An engineered right‐handed coiled coil domain imparts extreme thermostability to the KcsA channel
Bibliographic record
Abstract
KcsA, a potassium channel from Streptomyces lividans, was the first ion channel to have its transmembrane domain structure determined by crystallography. Previously we have shown that its C‐terminal cytoplasmic domain is crucial for the thermostability and the expression of the channel. Expression was almost abolished in its absence, but could be rescued by the presence of an artificial left‐handed coiled coil tetramerization domain GCN4. In this study, we noticed that the handedness of GCN4 is not the same as the bundle crossing of KcsA. Therefore, a compatible right‐handed coiled coil structure was identified from the Protein Data Bank and used to replace the C‐terminal domain of KcsA. The hybrid channel exhibited a higher expression level than the wild‐type and is extremely thermostable. Surprisingly, this stable hybrid channel is equally active as the wild‐type channel in conducting potassium ions through a lipid bilayer at an acidic pH. We suggest that a similar engineering strategy could be applied to other ion channels for both functional and structural studies. Structured digital abstract MINT‐7260032 : kcsA (uniprotkb: P0A334 ) and kcsA (uniprotkb: P0A334 ) bind ( MI:0407 ) by molecular sieving ( MI:0071 ) MINT‐7260022 : kcsA (uniprotkb: P0A334 ) and kcsA (uniprotkb: P0A334 ) bind ( MI:0407 ) by circular dichroism ( MI:0016 )
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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".