Structure of Subtilosin A, an Antimicrobial Peptide from <i>Bacillus</i> <i>s</i> <i>ubtilis</i> with Unusual Posttranslational Modifications Linking Cysteine Sulfurs to α-Carbons of Phenylalanine and Threonine
Bibliographic record
Abstract
The complete primary and three-dimensional solution structures of subtilosin A (1), a bacteriocin from Bacillus subtilis, were determined by multidimensional NMR studies on peptide produced using isotopically labeled [(13)C,(15)N]medium derived from Anabaena sp. grown on sodium [(13)C]bicarbonate and [(15)N]nitrate. Additional samples of 1 were also generated by separate incorporations of [U-(13)C,(15)N]phenylalanine and [U-(13)C,(15)N]threonine using otherwise unlabeled media. The results demonstrate that in addition to having a cyclized peptide backbone (N and C termini), three cross-links are formed between the sulfurs of Cys13, Cys7, and Cys4 and the alpha-positions of Phe22, Thr28, and Phe31, respectively. Such posttranslational linkage of a thiol to the alpha-carbon of an amino acid residue is very unusual in natural peptides or proteins. Subtilosin A (1) belongs to a new class of bacteriocins.
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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".