A Tail-Based Mechanism Drives Nucleosome Demethylation by the LSD2/NPAC Multimeric Complex
Bibliographic record
Abstract
LSD1 and LSD2 are homologous histone demethylases with opposite biological outcomes related to chromatin silencing and transcription elongation, respectively. Unlike LSD1, LSD2 nucleosome-demethylase activity relies on a specific linker peptide from the multidomain protein NPAC. We used single-particle cryoelectron microscopy (cryo-EM), in combination with kinetic and mutational analysis, to analyze the mechanisms underlying the function of the human LSD2/NPAC-linker/nucleosome complex. Weak interactions between LSD2 and DNA enable multiple binding modes for the association of the demethylase to the nucleosome. The demethylase thereby captures mono- and dimethyl Lys4 of the H3 tail to afford histone demethylation. Our studies also establish that the dehydrogenase domain of NPAC serves as a catalytically inert oligomerization module. While LSD1/CoREST forms a nucleosome docking platform at silenced gene promoters, LSD2/NPAC is a multifunctional enzyme complex with flexible linkers, tailored for rapid chromatin modification, in conjunction with the advance of the RNA polymerase on actively transcribed genes.
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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".