Changes in peptidoglycan structure and metabolism during differentiation of<i>Proteus mirabilis</i>into swarmer cells
Bibliographic record
Abstract
The O-acetylation of peptidoglycan in Gram-negative bacteria occurs specifically at the C-6 hydroxyl group of muramoyl residues. The level of peptidoglycan O-acetylation was found to decrease from 51% to 29% upon differentiation of Proteus mirabilis vegetative cells to swarmers. This decrease was accompanied by a change in the muropeptide composition of the peptidoglycan. In particular, the content of anhydromuropeptides increased, while the amount of Lys-Lys-muropeptides arising from bound lipoprotein decreased. These changes together with a shift in proportion of larger muropeptides suggested a decrease in average chain length of the muropeptides from swarmer cells. Zymography using SDS-PAGE gels containing either O-acetylated or chemically de-O-acetylated peptidoglycan was used to monitor the activity of specific autolysins during the differentiation of vegetative to swarming cells of P. mirabilis. A 43 kDa autolysin with increased specificity for O-acetylated peptidoglycan was detected in vegetative cells, but its activity appeared to decrease as the cells began to differentiate, while the levels of 3 other autolysins with apparent specificity for non-O-acetylated peptidoglycan increased. These changes are discussed in relation to the autolysin profile of the bacteria and the changes in peptidoglycan composition with cell differentiation.
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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".