The olsA gene mediates the synthesis of an ornithine lipid in Pseudomonas aeruginosa during growth under phosphate-limiting conditions, but is not involved in antimicrobial peptide susceptibility
Bibliographic record
Abstract
Pseudomonas aeruginosa responds to phosphate limitation by inducing the expression of phosphate transport systems, phosphatases, hemolysins and a DNase, many of which are important for virulence. Here we report that under phosphate-limiting conditions, P. aeruginosa produces a phosphate-free ornithine lipid (OL) as the primary membrane lipid. The olsBA (PA4350-PA4351) genes were highly induced under phosphate-limiting conditions. The production and structure of the OL was confirmed by MS, revealing diagnostic fragment ions and mainly C16 : 0 and C18 : 1 dialkyl chains. It was shown that olsA is required for production of these lipids and genetic complementation of the olsA∷lux mutant restored OL production. Studies in other bacteria have correlated increased resistance to antimicrobial peptides with the production of OLs. Here it was demonstrated that resistance to antimicrobial peptides increased under phosphate-limiting conditions, but OLs were not required for this increased resistance. OL production was also not required for virulence in the Caenorhabditis elegans infection model. The production of OLs is a strategy to reduce phosphate utilization in the membrane, but mutants unable to produce OLs have no observable phenotype with respect to growth, antibiotic resistance or virulence.
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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 | 0.001 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".