Peptidoglycan recruitment by a penicillin binding protein
Bibliographic record
Abstract
The cell wall is essential for bacterial survival. Its core component is peptidoglycan (PG), a polymer comprised of disaccharide-peptides (stem peptides) that are cross-linked to one another via transpeptidation by penicillin-binding proteins (PBPs). While much is known about how PBPs are inactivated by β-lactam antibiotics, little is known about how PBPs bind and catalyze the transpeptidation of PG. Here we show how native PG and stem peptides are recruited to PBP5 of E. faecium, a critical ESKAPE pathogen. We discovered that PG binds PBP5 at the periphery of the PBP active site cleft, not the active site, and that the D-Ala leaving group contributes minimally to PBP binding. We show that β-lactam antibiotics and stem peptides can bind PBP5 simultaneously. We also show that only the single central residue of the stem peptide (L-Lys substituted by D-iAsn in E. faecium) is both necessary and sufficient for peptide recruitment. Finally, we translate our molecular findings by demonstrating that recruitment binding variants are unable to create a PG cell wall in E. faecium. Our studies define the key molecular interactions that govern bacterial cell wall formation and provide opportunities for the development of antibiotics that do not rely on PBP inactivation.
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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".