Identification and characterization of two closely related histone H4 arginine 3 methyltransferases in <i>Arabidopsis thaliana</i>
Bibliographic record
Abstract
Arginine methylation of histone H3 and H4 plays important roles in transcriptional regulation in eukaryotes such as yeasts, fruitflies, nematode worms, fish and mammals; however, less is known in plants. In the present paper, we report the identification and characterization of two Arabidopsis thaliana protein arginine N-methyltransferases, AtPRMT1a and AtPRMT1b, which exhibit high homology with human PRMT1. Both AtPRMT1a and AtPRMT1b methylated histone H4, H2A, and myelin basic protein in vitro. Site-directed mutagenesis of the third arginine (R3) on the N-terminus of histone H4 to lysine (H4R3N) completely abolished the methylation of histone H4. When fused to GFP (green fluorescent protein), both methyltransferases localized to the cytoplasm as well as to the nucleus. Consistent with their subcellular distribution, GST (glutathione transferase) pull-down assays revealed an interaction between the two methyltransferases, suggesting that both proteins may act together in a functional unit. In addition, we demonstrated that AtFib2 (Arabidopsis thaliana fibrillarin 2), an RNA methyltransferase, is a potential substrate for AtPRMT1a and AtPRMT1b, and, furthermore, uncovered a direct interaction between the protein methyltransferase and the RNA methyltransferase. Taken together, our findings implicate AtPRMT1a and AtPRMT1b as H4-R3 protein arginine N-methyltransferases in Arabidopsis and may be involved in diverse biological processes inside and outside the nucleus.
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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) | 0.000 | 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 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".