Functional significance of intermediate cleavages in the 3'ETS of the pre-rRNA from Schizosaccharomyces pombe
Bibliographic record
Abstract
Pathways for the maturation of ribosomal RNAs are complex with numerous intermediate cleavage sites that are not always conserved closely in the course of evolution. Both in eukaryotes and bacteria genetic analyses and in vitro studies have strongly implicated RNase III-like enzymes in the processing of rRNA precursors. In Schizosacharomyces pombe, for example, the RNase III-like Pac1 nuclease has been shown to cleave the free 3'ETS at two known intermediate sites but, in the presence of RAC protein, the same RNA also is cleaved at the 3'-end of the 25 S rRNA sequence. In this study normal and mutant 3'ETS sequences were digested with the Pac1 enzyme to further evaluate its role in rRNA processing. Accurate cleavage at the known intermediate processing sites was dependent on the integrity of the helical structure at these sites as well as a more distal upper stem region in the conserved extended hairpin structure of the 3'ETS. The cleavage of mutant 3'ETS sequences also generally correlated with the known effects of these mutations on rRNA production, in vivo. One mutant, however, was efficiently processed in vivo but was not a substrate for the Pac1 nuclease, in vitro. In contrast, in the presence of RAC protein, the same RNA remained susceptible to Pac1 nuclease cleavage at the 3'-end of the 25 rRNA sequence, indicating that the removal of the 3'ETS does not require cleavage at the intermediate sites. These results suggest that basic maturation pathways may be less complex than previously reported raising similar questions about other intermediate processing sites, which have been identified by analyses of termini, and/or processing, in vitro.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 teacher head, 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".