Thermodynamic and Functional Characterization of Protein W from Bacteriophage λ
Bibliographic record
Abstract
Gene product W (gpW), the head-tail joining protein from bacteriophage lambda, provides a fascinating model for studying protein interactions. Composed of only 68 residues, it must interact with at least two other proteins in the phage, and probably with DNA. To study the structural and functional properties of gpW, plasmids were constructed expressing gpW with hexahistidine tag sequences at either the N or C terminus. The purified wild type fusion proteins were found to be stably folded and biologically active. The protein is monomeric as judged by equilibrium ultracentrifugation, and appears to unfold by a cooperative two-state mechanism. Circular dichroism studies indicate that the protein is 47% helical, with a T(m) of 71.3 degrees C, and a DeltaG(u) of 3.01 kcal/mol at 25 degrees C. Mutagenesis of the three hydrophobic C-terminal residues of gpW showed that they are critical for activity, even though they do not contribute to the thermodynamic stability of the protein. Using secondary structure prediction as a guide, we also designed destabilized gpW mutants. The hydrophobic nature of the gpW C terminus caused these mutants to be degraded by the ClpP-containing proteases in Escherichia coli.
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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 | 0.001 |
| 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".