS protein. Cordycepin, an inhibitor of transcript synthesis and processing, has the same effect. Both of these inhibitors also prevent the activation phase of the circadian rhythm in SPS activity. Conversely, cycloheximide and cordycepin do not prevent the decline in circadian SPS activity that normally occurs at night. These observations indicate that SPS phosphatase activity but not SPS kinase activity is controlled, directly or indirectly, at the level of gene expression. Taken together, these data imply that there is a circadian rhythm controlling the transcription of a protein phosphatase that subsequently dictates the circadian rhythm in SPS activity via effects on this enzyme's phosphorylation state.
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Claims 10
Claim · model-written summary
Tomato SPS activity followed a circadian pattern and was highest when dephosphorylated during daytime.
- Taxon
- Tomato
Solanum lycopersicumt0 - Gene
- SPSe0
- Outcome
- SPS is most active in its dephosphorylated statee0
Not reportedOrgan / stage
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“SPS is most active in its dephosphorylated state, which normally coincides with daytime.”
t0“Tomato”
Claim · model-written summary
Okadaic acid prevented SPS activation.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- okadaic acide0
- Gene
- SPSe0
- Outcome
- SPS activatione0
- Direction
- preventse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Applying okadaic acid, a potent protein phosphatase inhibitor, prevents SPS activation.”
t0“Tomato”
Claim · model-written summary
Cycloheximide prevented light activation of SPS.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- cycloheximidee0
- Gene
- SPSe0
- Outcome
- light activation of SPSe0
- Direction
- preventse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a brief treatment with cycloheximide, a cytoplasmic translation inhibitor, also prevents the light activation of SPS without any effect on the amount of SPS protein.”
t0“Tomato”
Claim · model-written summary
Cycloheximide did not change the amount of SPS protein.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- cycloheximidee0
- Gene
- SPSe0
- Outcome
- amount of SPS proteine0
- Direction
- without any effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a brief treatment with cycloheximide, a cytoplasmic translation inhibitor, also prevents the light activation of SPS without any effect on the amount of SPS protein.”
t0“Tomato”
Claim · model-written summary
Cordycepin likewise prevented light activation of SPS.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- Cordycepine0
- Gene
- Sucrose Phosphate Synthaset0
- Outcome
- same effecte0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cordycepin, an inhibitor of transcript synthesis and processing, has the same effect.”
t0“Sucrose Phosphate Synthase Activity in Tomato”
Claim · model-written summary
Cycloheximide prevented the activation phase of the SPS circadian rhythm.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- inhibitorse0
- Gene
- SPSe0
- Outcome
- activation phase of the circadian rhythm in SPS activitye0
- Direction
- prevente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both of these inhibitors also prevent the activation phase of the circadian rhythm in SPS activity.”
t0“Tomato”
Claim · model-written summary
Cycloheximide did not prevent the nighttime decline in SPS activity.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- cycloheximidee0
- Gene
- SPSe0
- Outcome
- decline in circadian SPS activitye0
- Direction
- do not prevente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“cycloheximide and cordycepin do not prevent the decline in circadian SPS activity that normally occurs at night.”
t0“Tomato”
Claim · model-written summary
Cordycepin did not prevent the nighttime decline in SPS activity.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- cordycepine0
- Gene
- SPSe0
- Outcome
- decline in circadian SPS activitye0
- Direction
- do not prevente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“cycloheximide and cordycepin do not prevent the decline in circadian SPS activity that normally occurs at night.”
t0“Tomato”
Claim · model-written summary
Authors inferred that phosphatase activity, but not kinase activity, is controlled at the level of gene expression.
- Taxon
- TomatoSolanum lycopersicumt0
- Gene
- SPSe0
- Outcome
- SPS phosphatase activitye0
- Qualifier
- at the level of gene expressione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“SPS phosphatase activity but not SPS kinase activity is controlled, directly or indirectly, at the level of gene expression.”
t0“Tomato”
Claim · model-written summary
Authors proposed circadian control of phosphatase transcription that governs SPS phosphorylation and activity.
- Taxon
- TomatoSolanum lycopersicumt0
- Gene
- protein phosphatasee0
- Outcome
- circadian rhythm in SPS activitye0
- Qualifier
- via effects on this enzyme's phosphorylation statee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there is a circadian rhythm controlling the transcription of a protein phosphatase that subsequently dictates the circadian rhythm in SPS activity via effects on this enzyme's phosphorylation state.”
t0“Tomato”
The same questions in other papers
cycloheximide · molecular: metabolites · Solanum lycopersicum (tomato)Positive and negative results
2 papers in the same direction as this paper · 1 in the opposite direction
- positive
- negative
- no effect
cordycepin · molecular: metabolites · Solanum lycopersicum (tomato)Results agree
2 papers in the same direction as this paper
- no effect
- no effect
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.