Involvement of the rml locus in core oligosaccharide and O polysaccharide assembly in Pseudomonas aeruginosa
Bibliographic record
Abstract
L-Rhamnose (L-Rha) is a component of the lipopolysaccharide (LPS) core, several O antigen polysaccharides, and the cell surface surfactant rhamnolipid of Pseudomonas aeruginosa. In this study, four contiguous genes (rmlBDAC) responsible for the synthesis of dTDP-L-Rha in P. aeruginosa have been cloned and characterized. Non-polar chromosomal rmlC mutants were generated in P. aeruginosa strains PAO1 (serotype O5) and PAK (serotype O6) and LPS extracted from the mutants was analysed by SDS-PAGE and Western immunoblotting. rmlC mutants of both serotype O5 and serotype O6 synthesized a truncated core region which was unable to act as an attachment point for either A-band or B-band O antigen. A rmd rmlC PAO1 double mutant (deficient in biosynthesis of both D-Rha and L-Rha) was constructed to facilitate structural analysis of the mutant core region. This strain has an incomplete core oligosaccharide region and does not produce A-band O antigen. These results provide the genetic and structural evidence that L-Rha is the receptor on the P. aeruginosa LPS core for the attachment of O polysaccharides. This is the first report of a genetically defined mutation that affects the synthesis of a single sugar in the core oligosaccharide region of P. aeruginosa LPS, and provides further insight into the mechanisms of LPS biosynthesis and assembly in this bacterium.
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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) | 0.001 | 0.001 |
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".