Probing Zn2+-binding effects on the zinc-ribbon domain of human general transcription factor TFIIB
Bibliographic record
Abstract
The general transcription factor, TFIIB, plays an important role in the assembly of the pre-initiation complex. The N-terminal domain (NTD) of TFIIB contains a zinc-ribbon motif, which is responsible for the recruitment of RNA polymerase II and TFIIF to the core promoter region. Although zinc-ribbon motif structures of eukaryotic and archaeal TFIIBs have been reported previously, the structural role of Zn2 binding to TFIIB remains to be determined. In the present paper, we report NMR and biochemical studies of human TFIIB NTD, which characterize the structure and dynamics of the TFIIB Zn2-binding domain in both Zn2-bound and -free states. The NMR data show that, whereas the backbone fold of NTD is pre-formed in the apo state, Zn2 binding reduces backbone mobility in the b-turn (Arg28-Gly30), induces enhanced structural rigidity of the charged-cluster domain in the central linker region of TFIIB and appends a positive surface charge within the Zn2-binding site. V8 protease-sensitivity assays of full-length TFIIB support the Zn2-dependent structural changes. These structural effects of Zn2 binding on TFIIB may have a critical role in interactions with its binding partners, such as the Rpb1 subunit of RNA polymerase II.
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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) | 0.001 | 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".