Yeast Enhancer of Polycomb defines global Esa1-dependent acetylation of chromatin
Bibliographic record
Abstract
Drosophila Enhancer of Polycomb, E(Pc), is a suppressor of position-effect variegation and an enhancer of both Polycomb and trithorax mutations. A homologous yeast protein, Epl1, is a subunit of the NuA4 histone acetyltransferase complex. Epl1 depletion causes cells to accumulate in G2/M and global loss of acetylated histones H4 and H2A. In relation to the Drosophila protein, mutation of Epl1 suppresses gene silencing by telomere position effect. Epl1 protein is found in the NuA4 complex and a novel highly active smaller complex named Piccolo NuA4 (picNuA4). The picNuA4 complex contains Esa1, Epl1, and Yng2 as subunits and strongly prefers chromatin over free histones as substrate. Epl1 conserved N-terminal domain bridges Esa1 and Yng2 together, stimulating Esa1 catalytic activity and enabling acetylation of chromatin substrates. A recombinant picNuA4 complex shows characteristics similar to the native complex, including strong chromatin preference. Cells expressing only the N-terminal half of Epl1 lack NuA4 HAT activity, but possess picNuA4 complex and activity. These results indicate that the essential aspect of Esa1 and Epl1 resides in picNuA4 function. We propose that picNuA4 represents a nontargeted histone H4/H2A acetyltransferase activity responsible for global acetylation, whereas the NuA4 complex is recruited to specific genomic loci to perturb locally the dynamic acetylation/deacetylation equilibrium.
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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) | 0.002 | 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".