The Pseudomonas aeruginosa alternative sigma factor PvdS controls exotoxin A expression and is expressed in lung infections associated with cystic fibrosis
Bibliographic record
Abstract
PvdS is an alternative sigma factor regulated by the global iron regulator Fur. It has been demonstrated that PvdS plays a role in the iron-dependent regulation of exotoxin A (ETA) in Pseudomonas aeruginosa strain PAO1. The goals of this research were to determine if pvdS was transcribed by the bacteria in the chronic lung infections associated with cystic fibrosis (CF) and to determine how PvdS interacts with the regAB promoters of the hyper-toxigenic strain PA103. It was found that pvdS is transcribed in the lungs of patients with CF and that it appears to be involved with the regulation of toxA in this environment. This correlated with the finding that in strain PA103, a mutation in pvdS reduced ETA activity while the same mutation in strain PAO1 abrogated ETA production. It was also shown that in strain PA103, pvdS was absolutely required for activation of the regAB P2 promoter. The effect of PvdS on the P2 promoter may be direct or indirect; however, in support of a direct role, an eight-out-of-nine base-pair match to the consensus sequence for PvdS binding was identified at the transcriptional start site for the P2 promoter. The effect of PvdS on the PA103 regAB P1 promoter under aerobic growth conditions was also examined. The results show that PvdS does modulate the expression from this promoter but that both the regAB operon and PvdS are required for optimal P1 promoter activity. These studies demonstrate that the alternative sigma factor PvdS acts as a regulator of ETA expression in P. aeruginosa strain PA103 through the regAB operon and that PvdS is expressed in lung infections associated with CF.
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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 | 0.000 | 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) | 0.000 | 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".