Alternative Pathway to a Glycopeptide-Resistant Cell Wall in the Balhimycin Producer <i>Amycolatopsis balhimycina</i>
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
Balhimycin, a vancomycin-type glycopeptide, is a lipid II targeting antibiotic produced by Amycolatopsis balhimycina. A. balhimycina has developed a self-resistance mechanism based on the synergistic action of different enzymes resulting in modified peptidoglycan. The canonical resistance mechanism against glycopeptides is the synthesis of peptidoglycan precursors ending with acyl-d-alanyl-d-lactate (d-Ala-d-Lac) rather than acyl-d-alanyl-d-alanine (d-Ala-d-Ala). This reprogramming is the result of the enzymes VanH, VanA, and VanX. VanH and VanA are required to produce d-Ala-d-Lac; VanX cleaves cytosolic pools of d-Ala-d-Ala, thereby ensuring that peptidoglycan is enriched in d-Ala-d-Lac. In A. balhimycina, the ΔvanHAXAb mutant showed a reduced glycopeptide resistance in comparison to the wild type. Nevertheless, ΔvanHAXAb was paradoxically still able to produce d-Ala-d-Lac containing resistant cell wall precursors suggesting the presence of a novel alternative glycopeptide resistance mechanism. In silico analysis, inactivation studies, and biochemical assays led to the characterization of an enzyme, Ddl1Ab, as a paraloguous chromosomal d-Ala-d-Lac ligase able to complement the function of VanAAb in the ΔvanHAXAb mutant. Furthermore, A. balhimycina harbors a vanYAb gene encoding a d,d-carboxypeptidase. Transcriptional analysis revealed an upregulated expression of vanYAb in the ΔvanHAXAb mutant. VanYAb cleaves the endstanding d-Ala from the pentapeptide precursors, reducing the quantity of sensitive cell wall precursors in the absence of VanXAb. These findings represent an unprecedented coordinated layer of resistance mechanisms in a glycopeptide antibiotic producing bacterium.
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.
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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) | 0.000 | 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 it