The E2 Ubiquitin Conjugase Rad6 Is Required for the ArgR/Mcm1 Repression of <i>ARG1</i> Transcription
Bibliographic record
Abstract
Transcription of the Saccharomyces cerevisiae ARG1 gene is under the control of both positive and negative elements. Activation of the gene in minimal medium is induced by Gcn4. Repression occurs in the presence of arginine and requires the ArgR/Mcm1 complex that binds to two upstream arginine control (ARC) elements. With the recent finding that the E2 ubiquitin conjugase Rad6 modifies histone H2B, we examined the role of Rad6 in the regulation of ARG1 transcription. We find that Rad6 is required for repression of ARG1 in rich medium, with expression increased approximately 10-fold in a rad6 null background. Chromatin immunoprecipitation analysis indicates increased binding of TATA-binding protein in the absence of Rad6. The active-site cysteine of Rad6 is required for repression, implicating ubiquitination in the process. The effects of Rad6 at ARG1 involve two components. In one of these, histone H2B is the likely target for ubiquitination by Rad6, since a strain expressing histone H2B with the principal ubiquitination site converted from lysine to arginine shows a fivefold relief of repression. The second component requires Ubr1 and thus likely the pathway of N-end rule degradation. Through the analysis of promoter constructs with ARC deleted and an arg80 rad6 double mutant, we show that Rad6 repression is mediated through the ArgR/Mcm1 complex. In addition, analysis of an ada2 rad6 deletion strain indicated that the SAGA acetyltransferase complex and Rad6 act in the same pathway to repress ARG1 in rich medium.
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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 | 0.000 | 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) | 0.000 | 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".