The role of the stringent response in the regulation of anti-oxidant defenses in «Pseudomonas aeruginosa»
Bibliographic record
Abstract
The stringent response (SR) is a conserved bacterial stress response mechanism that allows bacteria to survive during stress and starvation. This response is mediated by (p)ppGpp, a hyperphosphorylated guanosine signal that regulates expression of genes to inhibit cellular proliferation and induce genes important for survival and adaptation. This study investigates the role of the SR in regulating oxidative stress pathways in Pseudomonas aeruginosa (PA), a human opportunistic pathogen that can cause infections in immunocompromised patients, and patients suffering from cystic fibrosis. Our results demonstrate that inactivation of the SR significantly increased susceptibility to killing by multiple oxidants, impaired anti-oxidant defenses, and increased the levels of endogenous reactive oxygen species (ROS). In addition, we demonstrated that overexpressing KatA, the primary catalase in PA, protected the ΔSR mutant from hydrogen peroxide killing as well as several antibiotics. Our results also suggested that hydroxyalkyl quinolone molecules were responsible for increased intracellular levels of ROS but did not impair catalase activity. In summary, we found that the SR was required for tolerance against oxidative stress, and regulated expression of both catalases katA and katB. Finally, overexpression of the KatA catalase was sufficient to protect against hydrogen peroxide killing, and partially protected against antimicrobial killing.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| 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".