Conserved glycolipid termini in capsular polysaccharides synthesized by ATP-binding cassette transporter-dependent pathways in Gram-negative pathogens
Bibliographic record
Abstract
Bacterial capsules are surface layers made of long-chain polysaccharides. They are anchored to the outer membrane of many Gram-negative bacteria, including pathogens such as Escherichia coli, Neisseria meningitidis, Haemophilus influenzae, and Pasteurella multocida. Capsules protect pathogens from host defenses including complement-mediated killing and phagocytosis and therefore represent a major virulence factor. Capsular polysaccharides are synthesized by enzymes located in the inner (cytoplasmic) membrane and are then translocated to the cell surface. Whereas the enzymes that synthesize the polysaccharides have been studied in detail, the structure and biosynthesis of the anchoring elements have not been definitively resolved. Here we determine the structure of the glycolipid attached to the reducing terminus of the polysialic acid capsular polysaccharides from E. coli K1 and N. meningitidis group B and the heparosan-like capsular polysaccharide from E. coli K5. All possess the same unique glycolipid terminus consisting of a lyso-phosphatidylglycerol moiety with a β-linked poly-(3-deoxy-d-manno-oct-2-ulosonic acid) (poly-Kdo) linker attached to the reducing terminus of the capsular polysaccharide.
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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) | 0.000 | 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 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".