A bacterial toxin-antitoxin system involved in an unusual response to genotoxic stress
Bibliographic record
Abstract
To contend with environmental challenges, bacteria have evolved numerous stress response pathways. A notable example is the adoption of a dormant state called persistence, whereby cells reversibly restrict their growth and await favorable conditions. The genetics of persistence remain poorly understood, and genes called toxin-antitoxin (TA) systems have controversially been implicated in this phenotype. To examine their role in persistence, we construct a pan-TA deletion strain of the bacterial pathogen Legionella pneumophila and test its capacity to survive diverse stresses. We identify a single predicted TA system, GndRX, that under genotoxic stress conditions leads to cell death rather than promoting survival, whereas ∆gndRX cells adopt a viable but nonculturable state. Strikingly, this enhanced survival is conferred to wild-type cells in a contact-dependent manner during co-culture. Despite having homology to other TA systems, GndRX displays non-canonical activity, and we hypothesize that it has undergone functional domestication by the cell. Overall, our work reveals both a new physiological function for TA systems in bacteria as well as a heretofore undescribed phenomenon of contact-dependent survival within persister cells.
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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 | 0.000 | 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) | 0.001 | 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".