Abstract
TARGET OF RAPAMYCIN (TOR) is a conserved eukaryotic Ser/Thr protein kinase that coordinates growth and metabolism with nutrient availability. We conducted a medium-throughput functional genetic screen to discover essential genes that promote TOR activity in plants, and identified a critical regulatory enzyme, cytosolic phosphoribosyl pyrophosphate (PRPP) synthetase (PRS4). PRS4 synthesizes cytosolic PRPP, a key upstream metabolite in nucleotide synthesis and salvage pathways. We found that prs4 knockouts are embryo-lethal in Arabidopsis thaliana, and that silencing PRS4 expression in Nicotiana benthamiana causes pleiotropic developmental phenotypes, including dwarfism, aberrant leaf shape, and delayed flowering. Transcriptomic analysis revealed that ribosome biogenesis is among the most strongly repressed processes in prs4 knockdowns. Building on these results, we discovered that TOR activity is inhibited by chemical or genetic disruption of nucleotide biosynthesis, but that this effect can be reversed by supplying plants with nucleobases. Finally, we show that TOR transcriptionally promotes nucleotide biosynthesis to support the demands of ribosomal RNA synthesis. We propose that TOR coordinates ribosome biogenesis with nucleotide availability in plants to maintain metabolic homeostasis and support growth.
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Claims 11
Claim · model-written summary
A genetic screen identified PRS4 as a critical TOR regulatory enzyme.
- Taxon
- plantsViridiplantaee0
- Gene
- cytosolic phosphoribosyl pyrophosphate (PRPP) synthetase (PRS4)e0
- Outcome
- identified a critical regulatory enzymee0
- Value
- PRS4e0
Verbatim
e0“We conducted a medium-throughput functional genetic screen to discover essential genes that promote TOR activity in plants, and identified a critical regulatory enzyme, cytosolic phosphoribosyl pyrophosphate (PRPP) synthetase (PRS4).”
Claim · model-written summary
PRS4 synthesizes cytosolic PRPP.
- Taxon
- plantsViridiplantaee1
- Gene
- PRS4e0
- Compound
- cytosolic PRPPe0
- Outcome
- synthesizes cytosolic PRPPe0
Verbatim
e0“PRS4 synthesizes cytosolic PRPP, a key upstream metabolite in nucleotide synthesis and salvage pathways.”
e1“TOR activity in plants”
Claim · model-written summary
PRS4 knockouts are embryo lethal in Arabidopsis thaliana.
- Taxon
- Arabidopsis thaliana
Arabidopsis thalianae0 - Material
- prs4 knockoutse0
- Outcome
- embryo-lethale0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“prs4 knockouts are embryo-lethal in Arabidopsis thaliana”
Claim · model-written summary
Silencing PRS4 in Nicotiana benthamiana caused dwarfism and abnormal leaf shape.
- Taxon
- Nicotiana benthamiana
Nicotiana benthamianae0 - Treatment
- silencing PRS4 expressione0
- Gene
- PRS4e0
- Outcome
- dwarfism, aberrant leaf shapee0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“silencing PRS4 expression in Nicotiana benthamiana causes pleiotropic developmental phenotypes, including dwarfism, aberrant leaf shape, and delayed flowering.”
Claim · model-written summary
Silencing PRS4 in Nicotiana benthamiana delayed flowering.
- Taxon
- Nicotiana benthamianaNicotiana benthamianae0
- Treatment
- silencing PRS4 expressione0
- Gene
- PRS4e0
- Outcome
- floweringe0
- Direction
- delayede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“silencing PRS4 expression in Nicotiana benthamiana causes pleiotropic developmental phenotypes, including dwarfism, aberrant leaf shape, and delayed flowering.”
Claim · model-written summary
Ribosome biogenesis was strongly repressed in prs4 knockdowns.
- Taxon
- Nicotiana benthamianaNicotiana benthamianae1
- Material
- prs4 knockdownse0
- Outcome
- ribosome biogenesise0
- Direction
- repressede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ribosome biogenesis is among the most strongly repressed processes in prs4 knockdowns.”
e1“Nicotiana benthamiana”
Claim · model-written summary
Chemical disruption of nucleotide biosynthesis inhibited TOR activity.
- Taxon
- plantsViridiplantaee1
- Treatment
- chemicale0
- Outcome
- TOR activitye0
- Direction
- inhibitede0
Not reportedComparator
Verbatim
e0“TOR activity is inhibited by chemical or genetic disruption of nucleotide biosynthesis”
e1“TOR activity in plants”
Claim · model-written summary
Genetic disruption of nucleotide biosynthesis inhibited TOR activity.
- Taxon
- plantsViridiplantaee1
- Treatment
- genetic disruption of nucleotide biosynthesise0
- Outcome
- TOR activitye0
- Direction
- inhibitede0
Not reportedComparator
Verbatim
e0“TOR activity is inhibited by chemical or genetic disruption of nucleotide biosynthesis”
e1“TOR activity in plants”
Claim · model-written summary
Nucleobase supply reversed TOR inhibition.
- Taxon
- plantsViridiplantaee0
- Treatment
- supplying plants with nucleobasese0
- Outcome
- this effecte0
- Direction
- reversede0
- Qualifier
- TOR activity is inhibited by chemical or genetic disruption of nucleotide biosynthesise1
Not reportedComparator
Verbatim
e0“this effect can be reversed by supplying plants with nucleobases.”
e1“TOR activity is inhibited by chemical or genetic disruption of nucleotide biosynthesis”
Claim · model-written summary
TOR transcriptionally promotes nucleotide biosynthesis to support ribosomal RNA synthesis.
Verbatim
e0“TOR transcriptionally promotes nucleotide biosynthesis to support the demands of ribosomal RNA synthesis.”
e1“TOR activity in plants”
Claim · model-written summary
The authors propose that TOR coordinates ribosome biogenesis with nucleotide availability.
- Taxon
- plantsViridiplantaee0
- Gene
- TORe0
- Outcome
- ribosome biogenesise0
- Qualifier
- nucleotide availabilitye0
Verbatim
e0“We propose that TOR coordinates ribosome biogenesis with nucleotide availability in plants to maintain metabolic homeostasis and support growth.”
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See all 21 papers →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.