Structural Analysis of the Capsular Polysaccharide from <i>Campylobacter jejuni</i> RM1221
Bibliographic record
Abstract
The complete genome of Campylobacter jejuni strain RM1221 (Penner serotype HS:53) was reported recently and contains a novel capsular polysaccharide (CPS) biosynthesis locus. Cell-surface carbohydrates such as CPS are known to be important for bacterial survival and often contribute to pathogenesis. In this study, we describe the complete structure of the CPS of C. jejuni RM1221, which was determined by using NMR spectroscopy, MS, and chemical methods. The CPS contains 6-deoxy-D-manno-heptose and D-threo-pent-2-ulose (D-xylulose), two monosaccharides that are rarely found in bacterial polysaccharides. The CPS has a regular structure of a linear main chain of trisaccharide repeating units, composed of two alpha- and one beta-6-deoxy-D-manno-heptopyranose residues, which are linked through a phosphodiester linkage. Branching residues of xylulose are incorporated nonstoichiometrically: each trisaccharide repeating unit of the main chain bears no, one, or two xylulose residues. The xylulose glycosidic linkages are extremely acid labile, and it is not clear how they can be preserved under the acidic conditions of the gastrointestinal tract, where Campylobacter resides during infection. We have also shown that the CPS biosynthesis genes of C. jejuni RM1221 are conserved in other C. jejuni strains of the Penner serotype HS:53, including serotype HS:53 reference strain RM3435.
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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) | 0.001 | 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) | 0.001 | 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".