Vacuolar phosphatases are essential for efficient nucleotide salvage in Arabidopsis
Bibliographic record
Abstract
The salvage pathway that recycles nucleotides from RNA is an important contributor to cellular homeostasis. In Arabidopsis, RNA salvage occurs in the vacuole, in a process started by RNS2. Defects in this pathway lead to constitutive autophagy. How nucleosides are generated from RNS2-catalyzed RNA degradation remains unclear. Using a combination of biochemistry and molecular genetics, we showed that RNS2 produces 2',3'-cAMP and 3'-AMP from poly(A) degradation but only 2',3'-cUMP from poly(U). Mutants lacking PAP26, the major vacuolar acid phosphatase (APase), displayed increased basal autophagy that was rescued by inosine treatment, mirroring rns2 phenotypes. PAP26-deficient vacuoles have lower total APase activity than wild type, but nucleotide processing is not fully disrupted. Further analyses showed that VSP3 also contributes to the total vacuolar APase activity. Nucleotide metabolism in pap26 vsp3 double mutants is severely disrupted, and mutant vacuoles accumulate 3'-NMP, 5'-NMP, and, surprisingly, 2'-AMP. We propose that PAP26 and VSP3 are the main APases involved in vacuolar RNA salvage. In addition, our results suggest that other activities, including cyclic phosphodiesterases and possibly a 5'-NMP-producing exoribonuclease, are needed to facilitate this process in Arabidopsis, producing the metabolites that are transported to the cytoplasm to maintain nucleotide homeostasis.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".