The ribosome quality control factors Asc1 and Hel2 regulate the expression of HSP70 during heat shock and recovery
Bibliographic record
Abstract
ABSTRACT Cells rapidly adapt to survive harsh environmental conditions through the potent upregulation of molecular chaperones or heat shock proteins (HSPs). The inducible members of the HSP70 family are the fastest and most transcriptionally induced chaperone upon stress. The HSP70 mRNA life cycle regulation in the cytoplasm is unique because it is translated during stress when general translation is repressed and rapidly degraded once conditions are optimal for growth. Contrary to the role of the HSP70 mRNA 5’ untranslated region in maximizing the synthesis of HSP70, we discovered that the coding sequence (CDS) represses its translation through the ribosome quality control (RQC) mechanism. The CDS of the most inducible HSP70 in Saccharomyces cerevisiae, SSA4 , is uniquely biased with low-frequency codons that promote ribosome stalling during heat stress. The stalled ribosomes are recognized by RQC components Asc1p and Hel2p and two ribosome proteins, Rps28A and Rps19B, that we identified as new RQC components. Surprisingly, RQC does not signal the degradation of the SSA4 mRNA by no-go-decay (NGD). Instead, Asc1p destabilizes the SSA4 mRNA during recovery from heat stress by a mechanism independent of its ribosome binding and SSA4 CDS codon optimality. Therefore, Asc1p operates two synergistic mechanisms that converge to regulate the life cycle of HSP70 mRNA during stress and recovery. Our research identifies Asc1p as a critical regulator of the stress response and RQC as the system tuning HSP70 synthesis.
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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) | 0.000 | 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".