Depurination of Brome Mosaic Virus RNA3 in Vivo Results in Translation-dependent Accelerated Degradation of the Viral RNA
Bibliographic record
Abstract
Pokeweed antiviral protein (PAP) is a ribosome-inactivating protein isolated from the pokeweed plant (Phytolacca americana) that exhibits antiviral activity against several plant and animal viruses. We have shown previously that PAP depurinates Brome mosaic virus (BMV) RNAs in vitro and that prior incubation of these RNAs with PAP reduced their synthesis in barley protoplasts. To investigate the post-transcriptional effect of PAP on viral RNA in vivo, we transcribed BMV RNA3 and expressed PAP in the yeast, Saccharomyces cerevisiae, which is a surrogate host for BMV. With an inducible transcription system, we show that the half-life of RNA3 in PAP-expressing cells was significantly less than in cells expressing PAPx, its enzymatically inactive form. PAP bound to RNA3 and depurinated the RNA within open reading frames 3 and 4 and within untranslated regions of the RNA. The depurinated RNA was associated with polysomes, caused ribosomes to stall at the point of depurination, and was targeted for accelerated degradation by components of the No-go decay pathway. As a consequence of translation elongation arrest and increased RNA degradation, expression of PAP in yeast also decreased the level of protein 3a, encoded by the 5'-proximal open reading frame 3 of BMV RNA3. These data provide the first evidence of viral RNA depurination in vivo by any ribosome-inactivating protein and support our hypothesis that depurination contributes to the antiviral activity of PAP, by enhancing viral RNA degradation and reducing translation of viral protein product.
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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 | 0.001 |
| 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".