Structural analysis of lipopolysaccharide produced by Heddleston serovars 10, 11, 12 and 15 and the identification of a new Pasteurella multocida lipopolysaccharide outer core biosynthesis locus, L6
Bibliographic record
Abstract
Pasteurella multocida is a Gram-negative bacterial pathogen classified into 16 serovars based on lipopolysaccharide (LPS) antigens. Previously, we have characterized the LPS outer core biosynthesis loci L1, L2, L3, L5 and L7, and have elucidated the full range of LPS structures associated with each. In this study, we have determined the LPS structures produced by the type strains representing the serovars 10, 11, 12 and 15 and characterized a new LPS outer core biosynthesis locus, L6, common to all. The L6 outer core biosynthesis locus shares significant synteny with the L3 locus but due to nucleotide divergence, gene duplication and gene redundancy, the L6 and L3 LPS outer cores are structurally distinct. Using LPS structural and genetic differences identified in each L6 strain, we have predicted a role for most of the L6 glycosyltransferases in LPS assembly. Importantly, we have identified two glycosyltransferases, GctD and GatB, that differ by one amino acid, A162T, but use different donor sugars [uridine diphosphate (UDP)-Glc and UDP-Gal, respectively]. The longest outer core oligosaccharide, produced by the serovar 12 type strain, contained a terminal region consisting of β-Gal-(1,4)-β-GlcNAc-(1,3)-β-Gal-(1,4)-β-Glc that was identical in structure to the vertebrate glycosphingolipid, paragloboside. Mimicry of host glycosphingolipids has been observed previously in P. multocida strains belonging to L3 LPS genotype, which produce LPS similar in structure to the globo-series of glycosphingolipids. The expression of a paragloboside-like oligosaccharide on the LPS produced by the serovar 12 type strain indicates that strains belonging to the L6 LPS genotype may also engage in molecular mimicry.
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How this classification was reachedexpand
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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| 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 teacher head, 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".