Abstract
Chloroplast ribulose-5-phosphate-3-epimerase (RPE) is a critical enzyme involved in the Calvin-Benson cycle and oxidative pentose phosphate pathways in higher plants. Three Arabidopsis rpe mutants with reduced level of RPE were identified through their high NPQ (nonphotochemical quenching) phenotype upon illumination, and no significant difference of plant size was found between these rpe mutants and WT (wild type) plants under growth chamber conditions. A decrease in RPE expression to a certain extent leads to a decrease in CO 2 fixation, V cmax and J max . Photosynthetic linear electron transport was partially inhibited and activity of ATP synthase was also decreased in the rpe mutants, but the levels of thylakoid protein complexes and other Calvin-Benson cycle enzymes in rpe mutants were not affected. These results demonstrate that some degree of reduction in RPE expression decreases carbon fixation in chloroplasts, which in turn feedback inhibits photosynthetic electron transport and ATP synthase activity due to the photosynthetic control. Taken together, this work provides evidence that RPE plays an important role in the Calvin-Benson cycle and influences the photosynthetic capacity of chloroplasts.
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Claims 7
Claim · model-written summary
Three Arabidopsis rpe mutants with reduced RPE level were identified by their high NPQ phenotype upon illumination.
- Taxon
- Arabidopsis
Arabidopsise1 - Material
- rpe mutantse1
- Gene
- RPEe1
- Outcome
- NPQ (nonphotochemical quenching) phenotypee1
- Direction
- highe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Arabidopsis”
e1“Three Arabidopsis rpe mutants with reduced level of RPE were identified through their high NPQ (nonphotochemical quenching) phenotype upon illumination”
Claim · model-written summary
The rpe mutants showed no significant difference in plant size from WT under growth chamber conditions.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- rpe mutantse2
- Outcome
- plant sizee2
- Direction
- no_changeinferrede2
- Comparator
- WT (wild type) plantse2
- Setting
- growth chamber conditionse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Arabidopsis”
e2“no significant difference of plant size was found between these rpe mutants and WT (wild type) plants under growth chamber conditions”
Claim · model-written summary
A decrease in RPE expression decreased CO2 fixation, Vcmax and Jmax.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- a decrease in RPE expressione3
- Gene
- RPEe3
- Outcome
- CO 2 fixation, V cmax and J maxe3
- Direction
- decreasee3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Arabidopsis”
e3“A decrease in RPE expression to a certain extent leads to a decrease in CO 2 fixation, V cmax and J max”
Claim · model-written summary
Photosynthetic linear electron transport was partially inhibited in the rpe mutants.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- rpe mutantse4
- Outcome
- Photosynthetic linear electron transporte4
- Direction
- partially inhibitede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Arabidopsis”
e4“Photosynthetic linear electron transport was partially inhibited and activity of ATP synthase was also decreased in the rpe mutants”
Claim · model-written summary
Activity of ATP synthase was decreased in the rpe mutants.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- rpe mutantse4
- Outcome
- activity of ATP synthasee4
- Direction
- decreasede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Arabidopsis”
e4“Photosynthetic linear electron transport was partially inhibited and activity of ATP synthase was also decreased in the rpe mutants”
Claim · model-written summary
Levels of thylakoid protein complexes and other Calvin-Benson cycle enzymes were not affected in the rpe mutants.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- rpe mutantse5
- Outcome
- levels of thylakoid protein complexes and other Calvin-Benson cycle enzymese5
- Direction
- no_changeinferrede5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Arabidopsis”
e5“but the levels of thylakoid protein complexes and other Calvin-Benson cycle enzymes in rpe mutants were not affected”
Claim · model-written summary
Reduced carbon fixation feeds back to inhibit photosynthetic electron transport and ATP synthase activity through photosynthetic control.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- photosynthetic electron transport and ATP synthase activitye6
- Qualifier
- due to the photosynthetic controle6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Arabidopsis”
e6“which in turn feedback inhibits photosynthetic electron transport and ATP synthase activity due to the photosynthetic control”