Achieving photo-control of protein conformation and activity: producing a photo-controlled leucine zipper
Bibliographic record
Abstract
We have recently developed a technique that has great potential in producing proteins with photo-control of conformation and consequently activity (J. R. Kumita, O. S. Smart and G. A. Woolley, Proc. Natl. Acad. Sci. U. S. A., 2000, 97, 3803-3808). The method is based on incorporating two cysteine residues into the sequence of a polypeptide. An azobenzene derivative is subsequently used to produce an intramolecular cross-link between the cysteine sulfhydryl groups. In previous work photo-isomerisation of the azobenzene moiety has been used to control the helicity of a monomeric peptide. In the experiments described here this method has been applied to the coiled coil leucine zipper peptide GCN4-p1. The aim was to produce a variant of GCN4-p1 whose helicity and consequently dimerisation is under direct photo-control. We have produced a modified GCN4-p1 incorporating two cysteine residues. The mutations introduced are shown to interfere with the ability of the uncross-linked peptide to form a coiled coil. After the peptide was cross-linked with the azobenzene derivative more normal coiled-coil behaviour was restored. Irradiation of the peptide producing a conformational change in the azobenzene cross-linker was accompanied by an increase in the helicity of the peptide. The work presented here highlights the potential of the use of photo-isomerisable cross-linkers to control protein activity through induced conformational change. In addition, the methodology has the potential to provide a fast trigger for the initiation of protein conformational changes.
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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 | 0.001 |
| 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".