Structure of the human RECQ1 helicase reveals a putative strand-separation pin
Bibliographic record
Abstract
RecQ-like helicases, which include 5 members in the human genome, are important in maintaining genome integrity. We present a crystal structure of a truncated form of the human RECQ1 protein with Mg-ADP. The truncated protein is active in DNA fork unwinding but lacks other activities of the full-length enzyme: disruption of Holliday junctions and DNA strand annealing. The structure of human RECQ1 resembles that of Escherichia coli RecQ, with some important differences. All structural domains are conserved, including the 2 RecA-like domains and the RecQ-specific zinc-binding and winged-helix (WH) domains. However, the WH domain is positioned at a different orientation from that of the E. coli enzyme. We identify a prominent beta-hairpin of the WH domain as essential for DNA strand separation, which may be analogous to DNA strand-separation features of other DNA helicases. This hairpin is significantly shorter in the E. coli enzyme and is not required for its helicase activity, suggesting that there are significant differences between the modes of action of RecQ family members.
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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 | 0.001 | 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".