Phenotypic Screening of a Targeted Mutant Library Reveals Campylobacter jejuni Defenses against Oxidative Stress
Bibliographic record
Abstract
During host colonization, Campylobacter jejuni is exposed to harmful reactive oxygen species (ROS) produced from the host immune system and from the gut microbiota. Consequently, identification and characterization of oxidative stress defenses are important for understanding how C. jejuni survives ROS stress during colonization of the gastrointestinal tract. Previous transcriptomic studies have defined the genes belonging to oxidant stimulons within C. jejuni. We have constructed isogenic deletion mutants of these identified genes to assess their role in oxidative stress survival. Phenotypic screening of 109 isogenic deletion mutants identified 22 genes which were either hypersensitive or hyposensitive to oxidants, demonstrating important roles for these genes in oxidant defense. The significance of these genes in host colonization was also assessed in an in vivo chick model of C. jejuni colonization. Overall, our findings identify an indirect role for motility in resistance to oxidative stress. We found that a nonmotile flagellum mutant, the ΔmotAB mutant, displayed increased sensitivity to oxidants. Restoration of sensitivity to superoxide in the ΔmotAB mutant was achieved by fumarate supplementation or tandem deletion of motAB with ccoQ, suggesting that disruption of the proton gradient across the inner membrane resulted in increased superoxide production in this strain. Furthermore, we have identified genes involved in cation transport and binding, detoxification, and energy metabolism that are also important factors in oxidant defense. This report describes the first isogenic deletion mutant library construction for screening of relevant oxidative stress defense genes within C. jejuni, thus providing a comprehensive analysis of the total set of oxidative stress defenses.
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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".