Role of the Asymmetry of the Homodimeric b2 Stator Stalk in the Interaction with the F1 Sector of Escherichia coli ATP Synthase
Bibliographic record
Abstract
The b subunit dimer in the peripheral stator stalk of Escherichia coli ATP synthase is essential for enzyme assembly and the rotational catalytic mechanism. Recent protein chemical evidence revealed the dimerization domain of b to contain a novel two-stranded right-handed coiled coil with offset helices. Here, the existence of this structure in more complete constructs of b containing the C-terminal domain, and therefore capable of binding to the peripheral F1-ATPase, was supported by the more efficient formation of intersubunit disulfide bonds between cysteine residues that are proximal only in the offset arrangement and by the greater thermal stabilities of cross-linked heterodimers trapped in the offset configuration as opposed to homodimers with the helices trapped in-register. F1-ATPase binding analyses revealed the offset heterodimers to bind F1 more tightly than in-register homodimers. Mutations near the C terminus of b were incorporated specifically into either the N-terminally or the C-terminally shifted polypeptide, bN or bC, respectively, to determine the contribution of each position to F1 binding. Deletion of the last four residues of bN substantially weakened F1 binding, whereas the effect of the deletion in bC was modest. Similarly, benzophenone maleimide introduced at the C terminus of bN, but not bC, mediated cross-linking to the delta subunit of F1. These results imply that the polypeptide in the bN position is more important for F1 binding than the one in the bC position and illustrate the significance of the asymmetry of the b dimer in the enzyme.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".