Synthesis of 4-acetamidohexoses in bacteria: structural insights from the bacillosamine and nonulosonic acid pathways
Bibliographic record
Abstract
Many hexose sugars in bacteria undergo a variety of modifications, including oxidation/reduction, amination and acetylation, as part of biosynthesis into their final biologically-active forms. Enzymes that catalyze these reactions normally utilize nucleotide-linked sugar substrates, utilizing the nucleotide as an 'ancient handle' to bind and orient the sugar within the enzymes' active site. We and others have focused efforts on elucidating structure-function relationships for a subset of such biosynthetic enzymes, those associated with the synthesis of trideoxy-diacetamidohexoses, and the nonulsonate sugars subsequently derived from them. With structural information combined with site-directed mutagenesis, enzymatic analysis and molecular modeling, these studies have been essential to understanding the chemistry of how these enzymes bind their substrates and effect catalysis. Enzymes having different folds, such as N-acetyltransferases, can utilize different scaffolds to attain the same 4-acetamido-sugar product. In the case of dehydratases/epimerases and aminotransferases, the enzymes have a conserved structure, but utilize subtle differences within their active site to confer substrate binding and the nature of the final product. These studies depict the structural relationships between these enzymes, while at the same time high-lighting important differences that are beginning to reveal their function at the molecular level.
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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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".