rhlA is required for the production of a novel biosurfactant promoting swarming motility in Pseudomonas aeruginosa: 3-(3-hydroxyalkanoyloxy)alkanoic acids (HAAs), the precursors of rhamnolipids
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
Pseudomonas aeruginosa produces extracellular glycolipids composed of L-rhamnose and 3-hydroxyalkanoic acid called rhamnolipids. Although these compounds are usually regarded as biosurfactants or haemolysins, their exact physiological function is not well understood. Rhamnolipids are synthesized by a rhamnosyltransferase, encoded by the rhlAB operon, which catalyses the transfer of TDP-L-rhamnose to 3-(3-hydroxyalkanoyloxy)alkanoic acid (HAA) moieties of various lengths. RhlB is the catalytic protein of the rhamnosyltransferase. rhlA is indispensable for rhamnolipid synthesis, but its function is unknown. Using a liquid chromatography/mass spectrometry method, the production of extracellular HAAs by P. aeruginosa was detected previously and it was demonstrated that they are the actual precursors of rhamnolipid biosynthesis. In this report, evidence is presented indicating that rhlA is required for production of HAAs and that these HAAs display potent surface-active properties. P. aeruginosa can colonize surfaces by swarming motility, a form of organized translocation requiring the production of wetting agents. Using rhlA and rhlB mutants it was observed that swarming requires the expression of the rhlA gene but does not necessitate rhamnolipid production, as HAAs act as surfactants. Finally, it was shown that the use of ammonium instead of nitrate as source of nitrogen and an excess of available iron both decrease rhlA expression and swarming motility.
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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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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 it