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 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 | 0.001 |
| 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".