Induction of<i>Pseudomonas aeruginosa</i><i>fhp</i>and<i>fhpR</i>by reactive oxygen species
Bibliographic record
Abstract
In Pseudomonas aeruginosa, flavohemoglobin (Fhp) and its cognate regulator FhpR (PA2665) form a protective regulatory circuit, which responds to reactive nitrogen species and is also capable of protecting cells against nitrosative stress. Recently, it has been shown that the expression of the fhp promoter is regulated not only by FhpR, but also by two new regulators, PA0779 and PA3697. It has also been suggested that the bacterial flavohemoglobins (flavoHbs) could play a crucial role in the protection of cells against reactive oxygen species (ROS). Therefore, the role and function of the Fhp/FhpR system during oxidative stress were studied by assessing the viability and membrane integrity of P. aeruginosa cells and by analyzing the promoter activities of fhp and fhpR upon exposure to paraquat, hydrogen peroxide, and tert-butyl hydroperoxide, under both aerobic and low-oxygen conditions. The results showed that under aerobic conditions, both fhp and fhpR promoters are induced by ROS generated by the stressors. Thus, the Fhp/FhpR system is implicated in the oxidative stress response. ROS-induced fhp promoter activity was dependent on FhpR, PA0779, and PA3697 regulators. Tert-butyl hydroperoxide-induced fhpR promoter activity was found to be highly repressed by PA0779, and FhpR showed negative autoregulation of its own promoter. Under low-oxygen conditions, the activity of the fhp promoter was not inducible by ROS, but fhpR promoter activity was induced by paraquat, and hydrogen peroxide was repressed in both cases by the regulators PA0779 and PA3697.
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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) | 0.001 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".